Isosorbide dinitrate/hydralazine

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 Nitromed under the trade name BiDil.

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Originally rejected by the Food and Drug Administration (FDA) in 1997, the combination preparation was approved by the FDA in June 2005 for African American-use only based on the results of a study by Taylor et al. (2004). It was already known that African Americans with congestive heart failure (CHF) respond less effectively to conventional CHF treatments (particularly ACE inhibitors) than Caucasians. (Exner, 2001) The study by Taylor et al. demonstrated that isosorbide dinitrate with hydralazine reduced mortality by 43%, reduced hospitalizations by 39%, and quality of life markers in African Americans patients with CHF.

Some argue that because the combination preparation comprises two generically-available drugs, widely available at a small fraction of the cost, BiDil is a marketing breakthrough, rather than a medical one but the 43% mortality benefit is striking statistic. Others argue that the combination reduces the "pill burden" for patients, which improves compliance and therefore the medical outcome. Moreover, 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 this disproportionately burdened 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 annual scientific meeting in New Oleans, 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.

It has also been pointed out that the FDA has only approved use of this drug for African Americans, implying that there is some fundamental physiological difference between black and white Americans. There is also some concern over how the implications of this alleged difference may be used to promote racist thinking. It has also been argued that the drug could also be beneficial to whites and other ethnic groups but no such tests have been done yet.^[1]

See also

• Pharmacogenetics
• Pharmacogenomics

References

• Exner DV, Dries DL, Domanski MJ, Cohn JN. Lesser response to angiotensin-converting-enzyme inhibitor therapy in black as compared with white patients with left ventricular dysfunction. N Engl J Med 2001;344(18):1351-7. PMID 11333991
• Taylor AL, Ziesche S, Yancy C, Carson P, D'Agostino R Jr, Ferdinand K, Taylor M, Adams K, Sabolinski M, Worcel M, Cohn JN. Combination of isosorbide dinitrate and hydralazine in blacks with heart failure. N Engl J Med 2004;351:2049-57. PMID 15533851.