Ondansetron HCl Microemulsions for Transdermal Delivery: Formulation and In Vitro Skin Permeation.

Ondansetron HCl delivery through oral route suffers due to its low bioavailability due to first-pass metabolism. Therefore, the microemulsion-based transdermal delivery may be a better substitute for it. The pseudoternary phase diagrams were constructed to determine compositions of microemulsions, and ondansetron HCl microemulsions for transdermal delivery were developed using isopropyl myristate or oleic acid as the oil phase, Tween 80 as the surfactant, and isopropyl alcohol as the cosurfactant evaluated for in vitro skin permeation through excised porcine skin. The in vitro skin permeation from these formulated microemulsions was sustained over 24 hours. The microemulsion F-8 (contained 10% of isopropyl myristate as oil phase, 8% of aqueous phase, and 82% of surfactant phase containing Tween 80 and isopropyl alcohol, 3 : 1) showed the highest permeation flux of 0.284 ± 0.003 μg/cm(2)/hour. All these microemulsions followed the Korsmeyer-Peppas model (R(2) = 0.971  to  0.998) with non-Fickian, "anomalous" mechanism over a period of 24 hours.