Abstract: AIM To optimize the preparation of 3′,5′-dioctanoyl-5- fluoro-2′-deoxyuridine pharmacosomes (DO-FUdR-PS) by using central composite design. METHODS DO-FUdR-PS was prepared by a thin-layer ultrasonication technique. The effects of drug phosphatidycholine ratio, pluronic F-68 concentration (%, w/v) and glycerol tristearate (%, w/v) concentration on the mean particle size, entrapment ratio (ER) and drug loading (DL) were investigated. A second order polynomial equation was fitted to the data and the resulting model was used to predict the response in the optimal region. RESULTS All the investigated response variables were found to be highly dependent on the formulation variables. Under the optimized conditions, the mean particle size, ER and DL of DO-FUdR-PS were 76 nm, 97.49% and 31.44%, respectively, which highly agreed with the predicted values. CONCLUSION Central composite design was successfully used to optimize the preparation of DO-FUdR-PS.