Synthesis and relative bioavailability of meptazinol benzoyl esters as prodrugs

Three meptazinol benzoyl esters (1–3) were synthesized as prodrugs to minimize the first-pass effect of meptazinol and improve the bioavailability. Among these three esters, compound 3 showed better bioavailability than the parent meptazinol. Further, the relative regional bioavailability of prodrug 3 was evaluated using in situ closed loop study in rats, which showed that prodrug 3 has higher absorption efficacy in rat intestine. Thusly, prodrug 3 may be worth for further development.