In vitro antimicrobial activity of imipenem and clinical efficacy of intramuscular imipenem/cilastatin sodium (IPM/CS) in respiratory tract infections

We carried out bacteriological and clinical studies on intramuscular imipenem/cilastatin sodium (IPM/CS) developed as a new route of administration and obtained the following results. 1. Antimicrobial activity The In vitro antimicrobial activity of imipenem (IPM) against 330 clinical isolates of 11 species was determined and compared with that of piperacillin (PIPC), cefazolin (CEZ), cefotiam (CTM), aztreonam (AZT), sulbactam/cefoperazone (SBT/CPZ), ceftazidime (CAZ), minocycline (MING) and amikacin (AMK). The M IC₉₀ of IPM was 8 µg/ml against Pseudomonas aeruginosa and 1 µg/ml or less against the other organisms, except for methicillin-resistant Staphylococcus aureus (MRSA), whose MIC₉₀ was 128 µg/ml. 2. Clinical efficacy and safety 0.25 g/0.25 g or 0.5 g/0.5 g of intramuscular IPM/CS was administered twice a day for 2–16 days to 62 patients with respiratory tract infections, and clinical efficacy and safety were evaluated. Clinical efficacy in 60 evaluable patients was excellent in 12 patients, good in 33, fair in 10 and poor in 5, with an efficacy rating of 75.0%. The bacteriological eradication rate was 79.3%. Of the 61 patients evaluable for safety, gastrointestinal symptoms such as diarrhea were observed in 3 patients, and inflammation at the injection site and aggravation of pain/numbness in the lower extremities each occurred in one patient, resulting in a total of 5'patients with adverse experiences (8.2%). These improved after discontinuation or completion of the treatment. Abnormal laboratory findings such as abnormalities in liver function tests were observed in 13 patients; however, these findings were mild and transient.