Hemodynamic and therapeutic effects of guancydine in hypertension

Abstract

Guancydine, a new vasodilator and antihypertensive agent, increased cardiac output and lowered total peripheral resistance in hypertensive patients. Sympathetic reflexes were not blocked and there was no symptomatic orthostatic hypotension. Renal blood flow and glomerular filtration rate did not decrease. Although guancydine effectively reduced blood pressure, the side effects of fluid retention and sinus tachycardia preclude its long‐term use as a single agent. Fluid retention was prevented by giving a diuretic in conjunction with guancydine; tachycardia was considerably attenuated by the addition of reserpine. The following reductions in blood pressure occurred during a crossover trial in 14 outpatients who had an average control supine blood pressure of 185/119 mm. Hg: guancydine alone, 25/16; diuretic alone, 22/9; reserpine alone, 7/5; diuretic and guancydine, 42/32; reserpine and guancydine, 43/33; diuretic and reserpine, 23/15; and diuretic, reserpine, and a moderately redueed dose of guancydine, 40/31 mm. Hg. The last combination of antihypertensive agents resulted in an effective control of blood pressure with minimal side effects.