The synthesis of a mannosylated carrier used as a drug delivery system to target specifically an antileishmanial drug allopurinol riboside [4-hydroxy-1-β- D-ribofuranosyl-1H-pyrazolo(3,4-d) pyrimidine] into Leishmania donovani infected macrophages via their membrane lectin is described. The synthetic construct is made of a poly- L-lysine backbone, partially acylated with δ-gluconolactone to enhance its water-solubility and substituted with glycyl-glycine as a spacer arm. O- p-phenylisothiocyanate-5′-phosphodiester derivatives of allopurinol riboside and of inosine were synthesized and attached to the spacer arm, then the remaining spacer arms were substituted by reaction with phenyl acetate mannosyl residues.