Efficacy of Amphotericin B in Corneal Preservation Media After Extended Frozen Storage

Purpose: To investigate the antimycotic activity of amphotericin B deoxycholate that has been previously frozen for 28 days before supplementation of Optisol-GS. Methods: Triplicate Optisol-GS samples were inoculated with 10(6) colony-forming units (CFU) ofCandida albicans. Each set of triplicate cultures was supplemented with 2.5 mu g/mL of amphotericin B that was either freshly resuspended and never frozen, frozen overnight at -20 degrees C and thawed, or frozen at -20 degrees C for 4 weeks and thawed. The cultures were stored at 4 degrees C, with aliquots taken at 0, 6, 24, and 72 hours for quantification. The efficacy of each preparation of amphotericin B in reducingC. albicansgrowth was assessed at these time points. Results: Six hours after antifungal supplementation, there was a 1.33 log(10) CFU reduction with freshly resuspended amphotericin B, compared with a 1.31 log(10) reduction with amphotericin B that was frozen overnight (P= 0.20) and a 1.18 log(10) reduction with amphotericin B that was frozen for 4 weeks (P= 0.05). After 72 hours, there was a 2.72 log(10) CFU reduction with freshly resuspended amphotericin B, a 2.64 log(10) CFU reduction with amphotericin B that was frozen overnight (P= 0.45), and a 2.18 log(10) CFU reduction with amphotericin B that was frozen for 4 weeks (P= 0.05). Conclusions: Previously frozen amphotericin B remains highly effective againstC. albicans. Optisol-GS supplemented with 2.5 mu g/mL amphotericin B that was frozen for 4 weeks at -20 degrees C resulted in >90% CFU reduction by 6 hours and >99% reduction by 72 hours.