Microemulsion Based Transdermal Drug Delivery of Labetalol

Purpose: The purpose of the research was to formulate Microemulsion based transdermal drug delivery for a poorly soluble and low bioavailable drug, labetalol, an antihypertensive agent. Methodology: Based on solubility studies Isopropyl myristate, Tween 80 and 1,2-propylene glycol were selected as Oil, Surfactant and Co-surfactant respectively. Pseudo ternary phase studies were carried out. The optimum concentrations for labetalol microemulsion based on phase diagram and thermodynamic stability evaluation were found to be Isopropyl myristate (6.66% w/w), Mixture (36.66% w/w) of 1 part of Tween 80, 15 parts of 1,2-propylene glycol and remaining water. The labetalol microemulsions were prepared by phase titration method. Findings: The globule size, zeta potential, viscosity, in vitro and ex vivo release for the best formulation was found to be 9.826 nm, -15.96 mV, 0.8872 cP, 92.61% and 71.045% respectively. Permeation studies of labetalol microemulsions were performed through rat skin. The steady state flux (J ss ) was determined and found to be 4.912 mgcm −2 h −1 . Conclusion: Based on the responses labetalol microemulsion shows a potential drug delivery system with good stability and release profile.