Formulation and development of transdermal drug delivery system of ethinylestradiol and testosterone: In vitro evaluation

Abstract

Objective: The combination therapy of ethinylestradiol and testosterone in post-menopausal females has shown improved sexual response and libido. The present studies were designed to develop a suitable matrix-type transdermal drug delivery system (TDDS) of ethinylestradiol and testosterone using the polymer chitosan. Methods: Five formulations (ET1 to ET5) were developed by varying the concentration of polymer and keeping the drug load constant. Physical parameters and drug excipient interaction studies were evaluated in all the formulations. In vitro skin permeation profiles of ethinylestradiol and testosterone from various formulations were simultaneously characterized in a thermostatically controlled modified Franz Diffusion cell using HPLC. Based on the physical parameters and in vitro skin permeation profile formulation ET3 containing 30 mg/ml of chitosan was found to be the best and chosen for further studies. Optimized formulation was subjected to in vivo pharmacokinetic analysis in rats using ELISA. Results: Stability profile of patch formulation ET3 depicted stability up to 3 mo. One week skin irritation evaluation in rats indicated that formulation ET3 was nonirritating. Combination transdermal patch across rat skin showed a maximum release of 92.936 and 95.03 % in 60 h with a flux of 2.088 and 21.398 µg/cm2h for ethinylestradiol and testosterone respectively. Conclusion: The net result of this study is the formulation of a stable, non-irritating transdermal patch of ethinylestradiol and testosterone, with good bioavailability and can be used as Estrogen Replacement Therapy (ERT) in postmenopausal women.