Single or multiple daily doses of aminoglycosides: a meta-analysis

Audiologic monitoring of multi-drug resistant tuberculosis patients on aminoglycoside treatment with long term follow-up

BACKGROUND

Multi-drug resistant tuberculosis has emerged as a significant problem with the resurfacing of tuberculosis and thus the need to use the second line drugs with the resultant increased incidence of adverse effects. We discuss the effect of second line aminoglycoside anti-tubercular drugs on the hearing status of MDR-TB patients.

METHODS

Sixty four patients were put on second line aminoglycoside anti-TB drugs. These were divided into three groups: group I, 34 patients using amikacin, group II, 26 patients using kanamycin and group III, 4 patients using capreomycin.

RESULTS

Of these, 18.75% of the patients developed sensorineural hearing loss involving higher frequencies while 6.25% had involvement of speech frequencies also. All patients were seen again approximately one year after aminoglycoside discontinuation and all hearing losses were permanent with no threshold improvement.

CONCLUSION

Aminoglycosides used in MDR-TB patients may result in irreversible hearing loss involving higher frequencies and can become a hearing handicap as speech frequencies are also involved in some of the patients thus underlining the need for regular audiologic evaluation in patients of MDR-TB during the treatment.

Antibiotics for acute pyelonephritis in children

BACKGROUND

Urinary tract infection (UTI) is one of the most common bacterial infection in infants. The most severe form of UTI is acute pyelonephritis, which results in significant acute morbidity and may cause permanent renal damage. Published guidelines recommend treatment of acute pyelonephritis initially with intravenous (IV) therapy followed by oral therapy for seven to 14 days though there is no consensus on the duration of either IV or oral therapy.

OBJECTIVES

To determine the benefits and harms of different antibiotic regimens for the treatment of acute pyelonephritis in children.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, reference lists of articles and conference proceedings without language restriction. Date of most recent search: December 2006.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different antibiotic agents, routes, frequencies or durations of therapy in children aged 0 to 18 years with proven UTI and acute pyelonephritis were selected.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. Statistical analyses were performed using the random effects model and the results expressed as relative risk (RR) for dichotomous outcomes or mean difference (WMD) for continuous data with 95% confidence intervals (CI).

MAIN RESULTS

Twenty three studies (3295 children) were eligible for inclusion. No significant differences were found in persistent renal damage at 6 months (2 studies, 424 children: RR 0.87, 95% CI 0.35 to 2.16) or in duration of fever (2 studies, 693 children: WMD 1.54, 95% CI -1.67 to 4.76) between oral antibiotic therapy (10 to 14 days) and IV therapy (3 days) followed by oral therapy (10 days). Similarly no significant differences in persistent renal damage (3 studies, 341 children: RR 1.13, 95% CI 0.86 to 1.49) were found between IV therapy (3 to 4 days) followed by oral therapy and IV therapy for 7 to 14 days. No significant differences in efficacy were found between daily and thrice daily administration of aminoglycosides (1 study, 179 children, persistent symptoms at 3 days: RR 1.98, 95% CI 0.37 to 10.53).

AUTHORS' CONCLUSIONS

These results suggest that children with acute pyelonephritis can be treated effectively with oral antibiotics (cefixime, ceftibuten and amoxycillin/clavulanic acid) or with short courses (2 to 4 days) of IV therapy followed by oral therapy. If IV therapy is chosen, single daily dosing with aminoglycosides is safe and effective. Studies are required to determine the optimal total duration of therapy.

Pharmacology of drugs formulated with DepoFoam: a sustained release drug delivery system for parenteral administration using multivesicular liposome technology

Lamellar liposome technology has been used for several decades to produce sustained-release drug formulations for parenteral administration. Multivesicular liposomes are structurally distinct from lamellar liposomes and consist of an aggregation of hundreds of water-filled polyhedral compartments separated by bi-layered lipid septa. The unique architecture of multivesicular liposomes allows encapsulating drug with greater efficiency, provides robust structural stability and ensures reliable, steady and prolonged drug release. The favourable characteristics of multivesicular liposomes have resulted in many drug formulations exploiting this technology, which is proprietary and referred to as DepoFoam. Currently, two formulations using multivesicular liposome technology are approved by the US FDA for clinical use, and many more formulations are at an experimental developmental stage. The first clinically available formulation contains the antineoplastic agent cytarabine (DepoCyt) for its intrathecal injection in the treatment of malignant lymphomatous meningitis. Intrathecal injection of DepoCyt reliably results in the sustained release of cytarabine and produces cytotoxic concentrations in cerebrospinal fluid (CSF) that are maintained for at least 2 weeks. Early efficacy data suggest that DepoCyt is fairly well tolerated, and its use allows reduced dosing frequency from twice a week to once every other week and may improve the outcome compared with frequent intrathecal injections of unencapsulated cytarabine. The second available formulation contains morphine (DepoDur) for its single epidural injection in the treatment of postoperative pain. While animal studies confirm that epidural injection of DepoDur results in the sustained release of morphine into CSF, the CSF pharmacokinetics have not been determined in humans. Clinical studies suggest that the use of DepoDur decreases the amount of systemically administered analgesics needed for adequate postoperative pain control. It may also provide superior pain control during the first 1-2 postoperative days compared with epidural administration of unencapsulated morphine or intravenous administration of an opioid. However, at this timepoint the overall clinical utility of DepoDur has yet to be defined and some safety concerns remain because of the unknown CSF pharmacokinetics of DepoDur in humans. The versatility of multivesicular liposome technology is reflected by the many agents including small inorganic and organic molecules and macromolecules including proteins that have successfully been encapsulated. Data concerning many experimental formulations containing antineoplastic, antibacterial and antiviral agents underscore the sustained, steady and reliable release of these compounds from multivesicular liposomes after injection by the intrathecal, subcutaneous, intramuscular, intraperitoneal and intraocular routes. Contingent on the specific formulation and manufacturing process, agents were released over a period of hours to weeks as reflected by a 2- to 400-fold increase in elimination half life. Published data further suggest that the encapsulation process preserves bioactivity of agents as delicate as proteins and supports the view that examined multivesicular liposomes were non-toxic at studied doses. The task ahead will be to examine whether the beneficial structural and pharmacokinetic properties of multivesicular liposome formulations will translate into improved clinical outcomes, either because of decreased drug toxicity or increased drug efficacy.

Pseudomonas aeruginosa: resistance and therapeutic options at the turn of the new millennium

Pseudomonas aeruginosa is a major cause of nosocomial infections. This organism shows a remarkable capacity to resist antibiotics, either intrinsically (because of constitutive expression of beta-lactamases and efflux pumps, combined with low permeability of the outer-membrane) or following acquisition of resistance genes (e.g., genes for beta-lactamases, or enzymes inactivating aminoglycosides or modifying their target), over-expression of efflux pumps, decreased expression of porins, or mutations in quinolone targets. Worryingly, these mechanisms are often present simultaneously, thereby conferring multiresistant phenotypes. Susceptibility testing is therefore crucial in clinical practice. Empirical treatment usually involves combination therapy, selected on the basis of known local epidemiology (usually a beta-lactam plus an aminoglycoside or a fluoroquinolone). However, therapy should be simplified as soon as possible, based on susceptibility data and the patient's clinical evolution. Alternative drugs (e.g., colistin) have proven useful against multiresistant strains, but innovative therapeutic options for the future remain scarce, while attempts to develop vaccines have been unsuccessful to date. Among broad-spectrum antibiotics in development, ceftobiprole, sitafloxacin and doripenem show interesting in-vitro activity, although the first two molecules have been evaluated in clinics only against Gram-positive organisms. Doripenem has received a fast track designation from the US Food and Drug Administration for the treatment of nosocomial pneumonia. Pump inhibitors are undergoing phase I trials in cystic fibrosis patients. Therefore, selecting appropriate antibiotics and optimising their use on the basis of pharmacodynamic concepts currently remains the best way of coping with pseudomonal infections.

Therapeutic drug monitoring of gentamicin: evaluation of five nomograms for initial dosing at Al-Amiri Hospital in Kuwait

OBJECTIVE

To compare five published nomograms (Thomson guidelines, Mawer nomogram, rule of eights, Hull-Sarubbi table and Dettli method) for calculating the initial gentamicin dosage regimen in a Kuwaiti population.

MATERIALS AND METHODS

Based on measured peak and trough gentamicin concentrations, the elimination rate constant and volume of distribution of gentamicin were calculated for each patient (n = 56), using a modified two-point Sawchuk-Zaske method. The calculated individual set of pharmacokinetic parameters and the initial dose regimen recommended by each of the five methods were used to predict the steady-state peak and trough of gentamicin concentrations.

RESULTS

The Thomson guidelines produced consistent results in predicting gentamicin concentrations within the target ranges of peak plus trough, peak only and trough only (63, 75 and 75%, respectively). The Mawer nomogram, Hull-Sarubbi table and Dettli methods achieved similar percentages of patients (46-50%) within the target ranges (5-10 mg x l(-1) for peak and 0.5-2 for trough), whereas empirical dosing and the rule of eights showed the lowest percentages of patients within the peak plus trough target range (25 and 37%, respectively). However, with respect to the underdosing target range (predicted concentration <5 mg x l(-1)), the Thomson guidelines showed that 21% of patients were underdosed.

CONCLUSION

The results show that a large number of patients (37-63%) were outside the target ranges in all initial gentamicin dosing methods evaluated in this study. Therefore, serum concentration measurement can be advised to assist in the optimization of gentamicin dose selection.

Prevention of Acute Renal Failure

Acute renal failure (ARF) comprises a family of syndromes that is characterized by an abrupt and sustained decrease in the glomerular filtration rate. In the ICU, ARF is most often due to sepsis and other systemic inflammatory states. ARF is common among the critically ill and injured and significantly adds to morbidity and mortality of these patients. Despite many advances in medical technology, the mortality and morbidity of ARF in the ICU continue to remain high and have not improved significantly over the past 2 decades. Primary strategies to prevent ARF still include adequate hydration, maintenance of mean arterial pressure, and minimizing nephrotoxin exposure. Diuretics and dopamine have been shown to be ineffective in the prevention of ARF or improving outcomes once ARF occurs. Increasing insight into mechanisms leading to ARF and the importance of facilitating renal recovery has prompted investigators to evaluate the role of newer therapeutic agents in the prevention of ARF.

Pharmacokinetic profile of once daily intravenous tobramycin in children with cystic fibrosis

AIM

Once-daily tobramycin in patients with cystic fibrosis (CF) is a more convenient dosing regimen than thrice daily dosing. There are limited data on the pharmacokinetic (PK) profile for once-daily tobramycin in patients with CF. The aim of this study was to define the PK parameters for once-daily tobramycin in children with CF and develop an algorithm for therapeutic drug monitoring dosing.

METHODS

CF patients admitted to hospital were commenced on once-daily intravenous tobramycin (12 mg/kg/day) and ticarcillin/clavulinic acid. Serum tobramycin levels were taken at 30 min, 2-4 h and 12 h post dose. Data points for the PK model included: age, sex, weight, tobramycin dose, time of tobramycin doses and levels, tobramycin levels. WinNonMix was used to obtain the PK parameters.

RESULTS

Forty-four children with 86 admissions who were aged 9 months-20 years were included. A one-compartment intravenous infusion model with first order elimination kinetics produced the best model. Population parameters were: volume of distribution (V(d)) = 0.267 L/kg (95% confidence interval (CL) 0.260-0.272), clearance (CL) 0.103 L/kg/h (95% CI 0.098-0.107) and half-life (t(1/2)) 1.82 (95% CI 1.77-1.88) h. Once the population model was established post hoc analysis was used to calculate individual subject predictions. Plots of individual prediction curves agreed well with observed values.

CONCLUSION

This study has established an algorithm for routine monitoring of once-daily tobramycin in children with CF. Satisfactory serum levels of tobramycin were obtained with a dose of 12 mg/kg/day and a regimen algorithm that uses only one measurement to monitor the plasma concentration is suggested.

Increased amikacin dosage requirements in burn patients receiving a once-daily regimen

Altered pharmacokinetics in burn patients may affect antibiotic plasma concentrations. Typical once-daily dosing (ODD) of 15 mg/kg amikacin (AMK) in burn patients does not always produce peak concentrations (C(max)) reaching the therapeutic objective of six to eight times the minimal inhibitory concentration (MIC). We recorded plasma concentrations following administration of 20 mg/kg AMK in burn patients and studied factors affecting pharmacokinetics. Mean C(max) was 48.3+/-10.8 mg/L and the C(max)/MIC ratio was 6+/-1.35. Statistical analysis demonstrated a relationship between C(max) and the area of the burn and Unit Burn Standard, and between AMK clearance and creatinine clearance (Cl(CR)). We conclude that ODD regimens of AMK in patients with burns >15% body surface area and/or with Cl(CR) >120 mL/min could require doses >20 mg/kg to reach adequate C(max). In all cases, patient therapeutic drug monitoring is essential to ensure the safe usage of these dosing recommendations.

Absence of cochleotoxicity measured by standard and high-frequency pure tone audiometry in a trial of once- versus three-times-daily tobramycin in cystic fibrosis patients

We undertook assessment of hearing in patients with cystic fibrosis who were taking part in a large randomized controlled trial of once- versus three-times-daily tobramycin for pulmonary exacerbations of cystic fibrosis (the TOPIC study). All patients were eligible to have standard pure tone audiometry performed across the frequency range of 0.25 to 8 kHz. High-frequency pure tone audiometry over 10 to 16 kHz was also performed with a subset of patients. Audiometry was undertaken at the start of tobramycin treatment, at the end of a 14-day course of treatment, and at follow-up 6 to 8 weeks later. We enrolled 244 patients, of whom 219 (125 children and 94 adults) completed treatment. Nineteen patients were excluded from analysis due to abnormal baseline audiometry. Complete pre- and posttreatment standard audiological data were obtained for 168/219 patients. We found no significant differences in hearing thresholds when they were assessed at the baseline, at the end of treatment, and at follow-up 6 to 8 weeks later were compared. In addition, no significant differences in hearing thresholds were detected between treatment regimens. Similar results were obtained for the subset of 63/168 patients who underwent high-frequency audiometry. We conclude that for a single 14-day course of tobramycin treatment in patients with cystic fibrosis with no preexisiting auditory deficit, no measurable effect on hearing was apparent with either once- or three-times-daily treatment. Estimation of the cumulative cochleotoxic risk in cystic fibrosis patients due to repeated aminoglycoside therapy, as evidenced by the patients excluded from this study due to hearing loss, also requires further characterization.

The evolution towards ambulatory and day-case management of febrile neutropenia

Febrile neutropenia (FN) is only second to chemotherapy administration as a cause of hospital admission during treatment for cancer. As FN may signify serious or life-threatening infection, management protocols have focussed on trying to prevent adverse outcomes in these patients. However, it is now possible to identify a subset of patients with FN at low risk of life-threatening complications in whom duration of hospitalisation and intensity of therapy can be reduced safely. This review discusses how the management of FN has evolved to enable patients identified as low risk to be treated on specific low risk management strategies, with an emphasis on some of the practical considerations for the implementation of such strategies.

Once-daily versus multiple-daily dosing with intravenous aminoglycosides for cystic fibrosis

BACKGROUND

People with cystic fibrosis, who are chronically colonised with the organism Pseudomonas aeruginosa, often require multiple courses of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations. The properties of aminoglycosides suggest that they could be given in higher doses less often.

OBJECTIVES

To assess the effectiveness and safety of once-daily versus multiple-daily dosing of intravenous aminoglycoside antibiotics for the management of pulmonary exacerbations in cystic fibrosis.

SEARCH STRATEGY

We searched the Cystic Fibrosis Specialist Register held at the Cochrane Cystic Fibrosis and Genetic Disorders Group's editorial base, comprising references identified from comprehensive electronic database searches, handsearching relevant journals and handsearching abstract books of conference proceedings.Date of the most recent search: August 2005.

SELECTION CRITERIA

All randomised controlled trials, whether published or unpublished, in which once-daily dosing of aminoglycosides has been compared with multiple-daily dosing in terms of efficacy and/or toxicity, in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The two authors independently selected the studies to be included in the review and assessed methodological quality of each study. Data were independently extracted by each author. Authors of the included studies were contacted for further information. As yet unpublished data were obtained for one of the included studies.

MAIN RESULTS

Eleven studies were identified for possible inclusion in the review. Four studies reporting results from a total of 328 participants were included in this review. All studies compared once-daily dosing with thrice-daily dosing. There was no significant difference between treatment groups in: forced expiratory volume at one second, weighted mean difference (WMD) 0.33 (95% confidence interval (CI) -2.81 to 3.48); forced vital capacity, WMD 0.29 (95% CI -6.58 to 7.16); % weight for height, WMD -0.82 (95% CI -3.77 to 2.13); body mass index, WMD 0.00 (95% CI -0.42 to 0.42); or in the incidence of ototoxicity, relative risk 0.56 (95% CI 0.04 to 7.96). The percentage change in creatinine significantly favoured once-daily treatment in children, WMD -8.20 (95% CI -15.32 to -1.08), but showed no difference in adults, WMD 3.25 (95% CI -1.82 to 8.33).

AUTHORS' CONCLUSIONS

Once and three times daily aminoglycoside antibiotics appear to be equally effective in the treatment of pulmonary exacerbations of cystic fibrosis. There is evidence of less nephrotoxicity in children.

Nephrotoxicity due to Combination Antibiotic Therapy with Vancomycin and Aminoglycosides in Septic Critically Ill Patients

The aim of this prospective observational study was to evaluate the incidence of nephrotoxicity due to combination therapy with vancomycin and aminoglycosides in septic critically ill patients admitted to the intensive care unit.

METHODS

Thirty consecutive critically ill patients were treated with vancomycin concurrent with aminoglycosides for sepsis. Inclusion criteria were: the need for mechanical ventilation and the presence of severe infection due to bacteria susceptible to vancomycin and aminoglycosides. Exclusion criteria were: age <18 years, impaired renal function (24-hour creatinine clearance <90 ml/min) or previous adverse reaction to either drug. Serum creatinine and urea concentrations, creatinine clearance, 24-hour urinary excretion of proteins, beta2-microglobulin and enzymes were measured immediately before starting therapy and at different times thereafter.

RESULTS

Eleven of the 30 patients had a transient and modest increase in serum urea, 15 patients presented with urinary excretion of beta2-microglobulin and tubular enzymes, and 14 patients had urinary proteins. In the only patient with severe acute renal failure (serum creatinine 8.2 mg/dl), the clinical course was complicated by prolonged hypotension.

CONCLUSION

Concurrent administration of vancomycin and aminoglycosides to critically ill septic patients with normal renal function at baseline induced mainly slight and transient toxic tubular effects. The only clinically significant nephrotoxic event occurred in a patient with septic shock.

Extended-interval gentamicin administration in malnourished children

Malnourished children have several physiologic abnormalities that can affect drug distribution and elimination. The aim of this study was to determine the efficacy, safety and pharmacokinetics of a once-daily dose of gentamicin compared with conventional thrice-daily dosing in malnourished children. To our knowledge, it has not been investigated in this population so far. A total of 310 malnourished children of either gender aged 6 months to 5 years with diarrhea and pneumonia were randomized to receive intramuscular gentamicin 5 mg/kg/day once-daily (OD) (n=148) or the same total daily amount given in three divided doses (TD) (n=162) in addition to ceftriaxone 75 mg/kg/day. After 48 h at steady state, gentamicin pharmacokinetics was assessed by fluorescence polarization immunoassay in a subgroup of 59 children and 43 children in the OD and TD groups, respectively. The groups were equivalent in baseline demographic, clinical and laboratory characteristics. Good and partial clinical responses occurred in 64 per cent vs. 54 per cent and 25 per cent vs. 27 per cent in the OD and the TD children, respectively (p=NS for both comparisons). Five patients in each treatment group died. Renal toxicity defined by change in serum creatinine was not observed in any patient from either group. In the OD group, mean+/-SD serum gentamicin concentrations at 1 (peak), 3, 5, 8, 23, and 24 (trough value) hours after the dose were 11.7+/-4.1, 4.4+/-1.2, 2.08+/-0.9, 1.01+/-0.6, 0.31+/-0.09 and 0.29+/-0.07 mg/l respectively. In the TD group, mean +/-SD serum gentamicin concentration at 1 hour (peak) was 4.7+/-1.8 mg/l and the trough concentration was 0.48+/-0.21 mg/l. In OD group, the gentamicin trough concentration was significantly lower (p<0.001) and the peak concentration was significantly higher (p<0.001) compared to TD group. The results of this study indicate that once-daily gentamicin is effective and safe in malnourished children. Widespread implementation of once-daily dosing in malnourished children is appropriate and will reduce number of intramuscular injections and hospital costs.

Drug-induced acute kidney injury

PURPOSE OF REVIEW

The purpose of this review is to describe the most prevalent mechanisms of drug-induced acute kidney injury, to define the risk factors for nephrotoxicity, and to analyze the available evidence for preventive measures.

RECENT FINDINGS

Drug toxicity remains an important cause of acute kidney injury that, in many circumstances, can be prevented or at least minimized by vigilance and early intervention. Recent studies have resulted in increased insight into the subcellular mechanisms of drug nephrotoxicity. Further improvement is to be expected from the identification of early markers of nephrotoxicity and an increasing involvement of a clinical pharmacist.

SUMMARY

The main mechanisms of nephrotoxicity are vasoconstriction, altered intraglomerular hemodynamics, tubular cell toxicity, interstitial nephritis, crystal deposition, thrombotic microangiopathy, and osmotic nephrosis. Before prescribing a potentially nephrotoxic drug, the risk-to-benefit ratio and the availability of alternative drugs should be considered. Modifiable risk factors should be corrected. The correct drug dosage should be prescribed. Patients should be pre-hydrated and the glomerular filtration rate should be frequently monitored during the administration of a potentially nephrotoxic drug. Studies are needed to further elucidate the mechanisms of nephrotoxicity to design more-rational prevention and treatment strategies. Computer-based prescriber-order entry and an appropriately trained intensive care unit pharmacist are particularly helpful to minimize medication errors and adverse drug events.

"Random" gentamicin concentrations do not predict trough levels in neonates receiving once daily fixed dose regimens

BACKGROUND

Monitoring plasma gentamicin concentrations in neonates 24 hours after a once daily dose (4 mg/kg) often necessitates additional blood sampling. In adults a nomogram has been developed enabling evaluation of gentamicin doses by sampling concentrations with other blood tests, 4-16 hours after administration. We attempted to develop a similar nomogram for neonates.

METHODS

In addition to standard 24 hour sampling to monitor trough concentrations, one additional "random" gentamicin concentration was measured in each of 50 neonates < 4 days of age (median gestation 33 weeks [28-41]), when other blood samples were clinically necessary, 4-20 hours after gentamicin administration. 24 hour concentrations of > 1 mg/L were considered high, and an indication to extend the dosing interval.

RESULTS

Highest correlation (r2 = 0.51) of plasma gentamicin concentration against time (4 to 20 hours) was with logarithmic regression. A line drawn 0.5 mg/L below the true regression line resulted in all babies with 24 hr gentamicin concentrations > 1 mg/L having the additional "random" test result above that line, i.e. 100% sensitivity for 24 hour concentrations > 1 mg/L, though only 58% specificity. Having created the nomogram, 39 further babies (median gestation 34 weeks [28-41]), were studied and results tested against the nomogram. In this validation group, sensitivity of the nomogram for 24 hr concentrations > 1 mg/L was 92%; specificity 14%, positive predictive value 66%, and negative predictive value 50%. Prematurity (< or = 37 weeks) was a more sensitive (94%) and specific (61%) indicator of high 24-hour concentrations. 62 (87%) of 71 preterm babies had high 24-hour concentrations.

CONCLUSION

It was not possible to construct a nomogram to predict gentamicin concentrations at 24 hours in neonates with a variety of gestational ages. Dosage tailored to gestation with monitoring of trough concentrations remains management of choice.

Beta lactam antibiotic monotherapy versus beta lactam-aminoglycoside antibiotic combination therapy for sepsis

BACKGROUND

Optimal antibiotic treatment for sepsis is imperative. Combining a beta-lactam antibiotic with an aminoglycoside antibiotic may have certain advantages over beta-lactam monotherapy.

OBJECTIVES

We compared clinical outcomes for beta lactam-aminoglycoside combination therapy versus beta lactam monotherapy for sepsis.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), (The Cochrane Library, Issue 3, 2004); MEDLINE (1966 to July 2004); EMBASE (1980 to March 2003); LILACS (1982 to July 2004); and conference proceedings of the Interscience Conference of Antimicrobial Agents and Chemotherapy (1995 to 2003). We scanned citations of all identified studies and contacted all corresponding authors.

SELECTION CRITERIA

We included randomized and quasi-randomized trials comparing any beta-lactam monotherapy to any combination of one beta-lactam and one aminoglycoside for sepsis.

DATA COLLECTION AND ANALYSIS

The primary outcome was all-cause fatality. Secondary outcomes included treatment failure, superinfections, colonization, and adverse events. Two authors independently collected data. We pooled relative risks (RR) with their 95% confidence intervals (CI) using the fixed effect model. We extracted outcomes by intention-to-treat analysis whenever possible.

MAIN RESULTS

We included 64 trials, randomizing 7586 patients. Twenty trials compared the same beta-lactam in both study arms, while the remaining compared different beta-lactams using a broader spectrum beta-lactam in the monotherapy arm. In studies comparing the same beta-lactam, we observed no difference between study groups with regard to all-cause fatality, RR 1.01 (95% CI 0.75-1.35) and clinical failure, RR 1.11 (95% CI 0.95-1.29). In studies comparing different beta-lactams, we observed an advantage to monotherapy: all cause fatality RR 0.85 (95% CI 0.71-1.01), clinical failure RR 0.77 (95% CI 0.69-0.86). No significant disparities emerged from subgroup and sensitivity analyses, including the assessment of patients with Gram-negative and Pseudomonas aeruginosa infections. We detected no differences in the rate of resistance development. Adverse events rates did not differ significantly between the study groups overall, although nephrotoxicity was significantly more frequent with combination therapy, RR 0.30 (95% CI 0.23-0.39). We found no heterogeneity for all comparisons. We included a small subset of studies addressing patients with Gram-positive infections, mainly endocarditis. We identified no difference between monotherapy and combination therapy in these studies.

AUTHORS' CONCLUSIONS

The addition of an aminoglycoside to beta-lactams for sepsis should be discouraged. All-cause fatality rates are unchanged. Combination treatment carries a significant risk of nephrotoxicity.

One dose per day compared to multiple doses per day of gentamicin for treatment of suspected or proven sepsis in neonates

BACKGROUND

Gentamicin is widely used in the treatment of suspected or proven neonatal sepsis. Animal studies and systematic reviews from trials in older children and adults suggest that a one dose per day regimen is superior to a multiple doses per day regimen. Pharmacokinetic studies and retrospective audits in neonatal population also favour once a day administration of gentamicin. However, there is no consensus regarding the dose interval regimen in the neonatal population.

OBJECTIVES

To compare the efficacy and safety of one dose per day compared to multiple doses per day of gentamicin in suspected or proven sepsis in neonates.

SEARCH STRATEGY

Eligible studies were identified by searching MEDLINE (March 2005), EMBASE 1980 - 2004, Oxford Database of Perinatal Trials, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2005) and CINAHL (December 1982 - March 2005). Abstracts of the Society for Pediatric Research were hand searched from 1980 to 2004 inclusive. No language restrictions were applied.

SELECTION CRITERIA

All randomised or quasi randomised controlled trials comparing one dose per day ( 'once a day') compared to multiple doses per day ( 'multiple doses a day') of gentamicin to newborn infants < 28 days of life.

DATA COLLECTION AND ANALYSIS

Methodological quality of eligible studies was assessed according to allocation concealment, blinding of intervention, blinding of outcome assessment and completeness of follow up. Data were sought regarding effects on clinical efficacy, pharmacokinetic efficacy, ototoxicity and nephrotoxicity of the two regimens. When appropriate, meta-analysis was conducted to provide a pooled estimate of effect. For categorical data, the typical relative risk (RR), typical risk difference (RD) and number needed to treat (NNT) with 95% confidence intervals (CI) were calculated. Continuous data were analysed using weighted mean difference (WMD).

MAIN RESULTS

Twenty four studies were initially identified. Thirteen were excluded and eleven studies (N = 574) included. All studies compared the effectiveness and safety of 'once a day' versus 'multiple doses a day' regimen of gentamicin in newborn infants. Only one study enrolled infants less than 32 weeks gestation. All except one trial used intravenous infusion. One trial used gentamicin as a bolus dose over one minute. Two trials used intramuscular gentamicin in some of their study infants. For the primary outcome of 'clearance of sepsis', all infants in both 'once a day' as well as 'multiple doses a day' regimen showed adequate clearance of sepsis [Typical RD 0.00 (95% CI - 0.19, 0.19); 3 trials; N = 36]. For the other primary outcome measures relating to gentamicin pharmacokinetics, 'once a day dosing' of gentamicin was superior. 'Once a day' gentamicin regimen is associated with less failures to attain peak level of at least 5 microg/ml [Typical RR 0.22 (95% CI 0.11, 0.47); Typical RD -0.13 (95% CI -0.19, -0.08); 9 trials; N = 422]; less failures to achieve trough levels of < 2 microg/ml [Typical RR 0.38 (95% CI 0.27, 0.55); Typical RD -0.22 (95% CI -0.29, -0.15); 11 trials N = 503]; higher peak levels [WMD 2.58 (95% CI 2.26, 2.89); 10 trials; N = 440] and lower trough levels [WMD -0.57 (95% CI -0.69, -0.44); 10 trials; N = 440] compared to 'multiple doses a day' regimen. Ototoxicity and nephrotoxicity were not noted with either of the treatment regimens. Significant heterogeneity was noted for some of the outcomes measured. Hence the results need to be interpreted with caution. Possible reasons for heterogeneity are different gestational ages of study infants and the timing of collection of blood samples in relation to a particular dose and the day of therapy on which the samples were collected.

AUTHORS' CONCLUSIONS

There is insufficient evidence from the currently available RCTs to conclude whether 'once a day' or 'multiple doses a day' regimen of gentamicin is superior in treating proven neonatal sepsis. However data suggests that pharmacokinetic properties of 'once a day' gentamicin regimen are superior to 'multiple doses a day' regimen in that it achieves higher peak levels while avoiding toxic trough levels. There is no change in nephrotoxicity or auditory toxicity. Based on this assessment of pharmacokinetics, 'once a day regimen' may be superior in treating neonatal sepsis in neonates more than 32 weeks gestation.

Aminoglycoside extended interval dosing in neonates is safe and effective: a meta-analysis

OBJECTIVES

To review the evidence from controlled clinical trials of neonates given equal daily aminoglycoside doses as extended interval dosing (dosage interval typically 24 hours in term and 36-48 hours in immature neonates) compared with traditional dosing (dosage interval typically 8-12 hours in term and 12-24 hours in immature neonates).

DESIGN

Systematic review and meta-analysis of controlled trials found in electronic databases, trial registers, and references in reviews and selected trials.

SETTINGS

The selected trials were blinded and assessed for methodological quality. Each trial's own predefined criteria for treatment failure, nephrotoxicity, ototoxicity, and therapeutic serum drug concentrations were used.

SUBJECTS

Controlled trials of neonatal aminoglycoside treatment in which equal aminoglycoside daily doses were given at traditional and extended dosage intervals.

MAIN OUTCOME MEASURES

Serum drug concentrations outside the therapeutic range. Treatment failure and toxicity.

RESULTS

Sixteen trials involving 823 neonates met the inclusion criteria for the systematic review. Twelve trials involving 698 neonates were included in the meta-analysis of the pharmacokinetics. Compared with traditional dosing, extended interval dosing was associated with a significantly lower risk of both peak (summary risk ratio 0.50, 95% confidence interval 0.26 to 0.94) and trough (0.36, 0.25 to 0.56) serum drug concentrations outside the therapeutic range. Accurate information on treatment failure was obtained in nine trials involving 555 neonates. One trial reported treatment failure. In this trial two neonates in the traditional dosing group did not respond to treatment within 72 hours. Nephrotoxicity was investigated in 589 neonates in 12 trials and ototoxicity in 210 neonates in four trials, with no significant differences between the two dosing regimens.

CONCLUSIONS

Extended interval dosing of aminoglycosides in neonates is safe and effective, with a reduced risk of serum drug concentrations outside the therapeutic range.

Comparison of gentamicin dose estimates derived from manual calculations, the Australian 'Therapeutic Guidelines: Antibiotic' nomogram and the SeBA-GEN and DoseCalc software programs

AIM

To compare gentamicin dose estimates from four predictive methods.

METHODS

A retrospective study was conducted, comprising patients at Fremantle Hospital who received gentamicin therapy and had at least one gentamicin serum concentration reported. A manual calculation method, the Australian 'Therapeutic Guidelines: Antibiotic' (TGA) nomogram and the SeBA-GEN and DoseCalc software packages were compared. SeBA-GEN dose estimates were regarded as the reference standard.

RESULTS

There were 64 males and 30 females with mean age of 58 +/- 16 years. In patients with moderate renal impairment (CL(Cr) = 30-60 ml min(-1); n = 21), mean dose estimates using DoseCalc and the manual calculation method were comparable to SeBA-GEN but the mean TGA nomogram dose (230 mg; 95% confidence interval 179, 281) was significantly lower than SeBA-GEN (286 mg; 261, 311; P = 0.002; one-way RM anova). In patients with mild renal impairment (CL(Cr) = 60-90 ml min(-1); n = 48), DoseCalc (392 mg; 367, 427) was comparable to SeBA-GEN (377 mg; 362, 392). Although the manual method (341 mg; 306, 376; P = 0.007) and the TGA nomogram (335 mg; 302, 368; P < 0.001) estimates were significantly lower than SeBA-GEN, the practical difference was modest.

CONCLUSIONS

SeBA-GEN and DoseCalc are generally comparable for estimation of gentamicin doses in patients with renal impairment. The 'Therapeutic Guidelines: Antibiotic' nomogram is a valid approach to dosage estimation, but only when used in patients with normal renal function. Simple manual calculations are a suitable alternative in patients with renal impairment.

Antibiotics for acute pyelonephritis in children

BACKGROUND

Urinary tract infection (UTI) is one of the most common bacterial infection in infants. The most severe form of UTI is acute pyelonephritis, which results in significant acute morbidity and may cause permanent renal damage. Published guidelines recommend treatment of acute pyelonephritis initially with intravenous (IV) therapy followed by oral therapy for seven to 14 days though there is no consensus on the duration of either IV or oral therapy.

OBJECTIVES

To determine the benefits and harms of different antibiotic regimens for the treatment of acute pyelonephritis in children.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, reference lists of articles and abstracts from conference proceedings without language restriction. Date of most recent search: June 2004.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different antibiotic agents, routes, frequencies or durations of therapy in children aged 0 to 18 years with proven UTI and acute pyelonephritis were selected.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and the results expressed as relative risk (RR) for dichotomous outcomes or weight mean difference (WMD) for continuous data with 95% confidence intervals (CI).

MAIN RESULTS

Eighteen trials (2612 children) were eligible for inclusion. No significant differences were found in persistent renal damage at six months (one trial, 306 infants: RR 1.45, 95% CI 0.69 to 3.03) or in duration of fever (WMD 0.80, 95% CI -4.41 to - 6.01) between oral cefixime therapy (14 days) and IV therapy (three days) followed by oral therapy (10 days). Similarly no significant differences in persistent renal damage (three trials, 315 children: RR 0.99, 95% CI 0.72 to 1.37) were found between IV therapy (3-4 days) followed by oral therapy and IV therapy for 7-14 days. In addition no significant differences in efficacy were found between daily and thrice daily administration of aminoglycosides (one trial, 179 children, persistent symptoms at three days: RR 1.98, 95% CI 0.37 to 10.53).

AUTHORS' CONCLUSIONS

These results suggest that children with acute pyelonephritis can be treated effectively with oral cefixime or with short courses (2-4 days) of IV therapy followed by oral therapy. If IV therapy is chosen, single daily dosing with aminoglycosides is safe and effective. Trials are required to determine the optimal total duration of therapy and if other oral antibiotics can be used in the initial treatment of acute pyelonephritis.

Current use for old antibacterial agents: polymyxins, rifampin, and aminoglycosides

This article discusses three classes of antibacterial agents that are uncommonly used in bacterial infections (other than mycobacterial infections) and can be thought of as special-use agents. These are the polymyxins, rifampin, and the aminoglycosides.

Antibiotic pharmacokinetic and pharmacodynamic considerations in critical illness

BACKGROUND

Many factors over which there may be little control may influence the response of a patient to therapy. However, therapy with antibiotics can be readily optimised.

DISCUSSION

Concentration-dependent agents such as aminoglycosides appear effective and to entail fewer side effects when given in large, infrequent doses. There is also evidence that time-dependent antibiotics often fail to reach adequate concentrations throughout the treatment period. To date no randomised controlled prospective trial has demonstrated improvement in clinical outcome following infusion rather than intermittent boluses of time-dependent antibiotics. Critical illness alters antibiotic pharmacokinetics principally through increases in volume of distribution. Other than glycopeptides and aminoglycosides, antibiotic blood concentrations are rarely monitored and therefore adequate concentrations can only be inferred from clinical response.

CONCLUSIONS

Failure to respond within the first few days of empirical treatment may be due to antibiotic resistance or inadequate doses. Therefore the same rigor should be applied to achieving adequate antibiotic concentrations as is applied to inotropes, which are titrated to achieve predetermined physiological targets.

Antibiotic regimens for endometritis after delivery

BACKGROUND

Postpartum endometritis, which is more common after cesarean section, occurs when vaginal organisms invade the endometrial cavity during labor and birth. Antibiotic treatment is warranted.

OBJECTIVES

The effect of different antibiotic regimens for the treatment of postpartum endometritis on failure of therapy and complications was systematically reviewed.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's trials register (30 January 2004).

SELECTION CRITERIA

Randomized trials of different antibiotic regimens for postpartum endometritis, after cesarean section or vaginal birth, where outcomes of treatment failure or complications were reported were selected.

DATA COLLECTION AND ANALYSIS

We abstracted data independently and made comparisons between different types of antibiotic regimen based on type of antibiotic and duration and route of administration. Summary relative risks were calculated.

MAIN RESULTS

Thirty-eight trials with 3983 participants were included. Fifteen studies comparing clindamycin and an aminoglycoside with another regimen showed more treatment failures with the other regimen (relative risk (RR) 1.44; 95% confidence interval (CI) 1.15 to 1.80). Failures of those regimens with poor activity against penicillin resistant anaerobic bacteria were more likely (RR 1.94; 95% CI 1.38 to 2.72). In three studies that compared continued oral antibiotic therapy after intravenous therapy with no oral therapy, no differences were found in recurrent endometritis or other outcomes. In four studies comparing once daily with thrice daily dosing of gentamicin there were fewer failures with once daily dosing. There was no evidence of difference in incidence of allergic reactions. Cephalosporins were associated with less diarrhea.

REVIEWERS' CONCLUSIONS

The combination of gentamicin and clindamycin is appropriate for the treatment of endometritis. Regimens with activity against penicillin- resistant anaerobic bacteria are better than those without. There is no evidence that any one regimen is associated with fewer side effects. Once uncomplicated endometritis has clinically improved with intravenous therapy, oral therapy is not needed.

Application of Bayes theorem to aminoglycoside-associated nephrotoxicity: comparison of extended-interval dosing, individualized pharmacokinetic monitoring, and multiple-daily dosing

The objective of this study was to examine the incidence of aminoglycoside-associated nephrotoxicity related to extended-interval dosing, individualized pharmacokinetic monitoring, and multiple-daily dosing by applying Bayes theorem. An electronic literature search of MEDLINE (1966-2003) and a manual search of references from published meta-analyses and review articles were performed. Studies using extended-interval dosing, individualized pharmacokinetic monitoring, or multiple-daily dosing and reported aminoglycoside-associated nephrotoxicity for patients > or = 16 years of age were included. Quality scores were assigned based on the rigor of definition of aminoglycoside-associated nephrotoxicity, duration of therapy, and length of follow-up of renal function after completion of therapy. Inclusion criteria were then based on these quality scores. Quantitative data on the incidence of aminoglycoside-associated nephrotoxicity were abstracted. Twelve extended-interval dosing studies (n = 916), 10 individualized pharmacokinetic monitoring studies (n = 2066), and 27 multiple-daily dosing studies (n = 4251) met the inclusion criteria. Prior probabilities of aminoglycoside-associated nephrotoxicity were derived from a combination of a review of published studies and expert judgment. The maximum densities for the final posterior probabilities of aminoglycoside-associated nephrotoxicity for extended-interval dosing, individualized pharmacokinetic monitoring, and multiple-daily dosing were located at 12% to 13%, 10% to 11%, and 13% to 14%, respectively. Application of Bayes theorem demonstrates that aminoglycoside dosing by individualized pharmacokinetic monitoring results in less aminoglycoside-associated nephrotoxicity than extended-interval dosing or multiple-daily dosing.

Effect of once-daily dosing vs. multiple daily dosing of tobramycin on enzyme markers of nephrotoxicity

OBJECTIVE

To determine the incidence of nephrotoxicity of once-daily dosing (ODD) and multiple daily dosing (MDD) regimens of tobramycin in critically ill patients.

DESIGN

Randomized, prospective clinical trial.

SETTING

: Adult intensive care units at two university hospitals.

PATIENTS

Fifty-eight critically ill patients with a suspected or documented aerobic Gram-negative infection.

INTERVENTIONS

Patients were randomized to receive tobramycin by ODD (7 mg/kg) or MDD. Baseline urine aliquots and 24-hr urine collections were collected on days 3, 7, and 11 during therapy and on days 3, 7, and 11 following discontinuation of therapy for measurement of alanine aminopeptidase (AAP), N-acetyl-beta-d-glucosaminidase (NAG), and creatinine.

MEASUREMENTS AND MAIN RESULTS

Fifty-four patients were evaluable (ODD n = 25; MDD n = 29). The groups were similar with regard to demographic and clinical variables. The tobramycin dose was higher in the ODD group compared with the MDD group (425 +/- 122.5 mg vs. 312.8 +/- 116.6 mg, p <.001). Patients in the MDD group received a mean of 3.89 +/- 1.14 mg.kg(-1)day(-1) at intervals of 11.92 +/- 3.12 hrs. In the ODD group, patients had a higher measured creatinine clearance at the end of therapy compared with MDD group (70 +/- 18.6 vs. 64.8 +/- 17.5 mL/min, p =.047). Fewer patients in the ODD group developed nephrotoxicity than the MDD group (5 vs. 12, p =.142). Although there were increases in urinary enzymes in both treatment groups (AAP, 8.7 +/- 2.9 vs. 5.2 +/- 2.1 units/24 hrs, p <.01 MDD vs. ODD; NAG, 14.7 +/- 4.9 vs. 6.8 +/- 3.1, p <.01 MDD vs. ODD), the increases in the ODD group were significantly lower than in the MDD group.

CONCLUSIONS

: The ODD tobramycin regimen appeared to be less nephrotoxic than the MDD regimen despite significantly higher doses. Tobramycin administered by ODD may be the preferred dosing method in selected critically ill medical patients to reduce the incidence and extent of renal damage.

Extended-interval aminoglycoside administration for children: a meta-analysis

BACKGROUND

There has been a long-standing debate regarding whether aminoglycosides should be administered on a multiple daily dosing (MDD) or once-daily dosing (ODD) schedule. Several unique characteristics of the aminoglycosides make ODD an attractive and possibly superior alternative to MDD. These include concentration-dependent bactericidal activity; postantibiotic effect, which allows continued efficacy even when serum concentrations fall below expected minimum inhibitory concentrations; decreased risk of adaptive resistance; and diminished accumulation in renal tubules and inner ear.

OBJECTIVE

To assess the relative efficacy and toxicity of ODD, compared with MDD, of aminoglycosides among pediatric patients.

STUDY SELECTION

Randomized, controlled trials among children, evaluating the relative efficacy and toxicity of ODD versus MDD of aminoglycosides, with similar total daily doses in the compared arms, were selected.

DATA SOURCES

PubMed (1966-2003) and Embase (1982-2003) databases, the Cochrane Controlled Trials Registry (2003), and references of eligible studies and pediatric review articles were searched.

DATA EXTRACTION

Study population characteristics and outcome data were extracted independently in duplicate, and consensus was reached on all items. The following outcome data were considered: (1) clinical or microbiologic failure, as defined in each study; (2) clinical failure; (3) microbiologic failure; (4) primary nephrotoxicity, ie, any rise in serum creatinine or decrease in creatinine clearance with thresholds as defined in each study; (5) secondary nephrotoxicity, ie, urinary excretion of proteins or phospholipids; and (6) ototoxicity based on pure tone audiometry, brainstem auditory evoked responses, or otoacoustic emissions for neonates and infants, vestibular testing, clinical impression, or any other method. All of the efficacy and toxicity outcomes were evaluated at the end of therapy.

RESULTS

Identification of eligible studies and study characteristics: 24 eligible studies published between 1991 and 2003 were identified. Aminoglycosides were used in different clinical settings (neonatal intensive care unit: 6 studies; cystic fibrosis: 3 studies; cancer: 5 studies; urinary tract infections: 4 studies; diverse infectious indications: 5 studies; pediatric intensive care unit: 1 study). Aminoglycosides used included amikacin (9 studies), gentamicin (11 studies), tobramycin (2 studies), netilmicin (2 studies), and tobramycin or netilmicin (1 study).

EFFICACY

There was no significant difference between ODD and MDD in the clinical failure rate, microbiologic failure rate, and combined clinical or microbiologic failure rates, but trends favored ODD consistently. There was no between-study heterogeneity for any outcome. Efficacy analysis of all trials indicating either clinical or microbiologic failures demonstrated pooled failure rates of 4.6% (23 of 501 cases) in the ODD arms and 6.9% (34 of 494 cases) in the MDD arms. The fixed-effects risk ratio was 0.71 (95% confidence interval [CI]: 0.45-1.11). A statistically significant benefit was seen with ODD over MDD in trials using amikacin, whereas no statistical significance was seen in trials using other antibiotics. The pooled clinical failure rates were 6.7% (22 of 330 cases) in the ODD arms and 10.4% (34 of 327 cases) in the MDD arms. The fixed-effects risk ratio was 0.67 (95% CI: 0.42-1.07). The pooled microbiologic failure rates were 1.8% (5 of 283 cases) with ODD and 4.0% (11 of 275 cases) with MDD. The fixed-effects risk ratio was 0.51 (95% CI: 0.22-1.18). NEPHROTOXICITY: There was no significant difference between ODD and MDD in the primary nephrotoxicity outcomes. Secondary nephrotoxicity outcomes were significantly better with ODD. The pooled primary nephrotoxicity rates were 1.6% (15 of 955 cases) in the ODD arms and 1.6% (15 of 923 cases) in the MDD arms. The fixed-effects risk ratio was 0.97 (95% CI: 0.55-1.69). The pooled secondary nephrotoxicity rates were 4.4% (3 of 69 cases) in the ODD arms and 15.9% (11 of 69 cases) in the MDD arms, suggesting a statistically significant superiority of ODD. The fixed-effects risk ratio was 0.33 (95% CI: 0.12-0.89). Results were consistent across types of clinical settings and aminoglycosides. OTOTOXICITY: There was no significant difference between ODD and MDD in the primary ototoxicity outcomes. The pooled ototoxicity rates for studies that provided auditory testing results were 2.3% (10 of 436 cases) in the ODD arms and 2.0% (8 of 406 cases) in the MDD arms. The fixed-effects risk ratio was 1.06 (95% CI: 0.51-2.19). In studies that provided clinical vestibular function testing results, no toxicity was documented among 209 patients given ODD and 206 patients given MDD. Studies noting only the clinical impression of hearing impairment also failed to identify any toxicity (ODD: 114 cases; MDD: 114 cases). SUBGROUP AND BIAS ANALYSES: We detected no statistically significant differences between ODD and MDD in any of the examined subgroups (neonatal intensive care unit, cystic fibrosis, cancer, or urinary tract infection), with respect to combined clinical or microbiologic failure outcomes, primary nephrotoxicity outcomes, or ototoxicity (based on auditory testing), when sufficient data were available. Moreover, there was no significant relationship between the effect size (risk ratio) and the trial size for any of the outcomes. DATA INTERPRETATION: Clinical failures were uncommon in the pediatric trials, regardless of the regimen used. If anything, fewer clinical failures tended to occur with ODD. Moreover, we observed a trend toward decreased bacteriologic failures. One meta-analysis of adult data suggested that ODD might reduce nephrotoxicity, whereas other meta-analyses showed nonsignificant trends or no difference in nephrotoxicity outcomes. In our meta-analysis, we were not able to show any reduction in the risk of primary nephrotoxicity outcomes with ODD. However, the event rate was much lower among children, compared with adults, and the secondary nephrotoxicity outcomes favored ODD. Finally, although the 2 regimens seemed equivalent with respect to ototoxicity, reporting on ototoxicity outcomes was incomplete. Reassuringly, even in the trials that performed auditory testing, the rates of ototoxicity in the MDD arms were very low. These results were consistent with meta-analyses of adult data, which showed no difference in ototoxicity rates between ODD and MDD.

CONCLUSIONS

Although single trials have been small, the available randomized evidence supports the general adoption of ODD of aminoglycosides in pediatric clinical practice. This approach minimizes cost, simplifies administration, and provides similar or even potentially improved efficacy and safety, compared with MDD of these drugs.

A randomised, controlled trial of once daily and multi-dose daily gentamicin in young Kenyan infants

AIMS

To test the suitability of a simple once daily (OD) gentamicin regimen for use in young infants where routine therapeutic drug monitoring is not possible.

METHODS

In an open, randomised, controlled trial, infants with suspected severe sepsis admitted to a Kenyan, rural district hospital received a novel, OD gentamicin regimen or routine multi-dose (MD) regimens.

RESULTS

A total of 297 infants (over 40% < or =7 days) were randomised per protocol; 292 contributed at least some data for analysis of pharmacological endpoints. One hour after the first dose, 5% (7/136) and 28% (35/123) of infants in OD and MD arms respectively had plasma gentamicin concentrations <4 microg/ml (a surrogate of treatment inadequacy). Geometric mean gentamicin concentrations at this time were 9.0 microg/ml (95% CI 8.3 to 9.9) and 4.7 microg/ml (95% CI 4.2 to 5.3) respectively. By the fourth day, pre-dose concentrations > or =2 microg/ml (a surrogate of potential treatment toxicity) were found in 6% (5/89) and 24% (21/86) of infants respectively. Mortality was similar in both groups and clinically insignificant, although potential gentamicin induced renal toxicity was observed in <2% infants.

CONCLUSIONS

A "two, four, six, eight" OD gentamicin regime, appropriate for premature infants and those in the first days and weeks of life, seems a suitable, safe prescribing guide in resource poor settings.

Extended-interval aminoglycoside dosing for treatment of enterococcal and staphylococcal osteomyelitis

BACKGROUND

Gram-positive osteomyelitis requires long-term antibiotic therapy, much of which is often administered in the outpatient setting. Historically, synergistic aminoglycoside use in these infections requires multiple daily doses, which can be inconvenient. Data regarding extended-interval aminoglycoside dosing (EIAD), also known as once-daily dosing, in this setting are lacking.

OBJECTIVE

To evaluate the safety and efficacy of EIAD in the treatment of gram-positive osteomyelitis.

METHODS

Retrospective chart review of adult patients treated for documented, gram-positive osteomyelitis with EIAD at the University of New Mexico Home IV Antibiotic Clinic was conducted. The patients' medical records were reviewed by an infectious diseases clinical pharmacist. Clinical and microbiologic outcomes and the incidence of nephrotoxicity and ototoxicity were the main outcome measures.

RESULTS

Fifteen patients (16 events) were included. Enterococcus spp. was the most common organism isolated. Nine patients had infected equipment or devices; 6 of these had removal of these devices in conjunction with antibiotic therapy. The median duration of antibiotic therapy was 6 weeks (range 6-31). The median duration of aminoglycoside therapy was 28 days (range 6-43). Seven patients developed nephrotoxicity, 5 of whom received an aminoglycoside in combination with vancomycin. Male patients had a higher risk of developing nephrotoxicity compared with females (p = 0.04). The mean +/- SD duration of EIAD before the development of nephrotoxicity was 34 +/- 8 days. Clinical cure was achieved in 12 (75%) patients. Three patients achieved clinical cure without hardware removal.

CONCLUSIONS

Most of the patients with gram-positive osteomyelitis were successfully managed with EIAD. However, nephrotoxicity developed in a high proportion of patients and was likely related to prolonged aminoglycoside use.

Pharmacokinetics of a high dose of amikacin administered at extended intervals to neonatal foals

OBJECTIVE

To determine disposition kinetics of amikacin in neonatal foals administered high doses at extended intervals.

ANIMALS

7 neonatal foals.

PROCEDURE

Amikacin was administered (21 mg/kg, i.v., q 24 h) for 10 days. On days 1, 5, and 10, serial plasma samples were obtained for measurement of amikacin concentrations and determination of pharmacokinetics.

RESULTS

Mean +/- SD peak plasma concentrations of amikacin extrapolated to time 0 were 103.1 +/- 23.4, 102.9 +/- 9.8, and 120.7 +/- 17.9 microg/mL on days 1, 5, and 10, respectively. Plasma concentrations at 1 hour were 37.5 +/- 6.7, 32.9 +/- 2.6, and 30.6 +/- 3.5 microg/mL; area under the curve (AUC) was 293.0 +/- 61.0, 202.3 +/- 40.4, and 180.9 +/- 31.2 (microg x h)/mL; elimination half-life (t(1/2)beta) was 5.33, 4.08, and 3.85 hours; and clearance was 1.3 +/- 0.3, 1.8 +/- 0.4, and 2.0 +/- 0.3 mL/(min x kg), respectively. There were significant increases in clearance and decreases in t(1/2)beta, AUC, mean residence time, and plasma concentrations of amikacin at 1, 4, 8, 12, and 24 hours as foals matured.

CONCLUSIONS AND CLINICAL RELEVANCE

Once-daily administration of high doses of amikacin to foals resulted in high peak plasma amikacin concentrations, high 1-hour peak concentrations, and large values for AUC, consistent with potentially enhanced bactericidal activity. Age-related findings suggested maturation of renal function during the first 10 days after birth, reflected in enhanced clearance of amikacin. High-dose, extended-interval dosing regimens of amikacin in neonatal foals appear rational, although clinical use remains to be confirmed.

Acute renal failure in the newborn

Acute renal failure in the newborn is a common problem and is typically classified as prerenal, intrinsic renal disease including vascular insults, and obstructive uropathy. In the newborn, renal failure may have a prenatal onset in congenital diseases such as renal dysplasia with or without obstructive uropathy and in genetic diseases such as autosomal recessive polycystic kidney disease. Acute renal failure in the newborn is also commonly acquired in the postnatal period because of hypoxic ischemic injury and toxic insults. Nephrotoxic acute renal failure in newborns is usually associated with aminoglycoside antibiotics and nonsteroidal anti-inflammatory medications used to close a patent ductus arteriosis. Alterations in renal function occur in approximately 40% of premature newborns who have received indomethacin and such alterations are usually reversible. Renal artery thrombosis and renal vein thrombosis will result in renal failure if bilateral or if either occurs in a solitary kidney. Cortical necrosis is associated with hypoxic/ischemic insults due to perinatal anoxia, placenta abruption and twin-twin or twin-maternal transfusions with resultant activation of the coagulation cascade. As in older children, hospital acquired acute renal failure is newborns is frequently multifactorial in origin. Although the precise incidence and prevalence of acute renal failure in the newborn is unknown, several studies have shown that acute renal failure is common in the neonatal intensive care unit. Recent interesting studies have demonstrated that some newborns may have genetic risks factors for acute renal failure. Once intrinsic renal failure has become established, management of the metabolic complications of acute renal failure continues to involve appropriate management of fluid balance, electrolyte status, acid-base balance, nutrition and the initiation of renal replacement therapy when appropriate. Renal replacement therapy may be provided by peritoneal dialysis, intermittent hemodialysis, or hemofiltration with or without a dialysis circuit. The preferential use of hemofiltration by pediatric nephrologists is increasing while the use of peritoneal dialysis is decreasing except for neonates and small infants. Peritoneal dialysis has been a major modality of therapy for acute renal failure in the neonate when vascular access may be difficult to maintain. In the newborn, the prognosis and recovery from acute renal failure is highly dependent upon the underlying etiology of the acute renal failure. Factors that are associated with mortality include multiorgan failure, hypotension, need for pressors, hemodynamic instability, and need for mechanical ventilation and dialysis. The mortality and morbidity of newborns with acute renal failure is much worse in neonates with multiorgan failure. Newborns who have suffered substantial loss of nephrons as may occur in cortical necrosis are at risk for late development of renal failure after apparent recovery from the initial insult. Similarly, hypoxic/ischemic and nephrotoxic injury to the developing kidney can result is decreased nephron number. Newborns with acute renal failure need life-long monitoring of their renal function, blood pressure, and urinalysis. Typically, the late development of chronic renal failure will first becomes apparent with the development of hypertension, proteinuria, and eventually an elevated blood urea nitrogen and creatinine.

Evaluation of Once Daily Aminoglycoside Use in the Elderly

Purpose

This study evaluated the incidence of nephrotoxicity due to once daily aminoglycoside (ODA) use in elderly patients at two South Florida institutions.

Methods

A retrospective review of all patients who received 7 mg/kg/day of either gentamicin or tobramycin was conducted.

Results

Eighty-one (49%) males and 84 (51%) females with a mean age of 73 (range, 60 to 95) years were included. Nephrotoxicity was evident in 16 patients (9.7%). Of these, eight (4.8%) experienced nephrotoxicity possibly associated with aminoglycoside administration. A subgroup analysis of nonnephrotoxic patients compared with nephrotoxic patients revealed no significant differences in mean initial serum creatinine (1 mg/dL vs 0.95 mg/dL, P = 0.861) or dosing interval (31.4 vs 31.5 hours, P = 0.983). The mean duration of aminoglycoside treatment was less in the nonnephrotoxic group compared with the nephrotoxic group (5.2 vs 9.9 days, P < 0.05).

Conclusion

The results of this retrospective evaluation suggest that ODA dosing in the elderly is safe; however, patients should be monitored closely, especially when they require more than 5 days of aminoglycoside therapy, or are receiving concomitant nephrotoxic agents.

Evaluation of once daily tobramycin dosing in critically ill patients through Bayesian simulation

OBJECTIVE

To evaluate if once-daily dose (ODD) regimens of tobramycin attain pharmacodynamic goals using individualized pharmacokinetic monitoring of critically ill patients with creatinine clearance (Clcr) over 60 mL/min.

METHODS

Fifty-one adult critically ill patients treated with intravenous tobramycin with ODD were included in the study. The effect of dosing using the proposed method was compared with a weight-based (7 mg/kg) dosing method. Pharmacokinetics parameters, peak concentration (Cpeak), minimum concentration (Cmin) and the time below the minimum inhibitory concentration (MIC) were estimated using Bayesian analysis. Pharmacodynamic parameters used to evaluate both dosing regimens were Cpeak/MIC ratio and, secondly, time below MIC (T< MIC).

RESULTS

The median dose of tobramycin administrated in our hospital was too low for achieving pharmacodynamic goals. In contrast, the weight-based (7 mg/kg) method produced an adequate Cpeak/MIC ratio but an increase of the dose would not reduce the secondary pharmacodynamic index T<MIC.

CONCLUSION

The results from the current study explain why weight-based daily dosing of tobramycin in critically ill patients with Clcr>60 mL/min achieved the Cpeak/MIC target values of 10. However in critically ill patients with Clcr>80 mL/min, T<MIC is greater than the aminoglycoside post-antibiotic effect, so these patients do not attain the secondary pharmacodynamic index. These data show the need for rapid pharmacokinetic optimization with individualized aminoglycoside dosing. Additional studies are necessary to better define the best tobramycin regimen for critically ill patients.

Randomized controlled trial of once- versus thrice-daily tobramycin in febrile neutropenic children undergoing stem cell transplantation

BACKGROUND

The benefits of aminoglycoside antibiotics, such as tobramycin, administered as a once-daily dose to manage febrile neutropenia, have been demonstrated in many patient populations. However, toxicity and safety data are lacking for pediatric stem cell transplant recipients, who are at especially high risk for aminoglycoside-related toxicity and infectious morbidity. In particular, the relative nephrotoxicity and efficacy of tobramycin administered as a single daily dose or as three daily doses among this patient population is not known.

METHODS

We conducted a randomized, double-blind controlled study of tobramycin dosing among children 18 years or younger who had fever and neutropenia while undergoing stem cell transplantation. From October 2000 through November 2002, 60 children were randomly assigned to receive intravenous tobramycin, as either a single daily dose (n = 29) or every 8 hours (n = 31), in combination with either piperacillin or ceftazidime (intravenous). Tobramycin doses were adjusted to achieve pharmacokinetic targets. The primary outcome was nephrotoxicity, as represented by the maximal percent increase in serum creatinine concentration throughout the episode of febrile neutropenia relative to the baseline serum creatinine concentration. Efficacy was a secondary outcome and was defined as survival of the episode without modification of the antibacterial regimen. All statistical tests were two-sided.

RESULTS

In a modified intent-to-treat analysis, the mean maximal percent increase in serum creatinine concentration was 32% (N = 26) in the once daily dose group and 51% (N = 28) in the every 8 hours dose group (difference = 19%, 95% confidence interval [CI] = 0% to 38%; P =.054). Among patients evaluable for efficacy, 12 (46%) of 26 patients in the once daily dose group and five (19%) of 27 patients in the every 8 hours dose group survived the episode of febrile neutropenia without requiring antibacterial treatment modification (difference = 27%, 95% CI = 4% to 52%; P =.03). There was one death in each group.

CONCLUSIONS

In febrile neutropenic children undergoing stem cell transplantation, tobramycin may be less nephrotoxic and more efficacious when administered as a once daily dose than when administered every 8 hours.

Selecting antibacterials for outpatient parenteral antimicrobial therapy : pharmacokinetic-pharmacodynamic considerations

Some infectious diseases require management with parenteral therapy, although the patient may not need hospitalisation. Consequently, the administration of intravenous antimicrobials in a home or infusion clinic setting has now become commonplace. Outpatient parenteral antimicrobial therapy (OPAT) is considered safe, therapeutically effective and economical. A broad range of infections can be successfully managed with OPAT, although this form of treatment is unnecessary when oral therapy can be used. Many antimicrobials can be employed for OPAT and the choice of agent(s) and regimen should be based upon sound clinical and microbiological evidence. Assessments of cost and convenience should be made subsequent to these primary treatment outcome determinants. When designing an OPAT treatment regimen, the pharmacokinetic and pharmacodynamic characteristics of the individual agents should also be considered. Pharmacokinetics (PK) is the study of the time course of absorption, distribution, metabolism and elimination of drugs (what the body does to the drug). Clinical pharmacokinetic monitoring has been used to overcome the pharmacokinetic variability of antimicrobials and enable individualised dosing regimens that attain desirable antimicrobial serum concentrations. Pharmacodynamics (PD) is the study of the relationship between the serum concentration of a drug and the clinical response observed in a patient (what the drug does to the body). By combining pharmacokinetic properties (peak [C(max)] or trough [C(min)] serum concentrations, half-life, area under the curve) and pharmacodynamic properties (susceptibility results, minimum inhibitory concentrations [MIC] or minimum bactericidal concentrations [MBC], bactericidal or bacteriostatic killing, post-antibiotic effects), unique PK/PD parameters or indices (t > MIC, C(max)/MIC, AUC(24)/MIC) can be defined. Depending on the killing characteristics of a given class of antimicrobials (concentration-dependent or time-dependent), specific PK/PD parameters may predict in vitro bacterial eradication rates and correlate with in vivo microbiologic and clinical cures. An understanding of these principles will enable the clinician to vary dosing schemes and design individualised dosing regimens to achieve optimal PK/PD parameters and potentially improve patient outcomes. This paper will review basic principles of useful PK/PD parameters for various classes of antimicrobials as they may relate to OPAT. In summary, OPAT has become an important treatment option for the management of infectious diseases in the community setting. To optimise treatment course outcomes, pharmacokinetic and pharmacodynamic properties of the individual agents should be carefully considered when designing OPAT treatment regimens.

Critical issues in nephrology

Renal and electrolyte problems are common in patients in the ICU. Several advances that occurred in the recent past have been incorporated in the diagnosis and management of these disorders and were reviewed in this article. Unfortunately, many important questions remain unanswered, especially in the area of ARF, where new therapies are anxiously awaited to make the transition from bench to bedside. Better studies are sorely needed to define the best approach to dialysis in patients who have ARF.

Pharmacodynamics and dosing of aminoglycosides

Aminoglycosides are concentration-dependent killing agents whose pharmacodynamic predictors of efficacy are the area-under-the-curve to minimum inhibitory concentration ratio and the peak to minimum inhibitory concentration ratio. Prospective studies have shown that these agents can be given once-daily or less frequently in most clinical settings, with equal efficacy and possible reduced toxicity. Dosages for different clinical settings have been studied and methods are available to monitor once-daily dosing.

The current management strategies for community-acquired urinary tract infection

Acute uncomplicated UTI is one of the most common problems for which young women seek medical attention and accounts for considerable morbidity and health care costs. Acute cystitis or pyelonephritis in the adult patient should be considered uncomplicated if the patient is not pregnant or elderly, if there has been no recent instrumentation or antimicrobial treatment, and if there are no known functional or anatomic abnormalities of the genitourinary tract. Most of these infections are caused by E. coli, which are susceptible to many oral antimicrobials, although resistance is increasing to some of the commonly used agents, especially TMP-SMX. In women with risk factors for infection with resistant bacteria, or in the setting of a high prevalence of TMP-SMX-resistant uropathogens, a case can be made for using a fluoroquinolone or nitrofurantoin. Use of nitrofurantoin for the empiric treatment of mild cystitis is supportable from a public health perspective in an attempt to decrease uropathogen resistance because it does not share cross-resistance with more commonly prescribed antimicrobials. Beta-lactams and fosfomycin should be considered second-line agents for empiric treatment of cystitis. Acute pyelonephritis in an otherwise healthy woman may be considered an uncomplicated infection. Fluoroquinolone regimens are superior to TMP-SMX for empiric therapy because of the relatively high prevalence of TMP-SMX resistance among uropathogens causing pyelonephritis. TMP-SMX, effective for patients with mild to moderate disease, is an appropriate drug if the uropathogen is known to be susceptible. It is reasonable to use a 7- to 10-day oral fluoroquinolone regimen for outpatient management of mild to moderate pyelonephritis in the setting of a susceptible causative pathogen and rapid clinical response to therapy. Most women with acute uncomplicated pyelonephritis are now managed safely and effectively as outpatients. Acute uncomplicated cystitis or pyelonephritis in healthy adult men is very uncommon but is generally caused by the same spectrum of uropathogens with the same antimicrobial susceptibility profile as that seen in women. The choice of antimicrobials is similar to that recommended for cystitis in women except that nitrofurantoin is not considered a good choice. Treatment duration should generally be longer than that recommended for women.

The effect of vecuronium is enhanced by a large rather than a modest dose of gentamicin as compared with no preoperative gentamicin

We compared the effect of two doses of gentamicin versus no gentamicin (NG) given before surgery on the neuromuscular relaxant effect of vecuronium. Seventy patients (intraabdominal procedures) were randomly allocated to receive preoperative large-dose (4 mg/kg) gentamicin (LD), a modest dose (1.2 mg/kg) of gentamicin (MD), or NG. No more than one dose of gentamicin was given before the vecuronium administration. Serum gentamicin levels, the time for 25% recovery of the first twitch in the train-of-four after a bolus of vecuronium, and the time from cessation of the vecuronium infusion to extubation of the trachea were estimated. Serum gentamicin levels were higher (P < 0.001) for LD than MD. The time for 25% recovery of the first twitch after the vecuronium bolus was slightly longer with LD than MD (P = 0.06) and longer in LD than NG (P = 0.001) (42.9 +/- 23.6 min versus 36.2 +/- 17 min and 27.4 +/- 9 min, respectively). The time to extubation was similar with LD and MD and longer for LD than NG (P = 0.008) (34.7 +/- 19.2 min versus 27.4 +/- 19.3 min and 19.4 +/- 10.1 min, respectively). The differences in these times were insignificant between MD and NG. Gentamicin administered as a LD rather than MD enhanced the neuromuscular blockade of vecuronium as compared with NG given before surgery.

IMPLICATIONS

We demonstrated that the neuromuscular relaxant effect of vecuronium is enhanced by a large (4 mg/kg) rather than a modest (1.2 mg/kg) dose of gentamicin as compared with no gentamicin given before surgery.

Antibiotic safety assessment

Antibiotics usually have positive risk-benefit ratios, their adverse effects being generally mild and reversible on treatment cessation. However, severe adverse drug reactions (ADR), associated with significant mortality and morbidity have resulted in the withdrawal of several active antibiotics, including new fluoroquinolones. Adverse reactions to antibiotics are often poorly documented. The purpose of this article is to examine current tools for investigating and preventing antibiotic toxicity and to suggest future lines of investigation. Structure/ADR relationships have been investigated with various antibiotics (beta-lactams, macrolides, quinolones, etc.) in an attempt to reduce the risk of adverse reactions. Some reactions can be linked to the drug's stereochemical composition. In the case of quinolones for instance, particularly ofloxacin and its derivatives, experimental data show that individual enantiomers have different toxicities. Another major factor that influences the risk of ADRs in a given population is metabolic variability, due to genetic differences in the relevant drug-metabolizing enzymes. Idiosyncratic antibiotic toxicity can be caused by a chemically reactive metabolite. Recent advances in molecular biology, and especially in individual genomic characterization (DNA chip technology, etc.), could in future be useful for identifying patients who are at a special risk of ADR. Finally, certain pharmacokinetic parameters (AUC, Cmax, etc.) can be used to predict adverse effects.