Eli Lilly said on Tuesday it cut the price for vials of its weight-loss drug Zepbound by $50 or more and expanded the range of doses sold online to try to stave off competition from compounding pharmacies and rival Novo Nordisk .

Few big pharma stocks have been bigger winners over the last three years than Eli Lilly and Novo Nordisk. Lilly now ranks as the largest drugmaker in the world, with a market cap of $844 billion, after its shares skyrocketed more than 270%. Novo Nordisk stock is up around 75% despite a pullback in recent months.

Eli Lilly & Co. said Tuesday it’s cutting the price of single-dose vials of its Zepbound treatment for diabetes and obesity for patients who have to pay for the drug themselves. It said it will also be adding two new doses,