An alarming side effect was found.
Pfizer has discontinued the development of a once-daily oral medication aimed at treating obesity after a clinical trial participant showed potential signs of liver damage. The company noted that the individual’s condition improved once they stopped taking the experimental drug, danuglipron, according to a report by The Associated Press.
The drug was still in the early phases of testing, which focused on determining an appropriate dosage. Although Pfizer had originally intended to advance danuglipron to late-stage clinical trials — typically the final step before seeking approval from the U.S. Food and Drug Administration — all development of the drug has now been halted. This includes any studies evaluating its use in combination with other obesity treatments.
Despite the setback, Pfizer stated it remains committed to developing other obesity-related therapies that are currently in earlier research phases.
The market for weight-loss medications has become increasingly competitive and lucrative. Injectable drugs like Eli Lilly’s Zepbound and Novo Nordisk’s Wegovy have generated substantial revenue, with Zepbound alone bringing in nearly $5 billion in 2024, according to the AP. However, the injectable nature of these drugs can be a barrier for some patients, prompting pharmaceutical companies to pursue more convenient oral alternatives.
Eli Lilly, for instance, is expected to release results later this year from studies involving two of its own oral obesity drug candidates.
While demand for obesity treatments remains high, many patients struggle with limited insurance coverage or steep out-of-pocket expenses. Even after recent price reductions, the monthly cost for many of these medications still runs into the hundreds of dollars.
Pfizer had previously ended development of a twice-daily formulation of danuglipron in late 2023, following a high dropout rate among participants in that trial.
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