OCULAR TIMOLOL LEVELS AFTER DRUG-WITHDRAWAL - AN EXPERIMENTAL-MODEL

Carbon 14-labelled timolol maleate was instilled into both eyes of 12 pigmented rabbits daily for 42 days. Drug levels in the aqueous humour and ocular tissues were measured up to 42 days after drug withdrawal. The results indicate that timolol concentrates mainly in melanotic ti ssues, with slow release. Even 42 days after withdrawal the drug was s till present in pigmented ocular tissues. Timolol was detected in the aqueous up to 5 days after withdrawal. These findings explain the long -term depressant effect of topically administered timolol on aqueous p roduction. We conclude that lower or less frequent doses of timolol sh ould be considered in patients with glaucoma.