Abstract: A pharmaceutical composition containing an hydrophilic aminoglucoside antibiotic coupled with an organic acid. The coupled aminoglucoside antibiotic and organic acid are encapsulated in a liposome. The composition of the invention is self-regulating in that it liberates the active compound in inverse proportion to the concentration of the compound in the external medium. As a result, the composition serves as a long-acting antibiotic while avoiding the release of a toxic or ineffective dose of the antibiotic into the subject.