Effects of pindolol on renal function.

Because beta blockers have been shown to reduce glomerular filtration rate (GFR), the renal effect of intravenous and prolonged oral administration of pindolol was examined in 10 patients with essential hypertension. Intravenous pindolol decreased inulin clearance from 99 to 94 ml/min/1.73 m2 (p < 0.005), and pulse rate from 75 to 69/min (p < 0.005). Blood pressure and filtration fraction were not changed. Oral pindolol (10 to 20 mg/day) for a mean of 6 mo resulted in a decrease in mean blood pressure from 124 to 111 mm Hg (p < 0.001), in mean pulse rate from 76 to 69/min (p < 0.005), and in mean plasma renin activity (PRA) from 0.9 to 0.29 ng/ml/hr (p < 0.05). Inulin clearance and filtration fraction did not change. At the end of oral therapy, intravenous pindolol induced a greater reduction in inulin clearance than in the first study. These observations indicate that intravenous pindolol induces a decrease in GFR probably secondary to hemodynamic effects. On the other hand, prolonged oral pindolol has no effect on GFR despite decreases in blood pressure, pulse rate, and PRA.