The present invention provides compositions and methods and for increasing the bioavailability of therapeutic agents in a subject. The compositions include at least one alkyl glycoside and at least one therapeutic agent, wherein the alkylglycoside has an alkyl chain length from about 10 to about 16 carbon atoms. In various aspects, the invention provides compositions and methods for oral delivery of peptides containing non-naturally occurring structures including D-amino acids and/or chain cyclization.
