AS-924, a Novel Orally Active Bifunctional Prodrug of Ceftizoxime. Synthesis and Relationship between Physicochemical Properties and Oral Absorption

Ceftizoxime (CZX), a parenteral cephalosporin, has potent and broad antibacterial activity. To improve its oral absorption, we synthesized a series of monofunctional and bifunctional prodrugs of CZX. In rabbits, urinary recovery after oral administration of CZX was improved by esterification of the carboxyl group at the C-4 position with various lipophilic moieties (monofunctional prodrugs), and was further increased by introduciton of a hydrophilic L-alanine to the amino group on the thiazole ring at the C-7 position (bifuncional prodrugs). Least-squares analysis showed good parabolic correlatoins between log P and urinary recovery for monofunctional and bifunctional prodrugs, respectively. AS-924, a bifunctional prodrug with a pivaloyloxymethyl and L-alanyl moiety had the best balance of lipophilicity and water-solubility for oral absorption among the prodrugs synthesized.