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Pharmacology: Pharmacodynamics: Timolol maleate is a non-selective beta(1) and beta(2) adrenergic receptor blocking agent. Its effectivity in ocular hypertension is related to an increased outflow and decreased formation of the aqueous humor which results in a decreased intraocular pressure. It also exhibits an insignificant direct myocardial depressant activity, intrinsic sympathomimetic action and local anesthetic activity.
Pharmacokinetics: The degree of systemic absorption of timolol after topical application to the eye has not been fully elucidated; however, some absorption can apparently occur, since adverse systemic effects have occurred following ophthalmic instillation of the drug. Following topical administration of timolol 0.5% solution twice daily to the eye in a limited number of individuals, mean peak plasma concentrations were 0.46 or 0.35 ng/mL following the morning or afternoon dose, respectively. Following topical application to the eye of a 0.5% solution of the drug, reduction in IOP usually occurs within 15-30 minutes, reaches a maximum within 1-5 hours, and persists about 24 hours.
