Penetration of timolol eye drops into human aqueous humour: the first hour

Samples of aqueous humour were removed from 26 eyes at the start of cataract extraction. Two drops of timolol 0.5% had been instilled into the conjunctival sac 12-71 minutes before operation. Analysis by gas chromatography showed a mean timolol concentration of 55.46 ng/mg, with a range of 8 to 100 ng/mg.