Effects of prazosin therapy on BP, renal function, and body fluid composition

Abstract

Fourteen hypertensive men in whom the BP [blood pressure] was normalized with prazosin monotherapy, underwent assessment of renal function and body fluid composition following short-term (3-6 wk), long-term (5-6 mo.), and withdrawal (2 wk) therapy. Neither short- nor long-term prazosin therapy had any adverse effect on the glomerular filtration rate or effective renal plasma flow. Renal vascular resistance was decreased 14% during short-term therapy, but not during long-term therapy. Urine flow rate urine osmolality, free water clearance and fractional Na+ and K+ excretions were statistically unchanged throughout drug therapy. Plasma volume and extracellular fluid volume were increased following both short- and long-term therapy. Longterm prazosin monotherapy effectively lowers BP without resulting in drug tolerance, but Na+ retention probably limits its antihypertensive effectiveness.