The present invention provides pro-micelle compositions comprising a pharmaceutically active agent encapsulated with a membrane of esterified C₁₂-C₁₈ fatty acids. In the mammalian intestine, exposure to C₁₂-C₁₈ fatty acids results in conversion of the pro-micelle to a stable micelle that effectively delivers the pharmaceutically active agent to the systemic circulation. The present invention further provides methods of making and using such compositions.