When did the first generic amiloride hit the market?
The earliest U.S. generic approval for amiloride was granted on March 24, 1993. This entry followed the expiration of the original 1978 patent and cleared the way for generic manufacturers to offer the drug under the same dosage form and strength as the brand product[1].
What does the original patent say?
The key U.S. patent covering amiloride, granted in 1975, covered the drug’s chemical composition and its use as a diuretic. It ran to the mid‑1990s, but a secondary patent on a specific formulation (amiloride hydrochloride) expired a few months earlier, enabling generic entry in 1993[1].
Why did it take until 1993?
The 15‑year exclusivity period that applies to most prescription drugs meant that the generic manufacturer could only file an Abbreviated New Drug Application (ANDA) once the original patent term concluded. Regulatory review and the need to demonstrate bioequivalence also added several months, bringing the first approval to March 1993[1].
How did the generic compete with the brand?
After approval, generic amiloride was sold at a substantially lower price, typically 70‑80 % cheaper than the branded version. Because the drug’s therapeutic profile is straightforward—a potassium‑sparing diuretic—generic competitors quickly captured a sizable share of the hypertension and heart failure markets[1].
Are there still patents on amiloride?
While the original composition patents have long expired, a handful of formulation and delivery‑system patents remain active. These allow certain manufacturers to produce proprietary extended‑release or combination products, but they do not block the sale of standard amiloride tablets or capsules[1].
Where to find the full timeline
A comprehensive list of amiloride patents, their expiry dates, and generic filing information is available on DrugPatentWatch.com. The site tracks both U.S. and international data, including dates of first generic entry, patent term extensions, and active exclusivity periods[1].
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[1] https://www.drugpatentwatch.com/amiloride