Wednesday, July 8, 2026

Patent intelligence · US

US 6376536

Quaternary ammonium salts and their use

expired A61KA61K31/335A61K31/351A61K31/452
Status expired
Linked drugs 3
Pipeline programs 6
Years to expiry 0
Applicant portfolio 1,436
Patent details — US 6376536
Jurisdiction
US
Status
expired
Grant date
Apr 23, 2002
Expiration
Apr 18, 2022
Claims
7
CPC classes
A61K, A61K31/335, A61K31/351, A61K31/452
View on Google Patents ↗

Quick answer

US 6376536 (Quaternary ammonium salts and their use) is held by Takeda Chemical Industries Ltd.. Status: expired. Granted Apr 23, 2002. Expires Apr 18, 2022 (0 years remaining) — relevant for patent-cliff and LOE planning.

Key facts

Grant date
Expiration
Claims
7
CPC classes
A61K, A61K31/335, A61K31/351, A61K31/452, A61K31/4523, A61K31/5377

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Frequently asked questions

What is US patent 6376536?

US 6376536 (Quaternary ammonium salts and their use) is held by Takeda Chemical Industries Ltd.. Status: expired. Granted Apr 23, 2002. Expires Apr 18, 2022 (0 years remaining) — relevant for patent-cliff and LOE planning.

Who owns US 6376536?

Takeda Chemical Industries Ltd. is listed as the applicant in USPTO PatentsView records indexed by NovaPharmaNews. We track 1,436 pharmaceutical patents for this assignee.

When does US 6376536 expire?

Our index shows an expiration date of Apr 18, 2022 (0 years from today). Confirm material dates against USPTO, FDA Orange Book, or qualified counsel before contractual decisions.