Post-antibiotic effect of FK-037 and biapenem tested against five bacterial species

The in-vitro post-antibiotic effect (PAE) was determined for two newer beta-lactams, FK-037 (a cephalosporin) and biapenem (a carbapenem). Our PAE results for these drugs were consistent with what has been reported previously for similar beta-lactams, e.g. Gram-positive organisms had measurable effects (0.4-2.2 hours), while Gram-negatives had variable results (0.0 to 1.4 hours). Even though the PAE test conditions generally coincided with achievable clinical levels for most organisms tested (< or = 4 mg/L for biapenem and < or = 8 mg/L for FK-037), the marginal or species dependent, short PAE values support the selection of multiple daily doses (two-to-four) based on conventional pharmacokinetic parameters such as the Cmax, AUC, and serum elimination half-life.