MannKind Corp. plans to sell senior secured discount notes to raise about $370 million to help pay for additional drug trials that U.S. regulators are requiring for its experimental insulin inhaler.

The Valencia biotech on Friday said it plans to use the proceeds from the notes, due 2017, for development and operating capital, including two clinical trials of its product candidate Afrezza. MannKind expects to complete the studies next year and submit results to the U.S. Food and Drug Administration in early 2013.

MannKind also said that some of the money will be used to prepare for Afrezza’s commercialization by expanding its manufacturing facility in Danbury, Conn.

Shares closed up 56 cents, or 17.6 percent, to $2.74 on the Nasdaq.