More than 20,000 people have started taking Eli Lilly 's GLP-1 pill Foundayo in its first few weeks on the market, Lilly CEO Dave Ricks told CNBC on Thursday.

The FDA approved Lilly's once-daily pill Foundayo earlier this month, making it the second oral GLP-1 drug behind Novo Nordisk's Wegovy pill. Investors have been closely tracking weekly prescriptions for clues on how the launch is going.

More than 1,000 people are starting Foundayo a day, Ricks said in an exclusive interview with CNBC. He said it'll take time to build the brand since it's a new drug that doctors and patients don't know.…