Statistical optimization of tretinoin-loaded penetration-enhancer vesicles (PEV) for topical delivery

Background: The aim of this study was to develop and optimize deformable liposome for topical delivery of tretinoin. Methods: Liposomal formulations were designed based on the full factorial design and prepared by fusion method. The influence of different ratio of soy phosphatidylcholine and transcutol (independent variables) on incorporation efficiency and drug release in 15 min and 24 h (responses) from liposomal formulations was evaluated. Liposomes were characterized for their vesicle size and Differential Scanning Calorimetry (DSC) was used to investigate changes in their thermal behavior. The penetration and retention of drug was determined using mouse skin. Also skin histology study was performed. Results: Particle size of all formulations was smaller than 20 nm. Incorporation efficiency of liposomes was 79–93 %. Formulation F7 (25:5) showed maximum drug release. Optimum formulations were selected based on the contour plots resulted by statistical equations of drug release in 15 min and 24 h. Solubility properties of transcutol led to higher skin penetration for optimum formulations compared to tretinoin cream. There was no significant difference between the amount of drug retained in the skin by applying optimum formulations and cream. Histopatological investigation suggested optimum formulations could decrease the adverse effect of tretinoin in liposome compared to conventional cream. Conclusion: According to the results of the study, it is concluded that deformable liposome containing transcutol may be successfully used for dermal delivery of tretinoin.