The effect of triple drug therapy on renal function in patients with essential hypertension

The effects of long-term triple drug therapy on renal function in patients with moderate to severe essential hypertension have not been evaluated systematically. We prospectively studied fifteen male patients with moderate to severe essential hypertension receiving triple drug therapy (metolazone, atenolol or betaxolol, and minoxidil) for 16 weeks. Supplemental potassium was prescribed in an attempt to maintain serum potassium above 3.5 mEq/liter. Systemic blood pressure was well controlled with this regimen. However, glomerular filtration rate (assessed by inulin clearance), effective renal plasma flow (assessed by paraaminohippurate clearance), and renal blood flow were reduced. Filtration fraction and renal vascular resistance were not significantly altered. Plasma renin activity remained stimulated throughout the protocol. Weight gain occurred, and serum potassium remained low. These results suggest that triple drug therapy employing a diuretic, beta-adrenergic antagonist, and a potent vasodilator is effective therapy for controlling moderate to severe systemic hypertension. However this antihypertensive regimen may be associated with a decrement in renal function.