The decision puts another hurdle in the pharmaceutical giant’s race to develop an oral alternative to popular injectable obesity treatments
New York, 8 October 2026 – Pfizer has stopped the development of danuglipron, an experimental oral medicine being studied for weight management, after a participant in a clinical trial experienced a potential drug-induced liver injury. The decision marks a setback for Pfizer’s plans to establish a stronger position in the rapidly expanding obesity treatment market.
Danuglipron was designed as a GLP-1 receptor agonist, a type of medicine that works on pathways involved in appetite, blood sugar control, and digestion. Unlike widely used injectable treatments, Pfizer was developing danuglipron as a tablet that could potentially offer patients a more convenient option.
The company had been testing a once-daily version of the medicine after previously deciding not to advance a twice-daily formulation. Earlier clinical research showed that the twice-daily version could reduce body weight, but gastrointestinal side effects such as nausea, vomiting, and diarrhea were reported frequently. More than half of participants discontinued treatment across the tested doses in the Phase 2b study.
Pfizer later moved its attention toward improving the formulation and determining an appropriate once-daily dose. Those studies included more than 1,400 participants in the overall safety database. Pfizer said the overall frequency of liver enzyme elevations was in line with approved medicines in the same class. However, one participant developed a potential drug-induced liver injury. The condition was asymptomatic and resolved after the medicine was discontinued.
After reviewing the available clinical information and receiving input from regulators, Pfizer decided to end development of danuglipron. The company said the decision was based on the totality of the evidence rather than the single event alone.
The setback comes as pharmaceutical companies continue to compete for a larger share of the obesity treatment market. Medicines targeting GLP 1 pathways have transformed weight management, creating strong demand for treatments that can provide meaningful weight reduction while improving convenience and tolerability.
One major area of interest is oral obesity medicine. Tablets could appeal to patients who prefer not to use injections and could potentially simplify treatment. As a result, several pharmaceutical companies are working on oral GLP 1 drugs and other approaches designed to address obesity.
Pfizer is not leaving the obesity field. The company said it will continue developing other investigational treatments, including an oral medicine targeting the GIP receptor, along with additional early-stage obesity programs.
The company’s decision also highlights the challenges involved in developing new weight loss medicines. Strong demand alone does not guarantee success. Drug developers must demonstrate that a treatment can deliver meaningful benefits while maintaining an acceptable safety and tolerability profile through clinical testing.
For the broader pharmaceutical industry, Pfizer’s decision underscores the importance of safety monitoring as the next generation of obesity treatments moves through development. The search for effective weight loss pills continues, with researchers focusing on new mechanisms, improved formulations, and treatment options that could eventually expand access to obesity care.
