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Antihypertensive and β‐adrenoceptor antagonist action of timolol
Author(s) -
Simon Geza,
Kiowski Wolfgang,
Julius Stevo
Publication year - 1978
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1978232152
Subject(s) - timolol , placebo , heart rate , medicine , plasma renin activity , blood pressure , diastole , antagonist , endocrinology , anesthesia , renin–angiotensin system , surgery , intraocular pressure , receptor , alternative medicine , pathology
After a 4‐wk placebo period, 20 patients with essential hypertension received incremental doses of timolol (20, 40, and 60 mg daily) during three consecutive 3‐wk treatment periods. Throughout the study, home blood pressures (BP) were obtained twice daily. At the end of each study period, plasma renin activity (PRA), the maximum heart rate (RR) response to isoproterenol (30 ng/kg/min) and to ergometric exercise (750 to 1,050 kgm/min), and serum timolol levels were measured. Average weekly home BP of 150/100 on placebo fell to 139193 on 20 mg of timolol (p < 0.01). An additional fall in diastolic BP (4 mm Hg, p < 0.01) occurred as the dose was increased to 60 mg. PRA, 2.6 ng/ml/hr on placebo decreased to 1.2 on 20 mg of timolol (p < 0.05); thereafter it did not change. The mean maximum heart rates in response to isoproterenol and exercise were 117 and 158 beats/min on placebo; the maximum rates were 64 and 112 when the patients were receiving 20 mg of timolol (p < 0.001). On 60 mg, mean maximum heart rates decreased to 57 with isoproterenol and to 104 with exercise (p < 0.02). Timolol, 20, 40, and 60 mg daily, resulted in a wide range but increasing serum concentrations of the drug. The antihypertensive effect of timolol did not correlate with the fall in PRA. PRA and the maximum HR response to isoproterenol on placebo did not predict the BP response to timolol. That PRA was not predictive of the BP response cannot be taken as conclusive because of small number of low renin patients (3) in our series.