Efficacy and tolerability of hydralazine, in conventional and slow-release preparations, during long-term treatment of primary hypertension.

In 23 patients with primary hypertension, the efficacy and tolerability of slow-release hydralazine administered once daily were compared with those of conventional hydralazine given two to four times a day. All patients were treated concomitantly with beta-blockers, diuretics, or both. Blood pressure control achieved with multiple doses of conventional hydralazine was maintained with slow-release hydralazine, with no discrepancy between once- and twice-daily administration, when the same daily dose of hydralazine was given. A differentiated method of assessing tolerability demonstrated no differences between the hydralazine formulations and dose regimens in the incidence of side effects. This finding indicates that larger single doses than are normally given with hydralazine can be given with slow-release hydralazine without increased risk of side effects.