The present invention relates to a range of therapeutic compounds conjugated to one to three acyl groups derived from fatty acids. The therapeutic compounds are selected from the following group: 1) the corticosterone family of drugs; 2) opioids and opioid antagonists; 3) antiviral nucleosides, such as AZT; 4) cyclosporins and related cyclopeptides; 5) folate antagonists including methotrexate, folic acid and folic acid analogues; 6) catecholamine precursors, such as DOPA and Dopamine, and catecholamines, such as adrenaline and noradrenaline and derivatives; and 7) alkylating agents containing a carboxylic acid group, such as chlorambucil and melphalan. The therapeutic compound is conjugated to the fatty acid(s) by a link which includes a tromethamine or ethanolamine derivative. In particular the present invention relates to altering the pharmacokinetic profile and mode of delivery of these therapeutic compounds by conjugating them to one, two or three acyl derivatives of fatty acids.