HIGH-DOSE INTRAVITREAL GANCICLOVIR FOR CMV RETINITIS - A SHELF-LIFE AND COST COMPARISON STUDY

Background-It was previously found that high dose intravitreal gancicl ovir provided superior treatment of cytomegalovirus retinitis compared with intravenous treatment. This study examined the stability and sol ubility of the ganciclovir solution to determine the shelf life of pre pared solution, and compared the cost of intravitreal with intravenous therapy. Methods-For the solubility studies high performance liquid c hromatography was used to determine the ganciclovir concentration in v arious solutions. Measurements were taken of freshly made 20 mg/ml sol ution, the same solution stored at room temperature or frozen for 10, 17, and 24 days, after the solution was filtered, and after it was hea ted at 56 degrees C. For the cost comparison analysis the cost of 22 p atients treated exclusively with intravitreal high dose ganciclovir wa s compared with cost estimates for the same patients treated with a st andard intravenous therapy regimen over the same time. Results-There w as little variation in the concentration of ganciclovir regardless of the storage conditions, suggesting that the 20 mg/ml solution was very stable. The heating and filtering experiments suggest that maximum so lubility was achieved both in the freshly prepared and thawed frozen s tored solution. The total cost of the intravitreal treatment was Aus $ 172 435 and the estimate of intravenous treatment was Aus $490 521. Th is represents a total saving of $318 086 (65%), or $14 458 per patient . The average number of weeks of treatment for each patient was 27 . 9 (613 weeks/22 patients), so the saving per patient per year was $29 9 46. Conclusion-High dose intravitreal ganciclovir therapy may be admin istered in a very cost effective way, which along with its acceptabili ty, safety, and clinical efficacy make it an attractive method of trea tment of CMV retinitis.