The invention relates to compositions and methods for drug delivery suitable for promoting the transmucosal absorption of drugs, especially drugs with poor intrinsic bioavailability, such as peptides, proteins, vaccines, and nucleic acids. The delivery system of this invention preferably comprises fatty acid esters and their hydrophilic derivatives that associate with water and other polar solvents to form reverse micelles that are physically stabilized in the presence of gastrointestinal fluid, water, and other hydrophilic solvents. Such stable reverse micelles are formed by suitable mixtures of polymeric or non-polymeric compounds with amphiphiles. Micelles made using these methods undergo phase transformation more slowly resulting in delayed drug release profiles and sustained absorption. When administered as a pharmaceutical to mucosal surfaces following oral ingestion or intranasal administration, therapeutic molecules principally solubilized in the aqueous phase are protected from digestion by mucosal enzymes and other mucosal degradative processes and are taken up by absorptive cell mechanisms and reach appropriate body compartments. The reverse micelle compositions may comprise mono-, di-glycerides and/or their transesterified products containing C6-C12 fatty acids chains, wherein the transester groups consist of hydrophilic moieties.