title: Formulation optimization of estradiol microemulsion using response surface methodology.
abstract: The aim of the current study was to find an optimal estradiol-loaded microemulsion with higher permeation rate and shortened lag time (LT) for transdermal application by using a response surface methodology (RSM) and constrained mixture design. Isopropyl myristate (X1 ), distilled water (X2 ), and ethanol (X3 ) were selected as independent variables, whereas the viscosity of microemulsion and permeation parameters including the cumulative amount at 24 h (Q24h ) and LT of estradiol-loaded microemulsion through skin were set as dependent variables. The result showed that the three independent variables had a remarkable effect (p < 0.05) on the dependent variables. Moreover, the predicted and observed values of these three dependent variables of the optimal microemulsion formulations, which were produced by the RSM optimization technique, were close, demonstrating that RSM was a useful technique for optimizing pharmaceutical formulations. However, the experimental estradiol-loaded microemulsion with higher permeation rate was expected to provide effective therapeutic concentration in a workable administration area.
authors.affiliation: Graduate Institute of Clinical Pharmacy, Kaohsiung Medical University, Kaohsiung City 80708, Taiwan, Republic of China.
authors.forename: Yi-Hung
authors.initials: YH
authors.lastname: Tsai
authors.forename: Li-Tse
authors.initials: LT
authors.lastname: Fu
authors.forename: Chi-Te
authors.initials: CT
authors.lastname: Huang
authors.forename: Jui-Sheng
authors.initials: JS
authors.lastname: Chang
authors.forename: Yaw-Bin
authors.initials: YB
authors.lastname: Huang
authors.forename: Pao-Chu
authors.initials: PC
authors.lastname: Wu
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D002626:Chemistry, Pharmaceutical; D004655:Emulsions; D004958:Estradiol / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D000431:Ethanol / Q000737:chemistry; D066298:In Vitro Techniques; D015233:Models, Statistical; D009226:Myristates / Q000737:chemistry; D010539:Permeability; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000378:metabolism*; D012869:Skin Absorption; D013678:Technology, Pharmaceutical / Q000379:methods*; D014783:Viscosity; D014867:Water / Q000737:chemistry
chemical_list: D004655:Emulsions; D009226:Myristates; D014867:Water; C008205:isopropyl myristate; D000431:Ethanol; D004958:Estradiol