Long-term hemodynamic and metabolic effects of trimazosin in essential hypertension.

The long-term effects of trimazosin (TMZ) were studied in 26 male patients with mild essential hypertension. After a 2 wk single-blind placebo (P) period, 13 patients were randomly selected to receive TMZ and 13 P; they were followed for an additional 8 wk. TMZ was given in incremental doses of 25 to 50, 100 to 200, and finally 300 mg three times a day. The patients were seen at the clinic every 2 wk and their arterial pressures (AP) and heart rates (HRs) were measured in the supine (5 min) and upright (2 min) position. Blood chemistries, blood count, plasma volume (PV), plasma renin activity (PRA), plasma aldosterone (PA), and cardiac output (CO) were determined by ultrasound at the end of P and TMZ periods. TMZ decreased the AP and total peripheral resistance (TPR) at the higher dosages, but had no effect on PV, PRA, PA, CO, HR, or blood chemistry determinations. No effects were observed on any of the above parameters after P. We conclude that (1) TMZ is an effective and safe antihypertensive, (2) it lowers AP through reduction of TPR, and (3) its effect is dose related.