The pharmaceutical manufacturer Amgen announced on Tuesday that an experimental obesity drug helped patients lose up to 20 percent of their weight in a year. The drug, MariTide, is given by injection once a month, compared with once a week for other obesity drugs like Wegovy and Zepbound that are already on the market.

Shares in Amgen fell by double digits Tuesday on results for the company’s MariTide shot, which is viewed as a potential rival to Wegovy and Zepbound.

An Amgen obesity drug helped participants lose a substantial amount of weight, but questions about how competitive it could be remain

MariTide, which like Eli Lilly’s Zepound is a dual agonist of the GLP-1 and GIP receptors, demonstrated an average weight loss of up to 20% over 52 weeks in individuals living with obesity or overweight but without type 2 diabetes. For those with diabetes, the average weight loss reached 17%.

Amgen's experimental drug MariTide led to an average weight loss of up to 20% in a year-long mid-stage trial of nearly 600 people who were overweight or obese, the company said on Tuesday.

Shares of Amgen (NASDAQ: AMGN) recently ticked lower despite a very positive-sounding press release regarding its weight management candidate. According to the giant drugmaker, treatment with an anti-obesity candidate called MariTide helped patients reduce their weight by up to 20% after 52 weeks.