The stability of ten antibiotics in artificial tear solutions

We determined the relative potencies of penicillin G, carbenicillin, oxacillin, cephalothin, cephaloridine, gentamicin, kanamycin, neomycin, vancomycin, and bacitracin after their addition to three commercially available 0.5% hydroxypropyl methylcellulose artificial tear solutions in plastic squeeze bottles. We found no significant loss of antibiotic activity at room temperature over a period of seven days for all antibiotics except penicillin G, cephalothin, and cephaloridine. Three of the antibiotics were insoluble in one or more of the artificial tear solutions.