Sustained-release trimazosin in the treatment of mild-to-moderate hypertension

The efficacy and duration of action of the direct-acting vasodilator trimazosin in a sustained-release (SR) formulation was investigated in 59 adults with mild-to-moderate hypertension. Average systolic and diastolic blood pressures before treatment were 162 ± 1/103 ± 1 mmHg. SR-trimazosin was administered once daily and dosage was titrated from 150 mg/day to 900 mg/day over five weeks. At each dose level, blood pressure was measured hourly for six hours and at 24 hours after trimazosin administration. Both systolic and diastolic blood pressures were significantly decreased one hour after a single 150-mg dose of SR-trimazosin. At each dosage between 150 mg/day and 900 mg/day, maximum hypotensive effect occurred at five hours with an average fall in blood pressure of 22 ± 2/14 ± 2 mmHg at each dose tested. At dosages from 150 to 600 mg/day, both systolic and diastolic blood pressures returned to baseline values 24 hours after oral administration. However, at a dosage of 900 mg/day, systolic and diastolic blood pressures were still significantly lower than baseline values 24 hours after administration. No patient discontinued SR-trimazosin because of side effects, and no patients reported severe or frequent adverse effects. In addition, no laboratory abnormalities could be attributed to SR-trimazosin. SR-trimazosin is a well-tolerated and effective antihypertensive agent. Dosages of less than 900 mg/day were ineffective in controlling systolic and diastolic blood pressures for 24 hours, and such dosages require twice-daily administration for a sustained hypotensive effect. At a dosage of 900 mg/day hypotensive effect persisted for 24 hours, but wide fluctuations in blood pressure over the 24-hour period may limit the efficacy of this dosage when used as a once-daily antihypertensive agent.

Duke Scholars

Author Laura Pat Svetkey Medicine, Nephrology