United States Patent 5,250,534: A Comprehensive Analysis of Scope and Claims
Introduction
United States Patent 5,250,534, titled "Pyrazolopyrimidinone antianginal agents," is a significant patent in the pharmaceutical domain, particularly in the treatment of cardiovascular disorders. This patent, granted on October 5, 1993, outlines a series of compounds with therapeutic applications and provides a detailed description of their synthesis, properties, and uses.
Patent Overview
The patent describes a class of compounds known as pyrazolopyrimidinones, which are potent and selective inhibitors of cyclic guanosine 3',5'-monophosphate phosphodiesterase (cGMP PDE). These compounds are useful in treating various cardiovascular disorders, including stable, unstable, and variant (Prinzmetal) angina, hypertension, congestive heart failure, atherosclerosis, and other conditions related to reduced blood vessel patency[1][4].
Chemical Structure and Synthesis
The compounds of the patent are defined by the general formula (I), where various substituents (R1, R2, R3, and R4) can be modified to produce different derivatives. For example:
- R1 can be H, C1-C3 alkyl, C3-C5 cycloalkyl, or C1-C3 perfluoroalkyl.
- R2 can be H, C1-C6 alkyl optionally substituted by OH, C1-C3 alkoxy, or C3-C6 cycloalkyl, or C1-C3 perfluoroalkyl.
- R3 can be C1-C6 alkyl, C3-C6 alkenyl, C3-C6 alkynyl, C3-C7 cycloalkyl, C1-C6 perfluoroalkyl, or (C3-C6 cycloalkyl)C1-C6 alkyl.
- R4, along with the nitrogen atom, completes a pyrrolidinyl, piperidino, morpholino, or 4-N-(R6)-piperazinyl group[1][4].
Therapeutic Applications
The pyrazolopyrimidinone compounds are versatile and have a broad range of therapeutic applications. They are particularly useful in the treatment of:
- Cardiovascular disorders such as angina, hypertension, heart failure, and atherosclerosis.
- Conditions characterized by reduced blood vessel patency, including post-PTCA (percutaneous transluminal coronary angioplasty).
- Respiratory conditions like chronic asthma, bronchitis, allergic asthma, and allergic rhinitis.
- Other diseases such as glaucoma and disorders of gut motility, e.g., irritable bowel syndrome (IBS)[1][4].
Pharmaceutically Acceptable Salts and Derivatives
The patent includes the use of pharmaceutically acceptable salts of the compounds, which are formed with acids such as hydrochloride, hydrobromide, sulphate, phosphate, acetate, citrate, fumarate, gluconate, lactate, maleate, succinate, and tartrate. Additionally, the patent covers radiolabelled derivatives suitable for biological studies and the existence of these compounds in tautomeric forms and as mixtures or separate individual isomers[1].
Patent Claims
The patent claims are detailed and specific, covering the compounds of the general formula (I), their synthesis, and their therapeutic uses. Key claims include:
- The chemical structure of the pyrazolopyrimidinone compounds.
- Methods for synthesizing these compounds.
- The use of these compounds in the manufacture of medicaments for various therapeutic applications.
- The inclusion of pharmaceutically acceptable salts and derivatives[1].
Patent Scope and Breadth
The scope of the patent is broad, reflecting the versatility of the pyrazolopyrimidinone compounds. However, the claims are narrowed down to specific structures and uses to ensure clarity and validity. This is in line with the general trend observed in patent law, where narrower claims at publication are associated with a higher probability of grant and a shorter examination process[3].
Legal Status and Expiration
The patent has expired, as indicated by its legal status. This means that the exclusive rights to the invention have lapsed, and the technology is now in the public domain.
Impact on Pharmaceutical Industry
The patent has had a significant impact on the pharmaceutical industry, particularly in the development of treatments for cardiovascular diseases. The compounds described have been used as a foundation for further research and development of similar therapeutic agents.
Comparison with Other Patents
Other patents, such as WO2017168174A1, which describes new pharmaceutical forms of sildenafil, also a cGMP PDE inhibitor, highlight the ongoing innovation in this therapeutic area. However, US5250534A stands out for its comprehensive coverage of pyrazolopyrimidinone compounds and their diverse applications[2].
Conclusion
United States Patent 5,250,534 is a landmark patent in the field of cardiovascular therapeutics. It provides a detailed description of pyrazolopyrimidinone compounds, their synthesis, and their therapeutic applications. The patent's scope and claims are well-defined, ensuring clarity and validity. As the patent has expired, its technology is now available for public use, contributing to ongoing research and development in the pharmaceutical industry.
Key Takeaways
- Chemical Structure: The patent describes pyrazolopyrimidinone compounds with specific substituents.
- Therapeutic Applications: The compounds are useful in treating various cardiovascular and respiratory disorders.
- Synthesis and Derivatives: The patent includes methods for synthesizing the compounds and forming pharmaceutically acceptable salts and derivatives.
- Patent Scope and Claims: The claims are specific and cover the chemical structure, synthesis, and therapeutic uses.
- Legal Status: The patent has expired, making the technology publicly available.
- Impact: The patent has significantly influenced the development of treatments for cardiovascular diseases.
FAQs
Q: What are the primary therapeutic applications of the pyrazolopyrimidinone compounds described in US5250534A?
A: The primary therapeutic applications include the treatment of cardiovascular disorders such as angina, hypertension, heart failure, and atherosclerosis, as well as respiratory conditions like asthma and bronchitis.
Q: How are the pyrazolopyrimidinone compounds synthesized?
A: The compounds are synthesized through the reaction of specific precursors, with detailed methods described in the patent.
Q: What types of pharmaceutically acceptable salts are included in the patent?
A: The patent includes salts formed with acids such as hydrochloride, hydrobromide, sulphate, phosphate, and others.
Q: Has the patent expired?
A: Yes, the patent has expired, making the technology publicly available.
Q: How does this patent compare to other patents in the same therapeutic area?
A: This patent stands out for its comprehensive coverage of pyrazolopyrimidinone compounds and their diverse applications, while other patents like WO2017168174A1 focus on different aspects such as new pharmaceutical forms of sildenafil.
Sources
- US5250534A - Pyrazolopyrimidinone antianginal agents - Google Patents
- WO2017168174A1 - New pharmaceutical forms of sildenafil - Google Patents
- Patent Claims and Patent Scope - SSRN
- US5719283A - Intermediates useful in the synthesis of pyrazolopyrimidinone antianginal agents - Google Patents
- Federal Register, Volume 69 Issue 31 - GovInfo
