Isosorbide dinitrate/hydralazine is a fixed dose combination drug treatment specifically indicated for African Americans with congestive heart failure. It is a combination of hydralazine (an antihypertensive) and isosorbide dinitrate (a vasodilator). It is the first race-based prescription drug in the United States. The combination preparation is marketed in the United States by Arbor Pharmaceuticals, Inc. (who purchased the rights to market the drug in December of 2011 from NitroMed) under the trade name BiDil.
Originally rejected by the Food and Drug Administration (FDA) in 1997, the combination preparation was approved by the FDA in June 2005 for use in African Americans. It was already known that African-American blacks with congestive heart failure (CHF) respond less effectively to conventional CHF treatments (particularly ACE inhibitors) than Caucasians. The study by Taylor et al., based on which the FDA approved the medication demonstrated that isosorbide dinitrate with hydralazine reduced mortality by 43%, reduced hospitalizations by 39%, and improved quality of life markers in African-American patients with CHF.
Because the combination preparation comprises two generically-available drugs, widely available at a small fraction of the cost, BiDil is considered a marketing innovation, rather than a medical one; however, the 43% mortality benefit remains a notable benefit. Though BiDil must still be taken three times daily, as must the component pills in separate ISDN-H treatment, the reduction in pill burden has been suggested to improve compliance, and thus a better medical outcome.
The FDA issued a letter in May, 2006 stating that there is no bioequivalent, generic substitute to BiDil. With the 2005 FDA approval and with the issuance of a patent, BiDil is unique and no alternative therapy exists for the target patient population. In 2006, the Heart Failure Society of America included the use of the fixed dose combination of isosorbide dinitrate/hydralazine as the standard of care in the treatment of heart failure in blacks. In 2007, at the American College of Cardiology's annual scientific meeting in New Orleans, data was presented demonstrating a pharmacokenetic distinction between the fixed dose combination and the component agents that may account for the superior clinical benefit in mortality shown in the African American Heart Failure Trial.
There is, however, concern that the approval of this drug may be used to promote racist thinking, especially because the study data used to approve the medication only included self-described African-American participants and no other racial groups. BiDil could potentially be beneficial to all patients suffering from heart failure, even if not to the same statistically different extent compared to existing medications (that already provide benefit in racial groups other than African-American blacks).