Intravenous meropenem versus imipenem/cilastatin in the treatment of serious bacterial infections in hospitalized patients. Meropenem Serious Infection Study Group.

Meropenem was compared with imipenem/cilastatin for the treatment of serious bacterial infections in a randomized, prospective multicentre study. Both study drugs were given intravenously 1 g every 8 h and no other antimicrobial agents were permitted concomitantly. Of the 204 patients enrolled, the treatment of 177 was evaluable for clinical efficacy and 115 for bacteriological efficacy. In the clinically evaluable treatment population, 75 (83%) of the 90 patients in the meropenem group and 78 (90%) of the 87 in the imipenem/cilastatin group had a single site of infection whereas the remainder had two or more sites of infection. Infections of the lower respiratory tract and peritoneal cavity predominated accounting for 95 and 75 cases respectively. Other infections included skin and soft tissue infections, complicated urinary tract infections, bacteraemia and a case of meningitis treated with meropenem and one of mediastinitis treated with imipenem/cilastatin. One hundred and nineteen (67%) patients were in an intensive care unit, 105 (59%) were receiving assisted ventilation and 93 (53%) of the patients had failed previous antibiotic therapy. One hundred and ten organisms were identified as pathogens in the meropenem group and 109 in the imipenem/cilastatin group. Overall, treatment with meropenem was clinically successful in 68 (76%) of 90 cases and imipenem/cilastatin in 67 (77%) of 87 cases and the corresponding eradication rates of bacteria were 85 of 110 (77%) and 90 of 109 (83%) respectively. Superinfections due to resistant bacteria occurred in two patients treated with meropenem and three cases given imipenem/cilastatin. No statistically significant differences in the clinical or bacteriological outcome were observed between the treatment groups for any of the infection sites analysed. Both drugs were well tolerated with adverse events considered to be related to therapy being recorded for 10 (9%) of 106 patients treated with meropenem and 12 (12%) of 98 of those who had been given imipenem/cilastatin. Empirical monotherapy with meropenem was therefore as effective and as well tolerated as that with imipenem/cilastatin for the treatment of serious bacterial infections.

Safety profile of meropenem: international clinical experience based on the first 3125 patients treated with meropenem.

Data from 3125 patients (3220 patient exposures) treated with meropenem were compared with those from 2886 patients (2960 patient exposures) treated with a variety of comparator agents including cephalosporins (alone or in combination with aminoglycosides or an anti-anaerobe agent) and imipenem/cilastatin. Patients treated included those with bacterial infections of the lower respiratory tract, urinary tract and skin and soft tissues, abdominal, obstetric and gynaecological infections, meningitis, febrile episodes in neutropenic patients and paediatric patients with infections. In three studies, meropenem was administered intramuscularly; in the remainder, meropenem was given by 15-30 min iv infusion or by bolus injection over approximately 5 min. The usual dosages were 500 mg or 1 g 8 hourly in adults and 10 or 20 mg/kg 8 hourly in children. In bacterial meningitis, the meropenem dosage in adults was 2 g 8 hourly and 40 mg/kg 8 hourly in children. The overall pattern and frequency of adverse events with meropenem were similar to those of the other beta-lactam antibiotics with which it was compared. The most frequently reported adverse events were diarrhoea, rash, nausea and vomiting, thrombocytosis, eosinophilia and changes in hepatic biochemistry. Abnormal laboratory tests occurred with similar frequencies between meropenem and the comparator agents. The safety profile of meropenem was similar in adults and children, and the presence of renal impairment did not alter the safety profile of meropenem. Experience in clinical studies in 3220 patient exposures has revealed no unusual or unexpected toxicity. The possibility of administration by either iv infusion or bolus injection with a low incidence of nausea and vomiting also provides flexibility in the clinical management of patients. Moreover, the low incidence of reported seizures and good tolerability at high doses, make meropenem particularly useful for the treatment of meningitis and other indications which carry a risk of seizures, or in the treatment of serious infections where high doses of antibiotics are frequently indicated.

A compilation of meropenem tissue distribution data.

Meropenem body fluid and tissue concentration data from both published studies and samples obtained during efficacy evaluation have been compiled and presented according to a consistent format to facilitate comparison. The concentration data have been compared with the mode MIC data available for the pathogens isolated during the clinical evaluation of meropenem. These data support the widespread and rapid penetration of meropenem into the interstitial fluid of those tissues not protected by a tight epithelial barrier. Furthermore, they suggest that the proposed dosages of meropenem 500 mg or 1 g tds would provide an adequate duration of cover at tissue sites for the treatment of a range of commonly occurring pathogens. A higher dosage of 40 mg/kg or 2 g in adults given tds would be recommended for meningitis based on the penetration of meropenem into CSF. Overall, the tissue and body fluid data presented confirm the expectation, based on the plasma concentrations and theoretical arguments, that meropenem is rapidly and readily distributed into the interstitial fluid, thereby producing concentrations in tissues likely to be clinically effective. This is consistent with the available clinical data on the therapeutic efficacy of meropenem.