Shares of NitroMed ( NTMD) jumped Friday after the Lexington, Mass., company began distributing its congestive heart failure drug BiDil. The drug was approved by the Food and Drug Administration June 23 for treating African-Americans, the first instance of a drug being approved for a specific ethnic group. NitroMed advanced $2.34, or 12%, to $21.79 late Friday afternoon on trading volume that was eight times greater than the average daily volume for the past three months. BiDil will be priced at a wholesale acquisition cost of $1.80 per tablet and supplied to pharmacists in bottles of 180 tablets. NitroMed expects that BiDil samples will be available in doctors' offices next week and available in pharmacies during the following week. The FDA approved the drug based primarily on a clinical trial showing that BiDil had a significant beneficial effect on African-Americans with congestive heart failure. Previous clinical trials involving a more diverse population were inconclusive. The suggested price exceeds what some analysts had forecast. Patients will start by taking one pill three times a day; if necessary, they could take two pills three times a day, according to the BiDil prescribing instructions. Citing information from the federal Centers for Disease Control and Prevention, NitroMed says African-Americans between the ages of 45 and 64 are 2.5 times more likely to die from heart failure than Caucasians in the same age range. BiDil is a combination of two generic drugs -- hydralazine, for high blood pressure, and isosorbide dinitrate, for chest pains associated with heart disease. Neither of the components alone has been approved for treating heart failure.