Population pharmacokinetics of meropenem administered as a prolonged infusion in children with cystic fibrosis.

OBJECTIVES: Meropenem is frequently used to treat pulmonary exacerbations in children with cystic fibrosis (CF) in the USA. Prolonged-infusion meropenem improves the time that free drug concentrations remain above the MIC (fT> MIC) in adults, but data in CF children are sparse. We describe the population pharmacokinetics, tolerability and treatment burden of prolonged-infusion meropenem in CF children. METHODS: Thirty children aged 6-17 years with a pulmonary exacerbation received 40 mg/kg meropenem every 8 h; each dose was administered as a 3 h infusion. Pharmacokinetics were determined using population methods in Pmetrics. Monte Carlo simulation was employed to compare 0.5 with 3 h infusions to estimate the probability of pharmacodynamic target attainment (PTA) at 40% fT> MIC. NCT#01429259. RESULTS: A two-compartment model fitted the data best with clearance and volume predicted by body weight. Clearance and volume of the central compartment were 0.41 ±â€Š0.23 L/h/kg and 0.30 ±â€Š0.17 L/kg, respectively. Half-life was 1.11 ±â€Š0.38 h. At MICs of 1, 2 and 4 mg/L, PTAs for the 0.5 h infusion were 87.6%, 70.1% and 35.4%, respectively. The prolonged infusion increased PTAs to >99% for these MICs and achieved 82.8% at 8 mg/L. Of the 30 children, 18 (60%) completed treatment with prolonged infusion; 5 did so at home without any reported burden. Nine patients were changed to a 0.5 h infusion when discharged home. CONCLUSIONS: In these CF children, meropenem clearance was greater compared with published values from non-CF children. Prolonged infusion provided an exposure benefit against pathogens with MICs ≥1 mg/L, was well tolerated and was feasible to administer in the hospital and home settings, the latter depending on perception and family schedule.

Evaluation of a pharmacokineticpharmacodynamic approach using software to optimize the carbapenem antibiotic regimen.

OBJECTIVE: Meropenem (MEPM) and doripenem (DRPM), whose antipseudomonal activity is more potent than that of other carbapenem antimicrobials, were used in the study. Monte Carlo simulation of drug concentrations was performed to develop an administration plan for MEPM and DRPM that takes into account the pharmacokinetics (PK)-pharmacodynamics (PD) of MEPM and DRPM and the renal function of each patient. Drug administration plans were proactively applied to patients with pneumonia to determine the usefulness of the method by assessing treatment efficacy and safety. METHODS: Patients with healthcareassociated pneumonia and an indication for MEPM or DRPM chemotherapy underwent drug administration in accordance with the MEPM and DRPM treatment plan developed by the PK-PD software applications. The primary efficacy endpoints were the clinical and bacteriological efficacy of the drugs agains pneumonia. The safety of the antimicrobials was assessed based on abnormal laboratory findings and the seizure disorders in accordance with the criteria for safety evaluation of antimicrobial agents. RESULTS: This study examined 12 and 11 patients in the MEPM and DRPM group, respectively; however, 3 DRPM patients were excluded due to the administration of anti-methicillin-resistant Staphylococcus aureus drugs after the initiation of DRPM treatment. MEPM and DRPM drug administration was determined to be safe and effective in all patients. CONCLUSIONS: The present results suggest that the Monte Carlo simulation-based PK-PD software is an effective tool for planning individualized antimicrobial chemotherapy with carbapenem in accordance with the PK-PD theory of antimicrobials. It is also possible to propose safe and effective drug administration plans for patients with healthcare-associated pneumonia.

Monitoring of effectiveness and safety of generic formulation of meropenem for treatment of infections at Siriraj Hospital.

OBJECTIVE: In Siriraj Hospital, generic meropenem (Monem) has been available and was substituted for original meropenem, but the effectiveness and safety of using generic meropenem in a clinical setting are the main concern. MATERIAL AND METHOD: From July 2007 to June 2009, hospitalized patients aged 18 or older who received meropenem for 48 hours were identified from the pharmacy database of Siriraj hospital. A retrospective study was conducted. Three hundred patients in each of original and generic meropenem groups were required to demonstrate non-inferiority of generic to original meropenem. RESULTS: The mean age of all patients was 63 years. Most of the patients had co-morbidities. Approximately 90% of the infections were health-care associated. Drug-resistant gram-negative bacteria including ESBL producing E. coli and K. pneumoniae, P. aeruginosa and A. baumannii account for nearly 50% of all organisms. No significant difference was found regarding characteristics, type or site of infection and pathogen between generic and original groups but for more patients in the original group having cardiovascular disease and more patients in the generic group receiving immunosuppressive agents. Eighty-two to 85% received meropenem with one of appropriate indications. No statistically significant difference occurred either in an overall favorable outcome (63% vs.70.4%, p = 0.07) or in overall mortality (38% vs. 32%, p = 0.17), as well as adverse effects between the original and the generic groups. CONCLUSION: Generic meropenem (Monem) was not inferior to original meropenem for therapy of infections in the hospitalized patients at Siriraj Hospital.

Meropenem: a review of its use in the treatment of serious bacterial infections.

Meropenem (Merrem, Meronem) is a broad-spectrum antibacterial agent of the carbapenem family, indicated as empirical therapy prior to the identification of causative organisms, or for disease caused by single or multiple susceptible bacteria in both adults and children with a broad range of serious infections. Meropenem is approved for use in complicated intra-abdominal infection (cIAI), complicated skin and skin structure infection (cSSSI) and bacterial meningitis (in paediatric patients aged > or = 3 months) in the US, and in most other countries for nosocomial pneumonia, cIAI, septicaemia, febrile neutropenia, cSSSI, bacterial meningitis, complicated urinary tract infection (UTI), obstetric and gynaecological infections, in cystic fibrosis patients with pulmonary exacerbations, and for the treatment of severe community-acquired pneumonia (CAP). Meropenem has a broad spectrum of in vitro activity against Gram-positive and Gram-negative pathogens, including extended-spectrum beta-lactamase (ESBL)- and AmpC-producing Enterobacteriaceae. It has similar efficacy to comparator antibacterial agents, including: imipenem/cilastatin in cIAI, cSSSI, febrile neutropenia, complicated UTI, obstetric or gynaecological infections and severe CAP; clindamycin plus tobramycin or gentamicin in cIAI or obstetric/gynaecological infections; cefotaxime plus metronidazole in cIAI; cefepime and ceftazidime plus amikacin in septicaemia or febrile neutropenia; and ceftazidime, clarithromycin plus ceftriaxone or amikacin in severe CAP. Meropenem has also shown similar efficacy to cefotaxime in paediatric and adult patients with bacterial meningitis, and to ceftazidime when both agents were administered with or without tobramycin in patients with cystic fibrosis experiencing acute pulmonary exacerbations. Meropenem showed greater efficacy than ceftazidime or piperacillin/tazobactam in febrile neutropenia, and greater efficacy than ceftazidime plus amikacin or tobramycin in patients with nosocomial pneumonia. Meropenem is well tolerated and has the advantage of being suitable for administration as an intravenous bolus or infusion. Its low propensity for inducing seizures means that it is suitable for treating bacterial meningitis and is the only carbapenem approved in this indication. Thus, meropenem continues to be an important option for the empirical treatment of serious bacterial infections in hospitalized patients.

Empiric carbapenem monotherapy in pediatric bone marrow transplant recipients.

OBJECTIVE: To determine which carbapenem (imipenem/cilastatin or meropenem) was the preferable empiric antibiotic monotherapy in pre-engrafted pediatric bone marrow transplant (BMT) patients in terms of patient tolerance, therapeutic efficacy, and cost. METHODS: We prospectively analyzed 16 pediatric BMT patients who received meropenem, and retrospectively analyzed 16 matched patients who had received imipenem/cilastatin for BMT procedures during the prior 2-year period. We evaluated the patients for evidence of bacterial infection, necessity for concurrent antibiotics, vomiting episodes, duration of concurrent total parenteral nutrition (TPN), and cost of therapy. RESULTS: We found no differences in the number of culture proven or clinically suspected breakthrough bacterial infections or the need for concurrent additional antibiotics between the groups. Our analysis found that patients who received meropenem experienced significantly less vomiting than those in the imipenem/cilastatin cohort. Our data showed both direct and indirect cost savings for the meropenem group. The statistical and clinical differences in the number of vomiting episodes between these groups impacted other aspects of patient care, antiemetic use, and TPN duration. CONCLUSIONS: By switching to meropenem, we reduced the cost of antiemetic therapy per patient treatment course, and also showed a trend toward reduced duration of TPN. We found that meropenem provided both clinical and fiscal advantages over imipenem/cilastatin as empiric antibiotic monotherapy in neutropenic pediatric BMT patients.

Meropenem: an updated review of its use in the management of intra-abdominal infections.

UNLABELLED: Meropenem is a carbapenem antibacterial agent with a broad spectrum of activity which encompasses gram-negative, gram-positive and anaerobic bacteria. Like other carbapenems, meropenem is stable against chromosomal and extended-spectrum beta-lactamases. In patients with moderate to severe intra-abdominal infections, empirical monotherapy with meropenem achieved clinical response rates ranging from 91 to 100% in 7 randomised comparative trials. Efficacy rates were similar to those of imipenem/cilastatin (94 to 97%), clindamycin plus tobramycin (93%) and, overall, to cefotaxime plus metronidazole (75 to 100%), although there were differences between trials versus this combination regimen. According to limited data, meropenem also achieved clinical response rates of over 80% in patients with severe intra-abdominal infections. Meropenem is well tolerated, the most common adverse events being diarrhoea, rash, nausea/vomiting and inflammation at the injection site which are reported in <2.5% of patients each. Meropenem also has an improved CNS tolerability profile compared with imipenem/cilastatin. CONCLUSIONS: Extensive comparative clinical data demonstrate that meropenem can be used effectively as empirical monotherapy in moderate to severe intra-abdominal infections. It also shows potential in the most severe forms of infection, although experience in this infection type remains limited. Compared with standard combination regimens, meropenem offers the benefits of ease of administration without the need for monitoring. It also offers improved CNS tolerability compared with imipenem/cilastatin with the option of a higher maximum dosage, which may be a particular advantage in patients with severe intra-abdominal infections.

Carbapenems in serious infections: a risk-benefit assessment.

The tolerability of the 2 most frequently used carbapenems, imipenem/cilastatin and meropenem, is reviewed. Both of these drugs, but especially imipenem, are potentially neurotoxic and may cause seizures if overdosed relative to renal function and/or bodyweight. The therapeutic margin is considerably narrower with imipenem/cilastatin which cannot be given at doses required for treatment of bacterial meningitis. Meropenem on the other hand, is considerably less prone to cause seizures and its tolerability and efficacy are well documented in 3 relatively large, controlled studies in adults and children with meningitis. They showed that meropenem was as effective and well tolerated as cefotaxime or ceftriaxone. Another potential advantage of meropenem over imipenem/cilastatin is that it can be given intravenously at a high rate without increased risk of nausea or vomiting. An obvious reason for using a carbapenem instead of a cephalosporin for empirical treatment of life-threatening infections is that both imipenem/cilastatin and meropenem have a broader spectrum of activity. They are also more resistant to hydrolysis by the most common beta-lactamases, including the class I cephalosporinase frequently produced by Enterobacter spp. and Pseudomonas spp. and the extended spectrum enzymes, now commonly found in Escherichia coli and Klebsiella spp.

Clinical and economic evaluation of subsequent infection following intravenous ciprofloxacin or imipenem therapy in hospitalized patients with severe pneumonia.

A recent multicentre clinical study evaluated the safety and efficacy of i.v. ciprofloxacin therapy compared with imipenem-cilastatin in hospitalized patients with severe pneumonia. Monotherapy with i.v. ciprofloxacin was at least equivalent to imipenem in terms of bacteriological eradication and clinical response. In a single-centre, retrospective, post-therapy evaluation of persistent and subsequent infection, the incidence of gram-negative infections and associated costs were compared. The main elements of the economic analysis included costs of additional antimicrobial therapy and hospitalization. Thirty-two patients were randomized into the study, of whom 27 were efficacy-valid. The 13 patients randomized into the ciprofloxacin group were not significantly different from the 14 patients in the imipenem group in terms of clinical parameters. Clinical cure occurred in ten of 13 patients (77%) in the ciprofloxacin group and in seven of 14 (50%) in the imipenem group. Bacteriological eradication was achieved in 11 of 13 (85%) ciprofloxacin-treated and eight of 14 (57%) imipenem-treated patients. Five of 13 (38%) patients in the ciprofloxacin group and nine of 14 (64%) in the imipenem group experienced persistent or subsequent infection requiring post-treatment antimicrobials. In these five ciprofloxacin patients, three had cultures with gram-positive organisms only and two had cultures with both gram-positive and gram-negative organisms. In the nine imipenem-treated patients requiring post-study antimicrobials, all had gram-negative bacteria and three also had gram-positive organisms. The incidence of subsequent gram-negative infection in the two groups (15% vs 64%) was significantly different (P < 0.05). Pseudomonas aeruginosa was isolated from seven patients in the imipenem group but only one in the ciprofloxacin group (P < 0.05). Subsequent costs for post-therapy antimicrobials and hospital stay while receiving study and post-study drug therapy were evaluated; the cost per patient cure was US$29,000 for ciprofloxacin and US$76,000 for imipenem. Initial treatment of severe pneumonia with ciprofloxacin resulted in significantly less subsequent gram-negative infection and was associated with substantially lower curative costs.

Prospective randomized study to compare imipenem 1.5 grams per day vs. 3.0 grams per day in infections of granulocytopenic patients.

The objective of this presented prospective randomized study was to compare the efficacy of empirical antimicrobial monotherapy with imipenem 3 x 0.5 g per day to 3 x 1.0 g per day for treatment of infections in neutropenic patients. A total of 192/220 febrile episodes were evaluable for clinical efficacy. The overall response rate was 53/93 (57%) vs. 57/99 (58%). Of the different infection types, fever of unknown origin (FUO) showed the best response, with defervescence in 29/41 (71%) and 36/42 (86%) cases, respectively (not significant). Unfavourable results were found in pneumonias [5/20 (25%) vs. 4/23 (17%)]. The median time until persistent defervescence was equal in both groups (2 days), likewise the median duration of imipenem therapy in responders (7 days). The most frequent micro-organisms were Gram-negative, documented in 22% of the febrile episodes in the lower dosage group vs. 17% of all episodes in the patients with imipenem 3.0 g per day (Gram-positives 17% vs. 14%, fungal 5% vs. 8%). In the lower dosage group, fever with abdominal symptoms occurred less frequently (8% vs. 15%), and significantly more patients tolerated imipenem without any side-effects (95.8% vs. 79.4%), especially regarding severe nausea/vomiting (2.1% vs. 11.8%). Of the initial non-responders, 35/40 (88%) vs. 41/42 (98%) were cured after therapy modification. There was no significant difference in the use of further antibiotics such as aminoglycosides, glycopeptides, ceftazidime or amphotericin B, except a marginally higher use of metronidazole in patients with imipenem 3.0 g per day (3% vs. 10%). Overall, we found no significant differences in efficacy between the two study groups, but more frequent side-effects with imipenem 3.0 g per day.

[Carbapenems (thienam and Meronem). Their clinical and economic efficacy]. / Karbapenamy (tienam i meronem). K voprosu o klinicheskoi i ékonomicheskoi éffektivnosti.

The authors describe 229 cases of carbapenem use in intensive care wards. Tienam was used in 205 cases since 1993, meronem in 24 cases since 1996. There were 149 men and 80 women aged 15-76 years (mean age 46.4 +/- 0.7 years). Carbapenemes were administered by 5-7-day courses in a daily dose of 2-6 g (2-4 g for tienam and 2-6 g for meronem). Carbapenemes were administered as monotherapy; in 196 cases nisoral was added to antibiotic therapy starting from day 3 as an antimycotic agent. Bacteriological studies were carried out in 367 patients (413 inoculations). Sensitivity of cultured microflora to disks with tienam (329 tests) and meronem (97 tests) showed their high activity towards gram-positive and gram-negative flora. The results were less demonstrative in cerebral abscesses, which is explained by specific pharmacokinetics of tienam. Analysis of the cost/efficacy ratio confirmed the economic efficacy of this group of drugs.

Cost-effectiveness of ampicillin/sulbactam versus imipenem/cilastatin in the treatment of limb-threatening foot infections in diabetic patients.

A cost-effectiveness analysis was performed following a double-blind, randomized study of ampicillin/sulbactam (A/S) versus imipenem/cilastatin (I/C) for the treatment of limb-threatening foot infections in 90 diabetic patients. There were no significant differences between the treatments in terms of clinical success rate, adverse-event frequency, duration of study antibiotic treatment, or length of hospitalization. Costs of the study antibiotics, treatment of failures and adverse events, and hospitalization were calculated. Mean per-patient treatment cost in the A/S group was $14,084, compared with $17,008 in the I/C group (P = .05), primarily because of lower drug and hospitalization costs and less-severe adverse events in the A/S group. Sensitivity analyses varying drug prices or hospital costs demonstrated that A/S was consistently more cost-effective than I/C. Varying the clinical success rate for each drug revealed that I/C would have to be 30% more effective than A/S to change the economic decisions.