Ophthalmic timolol in a hydrogel vehicle leads to minor interindividual variation in timolol concentration in aqueous humor

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.