(Reuters)

Eli Lilly said on Tuesday it has begun selling vials of the lowest starter dose of its popular weight-loss drug Zepbound in the United States for $399 for a month's supply through its direct-to-consumer website to help increase its availability in the marketplace.

Zepbound is typically sold in auto-injector pens, but with easier-to-manufacture and fill vials Lilly will be able to get the drug to patients more quickly.

The 2.5 milligram and 5mg vials - the lowest doses of the drug - will cost $399 and $549 on its website LillyDirect, the company said.

That is a $250 discount, or 40%, for the lowest dose compared to the $650 per month Lilly now charges patients for the pen version of Zepbound on its website, an increase from the $550 launch price set early this year.

Lilly said the prices were in line with its current offering and a 50% discount to the list prices of competing products, including the popular Wegovy from Danish rival Novo Nordisk.