Sustained delivery formulations comprising a water-insoluble complex of a peptide and a plurality of ligands are disclosed. The formulations of the invention allow for loading of high concentrations of peptide in a small volume and for delivery of a pharmaceutically active peptide for prolonged periods, e.g., one month, after administration of the complex. The complexes of the invention can be milled or crushed to a fine powder. In powdered form, the complexes form stable aqueous suspensions and dispersions, suitable for injection. Methods of making the complexes of the invention, and methods of these complexes are also disclosed.