Formulation optimization of estradiol microemulsion using response surface methodology

PAO-CHU WU
School of Pharmacy, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung City 80708, Taiwan, ROC.

Abstract:

A constrained mixture design and response surface methodology (RSM) has been employed in order to investigate the effect of three formulations factors including isopropyl myristate (X₁), distilled-water (X₂) and ethanol (X₃) on dependent variables including the cumulative amount at 24 h (Q_24th), lag time (LT) and viscosity of estradiol-loaded microemulsions through rat skin. The analysis of variance showed that the three variables had a significant effect (P<0.05) on the dependent variables. The observed results of Q_24th, LT and viscosity of optimal microemulsion formulations coincided well with the predictions in the RSM optimization technique, indicating it was quite useful for optimizing pharmaceutical formulations. In conclusion, the transdermal estradiol microemulsion was formulated successfully using the technique of RSM. Moreover, the permeation rate of the optimized microemulsion was expected to be at an adequate level for providing therapeutic effects at workable administration area.