Hydralazine sensitivity: clinical features, autoantibody changes and HLA-DR phenotype.

The clinical features, autoantibody changes, acetylator and HLA-DR phenotype of 20 patients with hydralazine-induced systemic lupus erythematosus are described. Four cases of particular interest are discussed in greater detail. Hydralazine sensitivity is more common in women, slow acetylators and the HLA-DR4 phenotype. Symptoms can occur even after many years of treatment and clinical awareness must be maintained for all patients to detect sensitivity at an early stage; there is no timely safe dose even in rapid acetylators. Joint symptoms predominate and full resolution is usual on discontinuing hydralazine. Failure of resolution should raise the suspicion of an underlying cause for the arthritis.