Why Generic Tirzepatide Won't Be Here Any Time Soon

Originally posted on obesity.news on January 15th, 2026

The US Patent and Trademark Office has officially declined to review a petition from Empower Pharmacy seeking to invalidate a foundational Eli Lilly patent covering tirzepatide, the active ingredient in Zepbound and Mounjaro. The rejection leaves Lilly’s legal fortress around the GLP-1/GIP agonist intact, for now. This also puts pressure on the only remaining open challenge from BPI Labs.

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Empower had filed an inter partes review (IPR) last year targeting Patent No. 9,474,780 B2, one of the core patents in Lilly’s tirzepatide estate. The PTAB initially denied institution of the review. Empower appealed to the USPTO Director, a procedural long shot, and that request was officially rejected on January 12, 2026, ending the case.

The denial underscores the difficulty challengers face in attempting to unwind Lilly’s IP position on tirzepatide, a drug expected to generate $30B+ annually by decade’s end across obesity and diabetes indications.

BPI’s challenge remains, barely.

With Empower out, attention now turns to BPI’s pending IPR case, IPR2025-01346, which targets a separate tirzepatide patent. As of January 9, the USPTO Director acknowledged BPI’s request for Director Review following a similar initial denial from the PTAB. Lilly has been granted five business days to respond.

If the Director declines to grant review, as happened with Empower, that would mark the second straight win for Lilly and likely cement its short-term IP defense.

Why this matters

While a successful IPR wouldn’t immediately clear the way for generics or compounded alternatives, it would weaken Lilly’s ability to litigate and intimidate competitors (particularly the 503B compounders) still operating in the wake of last year’s tirzepatide shortage.

Lilly has pursued an aggressive post-shortage legal campaign against compounders, leveraging cease-and-desist letters and early injunction threats to narrow the playing field. Empower’s failed challenge suggests the company’s patent portfolio may be more durable than some industry watchers anticipated.

Still, the stakes remain high. Tirzepatide is protected under FDA new chemical entity exclusivity until at least May 2027, meaning generic ANDAs can’t be approved until that window closes. But successful patent invalidation through IPR could shorten litigation timelines, lower the barrier to generic entry, and embolden telehealth and compounding pharmacies to resume activity — if they’re willing to take the risk.

What’s next

The USPTO is expected to rule on whether BPI’s IPR request will be granted in the coming weeks. If denied, Lilly effectively avoids any near-term threat to its tirzepatide IP from administrative channels, at least until new challengers emerge with fresh claims or stronger prior art.

For now, though, Lilly’s position remains secure, and Empower is out of moves.

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