An Ozempic craze has swept across the United States. So many prescriptions were written for the type 2 diabetes drug marketed by Novo Nordisk (NVO -0.40%) that supplies weren't enough to meet the demand in late 2022.

It wasn't because so many patients were newly diagnosed with type 2 diabetes. Instead, Ozempic gained widespread popularity for helping people lose weight.

A sibling product, Wegovy, a higher-dose version of the active ingredient in Ozempic that is actually approved for weight loss, has flown off pharmacies' shelves as well. Unsurprisingly, Novo Nordisk's market cap has soared close to 40% over the past 12 months.

But the clock might be ticking on Ozempic's time in the sun. Could Pfizer (PFE -1.18%) have an Ozempic killer on the way?

Weighing in

Pfizer presented data from its phase 2 study evaluating danuglipron at a medical conference in late 2022. The experimental drug is targeting type 2 diabetes and weight loss. 

However, Pfizer didn't compare danuglipron against other weight-loss drugs in its presentation. But a peer-reviewed study published recently did. And it found that Pfizer's drug compares favorably with Ozempic.

In Pfizer's phase 2 study, patients who received a 120 mg dose of danuglipron lost close to 10 pounds on average over a 16-week period. That's nearly identical to the amount of weight lost by patients in a phase 3 study who received a 1 mg dose of Ozempic.

You might have noticed the big difference in dosage levels administered. That shouldn't be an issue for Pfizer for one key reason: Danuglipron is a pill, while Ozempic is an injection. The convenience to patients offered by an oral medication could give Pfizer a significant competitive advantage if danuglipron faces Ozempic in the marketplace.

Wait in line

As promising as danuglipron seems, though, it won't compete against Ozempic (or Wegovy) anytime soon. Pfizer's phase 2 study of the drug in treating obesity isn't scheduled to wrap up until October. Danuglipron would then need to advance into a late-stage study. Pfizer is at least a few years away from a potential commercial launch -- and that assumes all goes well with clinical testing.

Danuglipron will have to wait in line behind at least one other rival to Ozempic. Eli Lilly (LLY 4.28%) already markets Mounjaro as a treatment for type 2 diabetes. It hopes to win U.S. approval for the drug in treating weight loss as quickly as late 2023.

In the meantime, physicians can prescribe Mounjaro as an off-label treatment for weight loss. People taking Lilly's drug have often lost more weight than those taking Ozempic, according to GoodRx

Other weight-loss drugs could eventually compete against Ozempic and Wegovy as well. Viking Therapeutics announced promising results from a phase 1 study of VK2735 earlier this year. Novo Nordisk, Lilly, and Pfizer also each have other pipeline candidates targeting weight loss. 

Multiple winners

I don't think that Pfizer's danuglipron will be an Ozempic killer. My view is that none of the other potential rivals will be, either. Why? The market will be big enough for multiple winners.

Barclays projects that the global weight-loss drug market could be as much as $200 billion within the next decade. Other analysts aren't quite so optimistic but still estimate a market of around $100 billion.

Ozempic's sales could decline over time. That's to be expected with more effective and potentially more convenient therapies making it to market. However, it should still be a big moneymaker for Novo Nordisk for years to come.

But Lilly will also generate massive revenue with Mounjaro. Pfizer has a great chance to eventually have another blockbuster with danuglipron. The Ozempic craze could be just the beginning of a burgeoning weight-loss drug market.