Updated

An erectile dysfunction drug that reduces by half the time patients need to take the pill before sexual activity has won approval for marketing in the United States.

The drug, Stendra, is the first erectile dysfunction drug approved by the U.S. Food and Drug Administration that can be taken about 15 minutes prior to sexual activity.

Stendra was first approved in 2012 when it was indicated for use 30 minutes before sexual activity.

The drug, developed by Vivus Inc, is marketed in the United States and Canada by Auxilium Pharmaceuticals Inc.

Wells Fargo analyst Matthew Andrews said in a note that the label expansion was "incrementally positive".

Vivus' stock was up about 13 percent at $4.40 in afternoon trading. Shares of Auxilium, which got an unsolicited $2.2 billion buyout offer from Endo International Plc on Tuesday, were marginally down at $31.02.

Pfizer Inc's blockbuster erectile dysfunction drug, Viagra, can be taken about an hour before sexual activity.

Vivus, better known for its obesity drug Qysmia, owns the worldwide development and commercial rights to Stendra for use in sexual dysfunction, except for certain Asian countries in the Pacific Rim.

Sanofi SA holds a license to commercialize Stendra in Africa, the Middle East, Turkey, and the Commonwealth of Independent States including Russia.

Stendra, which is sold as Spedra in the European Union, is available in multiple dosages and may be taken with or without food and moderate alcohol consumption, the companies said on Thursday.