Pharmacokinetics, Safety, and Tolerability of Imipenem/Cilastatin/Relebactam in Children with Confirmed or Suspected Gram-Negative Bacterial Infections: A Phase 1b, Open-Label, Single-Dose Clinical Trial

Imipenem/cilastatin/relebactam is approved for the treatment of serious gram-negative bacterial infections in adults. This study assessed the pharmacokinetics (PK), safety, and tolerability of a single dose of imipenem/cilastatin/relebactam (with a fixed 2:1 ratio of imipenem/cilastatin to relebactam, and with a maximum dose of 15 mg/kg imipenem and 15 mg/kg cilastatin [≤500 mg imipenem and ≤500 mg cilastatin] and 7.5 mg/kg relebactam [≤250 mg relebactam]) in children with confirmed/suspected gram-negative bacterial infections receiving standard-of-care antibacterial therapy. In this phase 1, noncomparative study (ClinicalTrials.gov identifier, NCT03230916), PK parameters from 46 children were analyzed using both population modeling and noncompartmental analysis. The PK/pharmacodynamic (PD) target for imipenem was percent time of the dosing interval that unbound plasma concentration exceeded the minimum inhibitory concentration (%fT>MIC) of ≥30% (MIC = 2 mcg/mL). For relebactam, the PK/PD target was a free drug area under the plasma concentration-time curve (AUC) normalized to MIC (at 2 mcg/mL) of ≥8.0 (equivalent to an AUC from time zero extrapolated to infinity of ≥20.52 mcg·h/mL). Safety was assessed up to 14 days after drug infusion. For imipenem, the ranges for the geometric mean %fT>MIC and maximum concentration (Cmax ) across age cohorts were 56.5%-93.7% and 32.2-38.2 mcg/mL, respectively. For relebactam, the ranges of the geometric mean Cmax and AUC from 0 to 6 hours across age cohorts were 16.9-21.3 mcg/mL and 26.1-55.3 mcg·h/mL, respectively. In total, 8/46 (17%) children experienced ≥1 adverse events (AEs) and 2/46 (4%) children experienced nonserious AEs that were deemed drug related by the investigator. Imipenem and relebactam exceeded plasma PK/PD targets; single doses of imipenem/cilastatin/relebactam were well tolerated with no significant safety concerns identified. These results informed imipenem/cilastatin/relebactam dose selection for further pediatric clinical evaluation.

Effectiveness and Safety of Intra-arterial Imipenem/Cilastatin Sodium Infusion for Patients with Hand Osteoarthritis-Related Interphalangeal Joint Pain

PURPOSE

To evaluate the effectiveness and safety of intra-arterial imipenem/cilastatin sodium (IPM/CS) infusion for painful interphalangeal joint osteoarthritis (OA).

MATERIALS AND METHODS

Fifty-eight patients with interphalangeal joint OA who underwent intra-arterial IPM/CS infusion were retrospectively evaluated. Intra-arterial infusions were performed via percutaneous wrist arterial access. The Numerical Rating Scale (NRS), Functional Index for Hand Osteoarthritis (FIHOA), and Patient Global Impression of Change (PGIC) scale scores were assessed at intervals of 1, 3, 6, 12, and 18 months. Clinical success was evaluated based on PGIC.

RESULTS

All patients were followed up for at least 6 months after treatment. Of them, 30 and 6 patients were followed up for 12 and 18 months, respectively. No severe or life-threatening adverse events were encountered. The mean NRS score was 6.0 ± 1.4 at baseline, which significantly decreased to 2.8 ± 1.4, 2.2 ± 1.9, and 2.4 ± 1.9 at 1, 3, and 6 months after treatment, respectively (all P < .001). The mean NRS scores were 2.8 ± 1.7 and 2.9 ± 1.9 at 12 and 18 months, respectively, in the remaining patients. The mean FIHOA score significantly decreased from 9.8 ± 5.0 at the baseline to 4.1 ± 3.5 at 3 months (P < .001). The mean FIHOA score was 4.5 ± 3.3 at 12 months in the remaining 30 patients. The clinical success rates based on PGIC at 1, 3, 6, 12, and 18 months were 62.1%, 77.6%, 70.7%, 63.4%, and 50.0%, respectively.

CONCLUSIONS

Intra-arterial IPM/CS infusion is a potential treatment option for interphalangeal joint OA refractory to medical management.

A novel analytical method to assess the effect of imipenem/cilastatin on liver function laboratory indexes in Chinese underage inpatients: Probability distribution curve

Objectives

The primary objective of this study was to establish a novel method to assess the effect of imipenem/cilastatin (IMP) on liver function laboratory indexes in Chinese underage inpatients (inpatients aged <18 year-old).

Methods

A retrospective study was conducted in 188 underage inpatients who received IMP in Xiangya Hospital from January 2016 to April 2018. Demographic data and clinical information of these inpatients were collected. As there was no reference interval of minors, the occurrence of abnormal liver function was estimated by that of adults, temporarily. A new concept (mean-variance induced by drug, MVID) was introduced to analyze the characteristics of total bilirubin (TBil), direct bilirubin (DBil), alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Effect of MVID of TBil, DBil, ALT and AST in different patients (aged<1 year old and aged ≥ 1 year old) were compared by Mann-Whitney U test.

Results

Estimating by reference intervals of adults, 57.4% underage inpatients (108/188) had abnormal liver function. According to the probability distribution curve of MVID, IMP can cause the increase of AST in 24% (0.62–0.38) Chinese underage inpatients, and the increase of ALT in 20% (0.60–0.40) Chinese underage inpatients. And liver protecting drugs can decrease MVID of ALT and AST. There were not statistically significant differences in MVID of TBil, DBil, ALT and AST in different patients (aged<1 year old and aged ≥ 1 year old); P value was 0.711, 0.734, 0.067 and 0.086, respectively.

Conclusion

IMP can affect the liver function of 20–24% Chinese underage inpatients mainly by increasing the AST and ALT. IMP may induce hepatocellular injury, but not cholestasis. And liver protecting drugs can reverse the side effects caused by IMP. Age may not affect the effect of IMP on liver function.

Cefozopran, meropenem, or imipenem-cilastatin compared with cefepime as empirical therapy in febrile neutropenic adult patients: A multicenter prospective randomized trial

We conducted an open-label, randomized study to evaluate the clinical efficacy of cefozopran, meropenem or imipenem-cilastatin using cefepime as a control in febrile neutropenia (FN) patients. Three hundred and seventy-six patients received cefepime, cefozopran, meropenem or imipenem-cilastatinas initial therapy for FN. The primary endpoint was the non-inferiority of response rates including modification at day 7 in cefozopran, meropenem or imipenem-cilastatin patients compared with cefepime in the per-protocol population (delta = 10%). The response rates for cefozopran, meropenem and imipenem-cilastatin were not significantly different compared with cefepime (cefozopran: 54/90 (60%), meropenem: 60/92 (65%), and IPM/CS: 63/88 (72%) versus cefepime: 56/85 (66%) (p = 0.44, 1.0 and 0.51, respectively)), and the differences in treatment success for cefozopran, meropenem and imipenem-cilastatin compared with cefepime were -5.9% (95% confidence interval (CI): -20.1-8.4), -0.7% (95% CI: -14.6-13.3), and 5.7% (95% CI: -8.1-19.4), respectively. The same tendency was seen in the modified intention-to-treat population. Based on the evaluation of initial drug efficacy performed on days 3-5, there was no significant difference between the four drugs. In the subgroup with an absolute neutrophil count ≤ 100 × 10(6)/L for longer than seven days, there was significantly better efficacy in the carbapenem arm compared to 4th generation beta-lactams (52% versus 27% at days 3-5, p = 0.006, and 76% versus 48% at day 7, p = 0.002). Our results suggest that the effects of these four drugs as empiric therapy were virtually the same for adult FN patients, although non-inferiority was shown only in imipenem-cilastatin compared with cefepime (clinical trial number: UMIN000000462).

Adverse events associated with meropenem versus imipenem/cilastatin therapy in a large retrospective cohort of hospitalized infants

BACKGROUND

Carbapenems are commonly used in hospitalized infants despite a lack of complete safety data and associations with seizures in older children. We compared the incidence of adverse events in hospitalized infants receiving meropenem versus imipenem/cilastatin.

METHODS

We conducted a retrospective cohort study of 5566 infants treated with meropenem or imipenem/cilastatin in neonatal intensive care units managed by the Pediatrix Medical Group between 1997 and 2010. Multivariable conditional logistic regression was performed to evaluate the association between carbapenem therapy and adverse events, controlling for infant factors and severity of illness.

RESULTS

Adverse events were more common with use of meropenem compared with imipenem/cilastatin (62.8/1000 infant days versus 40.7/1000 infant days, P < 0.001). There was no difference in seizures with meropenem versus imipenem/cilastatin (adjusted odds ratio 0.96; 95% confidence interval: 0.68, 1.32). The incidence of death, as well as the combined outcome of death or seizure, was lower with meropenem use-odds ratio 0.68 (0.50, 0.88) and odds ratio 0.77 (0.62, 0.95), respectively.

CONCLUSION

In this cohort of infants, meropenem was associated with more frequent but less severe adverse events when compared with imipenem/cilastatin.

Efficacy and safety of ceftazidime-avibactam versus imipenem-cilastatin in the treatment of complicated urinary tract infections, including acute pyelonephritis, in hospitalized adults: results of a prospective, investigator-blinded, randomized study

OBJECTIVES

The aim of this prospective phase II, randomized, investigator-blinded study (NCT00690378) was to compare the efficacy and safety of ceftazidime-avibactam and imipenem-cilastatin in hospitalized adults with serious complicated urinary tract infection (cUTI) due to Gram-negative pathogens.

PATIENTS AND METHODS

Patients aged between 18 and 90 years with cUTI were enrolled and stratified by infection type (acute pyelonephritis or other cUTI) and randomized 1:1 to receive intravenous ceftazidime 500 mg plus avibactam 125 mg every 8 hours or imipenem-cilastatin 500 mg every 6 hours. Patients meeting pre-specified improvement criteria after 4 days could be switched to oral ciprofloxacin. Patients were treated for a total of 7-14 days. The primary efficacy objective was a favorable microbiological response at the test-of-cure (TOC) visit 5-9 days post-therapy in microbiologically evaluable (ME) patients.

RESULTS

Overall, 135 patients received study therapy (safety population); 62 were included in the ME population (ceftazidime-avibactam, n = 27; imipenem-cilastatin, n = 35). The predominant uropathogen was Escherichia coli. Favorable microbiological response was achieved in 70.4% of ME patients receiving ceftazidime-avibactam and 71.4% receiving imipenem-cilastatin at the TOC visit (observed difference -1.1% [95% CI: -27.2%, 25.0%]). Among ME patients with ceftazidime-resistant uropathogens, response was observed in 6/7 (85.7%) receiving ceftazidime-avibactam. Adverse events were observed in 67.6% and 76.1% of patients receiving ceftazidime-avibactam and imipenem-cilastatin, respectively. Limitations of the study include the small number of patients in the ME population.

CONCLUSION

The results suggest that the efficacy and safety of ceftazidime-avibactam may be similar to that of imipenem-cilastatin.

[Domestic imipenem cilastatin sodium for the treatment of severe aspiration pneumonia, a curative effect observation]

OBJECTIVE

To evaluate the efficacy and safety of domestic imipenem cilastatin sodium for the treatments of severe aspiration pneumonia.

METHODS

A randomize, open, parallel-controlled trial was conducted. Sixty-eight patients with severe aspiration pneumonia were divided into trial group (n=36) and control group (n=32) by random distribution method. The application of trial group domestic imipenem cilastatin sodium was 1.0 g intravenous drip, every 6-8 hours for 7-14 days. The control group application with imported injection imipenem cilastatin sodium was 1.0 g intravenous drip, every 6-8 hours for 7-14 days. The highest daily temperature (T), heart rate (HR), breathing rate (RR), pulse blood oxygen saturation (SpO(2)), blood oxygen partial pressure (PaO(2)), inhaled oxygen concentration (FiO(2)), oxygenation index (PaO(2)/FiO(2)), airway peak pressure (Paw), minute ventilation (MV) and white blood count (WBC), pro calcitonin (PCT), high-sensitivity C-reactive protein (hs-CRP) index before and 1, 3, 7 days after treatment, and liver and kidney function, chest X-rays, and sputum cultures of drug sensitive test were conducted. And the effectiveness and safety were determined according to the standards.

RESULTS

After treatment indexes of the two groups were obviously improved, i. e. T, HR, RR, Paw, MV, the WBC, PCT, CRP were gradually declined, PaO(2)/FiO(2) was gradually raised. There were statistical significance before and 3 days after treatment in the trial and the control group [T: 37.35±0.91 centigrade vs. 38.43±1.06 centigrade, 37.28±0.88 centigrade vs. 38.35±1.11 centigrade; HR: 90.25±10.60 bpm vs. 118.94±15.46 bpm, 89.31±11.17 bpm vs. 124.34±17.87 bpm; RR: 25.14±3.17 bpm vs. 32.28±4.49 bpm, 24.81±2.43 bpm vs. 33.13±4.17 bpm; Paw: 23.03±3.04 cm H(2)O vs. 33.22±4.59 cm H(2)O, 22.75±3.22 cm H(2)O vs. 33.63±4.79 cm H(2)O; MV: 8.67±1.26 L/min vs. 11.80±2.01 L/min, 8.88±1.45 L/min vs. 13.21±2.90 L/min; WBC: 11.26±1.96 ×10(9)/L vs. 14.57±3.10 ×10(9)/L, 12.28±3.38 ×10(9)/L vs. 15.25±4.93 ×10(9)/L; PCT: 6.90±5.46 μg/L vs. 16.97±7.93 μg/L, 6.17±6.13 μg/L vs. 21.26±11.54 μg/L; CRP: 85.50±37.91 mg/L vs. 120.17±45.47 mg/L, 94.31±38.51 mg/L vs. 142.34±53.57 mg/L; PaO(2)/ FiO(2): 182.06±40.88 mm Hg vs. 98.67±20.62 mm Hg, 184.09±43.78 mm Hg vs. 96.22±22.59 mm Hg, all P<0.05]. There was no significant change in SpO(2) before and after treatment in two groups. And the total clinical effective rate in trial and control group were 83.4% and 81.2%, adverse reaction rate were 13.9% and 9.4%, bacterial removal rate were 90.3% and 87.0% respectively, and there was no significant difference between the two groups (all P>0.05).

CONCLUSION

Domestic imipenem cilastatin sodium can effectively control severe aspiration pneumonia, and it is safe and effective antibiotics.

Therapeutic equivalence of generic imipenem/cilastatin for therapy of infections at Siriraj Hospital

BACKGROUND

Several generic imipenem/cilastatin formulations have been approved by Thai FDA and a generic imipenem/cilastatin (Yungjin) has been available in SirirajHospital since 2007. Since imipenem/cilastatin is usually given to the patients with serious hospital-acquired infections, the generic imipenem/cilastatin must be therapeutically equivalent to the original imipenem/cilastatin. The objective of the study was to compare effectiveness and safety of generic imipenem/cilastatin with original imipenem/cilastatin for therapy of infections in hospitalized patients at Siriraj Hospital.

MATERIAL AND METHOD

Medical records of adult hospitalized patients at Siriraj Hospital who received imipenem/cilastatin at least 48 hours during June 2007 to September 2008 were reviewed. The effectiveness data of 300 patients who received original imipenem/cilastatin were compared with those of 300 patients who received generic imipenem/cilastatin in order to determine if a difference in composite favorable outcome of both formulations was within 10%.

RESULTS

The demographics, clinical features of infections, site of infections, type of causative organisms and concomitant antibiotics of the patients in both groups were not significantly different. The overall favorable outcomes in the original imipenem/cilastatin and the generic imipenem/cilastatin groups were 65% and 58.7% respectively (absolute difference 6.3%, 95% CI -1.4% to 14%). Cure rates of infections in the original imipenem/cilastatin and the generic imipenem/cilastatin groups were 35% and 28.7% respectively (absolute difference 6.3%, 95% CI -1.1% to 13.7%). Super-infection rates in the original imipenem/cilastatin and the generic imipenem/cilastatin groups were 4.7% and 9% respectively (absolute difference -4.3%, 95% CI -8.5% to 0.3%). Mortality due to infections in the original imipenem/cilastatin and the generic imipenem/cilastatin groups were 18.3% and 21.3% respectively (absolute difference -3%, 95% CI -9.4% to 3.4%). Overall mortality in the original imipenem/cilastatin and the generic imipenem/cilastatin groups were 35.3% and 43% respectively (absolute difference -7.7%, 95% CI -15.3% to 0.1%). The occurrence of adverse events in the patients in both groups was not significantly different.

CONCLUSION

Although the point estimate of composite favorable outcome of the patients who received generic imipenem/cilastatin (Yungjin) was < 10% of those who received original imipenem/cilastatin (Tienam), generic imipenem/cilastatin showed a trend for therapeutic non-equivalence to original imipenem/cilastatin because the upper limits of 95% confidence interval of differences of several important clinical outcomes were more than 10%.

Cross-reactivity and tolerability of imipenem in patients with delayed-type, cell-mediated hypersensitivity to beta-lactams

BACKGROUND

Administration of imipenem-cilastatin to patients with IgE-mediated hypersensitivity to beta-lactams has always been considered potentially harmful. Recent studies have demonstrated the tolerability of carbapenems (imipenem-cilastatin and meropenem) in patients with IgE-mediated hypersensitivity to beta-lactams; there are no studies on this topic regarding patients with cell-mediated allergy to beta-lactams. The aim of this study is to assess cross-reactivity and tolerability of imipenem in patients with cell-mediated allergy to beta-lactams.

METHODS

From our database we selected 73 patients with cell-mediated allergy to beta-lactams, diagnosed by means of immediate-type skin tests, delayed reading intradermal tests, patch tests and detection of specific IgE. Patients with negative patch tests with imipenem-cilastatin underwent an intramuscular test dosing.

RESULTS

Our patients had a total of 94 nonimmediate reactions to penicillins. All patients had positive patch tests and/or delayed reading intradermal tests for at least one of the penicillin reagent tested and negative immediate-type skin tests and specific IgE. Four patients out of 73 had a positive patch tests to at least one penicillin reagent and imipenem-cilastatin showing cross-reactivity. Sixty-four patients underwent the imipenem-cilastatin intramuscular test dosing and none of them had a clinical reaction.

CONCLUSIONS

Our rate of cross-reactivity between imipenem-cilastatin and other beta-lactams was 5.5%. This result is different from previous findings and this may be explained by the fact that we investigated patients with cell-mediated allergy to beta-lactams. Patients with cell-mediated allergy to beta-lactams should undergo patch tests and a tolerance challenge test before treatment with imipenem-cilastatin.

Imipenem-cilastatin induced pure white cell aplasia

Antibiotic-induced severe neutropenia and less frequently agranulocytosis has been reported. In most of these cases a relatively normal myelopoiesis is found. We report on the first case of agranulocytosis with histological evidence of pure white cell aplasia associated with imipenem-cilastatin treatment.

[Convulsive liability of an oral carbapenem antibiotic, tebipenem pivoxil]

Tebipenem pivoxil (TBPM-PI), the first oral carbapenem antibiotic both in Japan and abroad, was examined on its convulsive liability. We used ICR male mice and Sprague-Dawley male rats to examine the pro-convulsive effect and anticonvulsive effect of TBPM-PI and its active metabolite, TBPM. (1) When mice were treated with TBPM-PI (30-1000 mg/kg, p.o.) or TBPM (10-300 mg/kg, i.v.), no convulsion was noted at any dose level. When rats were treated with TBPM (300 mg/kg, i.v.), no convulsant effects were noted in electroencephalography or behavioral observation. In intraventricular injection of TBPM in mice, clonic convulsion was observed in 7/10 animals at 100 microg but no effect at 30 microg. On the other hand, the administration of 10/10 microg imipenem/cilastatin (IPM/CS) resulted in clonic convulsion in all animals and tonic convulsion in 3/10 animals, and 4/10 animals died. The administration of 100 microg meropenem did not cause any effects. (2) When mice were co-administered with pentylenetetrazole (45 mg/kg: maximum dose level at which no convulsion is induced) and TBPM-PI (30-300 mg/kg, p.o.) or TBPM (300 mg/kg, i.v.), convulsion enhancing effect was not noted. On the other hand, the co-administration of pentylenetetrazole with IPM/CS (300/300 mg/kg, i.v.) enhanced a convulsive effect of pentylenetetrazole. (3) When mice were treated with TBPM-PI (30-300 mg/kg, p.o.) or TBPM (100 mg/kg, i.v.), inhibitory effect was not noted on convulsions induced by electrostimulation, pentylenetetrazole or strychinine. In conclusion, there were no pro-convulsive effects or anticonvulsive effect in the oral administration of TBPM-PI or intravenous administration of TBPM. Pro-convulsive effect was observed in the intraventricular injection of TBPM as in the case of other carbapenem antibiotics, but such action was weaker than that in IPM/CS administration. Accordingly, the risk of occurrence of convulsion related to TBPM-PI administration was low compared to IPM/CS administration, and TBPM-PI was considered to be less potential to induce convulsions in clinical use.

An unusual cause of seizures during subarachnoid anesthesia in a patient undergoing transurethral resection of the prostate: a case report

A 73-year-old, ASA I patient scheduled for transurethral resection of the prostate under subarachnoid anesthesia received, prior to the beginning of the surgery, intravenous imipenem/cilastatin 1 g for a urinary infection with multiresistant Escherichia coli. The patient developed seizures during the surgical procedure. Central nervous toxicity of imipenem/cilastatin might have been the cause of the seizures. After appropriate management, the patient recovered well and was discharged without complications. The differential diagnosis between systemic toxicity of local anesthetics and imipenem-related seizures is discussed.

Safe Use of Meropenem in a Patient with a Possible Nonimmediate Allergy to Imipenem

Strong data are lacking on the cross-reactivity between individual carbapenems. We describe a 48-year-old woman with ventilator-associated Pseudomonas aeruginosa pneumonia who received an 8-day course of imipenem-cilastatin and experienced a delayed (i.e., nonimmediate) hypersensitivity reaction, evidenced by an extensive erythematous macular morbilliform rash and an increased eosinophil count. Eight days after completion of therapy, the pneumonia returned, and it was decided to avoid using imipenem-cilastatin; she was administered a 14-day course of meropenem. To our knowledge, this is the first report of a nonimmediate hypersensitivity reaction to imipenem-cilastatin without cross-reactivity to meropenem. This suggests that if carbapenem therapy is unavoidable, meropenem may be cautiously administered in patients with a known allergy to imipenem-cilastatin.

Piperacillin/tazobactam vs imipenem/cilastatin in the treatment of nosocomial pneumonia--a double blind prospective multicentre study

BACKGROUND

Piperacillin/tazobactam (P/T) with its broad spectrum of antibacterial activity is used widely for the treatment of moderate to severe polymicrobial nosocomial infections.

PATIENTS AND METHODS

The efficacy and safety of P/T was compared with imipenem/cilastatin (I/C) in patients with established nosocomial pneumonia. This multicentre study took place from January 1999 to December 2001. Due to difficulties in recruiting sufficient patients it was terminated prematurely. In all, 221 patients were randomly assigned to either P/T at 4 g/0.5 g (n = 110) or I/C at 1 g/1 g (n = 111). Additional aminoglycoside therapy was mandatory if Pseudomonas aeruginosa was present. The ITT population (107 P/T and 110 I/C patients) was used for the analysis of efficacy.

RESULTS

The clinical efficacy was equally good for the P/T and I/C groups; 71% [95% CI 61.3, 79.2] vs 77.3% [95% CI 68.1, 84.5] at the end of therapy, 66.4% [95% CI 56.5, 75] vs 70% [95% CI 60.4, 78.2] on day 3, a nd 59.8% [95% CI 49.9, 69] vs 66.4% [95% CI 56.6, 74.9] on day 14 after therapy, respectively. Proven or assumed bacterial eradication at the end of therapy was 45.8% (P/T) and 52.7% (I/C). Treatment-related adverse events (AE) were recorded in 30% of P/T patients and 25.2% I/C patients. There were ten serious treatment-related AEs in the P/T group and five in the I/C group.

CONCLUSION

Although numbers were inadequate for full statistical evaluation, P/T and I/C were similarly effective in the treatment of severe nosocomially acquired pneumonia.

The efficacy and safety of tigecycline for the treatment of complicated intra-abdominal infections: analysis of pooled clinical trial data

This pooled analysis includes 2 phase 3, double-blind trials designed to evaluate the safety and efficacy of tigecycline, versus that of imipenem-cilastatin, in 1642 adults with complicated intra-abdominal infections. Patients were randomized to receive either tigecycline (initial dose of 100 mg, followed by 50 mg intravenously every 12 h) or imipenem-cilastatin (500/500 mg intravenously every 6 h) for 5-14 days. The primary end point was the clinical response at the test-of-cure visit (12-42 days after therapy) in the co-primary end point microbiologically evaluable and microbiological modified intent-to-treat populations. For the microbiologically evaluable group, clinical cure rates were 86.1% (441/512) for tigecycline, versus 86.2% (442/513) for imipenem-cilastatin (95% confidence interval for the difference, -4.5% to 4.4%; P < .0001 for noninferiority). Clinical cure rates in the microbiological modified intent-to-treat population were 80.2% (506/631) for tigecycline, versus 81.5% (514/631) for imipenem-cilastatin (95% confidence interval for the difference, -5.8% to 3.2%; P < .0001 for noninferiority). Nausea (24.4% tigecycline, 19.0% imipenem-cilastatin [P = .01]), vomiting (19.2% tigecycline, 14.3% imipenem-cilastatin [P = .008]), and diarrhea (13.8% tigecycline, 13.2% imipenem-cilastatin [P = .719]) were the most frequently reported adverse events. This pooled analysis demonstrates that tigecycline was efficacious and well tolerated in the treatment of patients with complicated intra-abdominal infections.

Risk factors of superinfection following imipenem/cilastatin therapy in hospitalised patients with acute exacerbations of severe chronic obstructive pulmonary disease

Imipenem is often used in treatment of acute exacerbations of severe chronic obstructive pulmonary disease (COPD). Superinfection following imipenem therapy is a common cause of treatment failure and high economic burden. This study is aimed to explore any clinical factors which determine the risk of superinfection after imipenem treatment in acute exacerbations of severe COPD. A prospective observational study was conducted in a 5-bed respiratory intensive care unit of a Chinese University hospital. Fifty-one patients with acute exacerbations of severe COPD who were hospitalised and treated with imipenem for more than 3 days were enrolled during 1.5 year. The associations between the risk of superinfection and potential factors were analysed by logistic regression. Forty-seven out of 51 patients (92.2%) had their symptoms and signs improved at the end of imipenem treatment. Superinfections were developed in 12 patients, and the superinfection rate was as high as 30.8% (12 out of 39 patients with definite bacteriologic responses). The frequent superinfecting organisms were Stenotrophomonas maltophilia and Pseudomonas aeruginosa. Among a wide range of potential risk factors, we found that lower blood pH, previous cephalosporines treatment and longer period of imipenem treatment are independently associated with a higher risk of superinfection. The risk of superinfection following imipenem treatment in hospitalised patients with acute exacerbations of COPD was high. Lower blood pH, previous cephalosporines treatment and longer period of imipenem treatment all increased the risk of superinfection.

Clinical comparative study of sulbactam/ampicillin and imipenem/cilastatin in elderly patients with community-acquired pneumonia

OBJECTIVE

To evaluate the clinical usefulness of sulbactam/ampicillin therapy for community-acquired pneumonia in the elderly.

METHODOLOGY

A randomized prospective clinical study was conducted in the elderly patients with moderate-to-severe community-acquired bacterial pneumonia.

RESULTS

Overall clinical efficacy of sulbactam/ampicillin therapy (6 g/day) in these patients (efficacy rate: 91.4%) was comparable to that of imipenem/cilastatin therapy (1 g/day; efficacy rate: 87.5%), when each therapy was administered intravenously twice daily for 7-14 days. With regard to clinical efficacy based on disease severity, bacteriological efficacy, improvement of chest X-ray findings and adverse reactions, the two therapies were comparable.

CONCLUSION

These results suggest that sulbactam/ampicillin therapy has excellent efficacy and tolerability and that it may be highly effective, even in severe cases of pneumonia. This regimen may thus serve as first-line treatment for the treatment of community-acquired pneumonia in elderly patients.

Meropenem versus imipenem-cilastatin for the treatment of hospitalized patients with complicated skin and skin structure infections: results of a multicenter, randomized, double-blind comparative study

BACKGROUND

Meropenem, a broad-spectrum carbapenem with potent in vitro activity, is postulated to be an effective monotherapy for the treatment of complicated skin and skin structure infections (cSSSI).

METHODS

This multicenter, international, double-blind, randomized, prospective study of hospitalized patients with cSSSI evaluated the efficacy, safety, and tolerability of meropenem (500 mg IV q8h) versus imipenem-cilastatin (500 mg IV q8h). The primary efficacy endpoint was clinical outcome at follow-up in the clinically evaluable (CE) and modified intent-to-treat populations (MITT; patients who met eligibility criteria and received at least one dose of study drug). The study aimed to demonstrate non-inferiority (delta of 10%, 95% confidence intervals) in clinical response in the CE population. Clinical responses for all pathogens at follow-up were assessed in the fully evaluable population (CE population with baseline pathogen and follow-up cultures).

RESULTS

In total, 1,076 patients were enrolled. Of these, 692 patients comprised the MITT population (334 and 358 patients randomized to meropenem and imipenem-cilastatin, respectively) and 548 the CE population (261 and 287 patients randomized to meropenem and imipenem-cilastatin, respectively). Cure rates were 86.2% (meropenem) and 82.9% (imipenemcilastatin; 95% CI, -2.8, 9.3) in the CE population and 73.1% (meropenem) and 74.9% (imipenem-cilastatin; 95% CI, -8.4, 4.7) in the MITT population. The frequencies of adverse events and drug-related adverse events were similar between treatment groups.

CONCLUSION

In one of the largest studies conducted to date of hospitalized patients with cSSSI, meropenem, 500 mg IV q8h had comparable safety and efficacy to imipenem-cilastatin, 500 mg IV q8h.

A multicenter trial of the efficacy and safety of tigecycline versus imipenem/cilastatin in patients with complicated intra-abdominal infections [Study ID Numbers: 3074A1-301-WW; ClinicalTrials.gov Identifier: NCT00081744]

BACKGROUND

Complicated intra-abdominal infections (cIAI) remain challenging to treat because of their polymicrobial etiology including multi-drug resistant bacteria. The efficacy and safety of tigecycline, an expanded broad-spectrum glycylcycline antibiotic, was compared with imipenem/cilastatin (IMI/CIS) in patients with cIAI.

METHODS

A prospective, double-blind, multinational trial was conducted in which patients with cIAI randomly received intravenous (IV) tigecycline (100 mg initial dose, then 50 mg every 12 hours [q12h]) or IV IMI/CIS (500/500 mg q6h or adjusted for renal dysfunction) for 5 to14 days. Clinical response at the test-of-cure (TOC) visit (14-35 days after therapy) for microbiologically evaluable (ME) and microbiological modified intent-to-treat (m-mITT) populations were the co-primary efficacy endpoint populations.

RESULTS

A total of 825 patients received >or= 1 dose of study drug. The primary diagnoses for the ME group were complicated appendicitis (59%), and intestinal (8.8%) and gastric/duodenal perforations (4.6%). For the ME group, clinical cure rates at TOC were 80.6% (199/247) for tigecycline versus 82.4% (210/255) for IMI/CIS (95% CI -8.4, 5.1 for non-inferiority tigecycline versus IMI/CIS). Corresponding clinical cure rates within the m-mITT population were 73.5% (227/309) for tigecycline versus 78.2% (244/312) for IMI/CIS (95% CI -11.0, 2.5). Nausea (31.0% tigecycline, 24.8% IMI/CIS [P = 0.052]), vomiting (25.7% tigecycline, 19.4% IMI/CIS [P = 0.037]), and diarrhea (21.3% tigecycline, 18.9% IMI/CIS [P = 0.435]) were the most frequently reported adverse events.

CONCLUSION

This study demonstrates that tigecycline is as efficacious as imipenem/cilastatin in the treatment of patients with cIAI.

Elevated plasma cysteinylglycine levels caused by cilastatin-associated antibiotic treatment

Imipenem (thienamycin formamidine), a broad-spectrum β-lactam antibiotic, is always used in combination with cilastatin in order to avoid the premature breakdown of imipenem by renal tubular dipeptidase. As this dipeptidase also hydrolyzes the glutathione metabolite cysteinylglycine, the therapeutic asso-ciation of imipenem and cilastatin might cause an accumulation of the aminothiol cysteinylglycine. We demonstrate here that when patients are treated with imipenem-cilastatin, their plasma levels of cysteinylglycine are significantly and specifically increased, while cysteine levels are decreased and homocysteine levels are unaffected. We conclude that antibiotic treatment using imipenem-cilastatin induces important metabolic changes that should not remain unrecognized.

Is it safe to use carbapenems in patients with a history of allergy to penicillin?

OBJECTIVES

The purpose of this retrospective study was to ascertain the clinical safety of administering carbapenems, namely imipenem/cilastatin and meropenem, in patients with a history of penicillin allergy compared with administering carbapenems in patients with no reported penicillin allergy. Carbapenems are similar in chemical structure to the penicillins and therefore are associated with a risk for allergic cross-hypersensitivity. Carbapenems are commonly avoided in patients with a reported penicillin allergy on the basis of a potential cross-hypersensitivity with penicillin, however, very few studies have been conducted describing the incidence of cross-hypersensitivity between penicillin and carbapenems.

METHODS

A retrospective review was conducted in a total of 266 patients who were administered either imipenem/cilastatin or meropenem. The patients were admitted to the Cleveland Clinic Health System--Eastern Region Hospitals during the years 2001 and 2002.

RESULTS

Fifteen of the 163 patients (9.2%) with reported penicillin allergy developed a hypersensitivity reaction to meropenem or imipenem/cilastatin whereas 3.9% of the 103 patients without penicillin allergy developed a hypersensitivity reaction to meropenem or imipenem/cilastatin. These results are not statistically significant.

CONCLUSIONS

Based on this study and other similar studies, the true incidence of cross-hypersensitivity reactions between penicillin and carbapenems may be lower than previously reported. Carbapenem use may be reasonable for penicillin allergic patients if caution is exercised.

Cefepime versus imipenem-cilastatin for treatment of nosocomial pneumonia in intensive care unit patients: a multicenter, evaluator-blind, prospective, randomized study

In a randomized, evaluator-blind, multicenter trial, we compared cefepime (2 g three times a day) with imipenem-cilastatin (500 mg four times a day) for the treatment of nosocomial pneumonia in 281 intensive care unit patients from 13 centers in six European countries. Of 209 patients eligible for per-protocol analysis of efficacy, favorable clinical responses were achieved in 76 of 108 (70%) patients treated with cefepime and 75 of 101 (74%) patients treated with imipenem-cilastatin. The 95% confidence interval (CI) for the difference between these response rates (-16 to 8%) failed to exclude the predefined lower limit for noninferiority of -15%. In addition, therapy of pneumonia caused by an organism producing an extended-spectrum beta-lactamase (ESBL) failed in 4 of 13 patients in the cefepime group but in none of 10 patients in the imipenem group. However, the clinical efficacies of both treatments appeared to be similar in a secondary intent-to-treat analysis (95% CI for difference, -9 to 14%) and a multivariate analysis (95% CI for odds ratio, 0.47 to 1.75). Furthermore, the all-cause 30-day mortality rates were 28 of 108 (26%) patients in the cefepime group and 19 of 101 (19%) patients in the imipenem group (P = 0.25). Rates of documented or presumed microbiological eradication of the causative organism were similar with cefepime (61%) and imipenem-cilastatin (54%) (95% CI, -23 to 8%). Primary or secondary resistance of Pseudomonas aeruginosa was detected in 19% of the patients treated with cefepime and 44% of the patients treated with imipenem-cilastatin (P = 0.05). Adverse events were reported in 71 of 138 (51%) and 62 of 141 (44%) patients eligible for safety analysis in the cefepime and imipenem groups, respectively (P = 0.23). Although the primary end point for this study does not exclude the possibility that cefepime was inferior to imipenem, some secondary analyses showed that the two regimens had comparable clinical and microbiological efficacies. Cefepime appeared to be less active against organisms producing an ESBL, but primary and secondary resistance to imipenem was more common for P. aeruginosa. Selection of a single agent for therapy of nosocomial pneumonia should be guided by local resistance patterns.

The effects of phenytoin and phenobarbital on seizures induced by imipenem/cilastatin in rats

The effects of phenytoin (PHT) and phenobarbital (PHB) on EEG activity and behavior was studied in the model of epilepsy induced by intracerebroventricular (i.c.v.) administration of imipenem/cilastatin (Imi/Cil). Under intraperitoneal (i.p.) sodium pentobarbital anesthesia adult male Wistar albino rats were implanted with electrodes and cannulas were placed into the right lateral ventricle. Animals were divided into groups: 1) Imi/Cil (100/100 microg, i.c.v.), 2) PHT (40 mg/kg) + Imi/Cil (100/100 microg, i.c.v), 3) PHT (80 mg/kg) + Imi/Cil (100/100 microg, i.c.v.), 4) PHT (160 mg/kg) + Imi/Cil (100/100 microg, i.c.v.), 5) PHB (50 mg/kg) + Imi/Cil (100/100 microg, i.c.v.), and 6) PHB (80 mg/kg) + Imi/Cil (100/100 microg, i.c.v.). PHT and PHB were injected intraperitoneally (i.p.) 1 h before Imi/Cil. Seizures were scored according to the scale: 0--normal behavior; 1--twitching, 2--head nodding, forelimb clonus, 3--rearing, and 4--clonic-tonic convulsions. Imi/Cil provoked maximal seizures in all animals, and all rats died 10 - 18 min after the injection. Epileptiform activity preceded behavioral seizures. Clonic-tonic seizures were associated with continuous bursts of high-frequency high-amplitude spikes in the EEG. PHT and PHB suppressed Imi/Cil-induced seizures dose-dependently. PHB reduced epileptiform discharges during behavioral seizures elicited by Imi/Cil, while PHT had no effect on EEG epileptic phenomena. These results suggest that PHT acts as anticonvulsant, and PHB as anticonvulsant and antiepileptic agent in the model of epilepsy induced by Imi/Cil.

Rapid imipenem/cilastatin desensitization for multidrug-resistant Acinetobacter pneumonia

OBJECTIVE

To report a successful case of rapid imipenem desensitization in a critically ill patient with multidrug-resistant Acinetobacter baumannii ventilator-associated pnemonia (VAP).

CASE SUMMARY

A 40-year-old white man who had a lengthy stay in the intensive care unit (ICU) following a motorcycle accident developed VAP caused by A. baumannii. treatment with imipenem was necessary due to the bacteria's resistance to all other antibiotics. However, this patient was diagnosed with an allergy to imipenem following exposure earlier in his hospitalization in addition to a positive penicillin skin test. Thus, we attempted rapid desensitization to imipenem using a continuous infusion protocol. The patient was desensitized within 4 hours and was successfully treated for 21 days with a continuous infusion of imipenem combined with daily amikacin. He experienced no adverse reaction during the desensitization process or the remainder of his treatment course.

DISCUSSION

The protocol used in this case was modified from a previously reported case, and differed in the speed of desensitization and total daily dose. We assumed that a more gradual escalation of the dose in our modified protocol would prevent the occurrence of adverse events, thereby resulting in more rapid desensitization. Rapid desensitization was necessary in this patient due to the presence of a life-threatening infection. The lower total daily dose of imipenem was in response to impaired renal function.

CONCLUSIONS

Therapeutic options for multidrug-resistant pneumonia in the ICU are significantly limited in the presence of imipenem allergy. An option of last resort is to desensitize the patient using a rapid administration protocol. Our modified rapid imipenem desensitization protocol was successful and allowed for effective treatment of life-threatening pneumonia.

A randomized, controlled clinical trial on meropenem versus imipenem/cilastatin for the treatment of bacterial infections

OBJECTIVE

To evaluate the efficacy and safety of meropenem in Chinese patients, we conducted a study for the treatment of patients with lower respiratory tract infections, urinary tract infections and other infections.

METHODS

A total of 182 hospitalized patients were enrolled in the study. 90 patients received 500 mg meropenem every 12 hours (or 1 g every 12 hours if necessary) and 92 patients received imipenem/cilastatin 500 mg/500 mg every 12 hours (or 1 g every 12 hours if necessary) by intravenous infusion. The duration of treatment was 7 - 14 days for both groups.

RESULTS

Seventy of 90 cases receiving meropenem and 70 of 92 cases receiving imipenem/cilastatin were assessable for clinical efficacy. The overall efficacy rates were 90% for the meropenem group and 87% for the imipenem/cilastatin group, and the bacterial eradication rates were 86% in both groups. 93 (76%) of 123 strains isolated from patients produced beta-lactamases. Adverse drug reactions were evaluated in 72 cases in the meropenem group and 70 cases in the imipenem/cilastatin group. The adverse drug reaction rates were 9.7% and 8.6%, respectively. The results showed that there were no statistical differences between these two groups (P > 0.05).

CONCLUSION

Meropenem is effective and safe for the treatment of bacterial infections caused mainly by beta-lactamase-producing strains.

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.

Piperacillin 2 g/tazobactam 0.5 g is as effective as imipenem 0.5 g/cilastatin 0.5 g for the treatment of acute uncomplicated pyelonephritis and complicated urinary tract infections

This randomised, double-blind, multicentre trial compared piperacillin/tazobactam (2 g/0.5 g/q8h) and imipenem/cilastatin (0.5 g/0.5 g/q8h) as monotherapy in patients with acute pyelonephritis or complicated urinary tract infections. In total, 237 patients were randomised to receive either piperacillin/tazobactam (n=161) or imipenem/cilastatin (n=166). At the early follow-up (=test-of-cure-visit) 5-9 days after antibiotic therapy, clinical success was noted in 122/147 (83.0%) piperacillin/tazobactam recipients compared with 123/154 (79.9%) imipenem/cilastatin recipients, thus proving that both treatments were equally effective. On a descriptive level, an advantage of piperacillin/tazobactam was demonstrated. Microbiological success at the early follow-up was 78/135 (57.8%) for piperacillin/tazobactam and 70/144 (48.6%) for imipenem/cilastatin. These results were confirmed by equivalent success rates on the last therapy day. Both drugs were generally well tolerated.

Cholangiopathy after short-term administration of piperacillin and imipenem/cilastatin

We describe a patient who suffered from intestinal perforation after abdominal trauma. Perioperatively, he was treated with a single dose of piperacillin and 9 doses of imipenem/cilastatin over 3 days. The patient was discharged 5 days after surgery in good clinical condition and with normal liver values except for a marginal elevation of alanine aminotransferase. Two weeks after discharge, he developed fatigue, fever and pruritus, necessitating rehospitalization. He was jaundiced and had elevated alkaline phosphatase and transaminases. After exclusion of an intra-abdominal fluid collection, a vascular problem, and infectious or autoimmune liver disease, a liver biopsy was performed. The biopsy revealed centrizonal bilirubinostasis, a portal infiltrate rich in eosinophils and cholangitis. Lymphocyte transformation tests for piperacillin and imipenem/cilastatin were positive, suggesting an immunological mechanism for the observed hepatopathy. Cholestasis gradually decreased but was detectable for several weeks. The patient had a full clinical and biochemical recovery after 3 months. We conclude that short-term therapy with piperacillin, imipenem/cilastatin or the combination of these drugs can lead to the same type of hepatopathy as described for amoxycillin/clavulanic acid or antistaphylococcal penicillins. Liver biopsy and positive lymphocyte transformation are compatible with an immunological mechanism.

Incidence of imipenem hypersensitivity reactions in febrile neutropenic bone marrow transplant patients with a history of penicillin allergy

The purpose of this retrospective study was to assess cross-hypersensitivity between imipenem/cilastatin and penicillin in patients with reported penicillin allergies. Medical records of febrile neutropenic, penicillin-allergic bone marrow transplant recipients who received imipenem/cilastatin treatment were retrospectively reviewed. The findings of this study indicate the incidence of cross-reactivity between imipenem/cilastatin and penicillin among patients with a history of penicillin allergy may be lower than previously reported.

Incidence of seizures in pediatric cancer patients treated with imipenem/cilastatin

Proconvulsive tendency of imipenem/cilastatin is one of its well-known side effects. Most studies report incidence rates ranging from 1.5 to 3%. There is no study on the incidence rate among children with systemic malignancies. Eighty-two patients with various malignancies who received imipenem/cilastatin 143 times for neutropenic fever between March 1994 and October 1999 in Department of Pediatric Oncology, Gazi University, were identified. Three of these patients had convulsions attributed to imipenem/cilastatin; 3.6% of the patients had seizure, or 2% of imipenem/cilastatin administrations was followed by a seizure attack.

Meropenem versus imipenem/cilastatin in the treatment of sepsis in Chinese patients

BACKGROUND

Meropenem and imipenem are beta-lactam antibiotics of the carbapenem group. Carbapenems have bactericidal activity against a broad spectrum of bacteria, including most gram-positive cocci, gram-negative bacilli and anaerobes. Experience in using meropenem in Chinese patients has not been previously reported.

METHODS

Meropenem (2 g daily) and imipenem/cilastatin (2 g daily) were compared in an open, randomized, prospective study on the treatment of hospitalized Chinese septic patients. All participants (male or female) were hospitalized with a diagnosis of sepsis. All patients were randomly allocated to one of the two treatment groups: the meropenem group or the imipenem/cilastatin group. Clinical status was evaluated daily during treatment and at the end of therapy or when treatment was withdrawn. Patients were checked every day for potential side-effects, according to subjective and objective symptoms.

RESULTS

Fifty-three patients were enrolled in the study; 50 were evaluated for clinical efficacy and 27 patients were evaluated for bacteriologic efficacy. The most frequent clinical diagnoses were pneumonia and urinary tract infection. The predominant pathogens were Pseudomonas aeruginosa, Escherichia coli and Enterobacter cloacae. There were 31 pathogens isolated from 27 patients. A single pathogen was identified in 23 patients, and two pathogens were isolated from four patients. Satisfactory clinical outcome (excellent and good) was 84% in the meropenem group and 76% in the imipenem/cilastatin group. Satisfactory bacteriologic response was 80% in the meropenem group and 75% in the imipenem/cilastatin group. Transiently elevated liver enzymes were the most common side-effect. One patient treated with imipenem/cilastatin experienced a seizure during the study, while another patient treated with meropenem withdrew due to urticaria.

CONCLUSIONS

The efficacy and safety data presented in this report indicate that meropenem was well tolerated and appeared to be as effective as standard monotherapy with imipenem in bacteremic patients. Meropenem and imipenem/cilastatin were highly effective for the treatment of bacteremia in Chinese patients and only mild or negligible side-effects were noted.

Multicenter randomized trial comparing meropenem (1.5 g daily) and imipenem/cilastatin (2 g daily) in the hospital treatment of community-acquired pneumonia

An open, multicenter study with 144 patients, aged between 18 and 94 years, was performed to compare the efficacy and safety of meropenem with imipenem/cilastatin in the hospital treatment of community-acquired pneumonia. Patients were randomized to receive either intravenous meropenem (500 mg every 8 h) or intravenous imipenem/cilastatin (1,000 mg every 12 h). The primary end point was considered to be clinical efficacy and the secondary end points were bacteriological response and safety assessment. At the end of therapy, cure or improvement in signs and symptoms as a satisfactory clinical response was observed in 57 of 64 (89.1%) meropenem-treated patients and in 60 of 66 (90.9%) imipenem/cilastatin patients. The mean duration of treatment was 10 days for meropenem and 9.7 days for imipenem/cilastatin. In patients who were followed up for weeks 2-4, the response was satisfactory (100%) for both treatments. A satisfactory bacteriological response, defined as either presumed or confirmed eradication of all pathogens, was found in eight patients who had received meropenem and in 14 patients who had received imipenem/cilastatin. Response was considered satisfactory in 100% of the meropenem group and in 92.9% of the imipenem/cilastatin group and at follow-up, it was 100% for both treatments. Drug-related adverse events were reported in three (4.2%) meropenem-treated patients and in eight (11.0%) imipenem/cilastatin-treated patients. None of these events was classified as serious. The results of this study show that the clinical and bacteriological efficacy and tolerability of meropenem (500 mg every 8 h) are similar to that of imipenem/cilastatin (1,000 mg every 12 h) in the hospital treatment of community-acquired pneumonia.

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.

[Imipenem/cilastatin sodium and other beta-lactams for respiratory tract infections: clinical benefit and treatment days for cure]

Therapeutic efficacy and the treatment days for cure of imipenem/cilastatin sodium (IPM/CS) in treatment of pulmonary infections were prospectively determined in comparison with those of beta-lactams other than carbapenems mainly ceftazidime (CAZ) or sulbactam/cefoperazone (SBT/CPZ). The overall response rate was 84.9% (62/73) in the IPM/CS group and 74.7% (56/75) in the beta-lactam group, the difference not being significant. In the subjects having underlying respiratory diseases, the response rate was 91.1% (41/45) and 73.9% (34/46) in the IPM/CS and beta-lactam groups, respectively. In patients with infections secondary to chronic respiratory disease, the rate was 91.2% (31/34) in the former group and 66.7% (24/36) in the latter group, respectively. The differences were significant for both stratified analyses. The treatment days for cure judged by the attending physician were 12.9 +/- 0.6 days in the IPM/CS group, and 14.5 +/- 0.7 days in the beta-lactam group. The difference was not, however, significant. In patients with mild to moderate infections, the treatment days for cure was 12.0 +/- 0.6 days (n = 64) in the IPM/CS group and 14.3 +/- 0.7 days (n = 70) in the beta-lactam group. In patients with underlying respiratory disease, the treatment days for cure were 11.8 +/- 0.7 days (n = 45) and 14.7 +/- 0.9 days (n = 46) in the IPM/CS and beta-lactam groups, respectively. In patients with infections secondary to chronic respiratory disease, the days were 11.1 +/- 0.7 days (n = 34) and 14.7 +/- 1.1 days (n = 36), respectively. Thus, IPM/CS therapy significantly reduced the number of treatment days until cure. There was, however, no significant difference between the two therapy groups in treatment of the patients with severe infections, those without underlying respiratory disease, or those with pneumonia and/or lung abscess. The treatment days for cure were also assessed by the members of review committee taking into consideration of body temperature, leukocyte count, and C-reactive protein. As the result, it was 6.9 +/- 0.5 days in the IPM/ CS and 10.3 +/- 0.7 days in the beta-lactam groups; respectively, and the difference was significant. Time (days) until cure was also compared between the two groups using survival time analysis, confirming a more rapid response in the IPM/CS group. Although IPM/CS therapy was associated with a shorter response time as assessed by both the attending physicians and the review committee, there were considerable differences between the results of these judgements. Thus, the duration of treatment with injectable antibiotics requires reevaluation in the future. No significant differences were observed between the groups with respect to parameters indicating side effects and laboratory abnormalities. There were no severe symptoms or laboratory findings, and symptoms and changes in laboratory values, if any resolved during the course of therapy or after the withdrawal of treatment. In conclusion, IPM/CS seems to be very useful as first-line therapy for respiratory tract infections and for shortening the duration of treatment.

Cefepime versus imipenem-cilastatin as empirical monotherapy in 400 febrile patients with short duration neutropenia. CEMIC (Study Group of Infectious Diseases in Cancer)

This open, comparative, randomized, multicentre equivalence study compared cefepime 2 g bd and imipenem-cilastatin 1 g tds (50 mg/kg/day) as empirical monotherapy for febrile episodes in a homogeneous cohort of cancer patients with short duration neutropenia following chemotherapy for solid tumour, lymphoma or myeloma. The study was conducted in 17 French anti-cancer centres in 1995 and 1996. Response to monotherapy was assessed 7 days after treatment and was based on resolution of fever and signs and symptoms, eradication of pathogens, absence of new infection, relapse, and death of infectious origin, without addition of other antibiotics. Patients were treated for a minimum of 4 days. Of the 400 episodes randomized, 344 (86%) were evaluable for efficacy. Patient characteristics were comparable between treatment groups. Success of monotherapy was observed in 79% of episodes with cefepime and 72% with imipenem-cilastatin (equivalence, P <0.0001). The response rate for microbiologically documented infections was 66% with cefepime and 61% with imipenem-cilastatin (bacteraemic episodes: 63% for cefepime; 44% for imipenem-cilastatin). A second antibiotic (usually a glycopeptide) was added in 20% and 21% of the cases, respectively. Overall, the response to therapy, with or without an additional antibiotic, was 95% (cefepime) and 90% (imipenem-cilastatin). Survival was similar in both groups (95% and 98%, respectively). Cefepime treatment was better tolerated, with 9% of the patients experiencing related intercurrent events compared with 19% in the imipenem-cilastatin group (P = 0.003). Nausea/vomiting was significantly more frequent in the imipenem-cilastatin group (15%) than in the cefepime group (5%; P = 0.001). Cefepime monotherapy was as effective as, and better tolerated than, imipenem-cilastatin in the empirical treatment of fever during short duration neutropenia.

[Comparative study of the cost-effectiveness of initial therapy with imipenem/cilastatin in secondary peritonitis]

The total costs of the hospital treatment of patients with secondary peritonitis were investigated with a prospective, randomized, multicenter study. Moreover, the cost-effectiveness of an initial therapy with Imipenem/Cilastatin was compared to selected alternative antibiotic regimens. Altogether 154 patients (77 Imipenem/Cilastatin group, 77 alternative group) that displayed Mannheim Peritonitis Scores between 16 and 26 (average 20.8) were analyzed. The average total cost of treatment was DM 11,140 per patient (range DM 2794-45,526). Patients receiving an initial therapy with Imipenem/Cilastatin incurred average costs of DM 10,455, while patients with alternative regimens caused average costs of DM 11,826. The difference between the two treatment groups was statistically significant (P = 0.037).

[Carbapenems (thienam and Meronem). Their clinical and economic efficacy]

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.

Neonatal Klebsiella pneumonia sepsis and imipenem/cilastatin

Efficacy and safety of imipenem/cilastatin in neonatal Klebsiella pneumonia sepsis was investigated in 45 infants compared to 39 control infants on conventional antibiotic regimen. Sensitivity to imipenem was 94% followed by cephoxitin (88%), quinolons (80%), and amikacin (52%) according to susceptibility results in the study group. Treatment duration of surviving infants was 16.5 +/- 4.6 and 20.3 +/- 6.4 days in the study and control groups respectively (p < 0.05). Five infants (11%) vs 27 (69%) were unresponsive (septic deaths) to treatment in the study and control groups respectively (p < 0.001). The cure rates were 73% and 28% respectively (p < 0.001). Sequelae free discharge rates were 67% and 23% respectively (p < 0.001). The most frequent adverse effects of imipenem/cilastatin were Candida albicans superinfection (20%); Candida albicans colonisation (10%); impairment of liver and renal functions (19% and 10% respectively); seizures (5%); thrombocytosis (3%); thrombophlebitis (3%); urine discoloration (3%); and Staphylococcus epidermidis colonisation (2%). Imipenem is considered a good alternative for neonatal Klebsiella pneumonia sepsis with these results, however, one must be aware of the increased risk of Candida albicans superinfection.

Prospective, randomised, multicentre study of meropenem versus imipenem/cilastatin as empiric monotherapy in severe nosocomial infections

The clinical and bacteriological efficacy and the tolerability of meropenem versus imipenem/cilastatin (both 1 g t.i.d.) in severe nosocomial infections were compared in a multicentre, randomised, nonblinded study. A total of 151 patients were recruited; 133 (66 meropenem, 67 imipenem/cilastatin) were clinically evaluable and 84 (42 meropenem, 42 imipenem/cilastatin) bacteriologically evaluable. Most clinically evaluable patients (90%) were in intensive care units, required mechanical ventilation (72%), and had received previous antibiotic therapy (62%). The mean (+/- SD) APACHE II score was 15.2 (+/- 6.6) in the meropenem group and 17.8 (+/- 6.8) in the imipenem/cilastatin group. The primary infections were nosocomial lower respiratory tract infections (56% of patients), intra-abdominal infections (15%), septicaemia (21%), skin/skin structure infections (5%), and complicated urinary tract infections (3%); 35% of the patients had two or more infections. There was no significant difference between the meropenem and imipenem/cilastatin groups in the rates of satisfactory clinical (weighted percentage 87% vs. 74%) or bacteriological (weighted percentage 79% vs. 71%) response. There was a slightly higher rate of clinical success with meropenem against primary or secondary lower respiratory tract infection (89% vs. 76%). Drug-related adverse events occurred in 17% and 15% of meropenem and imipenem/cilastatin patients, respectively. Meropenem (1 g t.i.d.) was as efficacious as the same dose of imipenem/cilastatin in this setting, and both drugs were well tolerated.

[Tolerance and safety of carbapenems: the use of meropenem]

The purpose of this article is to review the safety and tolerance of two carbapenems (imipenem/cilastatin and meropenem) in order to establish their possible use in different clinical settings. The tolerance and safety profile of both carbapemens in intravenous and intramuscular formulation is good. With imipenem/cilastatin, nausea and vomiting can constitute a practical problem requiring prolonged times of perfusion and high dilutions. The possibility of administering meropenem in intravenous infusion or bolus injection with lower volumes of fluid, without increasing the incidence of these adverse reactions, may have practical advantages in special situations. The possible neurotoxicity of the imipenem/cilastatin presents limitations of the use in high risk circumstances such as meningitis, previous alterations of CNS, renal insufficiency and concomitant administration of other drugs with neurotoxic profiles and when high doses of administration are needed. The meropenem, by the contrary, can be used in patients with infections of the CNS and other risk factors, at high doses, without increased risk of seizures.

Imipenem-cilastatin-induced leukocytoclastic vasculitis

A maculopapular rash has been associated with the administration of imipenem-cilastatin, an antibiotic that was used for treatment of a postoperative infection. This is a first-time association of imipenem with a leukocytoclastic vasculitic reaction. Leukocytoclastic vasculitis has been previously documented with ciprofloxacin, zidovudine, piperazine, and lithium.

Experience with imipenem in internal medicine--a postmarketing surveillance study

Imipenem was registered for clinical use in Germany in 1985. It is recommended for initial treatment in either severe nosocomial infections or infections in ICU or immunocompromised patients. In this study, we evaluated 1,215 patients who were prescribed imipenem at our Zentrum der Inneren Medizin-a major tertiary care university hospital-over a 6 year period. 650 of 1,215 patients (53.5%) had rapidly fatal disease; and the main indication for imipenem was pneumonia and fever of unknown origin. 56.2% received 500 mg imipenem t.i.d., 40.4% 500 mg b.i.d., 0.9% 1000 mg b.i.d.; and 2.5% 1000 mg t.i.d. Average duration of treatment was 11 days. Lower dose (500 mg b.i.d.) was used in patients with renal insufficiency; highest dose was used in severe infections or infections caused by moderately sensitive organisms. Imipenem was used as a single initial antibacterial agent in the majority of the patients. Success was seen in 80% of the episodes, irrespective of the dosage used; 89% at 500 mg b.i.d., 74% at 500 mg t.i.d., 77% at 1,000 mg b.i.d.; and 69% at 1,000 mg t.i.d. We observed the highest favourable response (91.5%) in the episodes treated initially with imipenem monotherapy. Overall, imipenem was well tolerated. The majority of the patients with untoward effects was on multiple-drug regimens. The most frequent untoward event observed involved the gastrointestinal tract.

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.