Chemical Stability and Sterility of Frozen Ganciclovir Injections

Abstract

Background: Intravitreal ganciclovir is a common treatment of cytomegalovirus retinitis in Thailand. Besides the adverse drug reactions, the major reason is that the cost of intravitreal ganciclovir therapy is far less than intravenous therapy. However, it is still considered expensive for many Thai patients to afford. It is pity that only 1-2 mg of ganciclovir is used and the rest of the solution (498 mg) is discarded for each vial. For economic reasons, the intravitreal injection is prepared as solution and stored in a frozen condition to extend the shelf life of the product.

Objective: To study chemical stability and sterility of the frozen ganciclovir solution (20 mg/ml) during 180 days.

Materials and Methods: Ganciclovir intravitreal injection was aseptically reconstituted with 0.9% sodium chloride injection (NSS) to make a final concentration of 20 mg/ml. The solution was filtered,  into aliquot for 1 ml each sterile 5-ml vial and stored at -20 ^oC. The samples were determined for the initial ganciclovir concentration on day 0 and the concentrations remaining on day 30, 60, 90 and 180 with high performance liquid chromatography (HPLC). The sterility of the samples was tested by direct inoculation method.

Design: Experimental study.

Setting: Faculty of Medicine, Khon Kaen University.

Results: Throughout the 180-day study period, means of the labeled amount were 100.69 – 101.1% and the mean ganciclovir concentrations at any sampling times were at least 99.66% of the initial concentration and no microbial growth was observed.

Conclusions: The results of this study indicated that ganciclovir 20 mg/ml in 0.9% sodium chloride injection when stored in amber glass vials and frozen at – 20 ^oC was both chemically and biologically stable at least 180 days.

Keywords: Chemical stability, Sterility, Frozen, Ganciclovir.