Here’s a practical way to think about histamine H1 receptor small-molecule drug patents, plus how I can help you assemble a focused patent landscape.
What you’re looking at
- The histamine H1 receptor antagonists are a large class of small molecules with a long patent history going back to mid-20th century. Major “second-generation” antihistamines (cetirizine, loratadine, fexofenadine, desloratadine, levocetirizine, rupatadine, ebastine, mizolastine, bilastine, etc.) are all small molecules but span many patent families, including original composition patents, salt/formulation patents, enantiomer-specific patents, and synthetic routes.
- In addition to systemic agents, there are topical/ocular antihistamines (e.g., olopatadine, azelastine) that have their own patent families focused on formulations and delivery.
What you might want to compile
- A landscape of key patent families by drug (e.g., cetirizine, loratadine, fexofenadine, desloratadine, rupatadine, ebastine, mizolastine, bilastine, olopatadine, azelastine, etc.).
- For each drug: earliest priority date, major patent families (composition, salts, polymorphs, enantiomers, formulations), and current status (in force, expired, or pending).
- Jurisdictions of interest (US, Europe, Japan, China, etc.) and any relevant regional equivalents (EP, US, WO, JP, CN).
- Notable shifts in patent protection (for example, when a parent compound patent expired and the market moved to generics, or when second/third-generation salt or formulation patents extended protection).
How to search effectively (recommended databases and search strategy)
- Databases to use:
- Google Patents (easy, broad)
- Espacenet (European Patent Office)
- USPTO Patent Full-Text and Image Database
- WIPO Patentscope (PCT)
- Local patent offices for specific jurisdictions
- Useful search strings and tactics:
- For a given drug name: “[drug name] patent” or “[drug name] composition patent” or “[drug name] salt patent” or “[drug name] enantiomer patent”
- Broader class searches: “histamine H1 receptor antagonist” or “H1 receptor antagonist” or “H1 antihistamine”
- Combine with “salts” (e.g., “loratadine salt patent”), “polymorph” or “crystal form,” “formulation,” “topical,” “ophthalmic,” depending on interest
- Use CPC/IPC classifications where possible (e.g., A61K for preparations; C07D for heterocyclic compounds; G06F for computational tools if you’re mining data)
- Track families by starting with a well-known drug and then use “family members” and “continuations” to capture related patents (enantiomers, salts, isotopologues, etc.)
- Look for “priority claims” and “family members” across jurisdictions to map who owns what in which region
Starter list of notable H1 antagonists you may want to map first
- Diphenhydramine, chlorpheniramine, promethazine (first-generation, classic antihistamines)
- Cetirizine (second-generation)
- Loratadine (second-generation)
- Desloratadine (active metabolite of loratadine; expanded patent family)
- Levocetirizine (active enantiomer of cetirizine)
- Fexofenadine (second-generation; metabolite of terfenadine)
- Rupatadine (later-generation antihistamine)
- Ebastine and mizolastine (second/third-generation)
- Bilastine (newer-generation)
- Olopatadine (ophthalmic/topical antihistamine)
- Azelastine (nasal/ocular topical antihistamine)
Notes and caveats
- Patent coverage is jurisdiction-specific and can be spread across core compound patents, salt/formulation patents, process patents, and use or method-of-treatment patents. Expirations vary by country and by patent term adjustments.
- Many early-generation antihistamine patents have long since expired and are generic in most markets; second- and later-generation drugs often have active patent families for specific salts, formulations, or enantiomeric forms that may still be in force in some jurisdictions.
- For regulatory and competitive intelligence, also consider marketing exclusivities and regulatory data protection, which can extend effective market exclusivity beyond patent expiry in some regions.
What I can do next
- If you tell me your target drugs (or jurisdictions) and whether you want a historical overview vs. a current, jurisdiction-specific map, I can draft a structured plan and provide a starter spreadsheet-like outline:
- Drug name
- Key patent families (in US, EP, and JP)
- Status (in force/expired/pending)
- Notable claims (e.g., composition, salt, polymorph, formulation, use)
- Link to public patent records
- I can also generate a tailored search checklist (exact queries to run in Google Patents, Espacenet, USPTO, and Patentscope) and an approach for validating status (e.g., checking maintenance fees, term adjustments, and any ongoing litigations).
If you want, tell me:
- Which drugs or drug classes you’re most interested in
- Which jurisdictions you care about
- Whether you want a high-level landscape or a detailed, patent-by-patent map
I can then provide a focused, actionable overview or a concrete search plan with example results, depending on your needs. Note: for formal legal or patent clearance, consult a patent attorney or a professional patent searcher.