A stable aqueous gel or semi-
solid gel pharmaceutical composition comprising a water-soluble
peptide having gel-forming ability, optionally in combination with appropriate excipients and therapeutic agents. Upon administration to an individual, the pharmaceutical composition forms a gel reservoir in which the gel
nanostructure releases the
peptide or encapsulated therapeutic
drug for a longer period of time. The gel-forming compound can be formulated as an aqueous formulation, a suspension or a
solid formulation, wherein the gel-forming polypeptide contained accounts for 0.01% to 99% of the total weight of the formulation. These formulations are useful for
drug delivery and implantable
drug depots, for long term delivery of therapeutic drugs, antigens or cells. Also provided are methods of preparing gel-forming compounds by gel formation enhancing motif modification compounds.