Fatty acid compositions for administration of of pharmaceutical agents, such as proteins and peptides, protein and peptide conjugates, and/or cation-polypeptide conjugate complexes. In particular, the invention provides a solid pharmaceutical composition formulated for oral administration by ingestion, having from about 0.1 to about 75% w/w fatty acid component, where the fatty acid component comprises saturated or unsaturated C4, C5, C6, C7, C8, C9, C10, C11, or C12 fatty acids and/or salts of such fatty acids; and a therapeutic agent. Further, the invention provides a liquid pharmaceutical composition formulated for oral administration by ingestion, comprising: from about 0.1 to about 10% w/v fatty acid component, where the fatty acid component comprises saturated or unsaturated C4, C5, C6, C7, C8, C9, C10, C11, or C12 fatty acids and/or salts of such fatty acids; and a therapeutic agent.