Hydralazine is used for treating hypertension; it is a muscle relaxant of direct action, and performs a vasodilating influence on arterioles and arteries, thus decreasing peripheral resistance and reducing blood pressure (Timbrell, 2002). This relaxant is used for treating severe hypertension, but it should not be used as a primary drug for cases of general hypertension. This drug has several side effects, such as heartbeat, headache, loss of appetite, ANCA-associated vasculitis and drug-induced lupus erythematosus (Timbrell, 2002). Long-term hydralazine treatment might lead to the development of immune-like diseases, and lupus-like syndrome in particular.
Individual susceptibility to hydralazine depends on individual factors; it was discovered that with regard to lupus erythematosus induced by hydralazine, patients with specific HLA types are more likely to be affected. In particular, according to Kuhn, Lehmann and Ruzicka, (2005), it was determined that for patients with DRW3 human leukocyte antigens the possibility of development of hydralazine-induced lupus erythematosus is significantly higher than for other types. According to Timbrell (2002), the percentage of HLA-DR4 type patients among those suffering from hydralazine-induced lupus erythematosus constituted 73%, and the proportion of HLA-DR4 type patients among those with idiopathic lupus.
Moreover, women are more likely to be affected by this syndrome than men. However, it was determined that certain categories of drugs (e.g. hydralazine) are more used by patients of one gender; for example, it was shown in the research (Kuhn & Lehmann & Ruzicka, 2005) that 2.8% of males were treated with hydralazine, and 11.6% of females. Thus, the relationship between gender and hydralazine-induced lupus erythematosus should be analyzed further with regard to gender. Overall, HLA DRW3 and DR4 types have been moderately associated with hydralazine-induced lupus erythematosus; such patients having hypertension should not be treated with hydralazine in order to avoid toxic drug reactions.
Kuhn, A. & Lehmann, P. & Ruzicka, T. (2005). Cutaneous lupus erythematosus. Springer.
Timbrell, J.A. (2002). Introduction to toxicology. Taylor & Francis.