Not every drug covered on this site made it to market, and the ones that didn't are often as instructive as the ones that did. Danuglipron, Pfizer's attempt at an oral GLP-1 weight-loss pill, is a useful case study in how a promising program can end before approval.
What It Was
Like orforglipron, danuglipron was a small-molecule (non-peptide) oral GLP-1 receptor agonist, intended as a once-daily pill competitor to injectable and other oral GLP-1 drugs. Pfizer had tested it in both twice-daily and once-daily formulations as part of its push into the obesity drug market.
A Program With a Troubled History
Danuglipron's path was rockier than most. Pfizer discontinued a related once-daily candidate, lotiglipron, in 2023 after it was associated with elevated liver enzymes in trial participants, and dropped the twice-daily danuglipron formulation that same year, continuing development only with a reformulated once-daily version of danuglipron, which the company had described as its strongest remaining contender in the category.
Why Development Stopped
That once-daily version was also discontinued. In April 2025, Pfizer ended the program after a Phase 1 dose-optimization study recorded a case of potential drug-induced liver injury in a trial participant. The injury reportedly resolved after the person stopped taking the drug, and Pfizer's own review found that the overall rate of liver enzyme elevations across the trial was broadly in line with other approved drugs in the GLP-1 class. Even so, combined with regulatory input and the program's prior history, the company chose to discontinue danuglipron entirely on April 14, 2025, rather than continue development.
Regulatory Status
Danuglipron was never submitted for, and never received, FDA approval. It is not available to patients in any form, and no fixed-dose combination product Pfizer had also been developing around it went forward either.
What It Means for the Field
Danuglipron's end illustrates two things at once. First, liver safety is something regulators and manufacturers are actively watching across this entire drug class, not just for one company's product, a useful reminder that "GLP-1 drugs" are not a monolithic risk category; different molecules in the same class can behave differently even when they target the same receptor. Second, it shows how competitive and unforgiving the oral GLP-1 race has become: Pfizer's exit from the once-daily oral market left more room for competitors, including Eli Lilly's orforglipron (Foundayo), which went on to win FDA approval in 2026.
It's also a reminder of how much drug development happens out of public view before a single pill reaches a pharmacy shelf. By the time danuglipron was discontinued, Pfizer had already spent years and, by most industry estimates, hundreds of millions of dollars on the program, across multiple reformulations and two related compounds. That kind of attrition is normal in drug development generally, not unique to GLP-1 drugs or to Pfizer, but it's easy to lose sight of amid news coverage that tends to focus only on the drugs that succeed.
The Bottom Line
Danuglipron is a discontinued, never-approved drug candidate, not a product anyone can currently obtain or be prescribed. Its story is a reminder that Phase 1 and Phase 2 trial data, even promising data, can still end in a safety-driven discontinuation before a drug ever reaches the market.