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The pharmacokinetics of ocularly applied timolol in rabbits
Author(s) -
Huupponen Risto,
Kaila Timo,
Salminen Lotta,
Urtti Arto
Publication year - 1987
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.1987.tb08493.x
Subject(s) - timolol , ciliary body , aqueous humour , iris (biosensor) , pharmacokinetics , chemistry , intraocular pressure , ciliary processes , ophthalmology , aqueous humor , kinetics , chromatography , pharmacology , medicine , physics , computer security , quantum mechanics , computer science , biometrics
. [ 3 H]timolol derived radioactivity and β‐antagonistic activity in the aqueous humour, iris, ciliary body and blood in rabbits were analyzed by liquid scintillation counting (LSC) and radioreceptor assay (RRA) after ocular timolol. After ocular application of tracer labelled timolol, the radioactivity decreased slowly in the iris (K el = 0.05 h −1 ) and ciliary body (K el = 0.02 h −1 ). In the aqueous humour the elimination rate was faster (K el = 0.57 h −1 ). The β‐antagonistic activities of the aqueous humour and plasma decreased rapidly when compared to LSC values. The ethanol extractable pool of the β‐antagonistic activity from the iris and ciliary body was only a few percent of the corresponding LSC estimates. The kinetics of β‐antagonistic activity extractable from iris and ciliary body was identical with that in the aqueous humour. Timolol concentrations in the untreated rabbit eye were sufficiently high to lower the intraocular pressure.