A transmembrane penetration enhancer includes a thermotropic liquid crystal suitably prepared for use in a therapeutic system to improve delivery of at least one active ingredient across a biomembrane and/or skin. The thermotropic liquid crystal comprises at least one cholesteryl ester and is effective in a mesomorphic state at a temperature of the biomembrane and/or skin. A therapeutic system includes the prepared thermotropic liquid crystal for enhanced transmembrane penetration and at least one active ingredient for delivery by the thermotropic liquid crystal. A method for making and using the transmembrane penetration enhancer is presented.