The US Food and Drug Administration has approved Auxilium Pharmaceuticals' Xiaflex to treat Peyronie's disease, which causes a bothersome curvature of the penis during sex.

Xiaflex (collagenase clostridium histolyticum) is the first FDA-approved non-surgical treatment option for men with this condition, who have a plaque in the penis that results in a curvature deformity of at least 30 degrees upon erection. Peyronie’s is caused by scar tissue that develops under the skin of the penis and Auxilium says that between 3%-9% of US men are affected by a disease which is thought to be underdiagnosed.

The approval is based on two studies involving 832 men with Peyronie’s who were given up to four treatment cycles of Xiaflex or placebo and were then followed for 52 weeks. The data revealed that the drug significantly reduced penile curvature deformity and related bothersome effects compared with placebo.

The FDA stressed that Xiaflex is available only through a restricted programme because of the risks of serious adverse reactions, including penile fracture. Martin Gelbard of the UCLA School of Medicine noted that treating Peyronie's "has been a challenge as, until now, we have had few options to offer our patients", so the FDA approval is "a significant achievement" to help doctors deal with "this physically and psychologically devastating disorder".

Xiaflex is already available on both sides of the Atlantic for Dupuytren's contracture, a condition that affects the connective tissue beneath the skin in the palm of the hand.