Pharmacokinetics of ampicillin and sulbactam in pediatric patients

Prediction of Tissue Exposures of Meropenem, Colistin, and Sulbactam in Pediatrics Using Physiologically Based Pharmacokinetic Modeling

BACKGROUND

The combination of polymyxins, meropenem, and sulbactam demonstrated efficacy against multi-drug-resistant bacillus Acinetobacter baumannii. These three antibiotics are commonly used against major blood, skin, lung, and heart muscle infections.

OBJECTIVE

The objective of this study was to predict drug disposition and extrapolate the efficacy in these tissues using a physiologically based pharmacokinetic modeling approach that linked drug exposures to their target pharmacodynamic indices associated with antimicrobial activities against A. baumannii.

METHODS

An adult physiologically based pharmacokinetic model was developed for meropenem, colistin, and sulbactam and scaled to pediatrics accounting for both renal and non-renal clearances. The model reliability was evaluated by comparing simulated plasma and tissue drug exposures to observed data. Target pharmacodynamic indices were used to evaluate whether pediatric and adult dosing regimens provided sufficient coverage.

RESULTS

The modeled plasma drug exposures in adults and pediatric patients were consistent with reported literature data. The mean fold errors for meropenem, colistin, and sulbactam were in the range of 0.710-1.37, 0.981-1.47, and 0.647-1.39, respectively. Simulated exposures in the blood, skin, lung, and heart were consistent with reported penetration rates. In a virtual pediatric population aged from 2 to < 18 years, the interpretive breakpoints were achieved in 85-90% of subjects for their targeted pharmacodynamic indices after administration of pediatric dosing regimens consisting of 30 mg/kg of meropenem, and 40 mg/kg of sulbactam three times daily as a 3-h or continuous infusion and 5 mg/kg/day of colistin base activity.

CONCLUSIONS

The physiologically based pharmacokinetic modeling supports pediatric dosing regimens of meropenem/colistin/sulbactam in a co-administration setting against infections in the blood, lung, skin, and heart tissues due to A. baumannii.

A green approach to the analysis of co-administered ampicillin/sulbactam and paracetamol in human urine

The novelty of this work is the simultaneous analysis of sulbactam (SUL), ampicillin (AMP), and paracetamol (PARA) in human urine samples, using the environmentally benign RP-HPLC method. A C18 column was used in chromatographic separation using potassium dihydrogen phosphate (10 mmol L^-1, pH 5)/ethanol (90 %, V/V) as the mobile phase; flow rate was 1.00 mL min^-1. UV detection at 220 nm was used for quantification. The proposed method showed good linearity in the concentration ranges of 2.20-250.00 μg mL^-1 for SUL, 2.50-250.00 μg mL^-1 for PARA, and 14.50-250.00 μg mL^-1 for AMP. Direct injection of urine samples with no prior extraction was performed. This method was found successful in moving towards greener studies of drugs' urinary excretion, by decreasing hazardous solvent consumption and waste. Moreover, the method was applied to investigate the urinary excretion of the drugs and possible interaction between ampicillin and paracetamol.

Pharmacodynamic Evaluation of Ampicillin-sulbactam in Pediatric Patients Using Plasma and Urine Data

BACKGROUND

We aimed to develop population pharmacokinetic (PK) models of ampicillin and sulbactam using pooled data analysis and to optimize dosing regimens of ampicillin-sulbactam (combination ratio of 2:1) in pediatric patients.

METHODS

Population PK models of ampicillin and sulbactam were separately developed by simultaneously fitting plasma and urine data from pediatric patients in 14 published studies. Based on these models, we estimated the probability of attaining a pharmacodynamic (PD) target [50% of time that free drug concentrations above the minimum inhibitory concentration, 50% fT > minimum inhibitory concentration (MIC)] against MIC90 [MIC that blocked the growth of 90% of the strains] of common bacteria in community-acquired pneumonia.

RESULTS

The analysis included 54 pediatric patients (0.083-16.42 years of age, 4.0-77.0 kg of body weight). A total of 284 plasma concentrations and 90 urinary excretions from 0 to 6 hours after administration were used for population PK modeling. The data were adequately described by 2-compartment models for ampicillin and sulbactam. Age was not a statistically significant covariate in the PK of either drug. The PK/PD breakpoint MICs for 45 mg/kg 3 times daily and 75 mg/kg 4 times daily (q.i.d.) were 0.25 and 1 μg/mL, respectively. For empiric therapy of community-acquired pneumonia, because MIC90 values for the main target pathogens is high (MIC90 = 2 μg/mL for Streptococcus pneumoniae and MIC90 = 4 μg/mL for Haemophilus influenzae), 75 mg/kg q.i.d. (Food and Drug Administration-approved maximum dosage in United States) might be better than 45 mg/kg 3 times daily (within approved dosage in Japan) to cover many pathogens.

CONCLUSIONS

From the results of this PK/PD approach, 75 mg/kg q.i.d. (Food and Drug Administration-approved maximum dosage) should be recommended in the empiric therapy of community-acquired pneumonia.

Simultaneous pharmacokinetic/pharmacodynamic (PKPD) assessment of ampicillin and gentamicin in the treatment of neonatal sepsis

Objectives

This study aimed to simultaneously investigate the pharmacokinetics of ampicillin and gentamicin, currently the WHO standard of care for treating neonatal sepsis.

Methods

Pharmacokinetic data were collected in 59 neonates receiving ampicillin and gentamicin for suspected or proven sepsis in the NeoFosfo trial (NCT03453177). A panel of 23 clinical Escherichia coli isolates from neonates with sepsis, resistant to either ampicillin, gentamicin or both, were tested for susceptibility using chequerboards. Pharmacokinetic/pharmacodynamic (PKPD) modelling and simulations were used to compare single-agent (EUCAST MIC) and combination (chequerboard MIC) target attainment with standard dosing regimens.

Results

A model was established that simultaneously estimated parameters of a one-compartment ampicillin model and a two-compartment gentamicin model. A common clearance for both drugs was used (6.89 L/h/70 kg) relating to glomerular filtration (CL_GFR), with an additional clearance term added for ampicillin (5.3 L/h/70 kg). Covariate modelling included a priori allometric weight and post-menstrual age scaling of clearance. Further covariate relationships on renal clearance were postnatal age and serum creatinine.

Simulation-based PKPD assessments suggest good Gram-positive (MIC ≤ 0.25 mg/L) cover. However, less than one-quarter of neonates were predicted to receive efficacious coverage against Enterobacterales (MIC ≤ 2 mg/L). The benefit of the ampicillin/gentamicin combination was limited, with only 2/23 E. coli clinical strains showing FIC index < 0.5 (synergy) and most in the range 0.5–1 (suggesting additivity). Simulations showed that feasible dosing strategies would be insufficient to cover resistant strains.

Conclusions

PKPD simulations showed ampicillin and gentamicin combination therapy was insufficient to cover Enterobacterales, suggesting the need for alternative empirical treatment options for neonatal sepsis.

Glutamine promotes antibiotic uptake to kill multidrug-resistant uropathogenic bacteria

[Figure: see text].

Oral Flora and Perioperative Antimicrobial Interventions in Cleft Palate Surgery: A Review of the Literature

BACKGROUND

The role of perioperative antibiotics in cleft palate remains a topic of debate. Advocates stress their importance in preventing local and systemic infections and decreasing the incidence of oronasal fistula formation. However, few studies to date have directly evaluated the role of antibiotics and other antimicrobial measures in cleft palate surgery.

OBJECTIVE

The aim of this review is to evaluate the evidence surrounding the use of perioperative antibiotics and other antimicrobial interventions in cleft palate surgery. Additionally, we review the literature on the oral flora unique to the cleft palate patient population.

METHODS

This was accomplished utilizing PubMed, Medline, and the Cochrane Library with MeSH and generic terms. Articles were selected based on predefined inclusion and exclusion criteria.

RESULTS

This review highlights the lack of higher level evidence on perioperative antibiotic use and other antimicrobial interventions in cleft palatoplasty and calls for further research on the matter.

CONCLUSIONS

The literature appears to support the use of preoperative antibiotics for cleft palatoplasty, but the benefits of prolonged postoperative antibiotic use remain questionable.

Applying Pharmacodynamics and Antimicrobial Stewardship to Pediatric Preseptal and Orbital Cellulitis

Orbital and preseptal cellulitis are most commonly caused by organisms that originate in the upper respiratory tract or from the skin. There is significant variation in antibiotics used, but ampicillin-sulbactam, ceftriaxone, metronidazole, clindamycin, amoxicillin, amoxicillin-clavulanate, cefuroxime, and vancomycin are often used in the treatment of these infections. The choice of antibiotic, however, is only one consideration. It is also important that antibiotics are dosed to optimize their pharmacodynamic target attainment. Like other serious infections, therapy can be transitioned from initial intravenous therapy to an oral regimen when there are clear signs of clinical and laboratory improvement. The total duration of therapy for these infections have also been decreasing in recent years with durations of approximately 2 weeks becoming more common, even for orbital or subperiosteal infections. Antimicrobial stewardship programs can work closely with providers who manage these infections to create pathways, choose optimal antibiotics and dosage, transition from intravenous to oral therapy, and provide shortest effective durations.

Management of Pediatric Acute Hematogenous Osteomyelitis, Part I: Antimicrobial Stewardship Approach and Review of Therapies for Methicillin-Susceptible Staphylococcus aureus, Streptococcus pyogenes, and Kingella kingae

Acute hematogenous osteomyelitis (AHO), often occurring in young children, is the most frequently diagnosed type of osteomyelitis in pediatric patients. Optimizing antibiotics is essential as delays to receipt of appropriate therapy can lead to chronic osteomyelitis, as well as impairments in bone growth and development. Antimicrobial stewardship programs (ASPs) are in a key position to help improve the care of patients with AHO as they contain a pharmacist with expertise in antibiotic drug selection, optimization of dosing, and microbiologic test review. A literature search of the MEDLINE database was conducted from initiation through January 2018. Articles selected for the review focus on pathogen identification, pharmacokinetics and pharmacodynamics, efficacy and safety in children, transition from intravenous to oral therapy, duration of treatment, and antimicrobial stewardship interventions. This review will highlight the potential roles ASPs can have in improving the management of AHO in pediatric patients. These roles include the creation of clinical pathways, improving testing algorithms, antibiotic choice and dosing, intravenous to oral transitions, duration of treatment, and therapy monitoring. Overall, patients are most effectively treated by focusing treatments on age, presentation, local sensitivities, and directed therapy with pathogen identification.

A reagentless and reusable electrochemical aptamer-based sensor for rapid detection of ampicillin in complex samples

We report the design and fabrication of a "signal-on" electrochemical aptamer-based (E-AB) sensor for detection of ampicillin. The signaling of the sensor is based on target binding-induced changes in the conformation and flexibility of the methylene blue-modified aptamer probe. The sensor's response is fast; signal saturation can be reached in ~ 200s. Since all the sensor components are surface-immobilized, it is regenerable and can be reused for at least three times. It has demonstrated good specificity and is capable of differentiating between ampicillin and structurally similar antibiotics such as amoxicillin. More importantly, it is selective enough to be employed directly in complex samples, including serum, saliva, and milk. Although both alternating current voltammetry (ACV) and square wave voltammetry (SWV) are suitable sensor characterization techniques, our results show that ACV is better suited for target analysis. Even under the optimal experimental conditions, the limit of detection of the sensor obtained in ACV (1µM) is significantly lower than that obtained in SWV (30µM).

Adsorption and release of ampicillin antibiotic from ordered mesoporous silica

In this work the adsorption and the release of ampicillin - a β-lactam penicillin-like antibiotic - from MCM-41, SBA-15, and (amino functionalized) SBA-15-NH₂ ordered mesoporous silica (OMS) materials were investigated. The silica matrices differ for their pore size (SBA-15 vs. MCM-41) mainly, and also for surface charge (SBA-15 and MCM-41, vs. SBA-15-NH₂). OMS samples were characterized through small-angle X-rays scattering (SAXS), transmission electron microscopy (TEM), N₂ adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and potentiometric titrations. The quantification of immobilized and released ampicillin was monitored by mean of UV-Vis spectroscopy. Experimental adsorption isotherms evidenced that ampicillin's loading is not related to the pore size (d_BJH) of the adsorbent. Indeed the maximal loadings were 237mg/g for SBA-15 (d_BJH=6.5nm), 278mg/g for MCM-41 (d_BJH=2.2nm), and 333mg/g for SBA-15-NH₂ (d_BJH=5.6nm). Loading seems, instead, to be related to the surface charge density (σ) of the sorbent surface. Indeed, at pH 7.4 ampicillin drug is negatively charged and likely prefers to interact with SBA-15-NH₂ (σ_SBA-15-NH2=+0.223Cm^-2) rather than the slightly negatively charged silicas (σ_SBA-15=-0.044Cm^-2 and σ_MCM-41=-0.033Cm^-2). Similarly, ampicillin release is affected by interfacial interactions. Indeed, we found a burst release from pure silica samples (SBA-15 and MCM-41), whereas a sustained one from SBA-15-NH₂ sample. We explain this behavior as a result of an attractive interaction between the protonated amino group of SBA-15-NH₂ and the negatively charged carboxylate group of ampicillin. In summary, in order to obtain a sustained drug release, the chemical nature of the matrix's surface plays a role which is more important than its textural features. SBA-15-NH₂ matrix is hence a suitable candidate for local sustained release of antibiotic drugs.

A 30-years review on pharmacokinetics of antibiotics: is the right time for pharmacogenetics?

Drug bioavailability may vary greatly amongst individuals, affecting both efficacy and toxicity: in humans, genetic variations account for a relevant proportion of such variability. In the last decade the use of pharmacogenetics in clinical practice, as a tool to individualize treatment, has shown a different degree of diffusion in various clinical fields.

In the field of infectious diseases, several studies identified a great number of associations between host genetic polymor-phisms and responses to antiretroviral therapy. For example, in patients treated with abacavir the screening for HLA-B*5701 before starting treatment is routine clinical practice and standard of care for all patients; efavirenz plasma levels are influenced by single nucleotide polymorphism (SNP) CYP2B6-516G> T (rs3745274). Regarding antibiotics, many studies investigated drug transporters involved in antibiotic bioavailability, especially for fluoroquinolones, cephalosporins, and antituberculars. To date, few data are available about pharmacogenetics of recently developed antibiotics such as tigecycline, daptomycin or linezolid. Considering the effect of SNPs in gene coding for proteins involved in antibiotics bioavailability, few data have been published.

Increasing knowledge in the field of antibiotic pharmacogenetics could be useful to explain the high drug inter-patients variability and to individualize therapy. In this paper we reported an overview of pharmacokinetics, pharmacodynamics, and pharmacogenetics of antibiotics to underline the importance of an integrated approach in choosing the right dosage in clinical practice.

Characterization of the population pharmacokinetics of ampicillin in neonates using an opportunistic study design

Although ampicillin is the most commonly used drug in neonates, developmental pharmacokinetic (PK) data to guide dosing are lacking. Ampicillin is primarily renally eliminated, and developmental changes are expected to influence PK. We conducted an open-label, multicenter, opportunistic, prospective PK study of ampicillin in neonates stratified by gestational age (GA) (≤ 34 or >34 weeks) and postnatal age (PNA) (≤ 7 or >7 days). Drug concentrations were measured by tandem mass spectrometry. PK data were analyzed using population nonlinear mixed-effects modeling in NONMEM 7.2. Monte Carlo simulations were conducted to determine the probability of target attainment for the time in which the total steady-state ampicillin concentrations remained above the MIC (T>MIC) for 50%, 75%, and 100% of the dosing interval. A total of 142 PK samples from 73 neonates were analyzed (median [range] GA, 36 [24 to 41] weeks; PNA, 5 [0 to 25] days). The median ampicillin dose was 200 (100 to 350) mg/kg/day. Postmenstrual age and serum creatinine were covariates for ampicillin clearance (CL). A simplified dosing regimen of 50 mg/kg every 12 h for GA of ≤ 34 weeks and PNA of ≤ 7 days, 75 mg/kg every 12 h for GA of ≤ 34 weeks and PNA of ≥ 8 and ≤ 28 days, and 50 mg/kg every 8 h for GA of >34 weeks and PNA of ≤ 28 days achieved the prespecified surrogate efficacy target in 90% of simulated subjects. Ampicillin CL was associated with neonatal development. A simplified dosing regimen stratified by GA and PNA achieves the desired surrogate therapeutic target in the vast majority of neonates.

Ampicillin/sulbactam: its potential use in treating infections in critically ill patients

The purpose of this paper was to review the potential utility of ampicillin/sulbactam (SAM) as a therapy for serious infections in critically ill patients. Data for this review were identified by searches of PubMed and of the reference lists of the included articles. We found that SAM appears to have a number of characteristics that support its use in the treatment of serious infections in critically ill patients. SAM demonstrates extensive penetration into many infection sites, supporting its use in a wide range of infection types. Microbiologically, sulbactam has strong intrinsic antibiotic activity against multidrug-resistant (MDR) bacteria, including Acinetobacter baumannii, which supports its use for the treatment of infections mediated by this pathogen. Of some concern, there have been reports showing a decline in susceptibility of some bacteria to SAM. As such, use of lower doses (4/2g/day), particularly for MDR A. baumannii, has been linked with a 30% reduced success rate in critically ill patients. The therapeutic challenges for ensuring achievement of optimal dosing of SAM result partly from bacterial susceptibility but also from the pharmacokinetic (PK) alterations common to β-lactam agents in critical illness. These PK changes are likely to reduce the ability of standard dosing to achieve the concentrations observed in non-critically ill patients. Optimisation of therapy may be more likely with the use of higher doses, administration by 4h infusion or by combination therapy, particularly for the treatment of infections caused by MDR pathogens.

Ampicillin-sulbactam: an update on the use of parenteral and oral forms in bacterial infections

Ampicillin-sulbactam has a wide range of antibacterial activity that includes Gram-positive and Gram-negative aerobic and anaerobic bacteria. However, the drug is not active against Pseudomonas aeruginosa and pathogens producing extended-spectrum beta-lactamases. The combination could be considered particularly active against Acinetobacter baumannii infections due to the intrinsic activity of sulbactam. The drug is indicated as empirical therapy for a broad range of community acquired infections supervened in adults or children and is effective in either parenteral (ampicillin-sulbactam) or oral (as a mutual prodrug sultamicillin) form. In clinical trials, sultamicillin has proved clinically and bacteriologically effective in adults and children against a variety of frequently encountered infections, including mild upper and lower respiratory tract infections, urinary tract infections, diabetic foot and skin and soft tissue infections. Furthermore, adverse effects rarely occur with the diarrhoea to represent the most commonly reported. The parenteral ampicillin-sulbactam is indicated for community infections of mild-to-moderate severity acquired infections such as intra-abdominal or gynecological. Moreover, it seems to represent the alternative of choice for the treatment of A. baumannii infections for carbapenem-resistant strains in the nosocomial setting. Thus, ampicillin-sulbactam remains a valuable agent in the physician's armamentarium in the management of adult and pediatric infections.

Rational antibiotic therapy and the position of ampicillin/sulbactam

In the current context of increasing antimicrobial resistance, it is important to use antibiotics rationally and to re-assess regularly the clinical usefulness of commonly used agents. This review focuses on the efficacy of the beta-lactam ampicillin co-administered with the beta-lactamase inhibitor sulbactam, either parenterally (ampicillin/sulbactam) or orally (sultamicillin), for the treatment of bacterial infections. Clinical findings from the past decade confirm the results of numerous older studies and together provide good evidence to support the continued use of ampicillin/sulbactam and sultamicillin in hospital- and community-acquired infections both in adults and children. This is also recognised in recent published national and international guidelines, many of which recommend ampicillin/sulbactam as first-line therapy for various respiratory and skin infections.

Staphylococcal skin infections in children: rational drug therapy recommendations

Staphylococcus aureus remains one of the most common and troublesome of bacteria causing disease in humans, despite the development of effective antibacterials and improvement in hygiene. The organism is responsible for over 70% of all skin and soft tissue infections in children and accounts for up to one-fifth of all visits to pediatric clinics. Skin and soft tissue infections that are predominantly caused by S. aureus include bullous and non-bullous impetigo, folliculitis, furunculosis, carbunculosis, cellulitis, surgical and traumatic wound infections, mastitis, and neonatal omphalitis. Other skin and soft tissue infections may also be caused by S. aureus but are often polymicrobial in origin and require special consideration. These include burns, decubitus ulcers (particularly in the perianal region), puncture wounds of the foot, as well as human and mammalian bites. Treatment of staphylococcal skin infections varies from topical antiseptics to prolonged intravenous antibacterials, depending on severity of the lesions and the health of the child. The treatment of choice for oral antibacterials remains the penicillinase-resistant penicillins such as flucloxacillin. Cefalexin and erythromycin are suitable cost-effective alternatives with broader cover, although care must be taken with the use of macrolides because of development of resistance to multiple families of antibacterials, particularly the lincosamides. Other cephalosporins such as cefadroxil and cefprozil are also effective, can be given once daily and have a better tolerability profile -- while azithromycin has a further advantage of a 3-day course. However, all of these agents are more expensive. Although the antibacterials have been given for 10 days in most clinical trials, there is no evidence that this duration is more effective than a 7-day course. In children requiring intravenous therapy, ceftriaxone has a major advantage over other antibacterials such as sulbactam/ampicillin and cefuroxime in that it can be given once daily and may, therefore, be suitable for outpatient treatment of moderate-to-severe skin infections. Newer-generation cephalosporins and loracarbef are also effective and have a broader spectrum of activity, but do not offer any added benefit and are significantly more expensive. Skin and soft tissue infections due to methicillin-resistant S. aureus (MRSA) are still relatively uncommon in children. Well children with community-acquired MRSA infections can be treated with clindamycin or trimethoprim-sulfamethoxazole (cotrimoxazole), but must be observed closely for potentially severe adverse effects. In severe infections, vancomycin remains the treatment of choice, while intravenous teicoplanin and clindamycin are suitable alternatives. Linezolid and quinupristin/dalfopristin are currently showing great promise for the treatment of multi-resistant Gram-positive infections. While the choice of antibacterial is important, supportive management, including removal of any infected foreign bodies, surgical drainage of walled-off lesions, and regular wound cleaning, play a vital role in ensuring cure.

Drug dosing during intermittent hemodialysis and continuous renal replacement therapy : special considerations in pediatric patients

Chronic renal failure is, fortunately, an unusual occurrence in children; however, many children with various underlying illnesses develop acute renal failure, and transiently require renal replacement therapy - peritoneal dialysis, intermittent hemodialysis (IHD), or continuous renal replacement therapy (CRRT). As children with acute and chronic renal failure often have multiple comorbid conditions requiring drug therapy, generalists, intensivists, nephrologists, and pharmacists need to be aware of the issues surrounding the management of drug therapy in pediatric patients undergoing renal replacement therapy. This article summarizes the pharmacokinetics and dosing of many drugs commonly prescribed for pediatric patients, and focuses on the management of drug therapy in pediatric patients undergoing IHD and CRRT in the intensive care unit setting. Peritoneal dialysis is not considered in this review. Finally, a summary table with recommended initial dosages for drugs commonly encountered in pediatric patients requiring IHD or CRRT is presented.

Ampicillin and penicillin concentration in serum and pleural fluid of hospitalized children with community-acquired pneumonia

BACKGROUND

Optimal therapeutic efficacy of beta-lactam antibiotics for treatment of pneumococcal pneumonia is thought to be associated with the serum concentration greater than the minimum inhibitory concentration for 40-50% of the interdose interval at site of infection.

OBJECTIVE

Establish whether intravenous administration of ampicillin 400 mg/kg/day or penicillin 200,000 IU/kg/day in 6 divided doses reaches serum and or pleural concentrations above 4 microg/ml for at least 40% of the interdose interval.

MATERIALS AND METHODS

Hospitalized healthy children 1 month-14 years old with community-acquired bacterial pneumonia and empyema were eligible. Blood samples were obtained 30 min (C1) and 3 h (C2) after an antibiotic dose. Pleural fluid samples were obtained 1 and 4 h after the same dose in which blood samples were obtained. The concentrations were measured by high performance liquid chromatography.

RESULTS

The study included 17 patients treated with ampicillin and 13 treated with penicillin. For ampicillin, mean serum concentrations were C1 37.3 +/- 19 microg/ml and C2 11 +/- 10.2 microg/ml and mean pleural fluid concentrations were C1 25.8 +/- 9.9 microg/ml and C2 16.2 +/- 7.9 microg/ml. For penicillin, mean serum concentrations were C1 21.8 +/- 16.4 microg/ml and C2 23.9 +/- 3.4 microg/ml. Mean pleural fluid concentrations were C1 10.9 +/- 2.2 microg/ml and C2 7.7 +/- 3.4 microg/ml. In 8 of 30 patients, serum C2 was <4 microg/ml; in all of them serum concentrations were >4 microg/ml for >40% of the interdose interval.

CONCLUSIONS

This study of the pharmacokinetics of beta-lactam antibiotics in children with bacterial pneumonia may help in the development of therapeutic guidelines for the treatment of pneumococcal pneumonia.

Commonly used antibacterial and antifungal agents for hospitalised paediatric patients: implications for therapy with an emphasis on clinical pharmacokinetics

Due to normal growth and development, hospitalised paediatric patients with infection require unique consideration of immune function and drug disposition. Specifically, antibacterial and antifungal pharmacokinetics are influenced by volume of distribution, drug binding and elimination, which are a reflection of changing extracellular fluid volume, quantity and quality of plasma proteins, and renal and hepatic function. However, there is a paucity of data in paediatric patients addressing these issues and many empiric treatment practices are based on adult data. The penicillins and cephalosporins continue to be a mainstay of therapy because of their broad spectrum of activity, clinical efficacy and favourable tolerability profile. These antibacterials rapidly reach peak serum concentrations and readily diffuse into body tissues. Good penetration into the cerebrospinal fluid (CSF) has made the third-generation cephalosporins the agents of choice for the treatment of bacterial meningitis. These drugs are excreted primarily by the kidney. The carbapenems are broad-spectrum beta-lactam antibacterials which can potentially replace combination regimens. Vancomycin is a glycopeptide antibacterial with gram-positive activity useful for the treatment of resistant infections, or for those patients allergic to penicillins and cephalosporins. Volume of distribution is affected by age, gender, and bodyweight. It diffuses well across serous membranes and inflamed meninges. Vancomycin is excreted by the kidneys and is not removed by dialysis. The aminoglycosides continue to serve a useful role in the treatment of gram-negative, enterococcal and mycobacterial infections. Their volume of distribution approximates extracellular space. These drugs are also excreted renally and are removed by haemodialysis. Passage across the blood-brain barrier is poor, even in the face of meningeal inflammation. Low pH found in abscess conditions impairs function. Toxicity needs to be considered. Macrolide antibacterials are frequently used in the treatment of respiratory infections. Parenteral erythromycin can cause phlebitis, which limits its use. Parenteral azithromycin is better tolerated but paediatric pharmacokinetic data are lacking. Clindamycin is frequently used when anaerobic infections are suspected. Good oral absorption makes it a good choice for step-down therapy in intra-abdominal and skeletal infections. The use of quinolones in paediatrics has been restricted and most information available is in cystic fibrosis patients. High oral bioavailability is also important for step-down therapy. Amphotericin B has been the cornerstone of antifungal treatment in hospitalised patients. Its metabolism is poorly understood. The half-life increases with time and can be as long as 15 days after prolonged therapy. Oral absorption is poor. The azole antifungals are being used increasingly. Fluconazole is well tolerated, with high bioavailability and good penetration into the CSF. Itraconazole has greater activity against aspergillus, blastomycosis, histoplasmosis and sporotrichosis, although it's pharmacological and toxicity profiles are not as favourable.

Use of ampicillin/sulbactam and sultamicillin in pediatric infections: a re-evaluation

Ampicillin/sulbactam is an effective solution to the emergence of beta-lactamase-mediated resistance among common pediatric pathogens, and is a widely recognized treatment option for a variety of pediatric infections. Recent antimicrobial surveillance data confirm the continued susceptibility of many Gram-positive and Gram-negative aerobes and anaerobes to ampicillin/sulbactam. Pharmacokinetic studies have demonstrated high drug concentrations at a variety of infection sites, including cerebrospinal fluid and bone. Furthermore, clinical studies have shown that ampicillin/sulbactam, administered intravenously, intramuscularly or orally (as the mutual prodrug sultamicillin), is clinically and bacteriologically effective against upper and lower respiratory tract infections, urinary tract infections, skin, bone and soft-tissue infections, and meningitis, and provides effective surgical prophylaxis. Sultamicillin has an excellent tolerability profile, which is associated with a low rate of treatment discontinuation. Accordingly, ampicillin/sulbactam and sultamicillin should be considered first-choice options for the management of a variety of pediatric infections.