PT-141, also called Bremelanotide (generic clinical name), is a heavily modified synthetic derivative of alpha-melanocyte-stimulating hormone. It has been tested in clinical trials as a treatment for both male/female hypoactive sexual desire disorder and acute hemorrhage. PT-141 is an agonist for the melanocortin-4 and melanocortin-1 receptors. Research shows that it promotes sexual arousal and stimulates the immune system.