In vitro antimicrobial activity of ritipenem acoxil, a new oral penem, and its therapeutic efficacy in respiratory infections

We performed a basic evaluation of ritipenem acoxil (RIPM-AC), a newly developed oral penem, and clinically studied its application in the treatment of respiratory infections, with the following results. 1) Laboratory activity The minimum inhibitory concentrations (MICs) of ritipenem (RIPM) for a total of 296 strains of 13 clinically isolated species were measured and compared with those of cefaclor (CCL), cefotiam (CTM), cefixime (CFIX), cefteram (CFTM) and amoxicillin (AMPC). The activity of RIPM against gram-positive bacteria was nearly equal to that of AMPC, and thus more active than that of other antibiotics. Against gram-negative bacteria, its activity was similar to that of the other antibiotics. 2) Clinical efficacy RIPM-AC was administered to 8 patients with respiratory infections (acute bronchitis 4, acute exacerbation of chronic bronchitis 2, pneumonia 2) at 150-400 mg t.i.d. for 6-14 days. The clinical efficacy was excellent in 1 case, good in 5 cases, fair in 1 case and was not evaluated in 1 case. Causative bacteria were Haemophilus influenzae (1) and Enterobacter cloacae (1). Both of 2 strains were eradicated. No side effects were observed in any patient. As abnormal laboratory findings, eosinophilia in 1 case and elevations of s-Cr, GOT and GPT in 1 case were observed, but they were mild and transient.