Physicochemical evaluation, study of stability and drug release kinetics from

Introduction: Acne is a disorder of the pilosebaceous unit of the skin and can present as non inflammatory and or inflammatory lesions. Tretinoin has been used therapeutically for over three decades. It is best known for its comedolytic effects on acne. It also inhibits comedone rupture, thus decreasing inflammatory events. Tretinoin is available in 0.01% to 0.1% as cream, gel or lotion. The objective of this investigation was to evaluate the physicochemical stability of various dermatological preparations of tretinoin marketed in Iran. Methods: The in vitro release and penetration characteristics of tretinoin from different formulations (Stieva-A solution, Retin-A cream, Retin-A gel and three Iranian brands) were studied through a hydrophilic Dora pore diffusion barrier and membrane excised rat skin using Franz cell over a period of 5th .The amount of drug released from topical preparations were determined spectrophotometrically at λmax=352 nm. Furthermore, the physicochemical stability of each formulation including drug assay, content uniformity, viscosity, pH, cyclical temperature test and centrifugal separation test were investigated. Results: The obtained results showed that the formulations studied presented both good chemical and physical stabilities. The generated rank order for the drug release from different preparations using membrane was observed to be Stieva A solution > IR-tretinoin lotion > Retin A cream > Retin A gel > IR-tretinoin gel > IR-tretinoin cream. The in vitro penetration of tretinoin through excised rat skin showed that the cumulative percent of penetrated drug at the end of each experiment were 10.8%, 14.75% and 25.2% for IR-cream, IR-gel, Retin A cream and Retin A gel respectively. Conclusion: The in vitro release kinetics of tretinoin is affected by the kind of pharmaceutical dosage form. The release of drug from gel formulation obeyed higuchi’s kinetics, whereas the kinetic of drug release from cream was first order model.