title: Relationships among timolol doses, plasma concentrations and beta-adrenoceptor blocking activity.
abstract: 1 We investigated the relationships among dose, plasma concentration and beta-adrenoceptor blockade after single and repeated doses (0.5-20 mg) of timolol and placebo in six normal men. 2 Maximal suppression of exercise-induced tachycardia (bicycle ergometry) was dose-dependent and greater at 2 than at 6 h after dosing; activity up to 12 h was evident on the last dosing day. 3 Attenuation of exercise-induced tachycardia was strongly correlated with the timolol dosage over the 0.5 to 5-10 mg range. 4 A plasma timolol concentration of 27 ng/ml was associated with maximal suppression of exercise-induced tachycardia. 5 Suppression of exercise-induced tachycardia and areas under the plasma concentration-time curves did not differ significantly on the first and last dosing days.
mesh_terms: D000319:Adrenergic beta-Antagonists; D000328:Adult; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D005082:Physical Exertion; D011412:Propanolamines / Q000097:blood*; D012083:Renin / Q000097:blood; D013999:Timolol / Q000008:administration & dosage / Q000097:blood*
chemical_list: D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D013999:Timolol; D012083:Renin