Shares of MannKind Corp. more than doubled in after-hours trading on Tuesday after an FDA advisory panel recommended the agency approve the Valencia company's Afrezza insulin inhaler.

An independent advisory panel at the Food and Drug Administration made its ruling after a long hearing in Washington D.C. MannKind and FDA officials made highly technical presentations that compared Afrezza to traditional diabetic treatments, and examined its side effects.

The panel voted 13-1 with one abstention to approve Afrezza for Type 1 diabetics, and 14-0 with one abstention for Type 2 diabetics.

While the FDA isn’t required to follow the panel’s recommendation, it rarely contradicts it. An official determination is expected by April 15.

Last week, an FDA staff report worried investors in the stock, as it noted the drug’s potential risk of causing lung infections and bronchial spasms and coughing that caused some patients to stop treatment. Staff also questioned the accuracy of insulin doses in MannKind’s clinical studies.

Alfrezza would be the company’s first drug to market. The company was founded by billionaire entrepreneur Alfred Mann more than a decade ago. Mann has pumped an estimated $900 million into the company over that period. One estimate puts potential annual sales at $1 billion to $4 billion.

Trading in MannKind was halted during Tuesday's regular session and were unchanged at $4.02 They soared 111 percent to $8.47 in after-hours trading following news of the panel's decision.