August 22 (HealthDay News) -- The U.S. Food and Drug Administration has approved Nplate (romiplostim), a drug that stimulates bone marrow to make needed platelets in people with a rare bleeding disorder called immune thrombocytopenic purpura (ITP).

The disorder, affecting about 140,000 people in the United States, causes a low count of platelets, a component that helps blood clot. In people with chronic ITP, it's believed the body's own immune system destroys platelets, and the bone marrow is unable to produce enough platelets to compensate.

People with ITP tend to bruise easily and are at risk for life-threatening bleeding, the FDA said in a news release.

During six months of clinical testing involving 125 people with ITP, those who received Nplate had significantly higher platelet counts than those who didn't get the drug, the agency said.

Possible risks from taking the drug include fibrous deposits in the bone marrow, a drop in platelet count to below pre-treatment levels if the drug is stopped, a form of blood cancer, and blood clots if excessive platelets are produced.

Nplate is manufactured by Amgen Inc. of Thousand Oaks, Calif.