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Abstract #5413 Published in IGR 1-2
Periocular accumulation of timolol and betaxolol in glaucoma patients under long-term therapy
Sponsel WE; Terry S; Khuu HD; Kwok-Wai Lam; Frenzel HSurvey of Ophthalmology 1999; 43 (S1): S210-S218
PURPOSE: To determine if betaxolol or timolol is present in measurable concentration in the Tenon capsule in patients under long-term topical therapy. METHODS: Small (1 ml) specimens of Tenon capsule were removed at the time of filtering surgery from 15 glaucoma patients under long-term preoperative topical therapy, nine of whom had been treated with timolol and six of whom had been receiving betaxolol. Methanol extracts of these tissue samples were analyzed quantitatively for the presence of either ß-adrenergic antagonist by high-performance liquid chromatography. RESULTS: Drug was detected in every specimen. A mean total of 2.6 (range, 0.1-30.0) ?g of betaxolol was detected per 1-ml specimen. CONCLUSION: Timolol and betaxolol penetrate the conjunctiva and accumulate in the Tenon capsule. In patients under long-term therapy, the periocular tissue can accumulate a greater quantity of ß-antagonist than is present in a daily dosage of applied eyedrops, many-fold higher than the maximal intraocular concentration.
W.E. Sponsel, Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX; USA
Classification:
11.3.4 Betablocker (Part of: 11 Medical treatment > 11.3 Adrenergic drugs)
