Dihydralazine therapy and acetylator phenotype.

The acetylator phenotype was studied in 21 hypertensive patients receiving chronic treatment with dihydralazine and other antihypertensive drugs. Plasma dihydralazine concentrations were measured 6 hours after the morning dose of the drug. There were no significant differences between the slow and fast acetylators 1) in the daily dose of dihydralazine needed, 2) in the concentrations of dihydralazine achieved in plasma, 3) in the dose/concentration-relationship of dihydralazine or 4) in the appearance of side effects. Antinuclear antibodies were found in five patients. Four of them were fast acetylators. The lowest dose/concentration relationship was found in a patient with impaired renal function. According to these results the acetylator phenotype seems to be an unimportant factor in therapy with dihydralazine. More investigation will be needed in order to elucidate the metabolism of dihydralazine.