Methods, compounds, and medicinal formulations utilizing biocompatible polymers for delivery of a drug, particularly for solubilizing, stabilizing and / or providing sustained release of drug from topical, implantable, and inhalation systems. Many of the methods, compounds, and medicinal formulations are particularly suitable for oral and / or nasal inhalation and use polymers of the formula —[X—R1—C(O)]— wherein each R1 is an independently selected organic group that links the —X— group to the carbonyl group, and each X is independently oxygen, sulfur, or catenary nitrogen.