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Ophthalmic timolol in a hydrogel vehicle leads to minor interindividual variation in timolol concentration in aqueous humor
Author(s) -
VAPAATALO H,
VOLOTINEN M,
MÄENPÄÄ J,
KAUTIAINEN H,
TOLONEN A,
UUSITALO J,
ROPO A,
AINE E
Publication year - 2008
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.1755-3768.2008.461.x-i1
Subject(s) - timolol , glaucoma , aqueous humor , ocular hypertension , ophthalmology , intraocular pressure , chemistry , aqueous solution , medicine , anesthesia , pharmacology , organic chemistry
Purpose Ophthalmic timolol has been used for decades in the treatment of glaucoma and ocular hypertension, traditionally in aqueous 0.5% eye drops. Recently a timolol 0.1% hydrogel has been developed to improve systemic safety. The aim of the present study was to compare aqueous humor timolol concentrations after administration of 0.1% hydrogel and aqueous 0.5% timolol in patients scheduled for a cataract operation. Results The concentration in the aqueous humor was 210 ± 175 ng/ml (mean ± SD) two hours after administration of timolol 0.1% hydrogel and 538 ± 304 ng/ml after aqueous 0.5% timolol. In the aqueous 0.5% timolol group more patients had unnecessarily high concentrations of timolol in the aqueous humor. Beta 1‐receptors and Beta 2‐receptors were practically 100% occupied after administration of both products. The hydrogel proved to be an excellent formulation in giving smaller inter‐individual variation in penetration of timolol into the aqueous humor. Only a weak correlation was seen between corneal thickness and the aqueous humor concentration of timolol in the aqeuous 0.5% timolol group. A similar correlation was observed between age and concentration of timolol in the aqeuous 0.5% timolol group. Conclusion In contrast to the conventional aqueous 0.5% timolol, 0.1% timolol hydrogel caused only slight inter‐individual variation in timolol concentration in the aqueous humor.