D-galactose as a vector for prodrug design.

D-galactose is a simple and natural compound that has mainly been exploited in prodrug strategies. Galactosyl prodrugs can be considered a good approach to reach different goals in clinical drug application, especially when traditional drugs are likely to fail therapeutically owing to reasons such as the lack of site specificity, toxicity, and chemical instability. Indeed, of paramount importance is their ability to increase the selectivity of the parent compound, a phenomenon that helps to reduce the incidence of adverse effects, while preserving intact the pharmacodynamic features of the parent drug. Study results have varied according to the type of linkage between the drug and the hydroxyl group exploited. By working with these parameters, researchers have been able not only to generate selective pharmacological targeting of brain, liver, and cancerous cells, but also to improve cellular permeability as well as the pharmacokinetic profile of parent drugs. This review describes the broad spectrum of possibilities for exploiting D-galactose as a vector for prodrug design and the synthetic strategies that allow its realization.