title: Pharmacokinetics and beta-blocking effects of transdermal timolol.
abstract: The pharmacokinetic profiles of transdermal timolol 6 and 24 mg (as 5 and 20% w/v patches) was studied in four healthy young volunteers. To assess its bioavailability, the pharmacokinetics of an IV infusion of timolol maleate 5 mg was also determined in the same subjects. When the 20% (w/v) timolol patch was applied, the mean bioavailability was 74.4%. Plasma timolol concentrations were below the detection limit when a 5% patch was applied to the same skin area in all four subjects, except for one in whom the bioavailability was 23.6%. Weak erythema developed at the application site in all of the volunteers after application of the 20% (w/v) patch. However, erythema did not develop in any volunteer when the 5% patch was applied. The beta-blocking effect was determined by exercise testing. Similar plasma levels generated similar changes in exercise-induced heart rate after the transdermal and intravenous administration of timolol.
authors.affiliation: Division of Clinical Pharmacology, National Medical Centre, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kubota
authors.forename: T
authors.initials: T
authors.lastname: Yamada
authors.forename: K
authors.initials: K
authors.lastname: Kikuchi
authors.forename: E
authors.initials: E
authors.lastname: Koyama
authors.forename: T
authors.initials: T
authors.lastname: Ishizaki
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D001682:Biological Availability; D004890:Erythema / Q000139:chemically induced; D005080:Exercise Test; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D013999:Timolol / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*
chemical_list: D013999:Timolol