US 5422368

I'll search for this specific patent number and any related CAFC 2026 docket activity.

Let me dig into the litigation references and check for any current docket activity.

Let me try to retrieve the remainder of the claim set (claims beyond 65) to identify all independent claims.

Summary of US Patent 5,422,368

Important note on scope: I searched for this exact number. I found extensive USPTO/Google Patents, Orange Book, and Federal Circuit records for the '368 patent, but no CAFC 2026 docket activity involving patent 5,422,368. The only CAFC litigation I can confirm is from 2005 (details below). I have flagged everything I could not verify authoritatively.

Bibliographic data (per Google Patents and Justia, both consistent)

Source: https://patents.google.com/patent/US5422368/en ; https://patents.justia.com/patent/5422368

Abstract

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 (upper) side chain contains a ring structure, in an ophthalmologically compatible carrier; plus preparation of such compositions and their use.

Plain‑language overview of the independent claims

The patent has 87 claims. Only claims 1–65 were fully returned in the source text I was given; claims 66–87 were truncated, so I cannot rule out additional independent claims there. Based on what is available, the independent claims are:

Claim 1 — Therapeutic composition (generic).
A topical composition for ocular hypertension/glaucoma containing a PGA, PGB, PGE or PGF prostaglandin (note: PGD is not included in claim 1) in an IOP‑lowering amount that does not cause substantial ocular irritation, plus an ophthalmologically compatible vehicle. The claim defines:

• an alpha chain of 6–10 carbons, saturated or unsaturated (double, allene, or triple bonds), unsubstituted or substituted with alkyl, alicyclic, aromatic, or heteroaromatic groups; and
• an omega chain of formula C₁₃–B–C₁₄–D₁₅₋₂₄–R₂, where B is a single, double, or triple bond; D is a 1–10 carbon sub‑chain with H/alkyl/oxo/hydroxyl substituents; and R₂ is (e) an aromatic ring (optionally substituted with C₁‑C₅ alkyl, C₁‑C₄ alkoxy, trifluoromethyl, C₁‑C₃ aliphatic acylamino, nitro, halogen, or phenyl), (f) a 5–6‑membered aromatic heterocycle, or (g) a C₃‑C₇ cycloalkane/cycloalkene (optionally lower‑alkyl substituted).

Essence: any prostaglandin (other than D‑type) bearing a ring in the omega chain, formulated for the eye, that lowers pressure without substantial irritation. The omega‑chain ring is the stated point of novelty.

Claim 29 — Therapeutic composition (heteroatom variant).
Substantively a broader/parallel independent composition claim covering the same concept, but (i) the alpha chain unsaturation is recited as "one or more non‑cumulated double bonds" (no allene wording), and (ii) the D sub‑chain may additionally contain 1–2 heteroatoms selected from oxygen, sulfur and nitrogen. Same R₂ options as claim 1. Again covers PGA, PGB, PGE, PGF (not PGD).

Claim 57 — Therapeutic composition (PGD‑specific).
An independent composition claim covering the PGD class specifically (the prostaglandin omitted from claims 1 and 29). Alpha chain and omega‑chain‑ring definitions track claim 1, except R₂ is limited to (e) an aromatic ring structure or (f) a 5–6‑membered aromatic heterocycle — the cycloalkane/cycloalkene option is dropped.

Claim 24 — Method of treatment.
A method of treating glaucoma or ocular hypertension by topical application of the therapeutic composition of claim 1.

Claim 52 — Method of treatment.
A method of treating glaucoma or ocular hypertension by topical application of the therapeutic composition of claim 28 — though claim 28 as written depends from claim 1, so this cross‑reference appears to be a parsing/numbering artifact; the parallel method claim for the heteroatom composition (claim 29) is the likely intended target.

Practical subject matter / notable dependent claims of commercial relevance: dependent claims 20–23 and 48–51 recite the isopropyl ester of 13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor‑PGF₂α and its free acid — i.e., latanoprost (Xalatan) and related compounds. The specification's most‑preferred embodiments are the 17‑phenyl‑18,19,20‑trinor PGF₂α derivatives (15‑(R)‑, 15‑dehydro‑, and 13,14‑dihydro‑ forms).

Claim‑drafting caveat: Several dependent method claims say "The method of claim 23" (claims 25–28) and "The method of claim 51" (claims 53–56), even though the corresponding method claims appear as claims 24 and 52. I flag this as an apparent numbering inconsistency in the text as presented rather than asserting how it was resolved on the face of the granted patent.

Litigation / enforceability (the only confirmed court record)

The '368 patent is the litigated, judicially defeated member of this patent family:

• Pharmacia Corp. v. Par Pharmaceutical, Inc., 417 F.3d 1369 (Fed. Cir. 2005), Nos. 04‑1478 and 04‑1496 (D.N.J. Civil No. 01‑6011). Google Patents itself links these two CAFC case numbers to US 5,422,368.
• Holding: the '368 patent was held unenforceable due to inequitable conduct during prosecution (a Stjernschantz declaration, ¶10, was found misleading and material). The sibling '504 patent (US 5,296,504) remained valid, infringed and enforceable, and an injunction blocked Par's generic approval until March 2011. The court rejected the theory that a terminal disclaimer transmitted the '368 inequitable conduct to the '504 patent.
• Sources: https://app.midpage.ai/document/pharmacia-corp-v-par-pharmaceutical-[211740](/patent/211740) ; https://case-law.vlex.com/vid/pharmacia-corp-v-par-891458566 ; https://www.courtlistener.com/opinion/211740/pharmacia-corp-v-par-pharmaceutical-inc/ ; https://www.medicalnewstoday.com/releases/10515

Regarding "CAFC 2026 dockets": My searches returned only general CAFC 2026 decisions (e.g., AudienceScience v. Google, mCom IP v. City National Bank, Ironburg v. Valve), none involving patent 5,422,368. Because the patent had already expired (2011/2012) and was adjudged unenforceable in 2005, no 2026 appellate activity is expected. I cannot authoritatively confirm the absence of a 2026 filing beyond what the searches showed.

Discrepancies / uncertainty to flag

1. Assignee mismatch: Google Patents lists "Pfizer Health AB" as current assignee and "Kabi Pharmacia AB" as original; Justia lists "Kabi Pharmacia AB (Upsala)." These are consistent with the known Pharmacia→Pfizer corporate chain, but Google's own disclaimer applies.
2. Conflicting citation of the number: One EPO search‑report PDF (EP 0941663 A1) cites "US 5422368 A 19950606 – TAKAHASHI JUN [JP], et al" — i.e., attributes this exact number and date to a different inventor. This conflicts with the authoritative full text and all other sources, which attribute US 5,422,368 to Stjernschantz/Resul. Per your instruction not to auto‑correct identifiers, I report the conflict as found, but the weight of evidence (Google Patents full text, Justia, the Federal Circuit opinion, and the Orange Book) ties 5,422,368 to the prostaglandin/glaucoma invention.
3. Expiration date: Google's "2012‑06‑06" vs. the Orange Book/CAFC "March 22, 2011" — reconcile via the terminal disclaimer of record.
4. Claims 66–87 were not retrievable within my search budget; there may be one or more additional independent claims (e.g., further composition or method claims) in that range that I have not summarized.

I'll search for litigation involving US patent 5422368.

Let me search for the specific CAFC cases noted in the patent record and related litigation.

I found key results. Let me dig deeper into the specific case details and any other defendants.

Litigation Involving U.S. Patent No. 5,422,368

Based on my searches (Google Patents litigation data, Court of Appeals for the Federal Circuit records via vLex/Justia, Unified Patents, and Pfizer/Pharmacia SEC filings), here is the known litigation. Note: I was able to complete only a limited number of searches before hitting the tool limit, so this may not be exhaustive; I flag the confidence level on each item.

1. Pharmacia Corp. v. Par Pharmaceutical, Inc. (district court)

2. Pharmacia Corp. v. Par Pharmaceutical, Inc. (Federal Circuit appeal)

These two CAFC dockets (04-1496 and 04-1478) are the ones listed on the Google Patents "Family has litigation" record for US 5,422,368.

Related / adjacent matters (NOT direct US 5,422,368 infringement suits)

• Pharmacia v. Alcon Laboratories, Inc. (D.N.J., filed March 30, 2001) — this was a Lanham Act trademark action over the XALATAN mark vs. Alcon's "TRAVATAN." It did not involve the '368 patent.
• Italian AGCM antitrust proceeding against Pfizer (decision ~2012; ~€10.6M fine; upheld on further appeal through the Italian Supreme Court) — concerned Pfizer's management of the European Xalatan patent lifecycle (the EP divisional patent, not US 5,422,368). Related subject matter, but not litigation of the '368 patent.
• Pharmascience Inc. v. Pfizer Canada Inc. (Federal Court of Appeal of Canada) — concerned the Canadian counterpart patents, not US 5,422,368.
• Google Patents also shows a Darts-ip "first worldwide family litigation filed" entry for family 26660291, but I could not retrieve the underlying case details for that entry.

Summary

The only U.S. litigation I can confirm that directly asserted/involved U.S. Patent No. 5,422,368 is Pharmacia Corp. v. Par Pharmaceutical, Inc. — D.N.J. No. 01-6011 (filed Dec. 21, 2001), affirmed by the Federal Circuit at 417 F.3d 1369 (Aug. 10, 2005). In that case the '368 patent was held unenforceable for inequitable conduct, and that holding was affirmed.

Caveat: Because my search was truncated, I cannot rule out additional ANDA suits or settlements involving the '368 patent (for example, against other latanoprost generic applicants). I recommend confirming via the Unified Patents litigation portal (https://portal.unifiedpatents.com/litigation) or PACER for D.N.J. case 1:01-cv-06011 and related dockets. I did not find any litigation involving a patent number different from 5,422,368 in these results.

I'll verify the "no PTAB activity" default against public sources before finalizing. The structured block is canonical, but let me check for anything the ODP ingest may have missed.

Let me run a couple of targeted checks for pre-AIA post-issuance proceedings (reexam) and any PTAB docket entry that the ODP ingest might have missed.

All checks came back negative for AIA-trial activity. Note the searches also confirm something important for framing: the two CAFC dockets Google Patents lists for this patent (04‑1478 / 04‑1496) are appeals from the D.N.J. district court, not from the PTAB. Nothing on the PTAB docket. Here is the analysis.

Proceedings overview

Total AIA trial proceedings on U.S. Patent 5,422,368: 0 (0 active, 0 with claims invalidated, 0 with claims sustained, 0 settled, 0 institution denials). The USPTO Open Data Portal returns no IPR, PGR, or CBM for this patent, and my independent web checks surfaced no proceeding the ODP ingest might have missed. The bottom line for a defendant is that the PTAB is irrelevant here for an unusual reason — not because the patent is hardened, but because it is (i) already expired and (ii) already adjudicated unenforceable in district court. Any demand letter that leans on the '368 patent is answered by the 2005 Federal Circuit decision, not by an IPR.

No proceedings to enumerate

Because the count is zero, there is no proceeding-by-proceeding block to populate. To make the negative finding auditable, here is the verification record:

Why the structured list is empty — and why that is the correct, expected answer

This is not a data gap; it is structural, and it is worth being precise because it shapes the defensive posture:

1. AIA trials did not exist during this patent's useful life. The '368 patent issued 1995‑06‑06 and reached the end of its term in 2011 (Orange Book / CAFC) to 2012‑06‑06 (Google Patents anticipated-expiration). IPR and CBM only became available on 2012‑09‑16, and the CBM program itself sunset on 2020‑09‑16. The patent was already at or past expiry when the AIA trial regime opened.

2. PGR was never available. PGR applies only to patents with an effective filing date on or after 2013‑03‑16 (first‑inventor‑to‑file). This patent's effective filing date is 1988‑09‑06 (SE 8803110 priority) / 1992‑12‑08 (the application 07/986,943, a continuation of 07/469,442 filed 1990‑04‑10). PGR is categorically unavailable.

3. CBM was never available. CBM covers "a method or apparatus for performing data processing or other operations used in the practice, administration, or management of a financial product or service." A prostaglandin/glaucoma pharmaceutical composition is not remotely a covered business method.

4. IPR was technically available but pointless. IPR is not barred by patent age, so an IPR could have been filed against the '368 patent in the 2012–2013 window. But the patent had already been held unenforceable for inequitable conduct in Pharmacia Corp. v. Par Pharmaceutical, No. 01‑6011 (D.N.J. July 6, 2004), aff'd, 417 F.3d 1369 (Fed. Cir. Aug. 10, 2005). An unenforceable patent cannot support an infringement claim, so there is no rational incentive for any party to spend IPR filing fees ($50k+) invalidating it. The absence of IPRs here is a non‑assertion signal, not a patent‑strength signal.

So there are also no Judge panels, no institution decisions, no Final Written Decisions, no settlements, and no PTAB‑originating CAFC appeals to report. I am not omitting them; they do not exist.

Strategic summary

Claim status — everything is UNTESTED by the PTAB, but the whole patent is UNENFORCEABLE by court judgment. No claim of the '368 patent has been canceled, confirmed, or amended through any AIA trial — the claims stand as issued (claims 1–87). Critically, though, that textual survival is meaningless in practice: the district court entered judgment that the '368 patent is unenforceable due to inequitable conduct, and the Federal Circuit affirmed on 2005‑08‑10 (417 F.3d 1369). A defendant facing assertion today can raise unenforceability — and, unlike an IPR, unenforceability is a complete defense that no PTAB outcome could have delivered. (For completeness on the counter‑intuitive point: the sibling '504 patent is the one that was held valid, enforceable, and infringed — the opposite result — so a defendant must not conflate the two. See https://www.courtlistener.com/opinion/211740/pharmacia-corp-v-par-pharmaceutical-inc/.)

Estoppel landscape — clean, because there was no IPR. Section 315(e)(2) estoppel attaches only to a petitioner that obtained a Final Written Decision. With zero instituted proceedings, no § 315(e)(1) or § 315(e)(2) estoppel exists against anyone. Every § 102/§ 103 ground on patents and printed publications is available to a current defendant in district court, unencumbered. That said, the most efficient defense is not a validity attack at all — it is the existing unenforceability judgment, which is stare decisis as to this patent and patentee and requires no new prior‑art work. A validity challenge would only matter if someone attempted to resurrect the claims in a reissue (not done - no reissue appears in the record) or if the enforceability holding were somehow collaterally attacked (it cannot be "un‑adjudged"; inequitable conduct as to particular claims is not curable retroactively).

Pattern signals — none of the usual flags. No serial petitioner (there are no petitioners). No patent owner PTAB‑appeal strategy (no FWDs to appeal). No defensive aggregator — I found no Unified Patents, RPX, or other aggregator IPR in the chain; Unified Patents' public portal shows no '368 proceeding. The only "litigation" labeled on the Google Patents record are the two CAFC district‑court appeals (04‑1478, 04‑1496), which are not PTAB appeals and should not be read as such.

Recommended next steps

• If you are a defendant being asserted against: Do not build an IPR or PGR strategy — both doors are closed or pointless (PGR: pre‑AIA patent; IPR: expired, unenforceable, no institution value). Instead, put the Pharmacia v. Par judgment front and center in your answer, motion practice, or demand response. The operative disposition: "the district court found only the '368 patent unenforceable due to inequitable conduct," affirmed at 417 F.3d 1369. Link the opinion: https://www.courtlistener.com/opinion/211740/pharmacia-corp-v-par-pharmaceutical-inc/. Also cite the terminal‑disclaimer/expiry record (March 2011) to dispose of any residual royalty theory.
• If you need the primary documents: Pull the D.N.J. Final Judgment, No. 01‑6011 (July 6, 2004), and the CAFC record for Nos. 04‑1478/04‑1496 (consolidated) via CourtListener or PACER. These, not any PTAB file, are the controlling artifacts.
• If you want an authoritative "no PTAB" certification for a client memo or an IPR‑avoidance opinion: Query PTAB E2E directly (https://ptacts.uspto.gov/ptacts/) and the USPTO Open Data Portal for patent 5,422,368, and screenshot the empty result set. That is the cleanest primary‑source confirmation of the negative finding.
• Timeline caveat for any future posture: because the patent expired (2011/2012), no reexamination amendment is even permissible, and no PTAB trial could issue a certificate affecting a live claim. The proceeding universe for this patent is permanently closed.

Explicit uncertainty to flag: my negative finding is based on the canonical ODP block plus web corroboration showing no '368 AIA proceeding. I could not query the USPTO ODP API directly in this session, so I cannot claim to have exhaustively crawled every PTAB docket identifier; however, the structural facts (pre‑AIA filing date / expired / adjudged unenforceable) make the absence the only coherent answer, and nothing in the public record contradicts it.

I'll research the assignment record for US 5422368. Let me start with several targeted searches.

Good context on the litigation and corporate chain. Now let me try to pin down the actual assignment reel/frame records and correspondents.

Ownership & Assignment Analysis — US 5,422,368

Data-availability note (read first): The USPTO Assignment Center (https://assignmentcenter.uspto.gov/) and the legacy Assignment Search UI render their results via JavaScript and are not directly retrievable by the search tooling used here. My searches did not return the underlying reel/frame numbers or the correspondent-of-record fields for this patent. What I can ground reliably are (a) the patent's own front-matter/description (authoritative, provided), (b) the Google Patents legal-events reassignment entries (which mirror the assignment record set, without reel/frame), and (c) the Federal Circuit record. I will not invent reel/frame numbers or attorney names. Where a field is missing, I say so. The reader should verify reel/frame and correspondent at the Assignment Center link below.

Inventors

Both are named on the face of US 5,422,368 and are the two inventors carried through the family. The application is a continuation of Ser. No. 07/469,442, filed 1990‑04‑10 (now abandoned), itself claiming priority to SE 8803110A filed 1988‑09‑06. The inventors are foreign nationals and the priority filing is Swedish — a normal pattern for a Swedish-headquartered pharmaceutical originator, not an anomaly.

Unusual-pattern check: No evidence either inventor departed the assignee within 12 months of filing. Stjernschantz continued as a Pharmacia scientist and is a co-editor of the Bito/Stjernschantz volume cited in the patent's own references (Table VI references, "Bito LZ, Camras CB, Gum GG and Resul B (1989)"). No inventor-departure signal.

Original assignee

Kabi Pharmacia AB (Sweden) — the entity named as original assignee on the issued patent (Google Patents record; the SE priority was likewise filed in the Kabi/Vitrum–Pharmacia lineage).

• Product embodying the claims: Yes. The lead compound of the specification is the 17‑phenyl‑18,19,20‑trinor PGF₂α isopropyl ester family; the claimed species 13,14‑dihydro‑17‑phenyl‑18,19,20‑trinor‑PGF₂α isopropyl ester is latanoprost, marketed as XALATAN®. The Federal Circuit confirms the '368 and '504 patents "are collectively owned by Pharmacia Corp., Pharmacia AB, Pharmacia Enterprises S.A. and Pharmacia & Upjohn Co." and that the Orange Book lists them as covering Xalatan.
• Primary line of business: Pharmaceutical R&D/manufacturing (ophthalmology among the pipelines).
• Current status: Acquired. Kabi Pharmacia → merged with Upjohn to form Pharmacia & Upjohn (1995) → merged with Monsanto, renamed Pharmacia Corporation (1999/2000) → acquired by Pfizer in April 2003. Per Google Patents, the current assignee is Pfizer Health AB (Sweden).

Assignment timeline

The Google Patents legal-events feed shows the following recorded reassignment entries for US 5,422,368. Reel/frame and correspondent-of-record were not retrievable in this session and are marked "not retrieved." The dates shown are the recordation dates surfaced by Google Patents; separately available execution dates were not exposed.

• recorded 1995‑09‑27 — Reel not retrieved

  • Conveyance: Merger (see document for details)
  • Assignor: KABI PHARMACIA AB
  • Assignee: PHARMACIA AB
  • Correspondent: not retrieved — cannot assess recurrence.
  • Context: internal corporate reorg (Kabi Pharmacia absorbed into Pharmacia AB).

• recorded 1995‑09‑28 — Reel not retrieved

  • Conveyance: Merger (see document for details)
  • Assignor: KABI PHARMACIA AB
  • Assignee: PHARMACIA AB
  • Correspondent: not retrieved.
  • Context: duplicate/near-duplicate recordal of the same 1995 merger reorganization.

• recorded 1996‑03‑12 — Reel not retrieved

  • Conveyance: Merger (see document for details)
  • Assignor: KABI PHARMACIA AKTIEBOLAG
  • Assignee: PHARMACIA AKTIEBOLAG
  • Correspondent: not retrieved.
  • Context: internal corporate reorg completing the Kabi‑Pharmacia → Pharmacia name/entity consolidation.

• recorded 2001‑08‑10 — Reel not retrieved

  • Conveyance: Change of Name
  • Assignor: PHARMACIA AKTIEBOLAG
  • Assignee: PHARMACIA & UPJOHN AKTIEBOLAG
  • Correspondent: not retrieved.
  • Context: change of name only (post‑1995 Pharmacia/Upjohn combination).

• recorded 2001‑08‑10 — Reel not retrieved

  • Conveyance: Change of Name
  • Assignor: PHARMACIA & UPJOHN AKTIEBOLAG
  • Assignee: PHARMACIA AKTIEBOLAG
  • Correspondent: not retrieved.
  • Context: reciprocal change-of-name recordal listed on the same date — an internally inconsistent pair on the feed; flag for verification. Note: a gap remains between these 2001 records and the current listed assignee, Pfizer Health AB (Pfizer acquired Pharmacia in April 2003). No assignment event recording the transfer to Pfizer Health AB was surfaced, and I do not have reel/frame for it.

Because the Assignment Center data could not be pulled, I am not asserting that the above list is exhaustive. It is what the Google Patents legal-events mirror shows. There are no shell-LLC assignees anywhere in this set — every assignee is a named operating pharmaceutical corporation.

Verification link: https://assignmentcenter.uspto.gov/ (search patent number 5422368) and https://assignment.uspto.gov/patent/index.html

Timeline diagram

timeline
    title Ownership of US 5422368
    1988 : Swedish priority filed
    1990 : US parent application filed
    1992 : Continuation filed
    1995 : Patent issued
         : Kabi Pharmacia merged into Pharmacia AB
    1996 : Pharmacia Aktiebolag recordal
    2001 : Name changed to Pharmacia and Upjohn
         : Pharmacia sues Par Pharmaceutical
    2003 : Pfizer acquires Pharmacia
    2005 : CAFC affirms 368 unenforceable
    2011 : Patent term ends

NPE / troll-pattern signals

Litigation context (color, not an NPE finding): In Pharmacia Corp. v. Par Pharmaceutical, Par conceded infringement of the '368 and '504 patents; the district court held only the '368 patent unenforceable for inequitable conduct (a Stjernschantz declaration concerning the 20‑ethyl compound vs. the claimed 17‑phenyl compound), affirmed at 417 F.3d 1369 (Fed. Cir. 2005). This is a prosecution-conduct holding against an operating-company patentee, the opposite of a troll profile.

Verdict

Operating-company assertion.

The record shows a single, continuous pharma lineage — Kabi Pharmacia AB → Pharmacia AB (mergers recorded 1995‑09‑27/28 and 1996‑03‑12) → Pharmacia & Upjohn Aktiebolag (change of name recorded 2001‑08‑10) → Pfizer Health AB as listed current assignee — with no shell entity, no known NPE, and no defensive aggregator at any link. The patent's claimed species (latanoprost) was commercialized as XALATAN®, and the patent was asserted by its owner against a generic competitor (Par Pharmaceutical, complaint 2001‑12‑21; appeal Nos. 04‑1478/04‑1496), which is the definition of an operating-company assertion rather than NPE activity. Two caveats: (i) I could not retrieve reel/frame or correspondent data, so the signal‑3 recurrence check is unresolved; (ii) there is an unrecorded (in the sources available to me) step between the 2001 change of name and the listed current assignee Pfizer Health AB, stemming from Pfizer's April 2003 acquisition of Pharmacia — this should be verified.

I'll research the prior art citations for US 5,422,368. Let me search the patent records and citation data.

Let me get the actual front-page references cited on US 5,422,368 and the EP counterpart's search report.

Prior Art Analysis — U.S. Patent No. 5,422,368

Note on method. I targeted the exact number, 5,422,368, and its USPTO/Google Patents record. Two limits must be stated up front: (i) the Google Patents full text supplied in the brief did not include the "Patent Citations / References Cited" block, so I could not read the front page of the '368 patent directly; and (ii) I hit the tool-step limit before I could verify each reference's disclosure. What follows therefore uses the authoritative "References Cited" list of the same-family continuations US 5,849,791 and US 7,163,959 (both Stjernschantz/Resul, both continuations of the '368 disclosure), which reproduces the examiner-cited art for this family. Every date is the reference's issue/publication date as printed in that list. I flag where I could not verify a disclosure and I do not invent one.

Critical framing carried over from the earlier sections (not repeated): the '368 patent was allowed over an obviousness rejection that turned on a "20-ethyl compound" reference; Par never litigated § 102/§ 103; and the broad genus claims (1, 29, 57) plus method claims (24, 52) are the vulnerable ones. That framing governs how the citations below should be read.

A. U.S. Patent Documents cited (examiner list, family record)

Family members appearing in the same reference list — NOT § 102 prior art to '368 (flag): US 5,296,504 (3/1994), US 5,321,128 (6/1994), US 5,422,368 (6/1995), US 5,422,369 (6/1995), US 6,030,999 (2/2000), US 6,187,813 (2/2001) — all Stjernschantz. These are same-inventor/same-family patents (the '504 and '368 were filed the same day, 12/8/1992), so they are not available as prior art against '368. Their presence in the printed list reflects the reference lists of the later family members (US 5,849,791, US 7,163,959), not a citation against the '368 patent itself. Do not treat them as anticipation art.

B. Foreign Patent Documents cited

C. Non-patent literature cited (from the family reference list)

(The specification's own "References" section additionally lists Camras 1981/1987a/1987b/1988, Crawford 1987, Giuffrè 1985, Kaufman 1986, Kerstetter 1988, Lee 1988, Nilsson/Stjernschantz/Bill 1987, Villumsen & Alm 1989, and Miller WL et al (1975), "Biological Activities of 17-Phenyl-18,19,20-Trinor Prostaglandins," Prostaglandins 9:9–18 — these are applicant-listed background citations, discussed in the Obviousness section already generated, and are the true § 103 anchors rather than anticipation art.)

D. Which cited references could anticipate under § 102 — bottom line

Because every one of the 87 claims requires a ring structure in the omega chain (R₂ = aromatic ring, aromatic heterocycle, or cycloalkane/cycloalkene), no cited reference that lacks that element can anticipate any claim. Applied to the record:

Key conclusion for the citations specifically: the cited-art set is overwhelmingly § 103 (obviousness) art, not § 102 (anticipation) art. The three Bito/Columbia references (US 4,599,353; US 4,883,819; EP 0 242 580) and the chemistry patents (Hess, Hayashi, Bundy, Axen, Miller Jr., Smith, Nelson, Kurono, Schneider; EP 170258, EP 242580, EP 253094) together disclose every claim element except the omega-chain ring — which is the patent's stated point of novelty. No cited single reference bridges that gap, so the substantive attack on the issued claims is a combination obviousness attack, not anticipation.

E. Explicit uncertainties (do not treat as settled)

1. I could not read the '368 patent's own front-page "References Cited" block. The list used above is the corroborated family list from US 5,849,791 / US 7,163,959. If a citation appears there that is not on the '368 front page (e.g., the post-1990 Ueno/Cooper references 5,001,153–5,194,429, which likely post-date the '368 prosecution), it may belong only to a later family member. Verify against the '368 front page at https://patents.google.com/patent/US5422368/en.
2. The examiner's "20-ethyl compound" reference is unidentified. The Federal Circuit described it as the sole prior-art reference in the obviousness rejection. I did not match it to any number above and will not guess.
3. Per-reference disclosures were not verified. I could not confirm, for any of US 3,956,284 / 3,962,312 / 3,987,087 / 4,001,300 / 4,011,262 / 4,061,865 / 4,115,586 / 4,116,988 / 4,117,119 / 4,128,713 / 4,131,738, whether the disclosed ω chain terminates in a ring. The § 102 column for those entries is therefore conditional.
4. Number-reading discipline. The printed list contains apparent original typos ("Hatashi et al." for Hayashi; "Schnieder") and reclassified USPC classes; I reproduced the identifiers literally and did not auto-correct them.
5. Date/priority sensitivity. US 4,820,728, US 4,824,857, US 4,883,819 and the 1988–89 journal items post-date the 9/6/1988 priority; they are prior art only as § 102(a)/§ 102(e) references if the invention date is not carried back. The ≥1976–1980 patents (Hess, Hayashi, Bundy, Axen, Miller Jr., Smith, Nelson, Kurono, Schneider) and EP 0 170 258 / EP 0 242 580 are solidly before any U.S. critical date and are § 102(b)-eligible if their disclosures support the read.

I'll ground this §103 analysis by verifying key facts about the closest prior-art references before building the combination analysis.

Now let me verify the secondary references and check whether the omega-chain ring concept appeared in other art.

Two more targeted checks — the Woodward ocular data and the citation the EPO examiner rated "X" against this family.

Obviousness Analysis — U.S. Patent No. 5,422,368 under 35 U.S.C. § 103

Scope note. This builds on the Prior Art section already generated (which established the reference pool) and does not repeat it. I add four references the earlier searches surfaced but did not fully develop — Woodward et al. (1989), the 1975 Eur. J. Biochem. SAR paper, Goh / U.S. 4,824,857, and the EPO "X"-rated EP 0093930 — because they materially change the § 103 calculus. Claims 66–87 remain unavailable (flagged earlier); this analysis covers claims 1–65.

Threshold caveat on the priority date. The § 103 outcome depends heavily on the operative date. If the claims carry the 1988-09-06 SE 8803110 priority, then the most dangerous references (Woodward 1989, Villumsen & Alm 1989) are not § 102(b) art. If any claims rely only on the 1990-04-10 parent (Ser. No. 07/469,442), those references become available. I analyze both. I have not verified from an assignment/priority document which claims received which date — that requires the PatentCenter IFW for 07/986,943, which was not reachable.

Threshold caveat on precedent. The patent was prosecuted pre‑KSR and litigated in 2004–2005, but the substantive § 103 standard applied today (including to pre‑AIA patents) is KSR Int'l v. Teleflex. I apply KSR and the Federal Circuit's chemical-compound line (In re Dillon; Otsuka v. Sandoz; Takeda v. Zydus).

Litigation posture (from the earlier sections). No court has decided the '368 patent's validity. Par conceded infringement and argued only inequitable conduct — the '504 sibling was held "valid" because validity was uncontested, not because a § 103 merits ruling issued. So any obviousness analysis here is a PTO-style hypothetical examination, not a report of an existing holding.

1. The claims to be tested (grouped by vulnerability)

2. The critical new reference: Woodward et al. (1989)

Woodward et al., Invest. Ophthalmol. Vis. Sci. 30(8):1838–1842 (1989) is the single most important reference for obviousness, and it cuts both ways:

• Pro-obviousness: Woodward actually tested 17-phenyltrinor PGF₂α and 16-phenoxytetranor PGF₂α topically for IOP in rabbits and cats. The precise compounds of the claimed genus were therefore already in the ocular-hypotension testing pipeline — a POSITA did not have to invent the compounds, only confirm them.
• Anti-obviousness (teaching away): Woodward's rank order of IOP potency was "PGF₂α > PGF₁α > 16-phenoxytetranor PGF₂α > 17-phenyltrinor PGF₂α = fluprostenol (inactive)." His own text states: "No decrease in intraocular pressure was apparent for 17-phenyltrinor PGF₂α at either the 0.1% or 1% concentration." The art affirmatively told the POSITA the key compound does not work for IOP. That is a textbook teach-away under In re Gurley / DePuy Spine v. Medtronic.

Woodward also concluded the ocular hypotensive effect is not FP-receptor mediated — which would have left a POSITA without a receptor rationale for pursuing FP-active analogs like 17-phenyltrinor at all.

Priority caution: the paper was submitted 1988-09-19 and presented at ARVO May 1988 — i.e., straddling the 1988-09-06 priority date. Its status as § 102 art is date-sensitive.

3. Combination analyses

Combination A — the backbone combination: Bito '353 + Miller 1975

(targets G1, G3)

• Bito '353 (iss. 1986) teaches topically applying PGE₂ and PGF₂α, and preferably the C₁–C₅ alkyl esters of PGF₂α, to lower IOP in glaucoma/ocular hypertension, and expressly teaches that esterification improves corneal penetration and potency.

• Miller 1975 discloses, by name, 17-phenyl-18,19,20-trinor-PGF₂α and -PGE₂ and their biological activities, and teaches the design rationale: "Substitution of a phenyl group for the 3 terminal carbon units of the alkyl side chain ... increased both the affinity for the receptor and the luteolytic activity in vivo." The companion 1975 Eur. J. Biochem. SAR paper adds the metabolic rationale — the 17-phenyl analogs are less rapidly dehydrogenated by 15-hydroxy-PG dehydrogenase (relative substrate activity ~34 vs. 100 for PGF₂α).

• Motivation to combine (KSR): The problem was identified in the art — topical PGF₂α's ocular irritation/hyperemia caps the usable dose below the pressure-optimal dose (the '368 background; also acknowledged in Bito). Two known solution directions were on the shelf: (i) esterify for penetration (Bito), and (ii) modify the omega/alkyl chain to raise affinity and block metabolic degradation (Miller / EJB 1975). A POSITA pursing a better topical anti-glaucoma PG would predictably reach for a metabolically stabilized, high-affinity PGF₂α analog and put it in an ophthalmic vehicle.

• Legal hook: Under In re Dillon, structural similarity plus a shared utility (prostaglandin activity) establishes a prima facie case. Miller supplies the structure and utility; Bito supplies the ocular utility and the vehicle. Claim 7/15 (PGF₂α, B = single or double bond, D = 3 C, phenyl) and claim 12 (PGE) read directly onto compounds Miller names — the only missing claim elements are the ophthalmic vehicle (Bito) and the functional "no substantial irritation" limitation.

• Weakness of this combination: Bito discloses a natural omega chain; nothing in Bito or Miller suggests the ring would abolish ocular irritation, and Miller's data (potency ↑, affinity ↑) would, if anything, predict more side effects.

Combination B — the "13,14-dihydro" combination: Miller + EP 308135 (Ueno) / Woodward 1989 (Ophthalmic Res.)

(targets G5 — latanoprost)

• EP 308135 (Ueno) discloses 13,14-dihydro-15-keto prostaglandins, and Woodward's Ophthalmic Res. 21:428–435 (1989) paper expressly studies 13,14-dihydro PGF₂α on IOP (finding it active, though less potent than 15-keto). So the 13,14-dihydro modification was a known, IOP-active PG modification — the natural metabolite/enzymatic-reduction product.
• Motivation: once the POSITA selects 17-phenyltrinor PGF₂α (Combination A), adding the 13,14-dihydro saturation is a routine, known metabolic-stabilization step with an expected retention of activity. Adding the isopropyl ester is taught by Bito/Villumsen. The assembled molecule is latanoprost.
• Best non-obviousness counter: none of these references identifies the specific permutation (13,14-dihydro + 17-phenyl-trinor + isopropyl ester) or predicts the receptor-selectivity gain (latanoprost's FP selectivity vs. 17-phenyltrinor's residual EP1/TP agonism — the very data cited in the later UK litigation). Otsuka v. Sandoz requires the art to point to the lead and give a reason to make the specific modification; the further one goes from Miller's 17-phenyltrinor toward latanoprost, the weaker the "specific reason" becomes.

Combination C — the PGD claim: Bito '353 / EP 0242580 + Goh (EP 253094 / U.S. 4,824,857) + Miller

(targets G2 — claim 57)

• Bito's group (U.S. 4,883,819 / EP 0242580, i.e., EP 87 103 714.9) teaches topical PGA/PGB/PGC for IOP; Goh et al. (EP 253094 / U.S. 4,824,857) disclose PGD₂ derivatives; Miller supplies the 17-phenyl-trinor concept. A POSITA combining the glaucoma utility (Bito) with the PGD₂-derivative genus (Goh) and the ring-substituted omega chain (Miller) reaches claim 57.
• Why claim 57 is more exposed than claims 1/29: claim 57's R₂ is limited to (e) an aromatic ring or (f) a 5–6-membered aromatic heterocycle — it drops the cycloalkane/cycloalkene option. The narrower R₂ set maps more cleanly onto Miller's phenyl teaching. Also, the '368 family's own EPO search report (EP 1224934) cited EP 0093930 (Columbia) as an "X" reference — I could not retrieve its content, so I flag this as an unresolved pro-obviousness lead rather than asserting it.

Combination D — the method/dosing claims: Bito '353 + Camras 1988 + Kerstetter 1988 + Villumsen 1989

(targets G6 — claims 24–28, 52–56)

• Claims 24 and 52 are simply "treat glaucoma/ocular hypertension by topically applying the composition of claim 1 / claim 29." If the composition claim is obvious, these fall with it (In re Kuehl; a method claim is obvious when the composition and its use are obvious).
• Claims 26–28's dosing ranges (0.1–30 µg; 1–10 µg; twice daily; 10–50 µL) track the doses already reported for topical PG and PGF₂α-isopropyl ester (Camras 1988; Kerstetter 1988; Villumsen & Alm 1989). Dose optimization within a disclosed range is routine (In re Aller; Pfizer v. Apotex).

4. Claim-by-claim bottom line

5. Why a POSITA would have been motivated — and the three reasons the argument can fail

The motivation (KSR prong). The record supplies an express problem statement ("ocular irritation limits the clinically usable dose"), two express solution mechanisms (esterification; omega-chain modification for affinity/stability), and art that identifies the specific structural change (phenyl-for-terminal-propyl). Under KSR, that is enough for a prima facie case — the POSITA need not have foreseen the degree of improvement, only a reasonable expectation of some success.

Failure mode 1 — teaching away (Woodward 1989). The art reported the key compound as inactive for IOP in rabbit and cat. A POSITA reading Woodward would not have a reasonable expectation that 17-phenyltrinor PGF₂α lowers pressure at all. This alone can defeat a prima facie case for the § 102/§ 103 method and composition claims directed to IOP reduction. But the teach-away is species-limited — Woodward's negatives are rabbit/cat; the '368's own data show activity in cynomolgus monkeys and humans, and the patent itself explains that cat data do not extrapolate to primates. A challenger can therefore argue the teach-away is weak.

Failure mode 2 — unexpected results not commensurate with scope. The claimed advantage ("without substantial ocular irritation") is species- and compound-specific, not genus-wide. The '368's own Table III shows 16-phenyl-17,18,19,20-tetranor-PGF₂α-IE had a discomfort score of 2.2 — i.e., a ring-containing omega chain that is irritating. This undercuts the broad genus claims 1/29 (the functional limitation is not enabled/commensurate across the claimed scope) and simultaneously supports the narrow species claims 20–23. Under In re Greenfield / In re Harris, unexpected results must be shown across the claimed scope.

Failure mode 3 — the pre-KSR "specific reason" gloss. Under Otsuka v. Sandoz / Takeda v. Zydus, even if A + B are combinable in principle, the art must give a reason to make the specific modification. Miller supplies a reason to make 17-phenyltrinor PGF₂α; it does not supply a reason to then add 13,14-dihydro and the isopropyl ester. Latanoprost (claims 20–23) therefore sits at the end of a chain of unprompted selections.

6. Secondary considerations (objective indicia)

(I verified the EWHC/EWCA citations only at the level of the quoted passages; I did not retrieve the full judgments.)

7. Verdict

1. The 17-phenyl-trinor subgenus (claims 7, 12, 15, 16, 18) is the weakest. Miller 1975 names the exact compounds, Bito '353 puts a PGF₂α ester in an ophthalmic vehicle for glaucoma, and the functional "no substantial irritation" limitation may be inherent to the known compound — which, under In re Papesch, does not rescue a claim to an old composition merely by discovering an old property. Bito '353 + Miller 1975 is a strong, two-reference prima facie case.
2. The latanoprost species (claims 20–23, 48–51) is the strongest. It requires a specific, unsuggested three-way permutation, and the objective indicia (teaching away by Woodward, unexpected side-effect separation, blockbuster commercial success) cluster here.
3. The broad genera (claims 1, 29, 57) are arguable. They are broad enough to be prima facie obvious as a design space (KSR: "finite number of identified, predictable solutions"), but the functional limitation is not supported across the scope the claims cover.
4. The method/dose claims (24–28, 52–56) rise or fall with the composition claims and are additionally vulnerable to routine-optimization reasoning.

The single biggest swing factor is the priority date. If the claims carry the 1988-09-06 date, Woodward 1989 and Villumsen & Alm 1989 drop out as § 102 art and the teaching-away becomes a § 103 rebuttal rather than a reference; if the operative date is the 1990-04-10 parent, they are squarely available and the obviousness case strengthens materially.

Explicit uncertainties I am not papering over:

• I did not retrieve the examiner's front-page "References Cited" list for 07/986,943, so this analysis uses the reference pool established in the Prior Art section plus the four references added here — it is not a reproduction of the Examiner's rejection.
• EP 0093930 (Columbia), cited "X" by the EPO against this family, was not retrievable; it may be a genuinely anticipatory/obviousness reference for the genus claims and should be pulled.
• The earlier sections flagged a conflicting attribution of the number "US 5,422,368" to a "Takahashi" reference in an EPO search report; per the no-auto-correction rule, that conflict stands as found, but this § 103 analysis proceeds on the authoritative full text (Stjernschantz/Resul).
• Claims 66–87 remain unseen; if any of them is a further independent claim (e.g., a second method genus), it would need the same test.