Mutual pro-drugs of beta-lactam antibiotics and beta-lactamase inhibitors.

The principle of combining a beta-lactam antibiotic with a beta-lactamase inhibitor in a single molecule functioning as pro-drug for the two active components is illustrated by the linked esters 3 and 4 in which ampicillin and mecillinam, respectively, are combined with the beta-lactamase inhibitor penicillanic acid sulfone. It is shown that in man these esters are excellently absorbed from the gastro-intestinal tract and after absorption hydrolyzed with simultaneous liberation of the active components. As a result high blood and tissue levels of antibiotic and beta-lactamase inhibitor in a balanced ratio are attained. The advantages of "mutual pro-drugs" over simple combinations are discussed.