US 5296504

I'll search for authoritative information on this specific patent number and any related appellate dockets.

Now let me check the appellate dockets referenced on the patent page and any 2026 activity.

Let me verify the appellate outcome and confirm whether any 2026 Federal Circuit activity exists for this patent.

Summary: US Patent 5,296,504

Source note: I retrieved the authoritative full text from Google Patents (https://patents.google.com/patent/[US5296504](/patent/US5296504)/en) and cross-checked bibliographic data against DrugPatentWatch. I did not obtain a live USPTO Patent Center or PACER/CAFC docket record in this session, and my searches returned no 2026 Federal Circuit activity for this patent (details under "Litigation" below). Treat docket-related statements accordingly.

Bibliographic data

Assignee chain (per reassignment records on the patent page): Kabi Pharmacia GmbH → Pharmacia Aktiebolag (merger, 1996; name/entity changes 2001) → ultimately associated with Pfizer Health AB. This reflects Pfizer's acquisition of Pharmacia, which occurred around 2002–2003. I would treat the "current assignee" as a bibliographic listing rather than a verified chain of title.

Family context: The US '504 is a sibling of US 5,422,368 ('368), both filed Dec 8, 1992 as continuations of 07/469,442. A later, related application US 10/288,732 (published as US 2003/0166729 A1) was filed Nov 5, 2002 claiming the same 1988 priority and was abandoned. The European counterpart is EP 0 364 417 B1.

Abstract (as issued)

The invention relates to ophthalmological compositions for topical treatment of glaucoma or ocular hypertension comprising an effective intraocular pressure reducing amount of a prostaglandin derivative of PGA, PGB, PGD, PGE or PGF, in which the omega chain contains a ring structure, in an ophthalmologically compatible carrier. The invention further relates to the preparation of said compositions and their use for treatment of glaucoma or ocular hypertension.

Important scope caveat

The specification is broad (a genus of omega-chain ring-modified PGA/PGB/PGD/PGE/PGF derivatives), but the claims as issued are extremely narrow — every one of the 16 claims is limited to a single compound, 13,14-dihydro-17-phenyl-18,19,20-trinor PGF2α isopropyl ester, which is latanoprost (the active in Xalatan®). The '504 patent is therefore commonly identified as the latanoprost product/substance patent, and it is cited that way in later patents (e.g., "latanoprost (US 5,296,504)").

Plain-language overview of the independent claims

Claims 1, 3, 9 and 11 are the independent claims; claims 4 and 12 are method claims written in dependent form (they incorporate claim 1 / claim 9 respectively).

• Claim 1 — Composition for ocular hypertension (no irritation). A topical eye composition containing latanoprost in an amount sufficient to reduce intraocular pressure without causing substantial ocular irritation, together with an ophthalmologically compatible vehicle. The "without substantial ocular irritation" limitation is a functional/negative limitation embedded in the claim.
• Claim 3 — Ocular hypertension composition with a defined vehicle. Same as claim 1, but the vehicle is specified as an aqueous saline solution containing benzalkonium chloride (a preservative).
• Claim 9 — Composition for glaucoma. Identical substance and irritation limitation as claim 1, but directed to treatment of glaucoma rather than ocular hypertension.
• Claim 11 — Glaucoma composition with defined vehicle. Same as claim 9, with the aqueous saline/benzalkonium chloride vehicle.
• Claim 4 — Method, ocular hypertension. Method of treating ocular hypertension by topically applying the composition of claim 1. (Dependent in form on claim 1 but method-of-use in substance.)
• Claim 12 — Method, glaucoma. Method of treating glaucoma by topically applying the composition of claim 9. (Dependent in form on claim 9.)

Dependent claims narrow the above:

• Claim 2 / claim 10: vehicle comprises a solubilizing agent.
• Claims 5 and 13: application once or twice a day.
• Claims 6 and 14: dose of about 0.1 µg to about 30 µg of latanoprost.
• Claims 7 and 15: dose of about 1.0 µg to about 10 µg.
• Claims 8 and 16: applied twice a day, about 1.0–10 µg in a volume of about 10–50 µL.

Litigation — the 2004 appeals referenced on the patent page

The two Federal Circuit docket numbers shown on the patent page (04-1478 and 04-1496) are the two consolidated appeals in Pharmacia Corp. v. Par Pharmaceutical, Inc., 417 F.3d 1369 (Fed. Cir. Aug. 10, 2005) (Rader, J., joined by Schall and Linn, JJ.). Underlying district court case: D.N.J. No. 01-6011 (Judge Stanley R. Chesler).

• Par filed ANDA No. 76-218 for generic Xalatan (latanoprost).
• Par conceded infringement of both the '504 and the sibling '368 patent and did not contest validity on prior art or § 112 grounds; it argued only inequitable conduct/unenforceability.
• The district court held only the '368 patent unenforceable (a § 1.132 declaration by Dr. Stjernschantz during '368 prosecution was found highly material and made with intent to deceive), and held the '504 patent valid and enforceable.
• On appeal, Par argued that the terminal disclaimer filed during the '368 prosecution "infected" the '504 patent. The Federal Circuit rejected that theory, holding that a terminal disclaimer alone does not merge two separate patents for inequitable-conduct purposes (citing In re Van Ornum, In re Griswold, Ortho Pharm. v. Smith). The court pointed out the '504 issued March 22, 1994, before the April 20, 1994 declaration at issue.
• Outcome: AFFIRMED — '368 unenforceable; '504 enforceable and infringed by Par.

On the 2026 docket check

I found no evidence of any 2026 (or other post-2005) Federal Circuit docket involving US 5,296,504. The only appellate activity I can substantiate is the 2004 appeals decided in 2005. Given the patent's recorded expiration status ("Expired – Lifetime," anticipated expiration 2011-03-22, i.e., 17 years from the 1994 issue date), further appellate activity is unlikely — but I could not verify this against a live CAFC/PACER docket in this session, so I flag it as an inference rather than a confirmed fact.

Points of uncertainty / caution

1. Term/expiration: The 2011-03-22 date is the "anticipated expiration" in the Google Patents record. Because the application was filed before June 8, 1995, the term would be the greater of 17 years from grant or 20 years from earliest US filing; the 2011 date is consistent with 17 years from the March 22, 1994 grant. Regulatory exclusivities (e.g., pediatric exclusivity) could have extended market protection separately from patent term — I did not verify this.
2. Current ownership: I could not independently confirm the present owner via USPTO assignment records.
3. Claim construction: Although the '504 claims are limited to latanoprost, I did not locate a US claim-construction ruling specifically construing the "without causing substantial ocular irritation" language in the '504 claims (that issue was litigated extensively for the Canadian counterpart, Canadian Patent 1,339,132).
4. The specification's broad genus (PGA/PGB/PGD/PGE/PGF with ring-containing omega chains) is not reflected in the issued US claims — a distinction important for any FTO or family analysis.

I'll research litigation involving US 5,296,504 using patent litigation databases.

Let me dig deeper into the specific CAFC appeals and district court cases noted on the patent record.

I found the principal case. Now let me search for other litigations and verify the recent D.N.J. case.

Scope and method

I ran searches against patent-litigation sources reachable via web search (Google Patents' litigation links for this patent, CourtListener/Justia, the Federal Circuit opinion databases, and secondary pharma-IP reporting). I was not able to load the Unified Patents litigation portal case list directly from the searches, so my results are grounded in the Federal Circuit's own opinion, the district-court record as recited there, and the litigation links on the patent's Google Patents page. Treat this as preliminary; a Lex Machina, Darts-IP, or PACER/CM-ECF docket sweep would be needed for completeness.

Patent identified

• US 5,296,504 (the "'504 patent"), application 07/987,520, filed 1992‑12‑08 as a continuation of 07/469,442, priority 1988‑09‑06 (SE 8803110), granted 1994‑03‑22, expired 2011‑03‑22.
• Claim 1 covers 13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor PGF2α isopropyl ester — i.e., latanoprost, the active in Xalatan. Assignee chain: Kabi Pharmacia → Pharmacia → Pfizer Health AB.
• I have kept this number literal and have not substituted it for any similarly numbered patent below.

Known litigation involving US 5,296,504

1. Pharmacia Corp. v. Par Pharmaceutical, Inc. (the only US case I could confirm asserting the '504 patent)

Grounded in: the Federal Circuit opinion text (Casetext/CourtListener: https://www.courtlistener.com/opinion/[211740](/patent/211740)/pharmacia-corp-v-par-pharmaceutical-inc/; vLex summary https://case-law.vlex.com/vid/pharmacia-corp-v-par-891458566) and contemporaneous reporting (https://www.medicalnewstoday.com/releases/10515). The two CAFC case links shown on the patent record (case/04-1496 and case/04-1478) are these same consolidated appeals — not two separate litigations.

2. Matters I could NOT confirm as asserting the '504 patent

• Oct. 2002 Pfizer/Pharmacia settlement with Allergan and Alcon over "Xalatan, Lumigan and Travatan" is reported in secondary sources, but the patent actually litigated there appears to have been US 4,599,353 (Columbia University's prostaglandin patent), not the '504 patent. I cannot confirm the '504 patent was asserted.
• The Google Patents record carries a Darts‑IP "first worldwide family litigation" link (family 27355447), and the prosecution history references an Australian opposition to AU 625096. This indicates non‑US proceedings on the family, but I could not retrieve docket-level detail for them and therefore cannot state foreign case numbers or outcomes.

3. Caution on similarly numbered patents (per your instruction not to auto-correct)

Several search hits referenced a different "'504 patent" in unrelated technologies and companies — e.g., AstraZeneca v. Hanmi (D.N.J. 11‑760), a Lupin ANDA No. 212934 complaint (D.N.J. 2:20‑cv‑…), and the VirnetX v. Apple "'504 patent." These are different patents and are not litigation involving US 5,296,504. I have excluded them.

Bottom line

The only litigation I can verify as asserting US 5,296,504 is Pharmacia Corp. v. Par Pharmaceutical, Inc., D.N.J. No. 01‑6011 (filed Dec. 21, 2001), affirmed at 417 F.3d 1369 (Fed. Cir. 2005) (Nos. 04‑1478/04‑1496). Pharmacia prevailed: the '504 patent was held valid, infringed and enforceable, and Par was enjoined until the patent's March 2011 expiration. I found no other US litigation asserting this patent, and I cannot rule out additional or foreign proceedings that a paid litigation database would reveal.

I'll start by verifying the canonical "no PTAB activity" signal against what's publicly discoverable, and chase the Federal Circuit litigation links in the structured data.

The canonical block says none, and my first pass surfaced no IPR. Let me check the two Federal Circuit dockets embedded in the structured data (04-1478, 04-1496) and probe specifically for any AIA trial naming this patent.

The Federal Circuit dockets are now resolved — they're ANDA appeals, not PTAB appeals. Let me do two final confirmation passes before writing up.

PTAB Proceedings on US 5,296,504 — Analyst Report

Analyst's note on sourcing: The structured "PTAB proceedings on file" block is the canonical list, and it reports zero AIA trial proceedings for US 5,296,504 as of the most recent ODP ingest. I ran independent web searches (patent number in tandem with "IPR," "PGR," "PTAB," and ptacts.uspto.gov) and found no IPR, PGR, or CBM naming this patent by any petitioner. I could not query the ODP API directly, so treat this as "canonical block + negative search corroboration," not as an affirmative TLS-level PTAB E2E query. I flag one important trap below: the "litigation" links embedded in the Google Patents record for this patent are not PTAB appeals.

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Proceedings overview

Total AIA trial proceedings on US 5,296,504: 0. No proceedings are active, none have invalidated claims, none have sustained claims, none have settled, and none have been instituted or denied — because none were ever filed. The bottom-line defensive posture is unusual and worth stating precisely: no claim of this patent has been tested at the PTAB at all, so there is no IPR-based roadmap, no claim-level kill shot, and no § 315(e)(2) estoppel to inherit. The correct defensive move is not an IPR strategy — it is a calendaring and standing check, because this patent expired on 2011-03-22 (per the structured data's "Anticipated expiration" entry). Any demand letter asserting it today is either asserting an expired patent or is aimed at the separate, still-live sibling/continuation family (e.g., US 5,422,368, US 5,321,128, and the Pharmacia continuations claiming the 1988-09-06 priority date, such as US 7,163,959).

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Proceedings

None on file

• Type: N/A — no Inter Partes Review, Post-Grant Review, or Covered Business Method review was ever filed against US 5,296,504.
• Filed: N/A
• Status: Per the structured data: "The USPTO ODP API returns no AIA trial proceedings for this patent as of the most recent ingest." Plain-English gloss: the Board has never opened a file on this patent.
• Judge panel: N/A — no panel ever convened.
• Petition grounds: N/A — no § 102, § 103, or § 112 grounds were ever presented to the Board. (Note: PGR was legally unavailable — the application was filed 1992-12-08, long before the AIA's first-to-file regime, so only IPR, and only for pre-AIA patents challenged on § 102/§ 103 grounds from patents and printed publications, was ever an option.)
• Institution decision: N/A
• Final Written Decision: N/A — no claim of US 5,296,504 has ever been canceled, confirmed, or otherwise adjudicated by the PTAB. All 16 issued claims stand in their original, unamended form as a matter of PTAB history.
• Settlement / termination: N/A
• Appeal: None from the PTAB. See the "adjacent proceedings" section below — the two Federal Circuit dockets the structured data surfaces are district court appeals, not IPR appeals.
• Defensive value: The absence of PTAB activity gives a defendant no ready-made invalidity record to lean on, but it also means there is no estoppel and no adverse claim construction. The dominant practical fact is expiration in 2011: an expired patent cannot support injunctive relief and can support only past damages within the § 286 six-year lookback, subject to laches/§ 282 defenses. If a demand letter cites the '504 patent today, the first question is whether the sender has confused it with a live sibling patent.

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Adjacent proceedings a defendant will likely mistake for PTAB activity

The structured data's "Family has litigation" links point to two CAFC dockets — 04-1478 and 04-1496 — and the Google Patents "US case filed in Court of Appeals for the Federal Circuit" labels make these look like PTAB appeals. They are not. They are the consolidated Hatch-Waxman appeals in:

Pharmacia Corp. v. Par Pharmaceutical, Inc., 417 F.3d 1369 (Fed. Cir. 2005) — Nos. 04-1478, -1496

• Type: District court appeal (28 U.S.C. § 1295(a)(1)), not an AIA trial appeal.
• Filed: 2004 (appeal from D.N.J. Final Judgment); decided 2005-08-10.
• Panel: Rader (author), Schall, Linn, Circuit Judges.
• Underlying case: Pharmacia Corp. v. Par Pharm., Inc., No. 01-6011 (D.N.J., Judge Stanley R. Chesler), final judgment 2004-07-06. Par filed ANDA No. 76-218 for generic Xalatan; Pharmacia sued 2001-12-21 after Par's 2001-11-06 notice.
• What happened: Par conceded infringement of both the '504 patent and US 5,422,368 (the '368 patent) and asserted no prior-art or § 112 invalidity defense. Its sole theory was inequitable conduct. The district court found only the '368 patent unenforceable; Par appealed as to the '504 patent, and Pharmacia cross-appealed as to the '368 patent.
• Disposition: AFFIRMED. The '368 patent is unenforceable for inequitable conduct (a misleading 37 C.F.R. § 1.132 declaration by Dr. Stjernschantz, ¶¶ 9–10, conflicting with his own published article). Critically, the Federal Circuit rejected Par's terminal-disclaimer taint theory and held the '504 patent valid, enforceable, and infringed:

"Because the record shows no inequitable conduct during prosecution of the '504 patent itself, the district court did not abuse its discretion in finding the '504 patent to be valid and enforceable. In fact, the '504 patent had already issued before the inequitable conduct occurred. The '504 patent issued on March 22, 1994; Stjernschantz executed his declaration on April 20, 1994."

• Link: https://www.courtlistener.com/opinion/[211740](/patent/211740)/pharmacia-corp-v-par-pharmaceutical-inc/
• Defensive value: Double-edged. The opinion is a clean holding that the '504 patent is enforceable — so a "sibling patent inequitable conduct" taint argument has already been litigated and lost at the Federal Circuit, and is largely foreclosed by stare decisis as to the same family. But it is also a treasure map to the 1994 prosecution record, including the Ueno patent (US 5,151,444) rejection, the Stjernschantz declaration, and the undisclosed Stjernschantz/Resul prior-art article — all of which is background art a defendant could still deploy outside the PTAB (district court, or as a § 102/§ 103 predicate for a new patent in the family).

EP 0364417 B1 — European opposition (non-US, non-PTAB)

The same invention was opposed at the EPO: initially revoked, then restored in amended form on appeal, with a latanoprost SPC running to 2011-07-17 plus a six-month pediatric extension (to early 2012). This is EPO opposition practice, not an AIA trial, and has no estoppel or preclusive effect in the US. It is relevant only as a prior-art and claim-scope research resource: the EPO opposition file contains third-party invalidity argumentation against the same Stjernschantz disclosure that a US defendant can mine freely.

Additional related family item (not a proceeding): US 10/288,732 (published US 2003/0166729 A1), filed 2002-11-05 claiming the 1988-09-06 priority date, is listed in the structured data as Abandoned. No PTAB activity attaches to it.

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Strategic summary

Claim status on US 5,296,504: all 16 claims are UNTESTED at the PTAB and stand as issued. There are no canceled claims, because no AIA trial was ever instituted. For the record, the claim set is unusually narrow and compound-specific: claim 1 covers a topical ocular-hypertension composition comprising 13,14-dihydro-17-phenyl-18,19,20-trinor PGF2α isopropyl ester (latanoprost) in an IOP-reducing, non-irritating amount plus an ophthalmologically compatible vehicle; claim 3 adds an aqueous saline/benzalkonium chloride vehicle; claims 4–8 are the corresponding ocular-hypertension method claims with dosing limitations (0.1–30 µg, 1–10 µg, twice daily, 10–50 µL); claims 9–16 mirror that set for glaucoma. Because no FWD exists, I cannot state that any specific claim was held patentable or unpatentable by the Board — and I will not manufacture such a finding. What I can state, verbatim from the Federal Circuit, is that the '504 patent was adjudged "valid and enforceable" and "infringed by Par" in 2005.

Estoppel landscape: there is none, and that cuts both ways. With no IPR, § 315(e)(2) estoppel never attached to any petitioner or privy. Par Pharmaceutical and its privies are not estopped from raising art in a fresh district court action, and no other party is either. Conversely, a current defendant inherits no benefit from an earlier petitioner's work — no institution decision, no FWD, no Board claim construction to point to. Every prior-art ground that exists against the '504 patent is theoretically still on the table, subject only to the ordinary limits of 35 U.S.C. §§ 102/103, the six-year damages window of § 286, and the fact that Par's inequitable-conduct theory as to the '504 patent was already tried and expressly rejected by the Federal Circuit.

Pattern signals: None of the classic PTAB fingerprints are present. No serial petitioner (no petitioner at all). No PTAB appeal history — the patent owner (Kabi Pharmacia → Pharmacia AB → Pharmacia & Upjohn → Pfizer Health AB) never had to defend this patent before the Board. No defensive aggregator (no Unified Patents, no RPX, no IPR-funder) appears anywhere in the chain; the only "litigation" links Google Patents flags are the Darts-IP family record and the Unified Patents CAFC docket entries for the Par appeal. The absence of PTAB activity here is best explained structurally rather than strategically: the patent issued in 1994, the AIA's IPR regime began in 2012, and the patent expired on 2011-03-22 — one year before IPRs became available. It was essentially never IPR-eligible in practice.

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Recommended next steps

• If you are a defendant facing assertion of US 5,296,504: treat expiration as your first-line defense. The structured data records "Anticipated expiration" on 2011-03-22, and the Federal Circuit opinion confirms the patent issued 1994-03-22. Confirm the expiration certificate and maintenance-fee history (two fee sets were paid across the terminally disclaimed '368/'504 pair). Injunctive relief is unavailable for an expired patent; past damages are limited to the § 286 six-year lookback. Do not budget for an IPR — the Board will not institute on a long-expired patent in any practical scenario, and there is no live claim to cancel.
• Do not cite a PTAB FWD — there isn't one. If a client or a demand letter asserts that the '504 patent has been "invalidated at the PTAB," that is a factual error. The only merits adjudication of the '504 patent is the 2005 Federal Circuit affirmance holding it valid, enforceable, and infringed. Quote the disposition directly: "[T]his court affirms the district court's finding that the '504 patent is enforceable and infringed by Par." (417 F.3d 1369, 1377 — https://www.courtlistener.com/opinion/211740/pharmacia-corp-v-par-pharmaceutical-inc/)
• Redirect any live controversy to the correct patents. The commercially significant latanoprost/Xalatan family extends beyond the '504 patent: US 5,422,368 (the '368 patent, held unenforceable for inequitable conduct), US 5,321,128, and continuation patents claiming the 1988-09-06 priority date, including US 7,163,959 (listed in the cited-by set as a Pharmacia Aktiebolag filing with the same 1988-09-06 priority date). Verify which patent the demand actually identifies before accepting the '504 framing.
• Re-run the PTAB check at filing time. Because AIA trial petitions can be filed and indexed with a lag, confirm directly against PTAB E2E (ptacts.uspto.gov) and the ODP API at the moment of engagement. My search found nothing, but a negative search is weaker evidence than a live database query. If any AIA proceeding does surface on a family member, note the trial-stage clock: institution decision within 6 months of the petition's complete filing (§ 314(b)), FWD within 12 months of institution (§ 316(a)(11)), extendable to 18 months for good cause.

Confidence statement: High confidence that no AIA trial proceeding exists against US 5,296,504. High confidence that the CAFC dockets 04-1478/-1496 are the Pharmacia v. Par ANDA appeal and not PTAB appeals — the opinion text and 417 F.3d 1369 citation are unambiguous. I did not independently confirm the ODP API response myself; I am relying on the canonical structured block plus negative web-search corroboration.

I'll research the assignment record for US 5296504 using multiple sources.

US 5296504 — Assignment / Ownership Reconstruction

Patent: US 5296504 A — "Prostaglandin derivatives for the treatment of glaucoma or ocular hypertension"
Application: US 07/987,520 (continuation of 07/469,442, filed 1990‑04‑10, abandoned); filed 1992‑12‑08
Priority: SE 8803110, 1988‑09‑06 · Issued: 1994‑03‑22 · Expired (anticipated): 2011‑03‑22
Claimed compound (as claimed): 13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor PGF2α isopropyl ester = latanoprost (Xalatan)

Data-integrity note (read first). The Assignment Center (assignmentcenter.uspto.gov / assignment.uspto.gov) and its mirrors (Google Patents "Reassignments"/legal-events table, uspto.report) were reached only at index level in this session. I was able to retrieve the conveyance types, assignors, assignees and dates, but not the reel/frame numbers or the correspondent‑of‑record for any of the recordings. I am therefore marking those two fields "not captured" rather than inventing them. The underlying records exist (they are the same records Google Patents renders as "Reassignments"); they simply were not exposed in the fetched snapshots. Re‑verify at the search URL in the Verdict section before relying on reel/frame in a filing.

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Inventors

Neither inventor's employment is recited on the patent face — the assignee line is the only employment evidence. The inference rests on (a) the assignee being the Kabi Pharmacia/Pharmacia Swedish entity, (b) the cited internal research literature (Miller et al. 1975, Biological Activities of 17‑Phenyl‑18,19,20‑Trinor Prostaglandins; Granström 1975, metabolism of 17‑phenyl‑18,19,20‑trinor‑PGF2α), and (c) Stjernschantz's and Resul's continued appearance as inventors on later family members (e.g., US 7,163,959, assigned to Pharmacia Aktiebolag, San Diego).

Unusual-pattern check — no fire‑sale precursor:

• No inventor departed the assignee within 12 months of filing. Both remained within the Pharmacia corporate family across the 1996 and 2001 reorganizations; Stjernschantz and Resul are named on subsequent continuations in the same franchise (US 5,321,128; 5,422,368; 5,422,369; 5,578,618; 5,627,208; 5,849,791; 7,163,959).
• The chain runs inward (operating pharma → operating pharma → operating pharma), which is the opposite of the pre‑fire‑sale signature (inventors and IP leaving together). No § "all inventors departing" flag.

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Original assignee

As printed / as listed by Google Patents front‑page field: Kabi Pharmacia GmbH.

Caveats on the literal record, because the entity names in this family are inconsistent:

• The PCT family member WO 1990/002553 A1 names Pharmacia AB as applicant.
• The first recorded post‑issuance reassignment names assignor Kabi Pharmacia Aktiebolag (Swedish aktiebolag, not GmbH).
• The litigation/family listing on Google Patents credits the 1994 issuance to Kabi Pharmacia.

I do not auto‑correct these; the discrepancy (GmbH vs. AB/Pharmacia AB) is a real feature of the record and worth confirming against the printed patent.

• Primary line of business: prescription pharmaceuticals — ophthalmology. Kabi Pharmacia/Pharmacia (Uppsala, Sweden) ran the prostaglandin/glaucoma program that produced this patent family.
• Did the original assignee ship a product embodying the claims? Yes. The claimed compound is latanoprost; the company commercialized it as Xalatan (US approval June 1996 — the same fact noted in the secondary literature, which observes that because FDA approval came in June 1996 the remaining term exceeded 14 years and patent term extension could not be requested, hence the hard 2011‑03‑22 expiry). Xalatan became the reference‑standard prostaglandin glaucoma drop and a >$1B/year franchise.
• Current status: The Swedish entity no longer exists independently. Kabi Pharmacia → Pharmacia AB, merged (1995) into Pharmacia & Upjohn, renamed (2000‑01) back to Pharmacia AB/Pharmacia Corp., and acquired by Pfizer in 2003 (announced 2002‑07, closed 2003‑04). Google Patents lists the current assignee as Pfizer Health AB — a Pfizer‑group Swedish entity. No bankruptcy, no Chapter 7/11, no insolvency sale.

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Assignment timeline

Recorded conveyances as surfaced (Google Patents legal‑events / USPTO assignment data). Reel/frame and correspondent were not captured in this session — see the note above; do not invent them.

• Executed date not shown / recorded 1996‑03‑12 — Reel not captured

  • Conveyance: Merger (Google Patents text: "MERGER (SEE DOCUMENT FOR DETAILS)")
  • Assignor: KABI PHARMACIA AKTIEBOLAG
  • Assignee: PHARMACIA AKTIEBOLAG
  • Correspondent: not captured — cannot assess recurrence. No flag raised.
  • Context: Internal corporate merger — the Kabi Pharmacia entity was absorbed into Pharmacia AB; ownership stayed inside the same operating pharma group.

• Executed date not shown / recorded 2001‑08‑10 — Reel not captured

  • Conveyance: Change of Name
  • Assignor: PHARMACIA (AKTIEBOLAG)
  • Assignee: PHARMACIA & UPJOHN AKTIEBOLAG
  • Correspondent: not captured — cannot assess recurrence. No flag raised.
  • Context: Change of name only — Swedish entity renamed following the Pharmacia/Upjohn combination; no change in beneficial ownership.

• Executed date not shown / recorded 2001‑08‑10 — Reel not captured

  • Conveyance: Change of Name
  • Assignor: PHARMACIA & UPJOHN AKTIEBOLAG
  • Assignee: PHARMACIA AKTIEBOLAG
  • Correspondent: not captured — cannot assess recurrence. No flag raised.
  • Context: Change of name only — entity renamed back to Pharmacia after the Pharmacia & Upjohn / Monsanto combination; again no change in beneficial ownership.

• Not an assignment — 2011‑03‑22: Anticipated expiration legal event; patent term ended (no PTE available because of the June 1996 Xalatan approval).

• Corporate event not recorded as an assignment on this patent's page: Pfizer's acquisition of Pharmacia (2003), after which Google Patents reports the current assignee as Pfizer Health AB. If a recordation exists (e.g., an intra‑group transfer to Pfizer Health AB), it was not captured here and should be pulled from Assignment Center directly.

Family-level litigation flags (attached by Google Patents to this patent family; subject matter not verified):

• CAFC 04‑1496 — https://portal.unifiedpatents.com/litigation/Court%20of%20Appeals%20for%20the%20Federal%20Circuit/case/04-1496
• CAFC 04‑1478 — https://portal.unifiedpatents.com/litigation/Court%20of%20Appeals%20for%20the%20Federal%20Circuit/case/04-1478

These are 2004 Federal Circuit appeals tied to the Xalatan/latanoprost pharmaceutical franchise (consistent with Hatch‑Waxman/ANDA‑type assertion by the innovator, not an NPE campaign). The record I retrieved does not confirm which patent was asserted or the parties; treat as unclear on the merits and verify from the dockets before citing.

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Timeline diagram

timeline
    title Ownership of US 5296504
    1988 : Priority filing in Sweden
    1992 : US continuation filed
    1994 : Patent issued to Kabi Pharmacia
    1996 : Merger into Pharmacia Aktiebolag
    2001 : Change of name to Pharmacia and Upjohn
         : Change of name back to Pharmacia
    2003 : Pharmacia acquired by Pfizer
    2011 : Patent term expires

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NPE / troll-pattern signals

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Verdict

Operating-company assertion.

The entire recorded chain stays inside one operating pharmaceutical group — merger 1996‑03‑12 (Kabi Pharmacia Aktiebolag → Pharmacia Aktiebolag), followed by two change‑of‑name recordings on 2001‑08‑10 (Pharmacia → Pharmacia & Upjohn → Pharmacia) — and the franchise's terminal owner per Google Patents is Pfizer Health AB, with the patent running to its natural 2011‑03‑22 expiry. The claimed compound is latanoprost, which the original assignee actually commercialized as Xalatan (US approval June 1996) and enforced against generic competitors (family litigation tied to CAFC 04‑1478 / 04‑1496), which is the textbook operating‑company pattern — no shell‑entity transfer, no known asserter, no chained‑LLC cascade, no bankruptcy sale, no defensive aggregator. The one genuine gap is the correspondent‑of‑record, which I could not retrieve for any recording; that gap does not change the verdict (frequent NPE correspondence is a tell only when paired with anonymous assignees, and none appear here), but it should be closed before this reconstruction is used in a filing.

Verify at:

• USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (search patent 5296504)
• Legacy index — https://assignment.uspto.gov/patent/index.html
• Google Patents legal events — https://patents.google.com/patent/US5296504/en
• Litigation linkage — https://portal.unifiedpatents.com/litigation/Court%20of%20Appeals%20for%20the%20Federal%20Circuit/case/04-1496 and https://portal.unifiedpatents.com/litigation/Court%20of%20Appeals%20for%20the%20Federal%20Circuit/case/04-1478

I'll research the specific patent citations for US 5,296,504. Let me search for authoritative records on the most relevant references.

Prior-Art Analysis — US 5,296,504 (Stjernschantz & Resul)

Analyst's sourcing note (read first): I ran the USPTO/Google Patents citation set for US 5,296,504 and pulled full text or authoritative bibliographic records for the Ueno/R-Tech Ueno family, Bito/Columbia, and the Pfizer 13,14‑dihydro series. My tool budget was exhausted mid‑sweep, so the remaining references are described from the citation table on the patent record (titles + dates) rather than from their full texts — those entries are marked [citation-table only]. The complete citation lists are authoritative (from the patent page); the § 102 characterizations are my analysis.

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A. What the claims actually require (the anticipation yardstick)

Every one of the 16 issued claims is limited to a single species:

13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor PGF2α isopropyl ester — i.e., latanoprost (Xalatan®)

plus (i) an IOP‑reducing, non‑irritating amount and (ii) an ophthalmologically compatible vehicle (claims 1, 3, 9, 11), together with mirror method/dosing claims (4–8, 12–16).

This matters enormously for the § 102 question. A reference anticipates a species claim only if it discloses that species — generically listing "PGF2α derivatives with an aryl group in the omega chain" is not enough. The specification's broad PGA/PGB/PGD/PGE/PGF genus is not reflected in the claims. So the correct § 102 answer for nearly every cited reference is "none," and the cited art functions as § 103 obviousness art and background, not as § 102 anticipation.

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B. The 30 patent citations, reference‑by‑reference

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C. The only references that even come close (and why they still don't anticipate)

1. US 4,011,262 (Pfizer) — closest structural art. Discloses 13,14‑dihydro‑16‑phenyl‑ω‑tetranor PGF2α/PGE2/PGA2. Latanoprost is the 17‑phenyl‑18,19,20‑trinor homolog. That single‑carbon shift in the omega chain plus the isopropyl ester is the whole inventive point (compare the '504 spec, which lists 16‑phenyl‑17,18,19,20‑tetranor‑PGF2α‑IE as compound (1) — an irritating compound — versus the claimed 17‑phenyl‑trinor series). Anticipates none of claims 1–16. Best deployed as § 103 art.
2. US 4,599,353 (Bito/Columbia) — closest use art. Discloses topical PGF2α isopropyl ester for ocular hypertension without a substantial initial pressure rise, at 50 µL, in saline. It supplies the "treat IOP topically with a PGF2α C1–C5 ester" teaching — but not the 17‑phenyl‑trinor‑13,14‑dihydro compound. Anticipates none. § 103 anchor.
3. The Ueno family (US 5,001,153; 5,151,444; 5,166,178; 5,194,429; EP 0 308 135; EP 0 289 349; EP 0 366 279). All disclose ocular‑hypotensive PGs with reduced conjunctival/iridal side effects — the same problem the '504 solves — but each requires either a 15‑keto group (the dihydro‑15‑keto series) or a 20‑substituted omega terminus, neither of which is the claimed 17‑phenyl‑18,19,20‑trinor‑13,14‑dihydro structure. Anticipate none.

Net § 102 result: no cited patent anticipates any of claims 1–16, because not one discloses 13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor PGF2α isopropyl ester. The correctness of that outcome is corroborated by the litigation posture: in Pharmacia v. Par, Par attacked only inequitable conduct and expressly did not raise prior‑art invalidity against the '504 patent (and conceded infringement).

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D. Non‑patent citations that matter (the tightest § 102 candidates live here)

The record carries 80 non‑patent citations. The only ones that disclose the claimed compound class are:

Note the record itself flags that one NPL item (Camras 1988) "was raised as prior art in an opposition to Australian patent application 625096, which is related to the instant application."

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E. Bottom line

• § 102 anticipation of US 5,296,504 claims 1–16: none by any cited patent or publication, because none discloses 13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor PGF2α isopropyl ester (latanoprost). The claims are species claims; the cited art is generic or directed to different species (15‑keto, 20‑substituted, 16‑phenoxy, 16‑phenyl‑tetranor, or plain PGF2α esters).
• The real prior‑art exposure, if any, is a § 103 combination, and the natural three‑way combination is: US 4,011,262 (13,14‑dihydro‑16‑phenyl‑ω‑tetranor PG) + US 4,599,353 (topical PGF2α isopropyl ester for IOP) + Miller/Granström 1975 (17‑phenyl‑18,19,20‑trinor PGs), optionally with the Ueno family (reduced‑side‑effect ocular PGs). That combination was never adjudicated — Par conceded infringement and raised no prior‑art defense.
• EP 0 364 417 B1 is the '504's own European family member (same 1988‑09‑06 priority) — cite it as a family cross‑reference, never as art.
• US 5,151,444 (Ueno) is the substantive reference the '504 had to overcome in prosecution and is the most important single piece of art to examine; it is also the reason the parallel EP patent was initially revoked before being restored in amended form.

Confidence & caveats:

• High confidence in the citation lists, dates, and the identity of the claimed compound (latanoprost), and in the § 102 conclusion that none of the cited references discloses the species.
• Medium confidence on the exact content of the "[citation-table only]" references (items 1–3, 5, 7–8, 10–18, 20–22, 26–27) — I did not open their full texts before the tool limit; descriptions are taken from their titles/abstracts in the patent record.
• Medium confidence that the Miller (1975) and Granström (1975) papers do not disclose the 13,14‑dihydro/isopropyl‑ester features; I inferred this from their titles/abstracts, not their full texts. Verify from the articles before relying on the § 102 "none" conclusion as to those two.
• Dates shown as "priority (filing) · publication": where the citation table lists a single "prior art date," that is the priority date; publication dates are as shown on the patent record and may differ for family members.

I'll ground a few key reference disclosures before building the § 103 analysis.

Two high-value leads surfaced: an EPO Board of Appeal obviousness decision on the counterpart, and an Australian opposition novelty decision. Let me ground both.

Obviousness Analysis — US 5,296,504 under 35 U.S.C. § 103

Analyst's note on sourcing. This section builds on the Prior-Art section above and does not restate it. I ran four targeted searches this session and hit the step limit before completing a second round; the results below are grounded in retrieved sources with URLs. Two retrieved items materially change the picture from the Prior-Art section and are flagged: an EPO Board of Appeal decision on the European counterpart that records a nearly identical obviousness theory, and an Australian Patent Office opposition decision that records a novelty attack on US 4,131,738. Neither is a US proceeding and neither is binding, but both are direct evidence of what skilled persons and adversaries actually argued about this exact molecule in this exact timeframe.

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1. Governing legal standard and the framework defect

The application was filed 1990‑04‑10 / 1992‑12‑08, so pre‑AIA § 103(a) applies: the inquiry is whether "the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art." The Graham v. John Deere factors govern (scope/content of prior art; differences; PHOSITA level; secondary considerations), and under KSR Int'l v. Teleflex the teaching‑suggestion‑motivation test is not exclusive — predictable variations of known elements, and combinations of a finite number of identified, predictable solutions, are obvious.

The structural problem for the patentee is that the claims sit at the intersection of two well‑worn, separately‑documented prostaglandin design strategies. The Prior-Art section correctly established that no single reference discloses latanoprost. That is a § 102 conclusion, not a § 103 one. The § 103 question is whether two known ω‑chain modifications, each with its own published rationale, combine.

Invention benchmark: 1988‑09‑06 (SE 8803110). § 102(b) critical date: ≈1989‑04‑10.

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2. Prior-art qualification for § 103 purposes (builds on the Prior-Art section)

The Prior-Art section analysed novelty; several entries need § 103 date treatment expressly, because one reference the Prior-Art section treated as available is in fact not available, and two it did not discuss are available.

Flag: the Prior-Art section listed US 4,820,728 and US 4,883,819 among the citations without noting that they fall on the wrong side of the § 102(b) bar. They remain usable as § 102(e) art, but any obviousness case built on them must plead the § 102(e) filing date. That is a real, correctible gap in the earlier analysis, not a contradiction.

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3. Level of ordinary skill

A POSITA here is a medicinal chemist or ocular pharmacologist with a Ph.D. or equivalent, ≥2–3 years in prostanoid synthesis/pharmacology, familiar with: (i) the A–J series nomenclature and the standard ω‑chain/α‑chain modification toolkit (16‑alkyl, 16‑phenoxy, 17‑phenyl‑trinor, 15‑methyl, 13,14‑dihydro); (ii) the metabolic degradation pathway (15‑hydroxydehydrogenase → 13,14‑reductase → β‑oxidation); and (iii) the C1 ester prodrug strategy for corneal penetration. The patent's own cited literature (Miller 1975, Granström 1975, Bito 1983, Camras 1981–88, Woodward 1988/89) defines the field exactly at that level. No reference in the record requires a POSITA to leave the prostanoid art.

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4. Claim 1 / claim 9 decomposed into limitations

Every limitation is separately met by art that pre‑dates the benchmark. The obviousness case is therefore a combination case — and the combination is unusually tractable because the prior art states its own motivations in express terms.

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5. Combination theories

Combination A (primary): US 4,011,262 + Miller 1975 / Magerlein 1975 + US 4,599,353

What each teaches.

• US 4,011,262 (Pfizer, Hess et al., 1977‑03‑08; https://patents.google.com/patent/US4011262) discloses 13,14‑dihydro‑15‑substituted‑ω‑pentanor prostaglandins of the A, E and F series, where the 15‑substituent Ar is phenyl or substituted phenyl, and expressly frames L, M and N as variables "so selected as to complete the structure of a prostaglandin of the A, E or F series" — i.e., the same ω‑chain is disclosed as transposable across ring types, including F. It recites the "zero series" concept (5,6‑ and 13,14‑saturated), the "one series" and the "two series," and lists species such as "13,14‑dihydro‑16‑phenyl‑ω‑tetranor PGE2" and "16‑phenyl 13,14‑dihydro‑ω‑tetranor PGA2." It teaches IOP‑lowering utility.
• Magerlein, Bundy, Lincoln & Youngdale (1975), "Synthesis of 17‑Phenyl‑18,19,20‑Trinorprostaglandins. II. PG2 Series," Prostaglandins 9(1) (https://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-S0090698075801122/first-page-pdf) states the design rationale verbatim: after "15‑methyl‑ and 16‑alkyl‑prostaglandins … selected in an attempt to hinder oxidation of the 15α‑hydroxyl group and thus retard metabolic degradation," the authors "in another attempt to influence prostaglandin metabolism … prepared a family of prostaglandins lacking carbons 18‑20 and bearing a 17‑phenyl substituent." The paper then synthesizes 17‑phenyl‑18,19,20‑trinor‑PGF2α (V, mp 79‑80°C) and 17‑phenyl‑18,19,20‑trinor‑PGE2 (VI, mp 95‑96°C) from the same Corey‑lactone chemistry the '504 patent itself uses (Example 7). This is an express motivation statement in the art, aimed at the identical objective the '504 patent pursues.
• Miller, Weeks, Lauderdale & Kirton (1975), "Biological activities of 17‑phenyl‑18,19,20‑trinorprostaglandins," Prostaglandins 9:9‑18 (https://www.sciencedirect.com/science/article/abs/pii/S0090698075801134) supplies the biological reason the modification works: "17‑phenyl‑trinor‑PGE2 and 17‑phenyl‑trinor‑PGF2α were substrates for the prostaglandin 15‑hydroxydehydrogenase … 17‑phenyl‑trinor analogs were less rapidly dehydrogenated," and 17‑phenyl‑trinor PGF2α was ~3× PGF2α potency in rat uterus, 5× pressor potency, ~90× in the hamster antifertility assay. In short, the reference teaches the 17‑phenyl‑trinor ω‑chain increases potency by retarding metabolic inactivation.
• US 4,599,353 (Bito/Columbia, 1986‑07‑08; https://patents.google.com/patent/US4599353) teaches topical ophthalmic treatment of ocular hypertension and glaucoma with PGF2α derivatives and states: "Ophthalmic compositions containing C1 to C5 alkyl esters of PGF2α are presently preferred," expressly naming "PGF2α isopropyl ester" as "suitable lipid soluble PGF2α" because lipid solubility "permits more ready penetration of the protective layers of the primate eye." Dose ranges are given: 0.01–1000 µg/eye; in man 0.1–1000 µg; for lipid‑soluble esters 0.01–100 µg/eye, in man "particularly between about 1 µg to 50 µg," with "repeated application, preferably daily."
• US 4,883,819 (Bito, 1989) reinforces: "Esterification of these prostaglandins was found to greatly improve the ocular hypotensive potency of PGF2α to the point where amounts in the range of 1–5 microgram per application … cause a significant reduction of IOP. The increase … could be correlated with their increased penetration into the anterior chamber."

The motivation to combine is supplied by the art itself, not by hindsight:

1. Common scaffold, common problem. Both US 4,011,262 (13,14‑dihydro) and Magerlein/Miller (17‑phenyl‑trinor) are ω‑chain/C13‑14 modifications to the same prostanoid skeleton, published from the same research tradition (Upjohn/Pfizer), and both are expressly justified by a metabolic‑stability rationale — retard 15‑hydroxydehydrogenase oxidation and β‑oxidation respectively. A POSITA seeking a longer‑acting, more potent PGF2α would not need to invent a new strategy; the art offered two, and combining two metabolic blocks on one molecule is the paradigm of a predictable variation under KSR.
2. Additivity is the expectation. Where two modifications act on different metabolic pathways (15‑OH oxidation vs. ω‑chain β‑oxidation), a POSITA would expect at minimum additive benefit, with no reason to expect the combination to be inert. KSR: "if a technique has been used to improve one device, and a person of ordinary skill in the art would recognize that it would improve similar devices in the same way, using the technique is obvious."
3. The ester is a separate, independent, disclosed solution to a different problem (corneal permeability, not metabolism). US 4,599,353 supplies it for this exact indication and this exact series, and expressly names the isopropyl ester. Under KSR, a known technique to improve one property, applied to a known compound for a known use, is obvious.
4. Express identification of the target class. US 4,131,738 (Combination B) and US 4,011,262 collapse the remaining gap; but Combination A alone reaches the claim via L2+L3+L4+L5+L1.

Weakness / counter‑argument. US 4,011,262 places the aryl at C15 (ω‑pentanor) rather than at C17 (trinor); the ω‑chain lengths differ by two methylenes. A patentee will argue that "13,14‑dihydro‑15‑phenyl‑ω‑pentanor" and "13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor" are non‑homologous and that the art gave no reason to prefer the C17 placement — but Miller/Magerlein supply precisely that reason, so the gap closes on combination.

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Combination B: US 4,131,738 (+ US 4,599,353)

What it teaches. Per the Australian opposition decision (APO 1995/59, https://henley.austlii.edu.au/cgi-bin/sign.cgi/au/cases/cth/APO/1995/59), US 4,131,738 discloses a genus of 6‑hydroxy‑PGE1‑type compounds whose specification lists ω‑chain substituents including "17‑Phenyl‑18,19,20‑trinor‑," "17‑(m‑trifluoromethylphenyl)‑18,19,20‑trinor‑," "15‑Methyl‑17‑phenyl‑18,19,20‑trinor‑," "16,16‑dimethyl‑17‑phenyl‑18,19,20‑trinor‑," and then states: "In addition, the 13,14‑didehydro, 13,14‑dihydro, 13‑cis, 2,2‑difluoro and trans‑2,3‑didehydro derivatives of the above compounds are also named." Its IOP teaching is expressly on‑point:

"direct application of a sterile ophthalmic solution (e.g., in the form of drops) is the preferred route … While ultimate dosage is readily determined by patient response in the exhibition of significantly lower intraocular pressure and the absence of localized side effects, such as irritation of eye tissues, initial dosage levels of about 0.05 mg to 50 mg per several drops of sterile ophthalmic solution, repeated 2 to 4 times per day, are employed…"

Why it matters. This is the single most dangerous reference. It names 13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor in express combination, and — critically for the '504's negative limitation L6 — it expressly links that chemistry to IOP reduction with absence of ocular irritation, in ophthalmic drops, 2–4×/day. The "without substantial ocular irritation" element is therefore not a novel discovery vis‑à‑vis this reference.

The residual gap and how it closes. The named species are 6‑hydroxy‑PGE1 (E‑series, 6‑substituted), not PGF2α; and no isopropyl ester is named (though R1 = alkyl C1–C12). Two bridging references close it:

• US 4,599,353 supplies (i) the PGF2α series as the preferred ocular‑hypotensive scaffold, (ii) the C1–C5 alkyl ester, expressly the isopropyl ester, and (iii) the topical ophthalmic vehicle.
• US 4,011,262 supplies the express teaching that the ω‑chain variable set "complete[s] the structure of a prostaglandin of the A, E or F series" — i.e., the art itself treats the 13,14‑dihydro‑15‑aryl ω‑chain as transposable between E and F rings without inventive consequence. The E↔F relationship (reduction of the 9‑keto to the 9α‑ol) is one of the most routine transformations in prostanoid chemistry and is the basis for the entire "E‑series/F‑series" nomenclature the art uses.

Motivation. A POSITA reading US 4,131,738 would see a named 13,14‑dihydro‑17‑phenyl‑trinor species already associated with IOP lowering and no ocular irritation. Selecting the F‑series congener (rather than 6‑hydroxy‑E1) and esterifying at C1 with the isopropyl group the Columbia patent expressly prefers, for the same topical indication, is optimization within a disclosed genus — In re Peterson / In re Rosuvastatin territory: a prior‑art disclosure of a genus and an express recitation of the species‑defining substituents renders the species obvious absent unexpected results.

Record evidence that this reference was actually treated as close. In the Australian opposition to AU 625096 the opponent ran: "claims 1 to 17, 21, 22 to 38 are prior published and not novel in the light of US 4131738." Pharmacia's response was that "the citation relates only to 6‑hydroxy PGE1 compounds rather than PGF2α compounds, and any overlap was accidental," and it "indicated that they would be prepared to disclaim any overlapping 6‑hydroxy PGE1 compounds." That is an admission that the reference reaches the claimed structural space, differing only in ring substituent pattern. Offering a disclaimer is strong evidence of § 103 closeness: a patentee does not disclaim around art it believes is irrelevant. Note also that the AU claims 42–44 were to the compound per se — "13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor‑PGF2α" — so the compound claim was the point of attack.

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Combination C: EP 0 289 349 / EP 0 308 135 / US 5,001,153 (Ueno) + Miller 1975

What each teaches.

• The Ueno family teaches 13,14‑dihydro‑15‑keto‑PGF derivatives as ocular hypotensive agents. EP 0 308 135 A2 (filed 1988‑09‑08; published 1989‑03‑22; https://patentimages.storage.googleapis.com/9b/ca/1a/3c36a295720b02/EP0308135A2.pdf) is unusually explicit about the problem the '504 patent claims to solve:

"[W]hen topical application of these PGs, topically to rabbit eyes, they are accompanied with transient ocular hypertensive response, and still pronounced conjunctival and iridal hyperemia, and further side effects such as lacrimation, eye mucus, lid closure … It has been found the above metabolites cause intraocular pressure reduction without any transient ocular hypertensive response … and with absolutely no or extremely reduced side effects."

That is a prior‑art statement that 13,14‑dihydro prostaglandins lower IOP with drastically reduced ocular side effects — the exact technical problem the '504 specification recites and the exact functional limitation (L6) in claims 1 and 9.

• Miller 1975 supplies the 17‑phenyl‑18,19,20‑trinor ω‑chain and its anti‑metabolic rationale (supra).

Motivation. A POSITA confronting the '504's stated problem — "it is clinically impossible to use PGF2α‑1‑isopropyl ester in the amount that would give maximum pressure reduction" because of irritation — would look to the two published side‑effect mitigations: the 13,14‑dihydro modification (Ueno) and the ω‑chain phenyl‑trinor modification (Miller/Magerlein). Combining them is the first thing a POSITA would try, because the two modifications act at different site(s) — C13‑14 saturation removes the Δ13,14 double bond that the 15‑hydroxydehydrogenase/Δ13‑reductase pathway requires, while the C17 phenyl sterically/electronically disfavors C15 oxidation. Neither modification is taught to be incompatible with the other.

Weakness / counter‑argument (the patentee's best point here). Ueno's compounds are 15‑keto — the natural inactivating metabolite. The claimed compound is 15‑hydroxy (the active form). A patentee will argue that the art's teaching is that the 13,14‑dihydro‑15‑keto metabolite is "pharmacologically and physiologically inactive" (EP 0 308 135 recites: "these 13,14‑dihydro‑15‑keto‑PGs have been reported to hardly exhibit various physiological activities"), so a POSITA would not expect a 13,14‑dihydro‑15‑hydroxy compound to retain potency — the prior art requires both the saturation and the ketone for its effect. That is a genuine non‑obviousness argument, and it is the strongest doctrinal foothold the patentee has against Combination C. It is partially blunted by Miller's teaching that the 17‑phenyl‑trinor modification slows 15‑dehydrogenation, i.e., the art offers a way to keep the 15‑hydroxyl intact while still gaining the 13,14‑dihydro benefit.

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Combination D: The EPO theory — "combine the 13,14‑dihydro bond with the 17‑phenyl‑trinor chain, then esterify"

This deserves separate treatment because it is the actual obviousness case run against this molecule, and it is cleaner than any of A–C because it starts from a reference that already teaches both features in the same PGF2α genus.

From the EPO Board of Appeal decision on the counterpart (T 1024/02; https://legacy.epo.org/boards-of-appeal/decisions/pdf/t102402eu1.pdf), the opponents' case as recorded:

"[T]he opponents … argue that the subject‑matter of claim 1 was obvious starting from document (7) as the closest prior art. Document (7) taught the IOP lowering effect of PGF2α and analogues such as 13,14‑dihydro‑PGF2α and 17‑phenyl‑18,19,20‑trinor PGF2α. There was no evidence in the patent‑in‑suit that the technical problem of providing pharmaceutical efficacy in the treatment of glaucoma and ocular hypertension with less irritation and vasodilatation was solved by using the PGF2α derivatives of granted claim 1 … The skilled man would have combined the structural characteristics of the 17‑phenyl‑18,19,20‑trinor PGF2α with the single bond between position 13 and 14 of the 13,14‑dihydro PGF2α, and thus would have arrived at the compounds of claim 1 without the exercise of inventive step. Furthermore, the fact that the derivatives of claim 1 were esters could not support an inventive step since document (10) already disclosed esters of prostaglandin derivatives."

This is the § 103 theory in one paragraph. Note its structure: (i) one reference teaches the 13,14‑dihydro modification and the 17‑phenyl‑trinor modification on the PGF2α scaffold; (ii) the second reference teaches esters; (iii) the combination is a straightforward structural union. Note too that the identity of documents (7) and (10) is not captured in the excerpt I retrieved — I will not guess. If documents (7)/(10) correspond to publications also cited on the US '504 record (the candidates among the cited literature are the Miller/Granström 1975 pair and US 4,599,353 respectively), the same theory translates directly.

The opponents' second, more damaging thrust — and the one the US litigation never tested — is:

"[T]he patent‑in‑suit states that the 13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor PGF2α isopropyl ester had poor intraocular pressure (IOP) reducing effects in cats. The objective technical problem had to be reformulated as providing further PGF2α derivatives, while accepting poor IOP lowering efficacy, and accepting the toxicity of the compounds."

That is a priority‑document‑as‑admission attack: the specification's own Table and text say the 17‑phenyl‑trinor compounds "had poor intraocular pressure lowering effect in cats, even at high doses." If the claimed compound is admitted to be a poor IOP‑lowering agent in one species, the "unexpected results" story is substantially weakened, because the asserted advantage is no longer "efficacy" but "reduced side effects," and the prior art (US 4,131,738; EP 0 308 135) already associated 13,14‑dihydro and ω‑chain‑phenyl compounds with reduced ocular side effects.

Cross-reference / consistency check. The earlier "PTAB challenges" section stated that the EP counterpart was "initially revoked, then restored in amended form on appeal," with claim 1 of the appellant's main request being a use claim to "13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor‑PGF2α‑isopropyl ester … 0.1–30 micrograms … in 10–50 microlitres." The T 1024/02 excerpt I retrieved is consistent with that: it shows the appellant‑proprietor appealing an Opposition Division decision and pressing an amended, dose‑limited claim 1. I did not capture the Board's disposition — the excerpt reproduces the parties' arguments and the Opposition Division's holdings on Art. 76(1)/123(2)/84 EPC, not the final outcome. Treat the outcome as unverified; do not represent that the Board affirmed, reversed or remitted.

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Combination E: The vehicle, dose and regimen claims

Once the compound is obvious, claims 2/3/10/11 and 5–8/13–16 fall with little resistance:

• Claims 2, 10 (solubilizing agent). US 4,599,353 teaches an "ophthalmically acceptable carrier" including "sterile saline solution, peanut oil and mineral oil"; the use of surfactants (polysorbate 80) for a lipophilic prostaglandin ester is routine and is what the '504 specification itself does. No unexpected result is asserted for the solubilizer.
• Claims 3, 11 (aqueous saline + benzalkonium chloride). Benzalkonium chloride is the standard ophthalmic preservative of the era and appears in the '504 specification's own list ("ophthalmologically compatible preservatives such as e.g. benzalkonium chloride"). Selecting a known preservative for a known ophthalmic vehicle is the definition of a predictable variation. Note: because Combination B's US 4,131,738 teaches "sterile ophthalmic solution" but does not name benzalkonium chloride (per the Prior-Art section), claims 3 and 11 are not anticipated by any single reference — but they are plainly obvious over US 4,131,738 or US 4,599,353 in view of routine ophthalmic formulation practice.
• Claims 6, 14 (0.1–30 µg) and 7, 15 (1–10 µg). US 4,599,353 expressly recites 0.01–1000 µg/eye; in man 0.1–1000 µg; and for the preferred lipid‑soluble esters 0.01–100 µg/eye, "in man … particularly between about 1 µg to 50 µg." The claimed ranges are substantially overlapped by, and subsumed within, the prior‑art ranges. Under In re Peterson and In re Woodruff, a claimed range overlapping or closely approaching a prior‑art range is obvious absent a showing of criticality. The '504 specification provides no criticality data separating 10 µg from, e.g., 50 µg.
• Claims 5, 13 (once or twice a day). US 4,131,738: "repeated 2 to 4 times per day." The cited non‑patent literature (Bito 1983, "daily or twice daily topical application"; US 4,599,353, "repeated application, preferably daily") expressly discloses twice‑daily dosing. A narrower one‑to‑two‑times‑a‑day recitation within a disclosed 2–4×/day regime is routine optimization.
• Claims 8, 16 (twice daily, 1–10 µg, in 10–50 µL). 10–50 µL is the standard ophthalmic drop volume; the '504 specification itself equates one drop with "about 30 µl." No inventive weight.

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6. Claim-by-claim § 103 summary

Net: the compound‑level claims (1, 9) carry the entire validity load. If they fall, the dependent set falls with them. If they survive on unexpected results, the dependents survive a fortiori — but note that the dependents' own limitations (vehicle, dose, regimen) add essentially no independent inventive weight, so they cannot rescue the claims if claim 1 is held obvious.

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7. Secondary considerations (the patentee's affirmative case)

Under Graham, objective indicia must be weighed. The record supports the patentee on some and cuts against on others:

Favoring non‑obviousness:

1. Unexpected elimination of irritation. The '504 specification's Table III reports that in the cat eye at 1–5 µg, PGF2α‑isopropylester produces irritation scored 3.0 ± 0.0 and 15‑propionate‑PGE2‑IE scores 3.0 ± 0.0, whereas 17‑phenyl‑18,19,20‑trinor‑PGF2α‑IE, 15‑dehydro, 15‑(R), and 13,14‑dihydro analogs all score 0. Table IV shows the 13,14‑dihydro analog's conjunctival hyperemia at 0.3 ± 0.3 versus 2.8 ± 0.2 for PGF2α‑IE. If credited, this is a magnitude difference (3.0 → 0), which is the classic "results not expected" showing. Nexus runs directly to the L6 negative limitation.
2. Long‑felt, unsolved need. The specification's own statement — "it has … been found … that for this reason it is clinically impossible to use PGF2α‑1‑isopropyl ester in the amount that would give maximum pressure reduction" — establishes a recognized problem the art had not solved despite the Bito/Camras/Villumsen clinical work.
3. Prior art taught the class was inactive. The EP 0 364 417 B2 specification (https://patentimages.storage.googleapis.com/02/9e/4e/654c228fc773c0/EP0364417B2.pdf) records that "Woodward et al (1988 and 1989) concluded that studies on cat IOP revealed a substantial decrease for PGF2α whereas identical doses of 16‑phenoxy‑17,18,19,20‑tetranor‑PGF2α and 17‑phenyl‑18,19,20‑trinor PGF2α were inactive." Woodward et al. 1989 ("Prostaglandin F2α Effects on Intraocular Pressure Negatively Correlate with FP‑Receptor Stimulation") is on the '504 citation list. Potential teaching away: the art told a POSITA the 17‑phenyl‑trinor class did not lower IOP. This is the single best non‑obviousness datum in the record and should be expected to be the patentee's centerpiece.

Cutting against:
4. The same specification undercuts #3 — and it is damaging. The '504 specification states that "most of the 17‑phenyl‑18,19,20‑trinor‑prostaglandin analogs had poor intraocular pressure lowering effect in cats, even at high doses," and that the 13,14‑dihydro‑17‑phenyl compound in particular performed poorly in cats. Where the specification both (a) asserts unexpected efficacy and (b) concedes poor efficacy for the claimed compound in the very model the art used, the EPO opponents' reformulation argument ("accepting poor IOP lowering efficacy") becomes potent. The patentee must relocate the invention's contribution entirely to side‑effect profile — which invites the response that US 4,131,738 already associated 13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor species with "the absence of localized side effects, such as irritation of eye tissues," and that EP 0 308 135 already associated 13,14‑dihydro PGs with "absolutely no or extremely reduced side effects." If both structural features were independently known to reduce side effects, the combination of them is, at most, additive — and additivity is presumptively obvious.
5. No unexpected‑results showing is provided for the vehicle, dose or regimen claims. Any secondary‑considerations argument directed to claims 2, 3, 5–8, 10, 11, 13–16 is unsupported.
6. Regulatory/market success is not in the record here. Xalatan's commercial success is real, but it was not litigated on obviousness (see below), and no nexus evidence (e.g., blocking‑patent analysis, marketing‑attributable share) is before me. Do not treat commercial success as an established, litigation‑tested secondary consideration for this patent.

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8. Procedural reality check — the US never decided this question

This is the most important practical caveat and it is easy to miss.

In Pharmacia Corp. v. Par Pharmaceutical, Inc., the parties' posture, as recorded in the 2005 Federal Circuit opinion, was:

• Par conceded infringement of both the '504 and '368 patents;
• Par did not contest validity on prior‑art (§ 102/§ 103) or § 112 grounds;
• Par's sole defense was inequitable conduct.

Therefore the district court's and the Federal Circuit's statements that the '504 patent is "valid and enforceable" are not § 103 holdings. They are holdings on the inequitable‑conduct defense and the terminal‑disclaimer taint theory. No US tribunal has ever adjudicated the obviousness of claims 1–16. This matters structurally:

1. A defendant is not bound by any prior § 103 determination — there is none.
2. Conversely, the Federal Circuit's affirmance that "'504 patent is enforceable and infringed by Par" forecloses only the inequitable‑conduct taint theory as to this family, and only between those parties/privies on that issue.
3. The '368 patent, terminally disclaimed against the '504, was held unenforceable — meaning the '504 is the only enforceable member of the pair, which is why it carried the exclusivity to 2011. Its validity is thus of outsized commercial significance and yet remains untested on § 103.
4. The '504 prosecution did involve a Ueno‑related rejection (the prior‑art section notes the US 5,151,444 rejection and the Stjernschantz § 1.132 declaration that Dr. Stjernschantz executed on April 20, 1994 — i.e., after the '504 issued on March 22, 1994, and which therefore could not have infected the '504 prosecution). That the examiner originally rejected over the 13,14‑dihydro Ueno art is itself evidence that the 13,14‑dihydro teaching is close art; the fact that a declaration was needed to overcome it strengthens, rather than weakens, the § 103 case against the claims.

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9. Bottom line

If I were attacking claims 1 and 9 under § 103, I would run Combination B as the lead and Combination D as the closing:

US 4,131,738 (expressly naming 13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor species; expressly teaching IOP reduction via ophthalmic drops with "the absence of localized side effects, such as irritation of eye tissues," 2–4×/day) in view of US 4,599,353 (expressly preferring C1–C5 alkyl esters of PGF2α, expressly naming PGF2α isopropyl ester, for topical treatment of ocular hypertension and glaucoma, at 0.1–100 µg/eye and "particularly between about 1 µg to 50 µg") and, if necessary, US 4,011,262 (teaching that the same 13,14‑dihydro‑15‑aryl ω‑chain "complete[s] the structure of a prostaglandin of the A, E or F series").

The motivation is not hindsight: the art states it. Magerlein 1975 says the 17‑phenyl‑trinor family was prepared "in another attempt to influence prostaglandin metabolism"; Miller 1975 confirms 17‑phenyl‑trinor analogs "were less rapidly dehydrogenated"; US 4,011,262 puts 13,14‑dihydro on the same scaffold with an express cross‑series teaching; and US 4,599,353 supplies both the PGF2α series and the isopropyl ester as the preferred topical ocular‑hypertension form. Every limitation of claims 1 and 9, including the negative limitation, is met by art pre‑dating the benchmark.

The honest counterweight: (i) Woodward et al. 1988/89 taught that 17‑phenyl‑18,19,20‑trinor PGF2α was inactive in the cat IOP model — real teaching‑away material; (ii) the '504's own Tables III–IV show a 3.0 → 0 irritation reversal, arguably a magnitude that cannot be dismissed as additive; (iii) Ueno's 13,14‑dihydro art is 15‑keto (inactive metabolite), giving a genuine argument that the 13,14‑dihydro‑15‑hydroxy combination was not suggested as retaining potency. On balance I assess claims 1 and 9 as more likely than not obvious (roughly 60–70% confidence, the irreducible uncertainty being how a factfinder credits the irritation data and the Woodward teaching‑away), with the dependent claims 2–8 and 10–16 obvious to a high degree of confidence once claim 1 falls.

Confidence statement.

• High confidence in the content of US 4,011,262, US 4,131,738, US 4,599,353, Miller 1975, Magerlein 1975 and EP 0 308 135 A2 — all verified from retrieved primary or quasi‑primary sources this session.
• High confidence that the EPO Board of Appeal decision at https://legacy.epo.org/boards-of-appeal/decisions/pdf/t102402eu1.pdf records an obviousness attack on the latanoprost claims framed as "combine the 13,14‑dihydro bond with the 17‑phenyl‑18,19,20‑trinor chain, then esterify." Lower confidence in the case number (inferred from the filename t102402eu1.pdf) and no confidence in the disposition, which was outside the retrieved excerpt. I did not capture the identities of that decision's "documents (7) and (10)."
• High confidence that no US tribunal has adjudicated § 103 for this patent — Par conceded infringement and pressed only inequitable conduct.
• Not verified this session: WO 92/02496 and the Pfizer DE 2,334,945 "X" citations noted in the Prior-Art section; the "Binder et al. 1978, Synthesis and biological activity of 15‑arylprostaglandins, Prostaglandins 15(5):773‑778" reference, which surfaced only as citation metadata in a different, later application and which is not on the '504 citation list; and the US filing dates underpinning the § 102(e) status of US 4,820,728, US 4,883,819 and US 5,057,621. Each of these should be confirmed against the primary documents before being relied on in a filing or an invalidity contention.