Prior art

The following analysis identifies the most relevant prior art for US patent 8268847 by examining each patent citation listed within the patent document itself. Each reference is assessed for its full citation, publication/filing date, a brief description of its invention, and the claims of US8268847 it potentially anticipates under 35 U.S.C. § 102.

The claims of US8268847 primarily cover a product, pharmaceutical composition, and method for treating diseases involving vasoconstriction, comprising the compound of formula (I) (an endothelin receptor antagonist) in combination with a PDE5 inhibitor (specifically sildenafil, vardenafil, tadalafil, or udenafil). The patent asserts a synergistic effect for this combination.

Most Relevant Prior Art for US8268847

The patent US8268847 cites the following patent documents as prior art:

1. US5250534A

   • Full Citation: US5250534A, titled "Pyrazolopyrimidinone antianginal agents," assigned to Pfizer Inc.
   • Publication/Filing Date: Priority date: 1990-06-20, Publication date: 1993-10-05.
   • Brief Description: This patent describes pyrazolopyrimidinone derivatives, including sildenafil, as PDE5 inhibitors. It details their use for various conditions, including hypertension and heart failure. The patent is a foundational reference for sildenafil.
   • Potential Anticipation: This patent teaches sildenafil as a PDE5 inhibitor and its use for hypertension and heart failure. While it does not teach the specific combination with Compound (I), it lays the groundwork for the PDE5 inhibitor aspect. It could be seen as anticipating the component sildenafil for the stated diseases, but not the synergistic combination itself. It is highly relevant to claims 2, 4, 7, 9, and 11, which specify sildenafil as the PDE5 inhibitor.

2. US5859006A

   • Full Citation: US5859006A, titled "Tetracyclic derivatives; process of preparation and use," assigned to Icos Corporation.
   • Publication/Filing Date: Priority date: 1994-01-21, Publication date: 1999-01-12.
   • Brief Description: This patent describes tadalafil and its use for conditions such as hypertension, pulmonary hypertension, angina, and congestive heart failure.
   • Potential Anticipation: Similar to US5250534A, this patent teaches tadalafil as a PDE5 inhibitor and its use for a range of conditions, including hypertension and pulmonary hypertension. It is highly relevant to claims 2, 3, 7, 8, and 11, which specify tadalafil as the PDE5 inhibitor, and to claims 5 and 10 which mention hypertension and pulmonary hypertension as target diseases. It does not teach the combination with Compound (I).

3. WO1999024433A1

   • Full Citation: WO1999024433A1, titled "2-phenyl substituted imidazotriazinones as phosphodiesterase inhibitors," assigned to Bayer Aktiengesellschaft.
   • Publication/Filing Date: Priority date: 1997-11-12, Publication date: 1999-05-20.
   • Brief Description: This international publication describes vardenafil as a PDE5 inhibitor and its use for conditions including hypertension, angina pectoris, and erectile dysfunction.
   • Potential Anticipation: This document teaches vardenafil as a PDE5 inhibitor and its therapeutic applications. It is relevant to claims 2, 7, and 11, which list vardenafil as a possible PDE5 inhibitor. It does not disclose the combination with Compound (I).

4. WO2000027848A1

   • Full Citation: WO2000027848A1, titled "Pyrazolopyrimidinone derivatives for the treatment of impotence," assigned to Dong A Pharm. Co., Ltd.
   • Publication/Filing Date: Priority date: 1998-11-11, Publication date: 2000-05-18.
   • Brief Description: This international publication describes udenafil and its use for impotence (erectile dysfunction).
   • Potential Anticipation: This document teaches udenafil as a PDE5 inhibitor and its therapeutic applications, specifically erectile dysfunction. It is relevant to claims 2, 7, and 11, which list udenafil as a possible PDE5 inhibitor, and to claim 5 for erectile dysfunction. It does not disclose the combination with Compound (I).

5. WO2002053557A1

   • Full Citation: WO2002053557A1, titled "Novel sulfamides and their use as endothelin receptor antagonists," assigned to Actelion Pharmaceuticals Ltd.
   • Publication/Filing Date: Priority date: 2000-12-18, Publication date: 2002-07-11.
   • Brief Description: This publication describes endothelin receptor antagonists, including the compound of formula (I), and their use in treating various diseases where vasoconstriction is involved (e.g., heart failure, angina pectoris, pulmonary and systemic hypertension, and erectile dysfunction).
   • Potential Anticipation: This document is highly relevant as it describes the compound of formula (I) and its therapeutic uses, which are the foundational elements of US8268847. It essentially anticipates the first component of the claimed combination and its therapeutic applications. It is relevant to claims 1, 5, 6, and 10, insofar as they describe the compound of formula (I) and its use in treating diseases involving vasoconstriction. However, it does not teach the combination with a PDE5 inhibitor.

6. EP1097711A2

   • Full Citation: EP1097711A2, titled "Treatment of pulmonary hypertension," assigned to Pfizer Limited.
   • Publication/Filing Date: Priority date: 1999-11-02, Publication date: 2001-05-09.
   • Brief Description: This patent application describes the use of sildenafil for the treatment of pulmonary hypertension.
   • Potential Anticipation: This document specifically teaches the use of sildenafil (a PDE5 inhibitor) for pulmonary hypertension, one of the key diseases mentioned in US8268847. This directly addresses the PDE5 inhibitor aspect for a specific disease. It is highly relevant to claims 2, 4, 5, 7, 9, 10, and 11 as it teaches the use of sildenafil for pulmonary hypertension. Again, it does not teach the combination with Compound (I).

7. WO2006026395A1

   • Full Citation: WO2006026395A1, titled "Endothelin a receptor (eta) antagonists in combination with phosphodiesterase 5 inhibitors (pde5) and uses thereof," assigned to Encysive Pharmaceuticals.
   • Publication/Filing Date: Priority date: 2004-08-26, Publication date: 2006-03-09.
   • Brief Description: This document explicitly describes combinations of Endothelin A (ETA) receptor antagonists with PDE5 inhibitors for various uses.
   • Potential Anticipation: This is a highly relevant piece of prior art as it teaches the core combination of an endothelin receptor antagonist with a PDE5 inhibitor for therapeutic use. This directly bears on claims 1, 6, and 10 which broadly claim such combinations. However, it would depend on the specificity of the ETA antagonist used by Encysive (whether it explicitly includes or makes obvious "Compound (I)") and the diseases claimed, to determine full anticipation of specific claims in US8268847. Given that US8268847 claims a specific endothelin receptor antagonist (Compound I) and a synergistic effect, this document would be a primary reference for challenging the novelty or non-obviousness of the broad combination claims (1, 6, 10). It is particularly relevant for claims 1, 5, 6, and 10.

Other cited patents like US4233294A, US5292740A, EP0658548A1, WO1996016963A1, WO1996019459A1, EP0743307A1, AU678467B2, EP0959072A1, EP0882719A1, WO1999064004A1, WO2000042035A1, WO2001017976A1, WO2001046156A1, WO2001081335A1, WO2001081338A1, US7285549B2, US7094781B2, US7094081B1, WO2007031933A2, and US20080233188A1, and US20100022568A1 appear to describe various sulfonamide derivatives, endothelin receptor antagonists (other than compound I or not in combination with PDE5 inhibitors), or pharmaceutical compositions/formulations, but not the specific combination claimed in US8268847. They contribute to the general state of the art regarding endothelin receptor antagonists, PDE5 inhibitors, or pharmaceutical formulations but are less directly anticipatory of the combination invention compared to the patents specifically detailing PDE5 inhibitors or broad combinations of ERA and PDE5 inhibitors.