The U.S. Food and Drug Administration said Friday that it's approved a first-of-its-kind drug to treat a rare blood disorder called paroxysmal nocturnal hemoglobinuria (PNH), which can cause disability and premature death.

The newly approved drug, Soliris (eculizumab), is a new molecular entity that contains an ingredient not previously marketed in the United States.

"This product is important in that it offers a treatment other than blood transfusion that may help this small population of patients who are often very ill," Dr. Steven Galson, director of the FDA's Center for Drug Evaluation and Research, said in a prepared statement.

Soliris does not cure PNH, but treats the breakdown of red blood cells, the most common characteristic of the disease. Patients with PNH can suffer pain, fatigue, debilitating weakness, blood clots and strokes, heart disease and intestinal disease.

The FDA approval of the drug was partly based on a study of 87 patients that found that half showed stabilization of blood hemoglobin over 26 weeks. The study was conducted by the maker of Soliris, Alexion Pharmaceuticals, Inc. of Cheshire, Ct.

Studies showed that serious meningococcal infection was a risk for patients taking Soliris, so the FDA ordered a boxed warning on the drug's labeling and said that all patients must receive meningococcal vaccination prior to being given Soliris.

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