San Diego drugmaker Neurocrine Biosciences Inc. is raising up to $502 million in an offering of convertible senior notes, the company announced Wednesday.

The company is offering $450 million of 2.25 percent convertible senior notes due 2024, which will be sold in a private offering to qualified institutional buyers. Then Neurocrine is granting purchasers a 30-day option to buy an additional $67.5 million.

The proceeds will be used for general corporate purposes, including commercialization expenses, clinical trial and other research and development expenses, among other uses.

Neurocrine just received regulatory approval to sell its drug, Ingrezza, earlier this month. The company’s CEO, Kevin Gorman, told the Business Journal that Neurocrine intended to take on domestic commercialization without a pharma partner.

“I’ve been in this business for 30 years now, and my definition of success has never changed: get into a position where you are a freestanding, independent biotech company that discovers, develops, and commercializes your own drugs,” Gorman said. “That way, you don’t have to depend on anyone else.”

The sale of the notes is expected to close on May 2.