The Formation of Crystals in Ganciclovir Used for Intraocular Injection

Ganciclovir sodium is often administered in intraocular doses of 200 to 2000 μg for the treatment of cytomegalovirus retinitis. 1 The higher dose has been advocated because it is believed that it may be more efficacious and result in a reduced risk of cytomegalovirus resistance. 1 Ganciclovir is commercially available in a 500-mg vial and, therefore, further dilution is required for intraocular injection. It is standard practice for pharmacies to refrigerate reconstituted ganciclovir for future injections. 2 Sterile water is used for reconstitution because paraben preservatives in bacteriostatic water for injection may cause precipitation. Stability is not a problem because reconstituted ganciclovir can be stored for up to 60 days at 4°C. 2,3 We report the appearance of crystals ( Figure ) in syringes of ganciclovir sodium, 2000 μg/0.05 mL, after storage for as little as 24 hours in the refrigerator at 4°C. The crystals dissolve within 4 hours at room temperature.