Plasma pharmacokinetics of daptomycin in critically ill patients with renal failure and undergoing CVVHD.

BACKGROUND: Daptomycin is a novel antibiotic with primarily renal elimination. METHODS: In an open-label, prospective trial, the pharmacokinetics of daptomycin after single (8 mg/kg BW) and multiple intravenous doses (4 mg/kg BW) at steady state were determined in critically ill, dialysis-dependent patients treated with continuous veno-venous hemodialysis (CVVHD). Daptomycin levels were determined by HPLC. Subjects with normal renal function received one dose of 4 mg/kg BW of daptomycin. RESULTS: In the normal controls, daptomycin administration resulted in a mean maximum concentration (Cmax) of 60.7 ± 10.7 mg/l and an area under the time-versus-concentration curve from 0 to 24 h (AUC0-24) of 402 ± 56 mg × h/l. In the CVVHD-treated patients, a loading dose of 8 mg/kg lead to Cmax of 87.5 ± 15.0 mg/l, AUC0-24 of 537 ± 97 mg × h/l and AUC24-48 of 193 ± 69 mg × h/l, respectively. After multiple doses of 4 mg/kg every 48 h, Cmax was 41.8 ± 5.0 mg/l, AUC0-24 302 ± 43 mg × h/l and AUC 24-48 h 102 ± 24 mg × h/l, respectively. Approximately 40% of the daptomycin dose administered was removed by CVVHD. Mean plasma half-lives of daptomycin in patients were 2 - 3 times longer than in healthy controls. CONCLUSIONS: The dosing regimen of 4 mg/kg TBW of daptomycin administered to CVVHD patients every 48 h is inappropriate to achieve effective antimicrobial plasma concentrations of daptomycin in the second half of the dosing interval (24 - 48 h). Doses of ≥ 4 mg/kg TBW administered intravenously every 24 h are necessary in CVVHD patients to assure that plasma daptomycin levels are comparably high to subjects with normal renal function and to avoid underdosing.

Etiology of Crohn's disease: Do certain food additives cause intestinal inflammation by molecular mimicry of mycobacterial lipids?

Crohn's disease is a chronic granulomatous inflammation of the gastrointestinal tract which was first described in the beginning of the 20th century. The histological similarity with intestinal tuberculosis has led to the assumption of an involvement of mycobacteria and mycobacterial antigens, respectively, in the etiology. A major defense mechanism against mycobacterial lipid antigens is the CD1 system which includes CD1 molecules for antigen presentation and natural killer T cells for recognition and subsequent production of cytokines like interferon-gamma and tumour necrosis factor-alpha. These cytokines promote granulomatous transformation. Various food additives, especially emulsifiants, thickeners, surface-finishing agents and contaminants like plasticizers share structural domains with mycobacterial lipids. It is therefore hypothesized, that these compounds are able to stimulate by molecular mimicry the CD1 system in the gastrointestinal mucosa and to trigger the pro-inflammatory cytokine cascade. The understanding of Crohn's disease as a CD1-mediated delayed-type hypersensitivity to certain food additives would lead to strong emphasis on a dietary treatment. Related aspects of pathology, physiology and epidemiology of Crohn's disease are presented.

Pharmacokinetics of cefpirome during continuous venovenous hemofiltration: rationale for an 8-hour dosing interval.

OBJECTIVE: Cefpirome is a new semisynthetic cephalosporin, primarily eliminated by the kidneys, that requires dosage adjustment in patients with kidney failure. The optimal dosing regimen of cefpirome in patients with continuous veno-venous hemofiltration (CVVH) is unknown. METHODS: Pharmacokinetic properties of cefpirome were investigated in eight anuric patients with acute kidney failure treated by CVVH. All patients received a dosage of 2 g cefpirome every 8 hours after starting the hemofiltration with high-flux polysulfone membranes. Concentrations of cefpirome in plasma and ultrafiltrate were measured by HPLC. RESULTS: Total clearance and hemofiltration clearance of cefpirome were 589.1 +/- 164.5 mL/min and 43.3 +/- 7.8 mL/min, respectively. Serum elimination half-life was 2.36 +/- 0.59 hours. The highest plasma drug concentration was 14.8 +/- 3.2 microg/mL, and it declined to trough levels of 3.1 +/- 0.8 microg/mL at the end of the dosing interval. CONCLUSION: On the basis of previously published pharmacodynamic characteristics of cefpirome and the pharmacokinetic parameters obtained in this study, we calculated a required total daily dose of 2 g every 8 hours to achieve sufficient plasma antibiotic levels to cover the majority of target pathogens. However, this dosage may be insufficient during CVVH for intermediate resistant strains of Pseudomonas aeruginosa.

Continuous beta-lactam antibiotic therapy in a double-lung transplanted patient with a multidrug-resistant Pseudomonas aeruginosa infection.

BACKGROUND: It is well known that the bactericidal effect of beta-lactam antibiotics is closely related to the time which the serum concentration of the antibiotic remains above the minimal inhibitory concentration of the target pathogen. Thus, the optimal administration of beta-lactam antibiotics would be the continuous infusion of the drug. METHODS: We present a case report with a critically ill double-lung transplanted patient with pneumonia due to a multidrug-resistant Pseudomonas aeruginosa who received continuously 8 g meropenem/24 hr. Based on a previous pharmacokinetic study showing that continuous infusion of meropenem is at least equivalent to intermittent administration this case report is reported to demonstrate the clinical efficacy of continuous infusion. RESULTS: C-reactive protein and pneumonia decreased rapidly when clinical conditions were improved significantly. Continuous administration of meropenem did not interfere with cyclosporine, no side effects were seen, and the patient's renal function was not impaired during the whole period of treatment. CONCLUSION: The continuous administration of beta-lactam antibiotics is a powerful application in critically ill patients to intensify antimicrobial therapy.

Ofloxacin clearance during hemodialysis: a comparison of polysulfone and cellulose acetate hemodialyzers.

The pharmacokinetics of ofloxacin were studied in 13 patients with end-stage renal disease during hemodialysis using two different dialyzers: a polysulfone membrane (Fresenius F6) and a cellulose acetate dialyzer (Nissho Nipro FB-150T). All patients received 100 mg ofloxacin orally per day before dialysis. The hemodialysis clearance per square meter surface area was significantly different, with 5.0+/-0.7 L/h and 3.7+/-1.6 L/h, respectively. The serum concentration was reduced by a 3-hour hemodialysis by 49.6%+/-5.8% per square meter surface area and 45.5%+/-4.8% per square meter surface area. The half-life was 4.2+/-1.8 hours and 4.8+/-1.6 hours during the hemodialysis period and 22.8+/-2.2 hours and 23.3+/-1.7 hours between the dialysis sessions, respectively. Comparing polysulfone and cellulose acetate dialyzers, the material of the membrane influences the half-life, the dialysis clearance, and the percentage of drug extracted during hemodialysis. We conclude that the type of dialyzer used has to be taken into account in dosage recommendations for antimicrobial therapy in hemodialysis patients.

Pharmacokinetics of teicoplanin during continuous hemofiltration with a new and a 24-h used highly permeable membrane: rationale for therapeutic drug monitoring-guided dosage.

OBJECTIVE: Continuous venovenous hemofiltration (CVVH) is widely used in the management of critically ill patients, but only few administration guidelines for antimicrobial drugs are available. It is unclear whether the use of a filter for more than 24 hours might lead to less efficient extraction. This study describes the pharmacokinetics of teicoplanin during CVVH using a highly permeable membrane. METHODS: Pharmacokinetics of teicoplanin during continuous hemofiltration with a new (group 1) and a 24-h used (group 2), highly permeable polyamide membrane were assessed in 3 patients. RESULTS: The teicoplanin serum concentrations (44.0 +/- 18.5 mg/l vs 109.5 +/- 34.5 mg/l) and half-life of teicoplanin (4.6 +/- 1.1 h vs 5.2 +/- 0.7 h) differed significantly between the 2 groups indicating a smaller elimination of the drug on the second day. Substantial binding of teicoplanin to filter membranes could explain this observation. CONCLUSION: The results suggest that daily adjustment of the dosage is necessary to achieve sufficient teicoplanin concentrations and a fixed dosage recommendation is not suitable for this drug.

Impact of plasma protein binding on antimicrobial activity using time-killing curves.

OBJECTIVES: Plasma protein binding (PPB) is known to impair the antimicrobial activity of beta-lactams, but its impact on the activity of other classes of antimicrobials such as fluoroquinolones is controversial. This study was undertaken to investigate the effect of PPB on bacterial killing by selected antibiotics and moxifloxacin, which served as a model compound for the class of fluoroquinolones. METHODS: Bacterial time-killing curves were employed in the absence and presence of physiological albumin concentrations (40 g/L). Moxifloxacin, ampicillin and oxacillin were investigated. Fosfomycin, a non-protein bound antibiotic was used for comparison. Simulations were carried out by employing concentrations of antibiotics of one-fourth of the minimal inhibitory concentration (MIC), equal to the MIC and four-fold the MIC of one select bacterial strain (Staphylococcus aureus ATCC 29213). To correlate bacterial killing to the extent of PPB, bacterial time-killing curves were plotted using the calculated free and the total drug concentration. RESULTS: Bacterial killing by fosfomycin was not affected by the addition of albumin. The antimicrobial activity of oxacillin and ampicillin was reduced in the presence of albumin as expected by the calculation of the free fraction of these antibiotics. Adding albumin to moxifloxacin resulted in a significant decrease in bacterial killing of more than 1 log10 cfu/mL after a period of 8 h when the moxifloxacin concentration was equal to the respective MIC. CONCLUSIONS: Our data confirm the view that albumin substantially impairs the antimicrobial activity of antibiotics including moxifloxacin, a member of the class of fluoroquinolones.

Single-dose pharmacokinetics of levofloxacin during continuous veno-venous haemofiltration in critically ill patients.

The present study was performed to analyse the pharmacokinetics of levofloxacin during continuous veno-venous haemofiltration (CVVH) with a high-flux polyamide membrane. Twelve patients received 500 mg levofloxacin intravenously. The mean levofloxacin concentration peak was 1.9 +/- 1.0 mg/L. The elimination half-life, haemofiltration clearance and total removal were 8.3 +/- 2.6 h, 27.6 +/- 8.4 mL/min and 56 +/- 19%, respectively. Further multiple-dose studies are required to enable dosage recommendations to be made for patients receiving renal replacement therapy with CVVH.

Cellular profile of cytokine production in a patient with visceral leishmaniasis: gammadelta+ T cells express both type 1 cytokines and interleukin-10.

The cytokine profile of CD4+, CD8+ T cells, gammadelta+ T cells and natural killer (NK) cells (CD94+CD3-) was studied in a patient with visceral leishmaniasis (VL). The otherwise healthy, human immunodeficiency virus-negative patient acquired the disease in Tuscany, Italy. Diagnosis was made by demonstration of high concentrations of antibodies against Leishmania antigens in serum. Flow cytometry for the detection of intracellular interferon-gamma (IFN-gamma), interleukin (IL)-2, IL-4, IL-6, IL-10, IL-13 and tumour necrosis factor (TNF)-alpha expression in peripheral blood mononuclear cells stimulated with phorbol 12-myristate 13-acetate and ionomycin was performed, followed by treatment with liposomal amphotericin B. CD4+ cells were identified as major cytokine-expressing cells, capable of producing both type 1 and type 2 cytokines. A high frequency of IL-4- and IL-13-expressing CD8+ cells was noted. NK cells and gammadelta+ T cells, thought to be involved in innate host defences against Leishmania, expressed IFN-gamma and TNF-alpha. Ten per cent of gammadelta+ T cells expressed IL-10, predominantly together with IFN-gamma, suggesting additional immune-regulatory roles for this T-cell subset in VL.

Multiple-dose pharmacokinetics of cefepime in long-term hemodialysis with high-flux membranes.

OBJECTIVE: Among uremic patients on hemodialysis, infectious complications leading to a high incidence of morbidity and mortality are a well-documented problem. In this multi-dose study, the safety, tolerance, and pharmacokinetics of cefepime during high-flux hemodialysis were investigated and an improved dosing schedule is presented. METHODS: Six long-term hemodialysis patients received 2 g cefepime i.v. at the end of hemodialysis three times per week. RESULTS: Trough levels of cefepime were 23.3 +/- 7.3 mg/l and peak serum concentrations 165.6 +/- 48.7 mg/l. After 3.5 h of high-flux hemodialysis, 72.2 +/- 6.4% of cefepime was eliminated. The intradialytic half-life was 1.6 +/- 0.29 h and the interdialytic half-life 22.0 +/- 2.14 h. CONCLUSION: A dosage of 2 g cefepime after each hemodialysis session achieved drug levels well above the minimal inhibitory concentration (MIC)90 for most of the target pathogens. Thus, the described dosing schedule is an efficient and cost saving antmicrobial therapy for severe infections in long-term hemodialysis patients with no residual renal function.

Continuous infusion versus intermittent administration of meropenem in critically ill patients.

This prospective crossover study compared the pharmacokinetics of meropenem by continuous infusion and by intermittent administration in critically ill patients. Fifteen patients were randomized to receive meropenem either as a 2 g iv loading dose, followed by a 3 g continuous infusion (CI) over 24 h, or by intermittent administration (IA) of 2 g iv every 8 h (q8h). Each regimen was followed for a period of 2 days, succeeded by crossover to the alternative regimen for the same period. Pharmacokinetic parameters (mean +/- SD) of CI included the following: concentration at steady state (Css) was 11.9+/-5.0 mg/L; area under the curve (AUC) was 117.5+/-12.9 mg/L x h. The maximum and minimum serum concentrations of meropenem (Cmax, Cmin) and total meropenem clearance (CItot) for IA were 110.1+/-6.9 mg/L, 8.5+/-1.0 mg/L and 9.4+/-1.2 L/h, respectively. The AUC during the IA regimen was larger than the AUC during CI (P < 0.001). In both treatment groups, meropenem serum concentrations remained above the MICs for the most common bacterial pathogens. We conclude that CI of meropenem is equivalent to the IA regimen and is therefore suitable for treating critically ill patients. Further studies are necessary to compare the clinical effects of CI and IA in this patient group.

Single-dose cefodizime as infection prophylaxis in abdominal surgery: a prospective multicenter study.

This prospective pilot study was performed to evaluate the efficacy, safety and tolerability of a single dose of cefodizime as infection prophylaxis in patients undergoing major abdominal surgery. One hundred forty-nine patients received 2g cefodizime, a third-generation cephalosporin, 30 min before abdominal surgery. The mean operation time was 116 +/- 66 min. Eighteen patients received metronidazole additionally. In 8/149 patients (5.4%) the final outcome was considered to be a treatment failure. 94.6% of the patients had no signs of infection. The long half-life of cefodizime allows a single-dose perioperative prophylaxis even in abdominal surgery lasting 3 to 4 h. Cefodizime can be regarded as a safe antibiotic prophylaxis with few side effects.