The authors demonstrate that three new carbapenems (BO-2727, DX-8739, S-4661) and one new penem (AMA-3176) are relatively stable to human recombinant dehydropeptidase-I in vitro.The rank order of the stability against hydrolysis by the enzyme was: BO-2727 > AMA-3176 > S-4661 > DX-8739 >> imipenem.The next steps will be to determine the in vivo stability of the antibiotics and to evaluate their clin. usefulness.