Effects of guanabenz therapy on renal function and body fluid composition.

Guanabenz acetate is a new centrally acting alpha 2-adrenergic agonist. Seventeen hypertensive men, in whom BP was normalized with guanabenz, underwent assessment of renal function, renal hemodynamics, and body fluid composition following short-term (three to six weeks), long-term (five to six months), and withdrawal (two weeks) therapy. Guanabenz therapy caused a modest but reversible reduction in glomerular filtration rate (12% to 18%), effective renal plasma flow (9% to 17%), and renal blood flow (12% to 20%). Renal vascular resistance was unchanged. Guanabenz therapy had no significant natriuretic or antinatriuretic effects in patients with an effective BP decrease, although it had the ability to produce and sustain a water diuresis. Guanabenz therapy was not associated with salt and water increases within body fluid compartments. Guanabenz, in some patients, is an effective monotherapy for the treatment of hypertension.