The present invention provides compositions and methods for extending the release times and lowering the toxicity of pharmacologically active compounds. The compounds comprise a salt of the pharmacologically active compound with a lipophilic counterion and a pharmaceutically acceptable water soluble solvent combined together to form an injectable composition. The lipophilic counterion may be a saturated or unsaturated C₈-C₂₂ fatty acid, and preferably may be a saturated or unsaturated C₁₀-C₁₈ fatty acid. The compounds precipitate in aqueous environments. When injected into a mammal, at least a portion of the composition precipitates and releases the active compound over time. Thus, the composition forms a slowly releasing drug depot of the active compound in the mammal. Therefore, the present invention enables one to provide a controlled dose administration of the active compound for a period of up to 15 days or even longer. Many compounds can be administered according to the present invention including, but not limited to, tilmicosin, oxytetracycline, metoprolol, fluoxetine, roxithromycin, and turbinafine.