Antihypertensive and Hemodynamic Properties of the New Beta Adrenergic Blocking Agent Timolol

Abstract

The antihypertensive activity of timolol, a new beta adrenergic blocking agent, was assessed in hypertensive patients. In hospitalized patients timolol, 5 mg orally every 8 hr for one week, resulted in a significant although mild reduction of blood pressure with diastolic pressure falling from a mean of 101 mm Hg to 91 mm Hg. Heart rate and cardiac output fell while total peripheral resistance increased. The Valsalva response, the reflex tachycardia following inhalation of amyl nitrite and the cardiovascular responses to infusion of isoproterenol were significantly inhibited. Timolol also was compared to propranolol in a randomized double-blind outpatient trial. The antihypertensive and bradycrotic effects of the two drugs were similar. Heart rate was reduced 18% by both drugs ( P < 0.05). Supine diastolic pressure fell 9% ( P < 0.05). Unlike the short term effects of timolol, and in contrast to propranolol, cardiac output did not remain reduced after five weeks of continuous treatment with timolol. It is concluded that timolol merits further investigation as an antihypertensive agent.