Eli Lilly CEO David Ricks on Monday said the company's powerful weight-loss drug Zepbound hit 25,000 new prescriptions per week at the end of December, and that its 2024 supply may not be enough to meet demand.

"I think it's important to set expectations, but we're working hard to fulfill demand," he told Reuters at the annual JPMorgan health conference in San Francisco.

Ricks declined to provide details on how much Zepbound Lilly can produce now, or to forecast 2024 demand and eventual supply.

The CEO said he expects wide coverage for the drug from pharmacy benefit managers (PBMs), and that at least one major PBM will start recommending coverage of the drug for its clients this year. But he cautioned that employers choosing not to cover weight loss drugs for their health plans would be a constraint on demand.

Lilly said in December that Zepbound has been added to the U.S. list of preferred medicines for reimbursement by one of the largest U.S. PBMs, Cigna's Express Scripts.

Ricks also disclosed that the company was in talks with UK health officials to set out terms for use of its weight-loss medicine there, and could launch in Britain after those discussions.

UK health regulator, the Medicines and Healthcare products Regulatory Agency, authorized Lilly's diabetes drug Mounjaro for weight management and weight loss in November, hours after a similar approval in the United States.