That decision, however, has investors fretting over whether danuglipron, which is taken twice a day, will be competitive with other pills that only need to be taken once daily. The company’s stock price fell by 5 percent in early trading Monday before rebounding slightly.

Drugs like Ozempic are causing a frenzy among people desperate to shed weight — and among investors eyeing the potential profits of a medication that could treat a huge swath of the American population that is obese. Ozempic and rival drugs are approved by the U.S. Food and Drug Administration only to treat diabetes, but they owe their viral fame to their effectiveness in helping people lose weight.

The popularity of this new class of weight-loss medications is already fueling a clash with insurers over prescriptions for patients who don’t have diabetes, foreshadowing more consequential debates over insurance for pricey drugs that affect millions of Americans.

Insurers clamping down on doctors who prescribe Ozempic for weight loss

The drugs mimic a hormone naturally produced by the body, glucagon-like peptide 1. GLP-1 drugs, as they are often called, slow the emptying of the stomach and suppress appetite. The most popular ones on the market, including Ozempic, Mounjaro and Wegovy — which is FDA-approved for obesity — are all injectable drugs, and manufacturers are betting there will be even more demand for a pill version.

“This is a big setback” for Pfizer, Umer Raffat, an analyst at Evercore ISI, wrote in a research note. Observing that the now-abandoned candidate was a once-a-day pill, he wrote of danuglipron, “it’s not the best shot they had.” Analysts at Cowen acknowledged the worries about competition but wrote, “we think it’s too early to call a winner yet.”

A Pfizer spokesperson said the company is developing a “modified once-daily version” of danuglipron and still believes it has the potential to bring in $10 billion a year in sales for both obesity and Type 2 diabetes.

Eli Lilly, the maker of Mounjaro, released results Friday from a study on an oral GLP-1 drug candidate that showed people lost 8.6 to 12.6 percent of their body weight after 26 weeks. It said side effects ranged from mild to moderate.

Novo Nordisk, which makes Ozempic and Wegovy, may have the pole position on developing a weight-loss pill. The company is conducting late-stage trials on a pill candidate using the same active ingredient as its hit injectable drugs, and it reported in May that patients lost 17.4 percent of their weight over 68 weeks on a once-daily dose.