Provided is a drug-conjugate product obtained by reacting the drug with an alpha-L- amino acid containing one or more hydroxyl groups on the side chains thereof under conditions effective to form a compound having a covalent bond between the drug and the alpha-L-amino acid, wherein the drug is selected from a list of specified drugs (including ibuprofen and aspirin), ), and characterized in that said drug-conjugate product provides for an enhanced therapeutic quality of the drug, the enhanced therapeutic quality being selected from the group consisting of: (a) improved taste or smell, (b) desired octanol/water partition coefficient, (c) improved stability, (d) enhanced penetration of blood-brain barrier, (e) elimination of first pass effect in the liver, (f) reduction of intero-hepatic recirculation, (g) painless injection with parental formulation, (h) improved bioavailability, (i) improved changes in the rate of absorption, (j) reduced side effects, (k) dose proportionality, (l) selective hydrolysis at site of action, (m) controlled release properties, (n) targeted drug delivery, (o) reduction in toxicity, (p) reduced dose, (q) alteration of metabolic pathway to deliver more drug at site of action, (r) increased solubility in aqueous solution and (s) enhanced efficacy, with the proviso that the amino acid moiety is not L-Proline, and L-Hydroxyproline.
