AbstractThe coupling reaction of ampicillin with the polysaccharide xanthane in DMSO, using dicyclohexylcarbodiimide as activator, was studied. To find the conditions for maximum yield a regression equation was established, describing the dependence of the yield of coupling product on the reaction parameters (drug/support mole ratio, activator/support mole ratio and duration), starting from an experimental, centrated rotable complex, second order program. The coupling product was spectroscopically characterized and the in vitro release rate of ampicillin in a weakly basic medium was established along with the determination of its antimicrobiological activity.