Scientists have developed the world's first race-specific medicine, reawakening a controversy over race and genetic makeup. BiDil, a drug combination for treating heart failure, has proved three times more effective in black patients than it has for their white counterparts, its manufacturers claim. Due to go before the US Food and Drug Administration for approval this week, BiDil is further proof that skin colour is a factor in human genetic makeup, NitroMed argues. 'There has been a lot of controversy, but we know we have to take ethnic origin into account,' the Boston-based pharmaceutical company's chief medical officer, Manuel Worcel, told New Scientist magazine. 'Heart failure is a catastrophe ... This is huge progress.' But others contend that NitroMed's argument could be based more on commercial considerations than hard science and that the reasons given for its efficacy in black patients might be misleading. 'You can't just say. 'We're saving people by using race' and imply races are genetically different when they're really not,' said Jonathan Kahn, a bioethicist at Hamline University in Minnesota. 'Some people talk about heart failure as a different disease in blacks in what I can only describe as an irresponsible manner.' NitroMed wants to market its product for use only by black people. If approved by the FDA, it would be the first drug to be licensed for use by a single ethnic group. The results of clinical trials are testament to its value - BiDil improved survival rates among blacks who had suffered heart failure by 47 per cent. In white patients, the figure was only 15 per cent. While no one contests the findings, there is long-standing debate over the reasons, based on conflicting opinions as to the root causes of heart disease in black people. BiDil works by boosting the level of nitrous oxide in the walls of the arteries and capillaries, allowing them to expand, thereby reducing the body's blood pressure. In turn, this reduces any strain on the heart. It proved more effective in African-American patients, its manufacturers suggest, because they have naturally lower levels of nitrous oxide in their blood vessels than Caucasians. When they suffer heart failure, it is generally a result of high blood pressure. By contrast, the leading causes of heart failure among whites are clogged arteries and damage to the cardiac muscle caused by prior heart attack. Experts such as Professor Kahn, however, point out that socio-economic factors are not being properly addressed - issues such as increased levels of poverty among African-Americans, which could be responsible for a poorer diet and less access to health care. Yet there is evidence suggesting race-related health problems exist. For example, a study led by Juan Celedon at Brigham and Women's Hospital in Boston concluded last year that Puerto Rican children with asthma were up to three times more likely to react to certain allergens than white children with the same condition.