The FDA approved AMAG Pharmaceutical’s Vylees (bremelanotide) injectable drug for restoring female libido.

The drug will now be available for premenopausal women with generalized hypoactive sexual desire disorder, one of a handful of diseases that the agency has singled out for priority attention.

The drug, injected at the abdomen or thigh at least 45 minutes before sex, activates the body’s melanocortin receptors but it’s not clear why it works. The drug has potent side effects, including high blood pressure. It also prevents the body from absorbing the anti-opioid rescue drug naltrexone into the bloodstream.