Tobramycin levels in aqueous humor after subconjunctival injection in humans.

Subconjunctival injection of 10 mg of tobramycin provided therapeutic levels in the aqueous humor of 25 patients (ranging in age from 51 to 89 years) who underwent cataract surgery. The absorption from the subconjunctival tissue into the anterior chamber was fairly rapid, reaching a peak in approximately two hours. Peak levels were usually 20 times the minimum inhibitory concentration for Pseudomonas aeruginosa. The drug then gradually disappeared from the aqueous but still exceeded the minimum inhibitory concentration for Pseudomonas organisms after eight hours.