Following the recommendation of its expert panel back in March, the Food and Drug Administration approved Amgen Inc's drug Nplate for treating a rare clotting disorder that can cause dangerous bleeding.

Nplate is intended to treat Idiopathic Thrombocytopenic Purpura (ITP), an autoimmune disorder characterized by very low levels of platelets leading to uncontrolled bleeding. Platelets are involved in clotting and are needed to stop bleeding, and Nplate is designed to boost levels in a different manner than other treatment.

ITP, which causes bruising and bleeding after minor injuries, affects about 200,000 people in the U.S., according to the Platelet Disorder Support Association. Amgen’s drug would treat chronic forms of ITP. To support the drug, Amgen submitted the results of two main clinical studies involving patients with ITP who failed other treatments.

Nplate works differently than other approved ITP treatments, which include steroids, immune-suppressing drugs or surgery to remove the spleen. Amgen Inc's drug helps stimulate bone marrow into producing blood platelets. FDA only approved Nplate for use after other available treatments fail to help.

Thus, long term safety tracking will start and eventually the FDA might approve Nplate as a first choice treatment if it proves safe enough. The drug has a niche market of only $66 million to $117 million in 2009 sales, because only around 60,000 U.S. adults have chronic ITP. Meanwhile, GlaxoSmithKline has a similar drug pending approval, Promacta, or eltrombopag.