Chloramphenicol toxicity in neonates: its incidence and prevention

A facile electrochemical aptasensor for chloramphenicol detection based on synergistically photosensitization enhanced by SYBR Green I and MoS2

This study reports the development of a photocatalytic electrochemical aptasensor for the purpose of detecting chloramphenicol (CAP) antibiotic residues in water by utilizing SYBR Green I (SG) and chemically exfoliated MoS2 (ce-MoS2) as synergistically signal-amplification platforms. The Au nanoparticles (AuNPs) were electrodeposited onto the surface of an indium tin oxide (ITO) electrode. After that, the thiolate-modified cDNA, also known as capture DNA, was combined with the aptamer. Subsequently, photosensitized SG molecules and ce-MoS2 nanomaterial were inserted into the groove of the resultant double-stranded DNA (dsDNA). The activation of the photocatalytic process upon exposure to light resulted in the generation of singlet oxygen. The singlet oxygen effectively split the dsDNA, resulting in significant enhancement in the current of [Fe(CN)6]3-/4-. When the CAP was present, both SG molecules and ce-MoS2 broke away from the dsDNA, which turned off the photosensitization response, leading to significant reduction in the current of [Fe(CN)6]3-/4-. Under the optimal conditions, the aptasensor exhibited a linear relationship between the current of [Fe(CN)6]3-/4- with logarithmic concentrations of CAP from 20 to 1000 nM, with a detection of limit (3σ) of 3.391 nM. The aptasensor also demonstrated good selectivity towards CAP in the presence of interfering antibiotics, such as tetracycline, streptomycin, levofloxacin, ciprofloxacin, and sulfadimethoxine. Additionally, the results obtained from the analysis of natural water samples using the proposed aptasensor were consistent with the findings acquired through the use of a liquid chromatograph-mass spectrometer. Therefore, with its simplicity and high selectivity, this aptasensor can potentially detect alternative antibiotics in environmental water samples by replacing the aptamers based on photosensitization.

Topical Chloramphenicol in Ophthalmology: Old is Gold

PURPOSE

Topical chloramphenicol is one of the most ubiquitous antibiotics used in ophthalmology and oculoplastic surgery globally. It shows broad-spectrum activity against a variety of different pathogenic organisms, is well tolerated on the ocular surface and displays excellent topical pharmacokinetics. Chloramphenicol has been available for purchase over the counter in the United Kingdom since 2005. Despite this, the largest health economy in the world, The United States has had a de-facto moratorium on its use for the past 30 years. In this review, we aim to evaluate topical chloramphenicol in ophthalmology and oculoplastic surgery and to determine whether its reputation within the US is warranted and justified.

METHODS

We conducted a comprehensive literature review to evaluate the different facets of chloramphenicol, providing a detailed understanding of the drug, its historical context, the benefits and perceived risks, including safety concerns, and clinical perspectives of its use in clinical practice.

RESULTS

The mechanism of chloramphenicol, the context around which the drug's use in the US declined, and the drug's evidence base and safety data, including published case reports of serious adverse events, were analysed. The perceived benefits of the drug, particularly in light of antimicrobial resistance and its economic impact, were reviewed. Finally, perspectives on its use in clinical practice in ophthalmology and associated allied specialities were presented.

CONCLUSION

Chloramphenicol and its topical application have been misunderstood for many decades, particularly in the United States. Its demise across the Atlantic was due to an overzealous response to a dubious association with a weak evidence base. Numerous authors have since validated the safety profile of the and its safety has been borne out. The benefits of chloramphenicol, an effective broad-spectrum agent with a positive cost differential in the era of anti-microbial resistance and fiscal tightening, cannot be understated. Its likely effectiveness as a therapeutic topical agent in ophthalmic surgery makes it a valuable tool in the ophthalmic anti-microbial armoury. We would encourage the reinstatement of this valuable yet misunderstood drug as a first-line agent for simple ophthalmic infections.

Development and Evaluation of Ontogeny Functions of the Major UDP-Glucuronosyltransferase Enzymes to Underwrite Physiologically Based Pharmacokinetic Modeling in Pediatric Populations

Uridine 5'-diphospho-glucuronosyltransferases (UGTs) demonstrate variable expression in the pediatric population. Thus, understanding of age-dependent maturation of UGTs is critical for accurate pediatric pharmacokinetics (PK) prediction of drugs that are susceptible for glucuronidation. Ontogeny functions of major UGTs have been previously developed and reported. However, those ontogeny functions are based on in vitro data (i.e., enzyme abundance, in vitro substrate activity, and so on) and therefore, may not translate to in vivo maturation of UGTs in the clinical setting. This report describes meta-analysis of the literature to develop and compare ontogeny functions for 8 primary UGTs (UGT1A1, UGT1A4, UGT1A6, UGT1A9, UGT2B7, UGT2B10, UGT2B15, and UGT2B17) based on published in vitro and in vivo studies. Once integrated with physiologically based pharmacokinetics modeling models, in vivo activity-based ontogeny functions demonstrated somewhat greater prediction accuracy (mean squared error, MSE: 0.05) compared to in vitro activity (MSE: 0.104) and in vitro abundance-based ontogeny functions (MSE: 0.129).

Quantitative Proteomics in Translational Absorption, Distribution, Metabolism, and Excretion and Precision Medicine

A reliable translation of in vitro and preclinical data on drug absorption, distribution, metabolism, and excretion (ADME) to humans is important for safe and effective drug development. Precision medicine that is expected to provide the right clinical dose for the right patient at the right time requires a comprehensive understanding of population factors affecting drug disposition and response. Characterization of drug-metabolizing enzymes and transporters for the protein abundance and their interindividual as well as differential tissue and cross-species variabilities is important for translational ADME and precision medicine. This review first provides a brief overview of quantitative proteomics principles including liquid chromatography-tandem mass spectrometry tools, data acquisition approaches, proteomics sample preparation techniques, and quality controls for ensuring rigor and reproducibility in protein quantification data. Then, potential applications of quantitative proteomics in the translation of in vitro and preclinical data as well as prediction of interindividual variability are discussed in detail with tabulated examples. The applications of quantitative proteomics data in physiologically based pharmacokinetic modeling for ADME prediction are discussed with representative case examples. Finally, various considerations for reliable quantitative proteomics analysis for translational ADME and precision medicine and the future directions are discussed. SIGNIFICANCE STATEMENT: Quantitative proteomics analysis of drug-metabolizing enzymes and transporters in humans and preclinical species provides key physiological information that assists in the translation of in vitro and preclinical data to humans. This review provides the principles and applications of quantitative proteomics in characterizing in vitro, ex vivo, and preclinical models for translational research and interindividual variability prediction. Integration of these data into physiologically based pharmacokinetic modeling is proving to be critical for safe, effective, timely, and cost-effective drug development.

The Blind Spot of Pharmacology: A Scoping Review of Drug Metabolism in Prematurely Born Children

The limit for possible survival after extremely preterm birth has steadily improved and consequently, more premature neonates with increasingly lower gestational age at birth now require care. This specialized care often include intensive pharmacological treatment, yet there is currently insufficient knowledge of gestational age dependent differences in drug metabolism. This potentially puts the preterm neonates at risk of receiving sub-optimal drug doses with a subsequent increased risk of adverse or insufficient drug effects, and often pediatricians are forced to prescribe medication as off-label or even off-science. In this review, we present some of the particularities of drug disposition and metabolism in preterm neonates. We highlight the challenges in pharmacometrics studies on hepatic drug metabolism in preterm and particularly extremely (less than 28 weeks of gestation) preterm neonates by conducting a scoping review of published literature. We find that >40% of included studies failed to report a clear distinction between term and preterm children in the presentation of results making direct interpretation for preterm neonates difficult. We present summarized findings of pharmacokinetic studies done on the major CYP sub-systems, but formal meta analyses were not possible due the overall heterogeneous approaches to measuring the phase I and II pathways metabolism in preterm neonates, often with use of opportunistic sampling. We find this to be a testament to the practical and ethical challenges in measuring pharmacokinetic activity in preterm neonates. The future calls for optimized designs in pharmacometrics studies, including PK/PD modeling-methods and other sample reducing techniques. Future studies should also preferably be a collaboration between neonatologists and clinical pharmacologists.

Treatment of Human Plague: A Systematic Review of Published Aggregate Data on Antimicrobial Efficacy, 1939-2019

BACKGROUND

Plague, caused by the bacterium Yersinia pestis, has killed millions in historic pandemics and continues to cause sporadic outbreaks. Numerous antimicrobials are considered effective for treating plague; however, well-defined information on the relative efficacy of various treatments is lacking. We conducted a systematic review of published data on antimicrobial treatment of plague reported in aggregate.

METHODS

We searched databases including Embase, Medline, CINAHL, Cochrane Library, and others for publications with terms related to plague and antimicrobials. Articles were included if they contained 1) a group of patients treated for plague, with outcomes reported by antimicrobial regimen, and 2) laboratory evidence of Y. pestis infection or an epidemiologic link to patients with laboratory evidence of Y. pestis. Case fatality rate by antimicrobial regimen was calculated.

RESULTS

In total, 5837 articles were identified; among these, 26 articles published between 1939 and 2008 met inclusion criteria. A total of 2631 cases of human plague reported within these articles were included. Among cases classified by primary clinical form of plague, 93.6% were bubonic, 5.9% pneumonic, and 0.5% septicemic with associated case fatalities of 14.2%, 31.1%, and 20.0%, respectively. Case fatality rate among patients who received monotherapy with tetracyclines, chloramphenicol, aminoglycosides, or sulfonamides was 1.3%, 1.4%, 7.5%, and 20.2%, respectively. Fluoroquinolones were only given as part of combination therapy. Penicillin was associated with a case fatality rate of 75%.

CONCLUSIONS

Tetracyclines, chloramphenicol, and aminoglycosides were associated with the lowest case fatality rates of all antimicrobials used for treatment of plague. Additional research is needed to determine the efficacy of fluoroquinolones as monotherapy.

Paediatric pharmacotherapy and drug regulation: Moving past the therapeutic orphan

The development of specific drug therapy for children was a paradigm-changing event that transformed paediatric medical practice. However, a series of tragedies involving drug treatment for children resulted in a gap developing between drug regulation and practice, with the majority of drugs used in child healthcare being used off-label, rendering children therapeutic orphans. Over the past two decades changes in drug regulation led by the US Food and Drug Administration and followed by the European Union's European Medicines Agency have led to substantial changes in how new drugs with potential use in children are studied and labelled. While these changes have substantially improved labelling for new drugs, there has been much less progress with older drugs. Although the unique challenges of conducting clinical research in children have been addressed by novel clinical trial designs, many of these innovations have not been translated into approaches accepted for the drug approval process. The regulations applying to the need for paediatric studies currently are only applicable in the United States and the European Union, and there is less impetus for paediatric labelling in other jurisdictions. This impacts on a number of issues beyond labelling, including the availability of child-friendly formulations. Finally, the impact of Brexit on paediatric drug studies in the UK remains unclear and is subject to ongoing negotiations between the UK government and the European Union.

Development of a Pediatric Mini-Tablet Formulation for Expedited Preclinical Studies

Multiple considerations are essential to address the main challenges of dose flexibility and patient adherence in pediatric drug development, particularly for oncology. Mini-tablets, 2 mm in diameter, were manufactured using a rotary tablet press at a set weight and compression force level. The physical characteristics were consistent for mini-tablets throughout multiple batches. Polymeric amorphous solid dispersion (ASD) was used as a solubility enhancing technique to increase solubility and exposure of lapatinib. The effects of the polymeric excipient and disintegrant on drug release properties were investigated. While having a lower apparent solubility and shorter storage stability, hydroxypropyl methylcellulose E3 (HPMCE3) formulation provided a higher percentage of drug release compared to hydroxypropyl methylcellulose phthalate (HPMCP). The intermolecular interaction within the ASD system plays a role in the level of apparent solubility, physical stability, and concentration of free drug available in an aqueous environment. Juvenile porcine models at two different weight groups (10 and 20 kg) were used to obtain the pharmacokinetic parameters of lapatinib. While the dose-normalized exposure of drug was found to be lower in the pig study, the dose flexibility of mini-tablets enabled a constant dose level to be administered to achieve equivalent plasma concentration-time profiles between the two groups. This linear scaling in the amount of drug in pediatric and adult population has also been observed in human clinical studies.

Antibacterial Porous Electrospun Fibers as Skin Scaffolds for Wound Healing Applications

Electrospun fiber scaffolds have a huge potential for the successful treatment of infected wounds based on their unique properties. Although several studies report novel drug-loaded electrospun fiber-based biomaterials, many of these do not provide information on their interactions with eukaryotic and bacterial cells. The main aim of this study was to develop antibacterial drug-loaded porous biocompatible polycaprolactone (PCL) fiber scaffolds mimicking the native extracellular matrix for wound healing purposes. Mechanical property evaluation and different biorelevant tests were conducted in order to understand the structure-activity relationships and reveal how the surface porosity of fibers and the fiber diameter affect the scaffold interactions with the living bacterial and eukaryotic fibroblast cells. Cell migration and proliferation assays and antibiofilm assays enabled us to enlighten the biocompatibility and safety of fiber scaffolds and their suitability to be used as scaffolds for the treatment of infected wounds. Here, we report that porous PCL microfiber scaffolds obtained using electrospinning at high relative humidity served as the best surfaces for fibroblast attachment and growth compared to the nonporous microfiber or nonporous nanofiber PCL scaffolds. Porous chloramphenicol-loaded microfiber scaffolds were more elastic compared to nonporous scaffolds and had the highest antibiofilm activity. The results indicate that in addition to the fiber diameter and fiber scaffold porosity, the single-fiber surface porosity and its effect on drug release, mechanical properties, cell viability, and antibiofilm activity need to be understood when developing antibacterial biocompatible scaffolds for wound healing applications. We show that pores on single fibers within an electrospun scaffold, in addition to nano- and microscale diameter of the fibers, change the living cell-fiber interactions affecting the antibiofilm efficacy and biocompatibility of the scaffolds for the local treatment of wounds.

Oral antibiotics for neonatal infections: a systematic review and meta-analysis

BACKGROUND

Worldwide many neonates suffer from bacterial infections. Adequate treatment is important but is associated with prolonged hospitalization for intravenous administration. In older children, oral switch therapy has been proven effective and safe for several indications and is now standard care.

OBJECTIVES

To evaluate the currently available evidence on pharmacokinetics, safety and efficacy of oral antibiotics and oral switch therapy in neonates (0-28 days old).

METHODS

We performed systematic searches in Medline, Embase.com, Cochrane, Google Scholar and Web of Science. Studies were eligible if they described the use of oral antibiotics in neonates (0-28 days old), including antibiotic switch studies and pharmacological studies.

RESULTS

Thirty-one studies met the inclusion criteria. Compared with parenteral administration, oral antibiotics generally reach their maximum concentration later and have a lower bioavailability, but in the majority of cases adequate serum levels for bacterial killing are reached. Furthermore, studies on efficacy of oral antibiotics showed equal relapse rates (OR 0.95; 95% CI 0.79-1.16; I2 0%) or mortality (OR 1.11; 95% CI 0.72-1.72; I2 0%). Moreover, a reduction in hospital stay was observed.

CONCLUSIONS

Oral antibiotics administered to neonates are absorbed and result in adequate serum levels, judged by MICs of relevant pathogens, over time. Efficacy studies are promising but robust evidence is lacking, most importantly because in many cases clinical efficacy and safety are not properly addressed. Early oral antibiotic switch therapy in neonates could be beneficial for both families and healthcare systems. There is a need for additional well-designed trials in different settings.

Adverse Drug Reactions Across the Age Continuum: Epidemiology, Diagnostic Challenges, Prevention, and Treatments

Adverse drug reactions (ADRs) are common and important complications of drug therapy for children. The risk for ADRs changes over childhood, as do the nature and types of ADRs. Importantly, the risk and nature of ADRs in children are markedly different from those of adults, and adult data cannot be relied on to guide safe drug therapy in children. There are groups of children, notably those with complex and chronic diseases, who are at substantial risk for ADRs. The evaluation of an undesired effect during therapy is ideally accomplished by an organized approach that is a skill that clinicians who care for children-especially those children at high risk for ADRs must have. Additionally, clinicians as well as drug regulatory agencies and industry need to be both vigilant and astute as well as aware that ADRs in children are often different in nature and frequency from those in adults. The increasing use of pharmacogenomics to guide drug dosing and the increasing number of biological agents will provide new sets of challenges to clinicians over the next decade.

Susceptibility to adverse drug reactions

The pharmacological effects of a drug depend on its concentration at the site of action, and therefore on the concentration in blood and on the dose. The relationship between the concentration or dose and the corresponding effect can usually be represented mathematically as a rectangular hyperbola; when effect is plotted against log concentration or log dose, the curve is sigmoidal. Inevitably, the effect size and the doses causing benefit and harm will differ among individuals, since they are biological phenomena: some individuals are more likely than others to suffer harm at any given dose. Some harmful effects can occur at much lower doses than those used in therapeutics; that is, the log dose-response curve for harm lies far to the left of the log dose-response curve for benefit. Those who suffer such reactions are hypersusceptible. When the dose-response curves for harm and therapeutic effect are in the same range, dose cannot separate the harmful effects from the therapeutic effects, and adverse reactions are collateral. Toxic effects occur when harmful doses are above the doses needed for benefit. In this review we consider factors that influence a subject's susceptibility to adverse drug reactions. Determinants of susceptibility include Immunological, Genetic, demographic (Age and Sex), Physiological and Exogenous factors (drug-drug interactions, for example), and Diseases and disorders such as renal failure, giving the mnemonic I GASPED. Some susceptibility factors are discrete (for example, all-or-none) and some are continuous; susceptibility can therefore be discrete or continuous; and the factors can interact to determine a person's overall susceptibility to harm.

Evaluating Safety Reporting in Paediatric Antibiotic Trials, 2000-2016: A Systematic Review and Meta-Analysis

BACKGROUND

There are very few options to treat multidrug-resistant bacterial infections in children. A major barrier is the duration and complexity of regulatory trials of new antibiotics. Extrapolation of safety data from adult trials could facilitate drug development for children.

OBJECTIVE

We performed a systematic review on the safety of antibiotic clinical trials (CTs) in children (0-18 years) to evaluate the overall quality of safety trials conducted in children and to determine if age-specific adverse events (AEs) could be identified for specific antibiotic classes.

DATA SOURCES

We searched the MEDLINE, Cochrane CENTRAL, and ClinicalTrials.gov electronic databases for trials conducted between 2000 and 2016.

STUDY SELECTION

All trials in which safety was declared a primary or secondary endpoint were included. Exclusion criteria were (1) topical or inhalational route of administration; (2) non-infectious conditions; (3) administration for prophylaxis rather than treatment; (4) selected population (i.e. cystic fibrosis, malignancies, HIV and tuberculosis); and (5) design other than randomized controlled trials. Trials reporting data on both adults and children were included only if paediatric results were reported separately.

DATA EXTRACTION AND SYNTHESIS

Two authors independently extracted the data. To assess the quality of published trials, the Extension for harms for Consolidated Standards of Reporting Trials (CONSORT) Statement 2004 was used.

MAIN OUTCOME AND MEASURE

In order to quantitatively assess the rate of developing AEs by drug class, the numbers of overall and body-system-specific AEs were collected for each study arm, and then calculated per single drug class as median and interquartile range (IQR) of the proportions across CTs. The AEs most frequently reported were compared in the meta-analysis by selecting the CTs on the most represented drug classes.

RESULTS

Eighty-three CTs were included, accounting for 27,693 children. Overall, 69.7% of CONSORT items were fully reported. The median proportion of children with any AE was 22.5%, but did not exceed 8% in any single body system. Serious drug-related AEs and drug-related discontinuations were very rare (median 0.3 and 0.9%, respectively). Limitations included the inability to stratify by age group, particularly neonates.

CONCLUSIONS AND RELEVANCE

Overall, AEs in paediatric antibiotic CTs were predictable and class-specific, and no unexpected (age-specific) side effects were identified. Smaller, open-label, dose-finding, high-quality, single-arm pharmacokinetic trials seem potentially sufficient for certain common antibiotic classes, extrapolating well-established safety profiles determined from large adult efficacy trials. This approach could reduce duration and enhance subsequent registration of urgently needed new antibiotics. This will need to be combined with enhanced methods of pharmacovigilance for monitoring of emerging AEs in routine clinical practice.

Age- and Genotype-Dependent Variability in the Protein Abundance and Activity of Six Major Uridine Diphosphate-Glucuronosyltransferases in Human Liver

The ontogeny of hepatic uridine diphosphate-glucuronosyltransferases (UGTs) was investigated by determining their protein abundance in human liver microsomes isolated from 136 pediatric (0-18 years) and 35 adult (age >18 years) donors using liquid chromatography / tandem mass spectrometry (LC-MS/MS) proteomics. Microsomal protein abundances of UGT1A1, UGT1A4, UGT1A6, UGT1A9, UGT2B7, and UGT2B15 increased by ∼8, 55, 35, 33, 8, and 3-fold from neonates to adults, respectively. The estimated age at which 50% of the adult protein abundance is observed for these UGT isoforms was between 2.6-10.3 years. Measured in vitro activity was generally consistent with the protein data. UGT1A1 protein abundance was associated with multiple single nucleotide polymorphisms exhibiting noticeable ontogeny-genotype interplay. UGT2B15 rs1902023 (*2) was associated with decreased protein activity without any change in protein abundance. Taken together, these data are invaluable to facilitate the prediction of drug disposition in children using physiologically based pharmacokinetic modeling as demonstrated here for zidovudine and morphine.

A Single Drop in the Eye - Effects on the Whole Body?

Introduction:

Although the local adverse effects of ophthalmic drugs, including allergic reactions, are well recognized, less is known about the systemic side- effects of eye drops, especially during pregnancy, breast-feeding and early childhood. Ophthalmologists should also be aware of unusual, in some cases even life-threatening, effects of commonly used eye drops.

Conclusion:

This brief review outlines the routes of systemic absorption and the kinetics of active components present in eye drops, and identifies the clinically relevant systemic adverse effects.

The Non-Linear Child: Ontogeny, Isoniazid Concentration, and NAT2 Genotype Modulate Enzyme Reaction Kinetics and Metabolism

N-acetyltransferase 2 (NAT2) catalyzes the acetylation of isoniazid to N-acetylisoniazid. NAT2 polymorphism explains 88% of isoniazid clearance variability in adults. We examined the effects of clinical and genetic factors on Michaelis-Menten reaction kinetic constants of maximum velocity (V_max) and affinity (K_m) in children 0–10 years old. We measured the rates of isoniazid elimination and N-acetylisoniazid production in the blood of 30 children. Since maturation effects could be non-linear, we utilized a pharmacometric approach and the artificial intelligence method, multivariate adaptive regression splines (MARS), to identify factors predicting NAT2 V_max and K_m by examining clinical, genetic, and laboratory factors in toto. Isoniazid concentration predicted both V_max and K_m and superseded the contribution of NAT2 genotype. Age non-linearly modified the NAT2 genotype contribution until maturation at ≥ 5.3 years. Thus, enzyme efficiency was constrained by substrate concentration, genes, and age. Since MARS output is in the form of basis functions and equations, it allows multiscale systems modeling from the level of cellular chemical reactions to whole body physiological parameters, by automatic selection of significant predictors by the algorithm.

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We identified the NAT2 K_m and V_max in children treated with isoniazid.

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Artificial intelligence (AI) algorithms were used to find predictors of K_m and V_max.

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Isoniazid concentration affected V_max and K_m, and superseded NAT2 genotype.

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Age non-linearly modified NAT2 genotype contribution until maturation at ≥ 5.3 years.

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AI output is in the form of equations that allow multiscale systems modeling.

The effects of maturation on drug metabolism have not been studied for the type phase II enzymes such as NAT2, which metabolizes the drug isoniazid. Genes have been found to control speed of isoniazid metabolism. Studies to characterize affinity and maximum velocity for isoniazid metabolism in people were last performed in two individuals' livers in the 1960s. We identified NAT2 affinity and maximum velocity in 30 tuberculosis children treated with isoniazid. Artificial intelligence methods found that metabolism was affected by the drug's concentration more than by genes, which were affected by age up to 5.3 years.

Exposure to topical chloramphenicol during pregnancy and the risk of congenital malformations: a Danish nationwide cohort study

PURPOSE

To investigate whether exposure to topical chloramphenicol in the first trimester of pregnancy is associated with congenital malformations.

METHODS

The authors conducted a nationwide cohort study including all women giving live birth between 1997 and 2011 in Denmark. All women redeeming at least one prescription of chloramphenicol eye drops or eye ointment during the first 84 days of pregnancy were identified. Logistic regression was used to estimate the odds ratios of malformations among exposed women compared to non-exposed women.

RESULTS

966 372 births between 1997 and 2011 were included. A total of 6024 women were exposed to topical chloramphenicol in the first trimester. The rate of congenital malformations was 3.50% among offspring of exposed mothers and 3.49% among unexposed. Exposure to topical chloramphenicol in the first trimester was not associated with major congenital malformations (adjusted odds ratio = 1.06, 95% CI 0.91-1.22) or specific major malformations. The number of redeemed prescriptions decreased significantly during pregnancy as compared to before and after pregnancy (p < 0.0001).

CONCLUSION

In this study, we found no association between dispensing of chloramphenicol eye drops or eye ointment in the first trimester of pregnancy and major congenital malformations. This is in accordance with a previous study analysing the risk of systemic chloramphenicol.

Ethics review of pediatric multi-center drug trials

The assessment of safety and efficacy of therapeutics for children and adolescents requires the use of multi-centered designs. However, the need to obtain ethical approval from multiple independent research ethics boards (REBs) presents as a challenge to investigators and sponsors who must consider local requirements while ensuring that the protection of human subjects is consistent across sites. In pediatrics, this requirement is complicated by pediatric-specific ethical concerns such as the acquisition of assent and consent and the need for pediatric expertise to assess the scholarly merit of the proposed research. Efforts to tackle these challenges have focused on the process of ethics review, which will improve efficiency. In addition to improving process, we suggest further research to fill gaps in the evidence base for recommendations and decisions made by REBs, specifically their effectiveness to protect human subjects. Evidence gathered will contribute to the successful development, adoption and implementation of harmonized guidance to apply ethics principles in order to protect children through research rather than from research.

ADRIC: Adverse Drug Reactions In Children – a programme of research using mixed methods

Aims

To comprehensively investigate the incidence, nature and risk factors of adverse drug reactions (ADRs) in a hospital-based population of children, with rigorous assessment of causality, severity and avoidability, and to assess the consequent impact on children and families. We aimed to improve the assessment of ADRs by development of new tools to assess causality and avoidability, and to minimise the impact on families by developing better strategies for communication.

Review methods

Two prospective observational studies, each over 1 year, were conducted to assess ADRs in children associated with admission to hospital, and those occurring in children who were in hospital for longer than 48 hours. We conducted a comprehensive systematic review of ADRs in children. We used the findings from these studies to develop and validate tools to assess causality and avoidability of ADRs, and conducted interviews with parents and children who had experienced ADRs, using these findings to develop a leaflet for parents to inform a communication strategy about ADRs.

Results

The estimated incidence of ADRs detected in children on admission to hospital was 2.9% [95% confidence interval (CI) 2.5% to 3.3%]. Of the reactions, 22.1% (95% CI 17% to 28%) were either definitely or possibly avoidable. Prescriptions originating in the community accounted for 44 out of 249 (17.7%) of ADRs, the remainder originating from hospital. A total of 120 out of 249 (48.2%) reactions resulted from treatment for malignancies. Off-label and/or unlicensed (OLUL) medicines were more likely to be implicated in an ADR than authorised medicines [relative risk (RR) 1.67, 95% CI 1.38 to 2.02;p < 0.001]. When medicines used for the treatment of oncology patients were excluded, OLUL medicines were not more likely to be implicated in an ADR than authorised medicines (RR 1.03, 95% CI 0.72 to 1.48;p = 0.830). For children who had been in hospital for > 48 hours, the overall incidence of definite and probable ADRs based on all admissions was 15.9% (95% CI 15.0 to 16.8). Opiate analgesic drugs and drugs used in general anaesthesia (GA) accounted for > 50% of all drugs implicated in ADRs. The odds ratio of an OLUL drug being implicated in an ADR compared with an authorised drug was 2.25 (95% CI 1.95 to 2.59;p < 0.001). Risk factors identified were exposure to a GA, age, oncology treatment and number of medicines. The systematic review estimated that the incidence rates for ADRs causing hospital admission ranged from 0.4% to 10.3% of all children [pooled estimate of 2.9% (95% CI 2.6% to 3.1%)] and from 0.6% to 16.8% of all children exposed to a drug during hospital stay. New tools to assess causality and avoidability of ADRs have been developed and validated. Many parents described being dissatisfied with clinician communication about ADRs, whereas parents of children with cancer emphasised confidence in clinician management of ADRs and the way clinicians communicated about medicines. The accounts of children and young people largely reflected parents’ accounts. Clinicians described using all of the features of communication that parents wanted to see, but made active decisions about when and what to communicate to families about suspected ADRs, which meant that communication may not always match families’ needs and expectations. We developed a leaflet to assist clinicians in communicating ADRs to parents.

Conclusion

The Adverse Drug Reactions In Children (ADRIC) programme has provided the most comprehensive assessment, to date, of the size and nature of ADRs in children presenting to, and cared for in, hospital, and the outputs that have resulted will improve the management and understanding of ADRs in children and adults within the NHS. Recommendations for future research: assess the values that parents and children place on the use of different medicines and the risks that they will find acceptable within these contexts; focusing on high-risk drugs identified in ADRIC, determine the optimum drug dose for children through the development of a gold standard practice for the extrapolation of adult drug doses, alongside targeted pharmacokinetic/pharmacodynamic studies; assess the research and clinical applications of the Liverpool Causality Assessment Tool and the Liverpool Avoidability Assessment Tool; evaluate, in more detail, morbidities associated with anaesthesia and surgery in children, including follow-up in the community and in the home setting and an assessment of the most appropriate treatment regimens to prevent pain, vomiting and other postoperative complications; further evaluate strategies for communication with families, children and young people about ADRs; and quantify ADRs in other settings, for example critical care and neonatology.

Funding

The National Institute for Health Research Programme Grants for Applied Research programme.

Antibiotics and Antifungals in Neonatal Intensive Care Units: A Review

The incidence of infections is higher in the neonatal period than at any time of life. The basic treatment of infants with infection has not changed substantially over the last years. Antibiotics (with or without supportive care) are one of the most valuable resources in managing sick newborn babies. Early-onset (ascending or transplacental) or late-onset (hospital acquired) infections present different chronology, epidemiology, physiology and outcome. Some classes of antibiotics are frequently used in the neonatal period: penicillins, cephalosporins, aminoglycosides, glycopeptides, monobactams, carbapenems. Other classes of antibiotics (chloramphenicol, cotrimoxazole, macrolides, clindamycin, rifampicin and metronidazole) are rarely used. Due to emergence of resistant bacterial strains in Neonatal Intensive Care Units (NICU), other classes of antibiotics such as quinolones and linezolid will probably increase their therapeutic role in the future. Although new formulations have been developed for treatment of fungal infections in infants, amphotericin B remains first-line treatment for systemic Candida infection. Prophylactic antibiotic therapy is almost always undesirable. Challenges from pathogens and antibiotic resistance in the NICU may warrant modification of traditional antibiotic regimens. Knowledge of local flora and practical application of different antibiotic characteristics are key to an effective and safe utilization of antibiotics and antifungals in critical newborns admitted to the NICU, and especially in very low birth weight infants.

Chloramphenicol toxicity revisited: a 12-year-old patient with a brain abscess

Chloramphenicol, a broad-spectrum antibiotic, is rarely used in the United States due to its well-described adverse effects. Because of its limited use, many clinicians are unfamiliar with its indications, spectrum of activity, and potential adverse drug effects. We describe a 12-year-old patient who presented after two craniotomies for a persistent brain abscess complicated by long-term chloramphenicol administration. Findings for this patient were consistent with many of the adverse drug effects associated with chloramphenicol, including elevated chloramphenicol serum concentrations, anemia, thrombocytopenia, reticulocytopenia, and severe metabolic acidosis. Rare manifestations of chloramphenicol toxicity that developed in this patient included neutropenia, visual field changes, and peripheral neuropathy. Chloramphenicol administration was discontinued, and hemodialysis was initiated for severe metabolic acidosis. The patient recovered with severe visual field deficits. Although chloramphenicol is rarely indicated, it remains an effective antibiotic. Healthcare providers should become familiar with the pharmacology, toxicology, and monitoring parameters for appropriate use of this antibiotic.

The ethics of paediatric research

Paediatric research is essential for improving health outcomes of children. Waiting for adult studies before conducting paediatric studies will prolong the denial of effective treatment for children. If we rely on information from adult studies rather than conducting studies with children, we risk causing harm to children. In this paper, we identify and examine ethical issues unique to conducting research with children. These include the function and the value of a child's assent and the criteria that should guide a proxy in making decisions about a child's involvement in research, offering payment to children for research participation and acceptable levels of risk for paediatric research. Justice demands that children not be denied the benefits of research, and it is the role of the paediatric medical community to advocate not only for more research for children but also to ensure that the research conducted is of the highest quality.

In vitro selection and characterization of DNA aptamers recognizing chloramphenicol

Chloramphenicol (Cam), although an effective antibiotic, has lost favour due to some fatal side effects. Thus there is an urgent need for rapid and sensitive methods to detect residues in food, feed and environment. We engineered DNA aptamers that recognize Cam as their target, by conducting in vitro selections. Aptamers are nucleic acid recognition elements that are highly specific and sensitive towards their targets and can be synthetically produced in an animal-friendly manner, making them ethical innovative alternatives to antibodies. None of the isolated aptamers in this study shared sequence homology or structural similarities with each other, indicating that specific Cam recognition could be achieved by various DNA sequences under the selection conditions used. Analyzing the binding affinities of the sequences, demonstrated that dissociation constants (K(d)) in the extremely low micromolar range, which were lower than those previously reported for Cam-specific RNA aptamers, were achieved. The two best aptamers had G rich (>35%) nucleotide regions, an attribute distinguishing them from the rest and apparently responsible for their high selectivity and affinity (K(d)∼0.8 and 1μM respectively). These aptamers open up possibilities to allow easy detection of Cam via aptamer-based biosensors.

Pediatric cardiovascular drug development and research: integration of modeling and simulation as one future direction

The integration of the needs of children into the legal drug development process since 1997 in the United States and since 2007 in the European Union has improved health and stimulated innovative approaches in the design of clinical trials and will benefit both current and future populations. According to the US Food and Drug Administration, to date, 394 pediatric labels together with safer medicines and better dosing practices have provided a sound basis for the safer and more effective use of drugs in a pediatric population. This may be measurable with fewer medication errors and perhaps shorter hospital stays in the future. Although relevant data have been generated by clinical trials in pediatric populations, challenges, such as nonefficacy and safety issues, have arisen. Heterogeneity in the physiological maturation and growth processes and differences in the etiology and pathogenesis of disease in patients from birth to 18 years of age may explain these results. The use of cutting-edge technology, such as modeling and simulation of "in silico" pediatric populations, may allow the integration of data from previous trials and experiments into the design of future clinical trials and allow exploration in other areas that have the potential to enhance the outcome of clinical trials in children.

Genetic polymorphism in metabolism and host defense enzymes: implications for human health risk assessment

Genetic polymorphisms in xenobiotic metabolizing enzymes can have profound influence on enzyme function, with implications for chemical clearance and internal dose. The effects of polymorphisms have been evaluated for certain therapeutic drugs but there has been relatively little investigation with environmental toxicants. Polymorphisms can also affect the function of host defense mechanisms and thus modify the pharmacodynamic response. This review and analysis explores the feasibility of using polymorphism data in human health risk assessment for four enzymes, two involved in conjugation (uridine diphosphoglucuronosyltransferases [UGTs], sulfotransferases [SULTs]), and two involved in detoxification (microsomal epoxide hydrolase [EPHX1], NADPH quinone oxidoreductase I [NQO1]). This set of evaluations complements our previous analyses with oxidative and conjugating enzymes. Of the numerous UGT and SULT enzymes, the greatest likelihood for polymorphism effect on conjugation function are for SULT1A1 (*2 polymorphism), UGT1A1 (*6, *7, *28 polymorphisms), UGT1A7 (*3 polymorphism), UGT2B15 (*2 polymorphism), and UGT2B17 (null polymorphism). The null polymorphism in NQO1 has the potential to impair host defense. These highlighted polymorphisms are of sufficient frequency to be prioritized for consideration in chemical risk assessments. In contrast, SNPs in EPHX1 are not sufficiently influential or defined for inclusion in risk models. The current analysis is an important first step in bringing the highlighted polymorphisms into a physiologically based pharmacokinetic (PBPK) modeling framework.

Successful treatment of vancomycin-resistant Enterococcus faecium ventriculitis with combined intravenous and intraventricular chloramphenicol in a newborn

Vancomycin-resistant Enterococcus faecium (VRE) infection is a rare event in paediatric patients and often occurs under immunosuppression or after surgical intervention. We report what we believe to be the first paediatric case of ventriculitis due to VRE (in a 2-month-old infant) to be successfully treated with combined intravenous (i.v.) and intraventricular chloramphenicol after failure of i.v. linezolid and intraventricular gentamicin.

Ureaplasma: pathogen or passenger in neonatal meningitis?

The significance of Ureaplasma species as pathogens in neonatal meningitis remains contentious. Using an illustrative case of a premature infant with Ureaplasma parvum meningitis, confirmed by cerebrospinal fluid cultures and both specific and 16s rDNA polymerase chain reaction, we discuss the epidemiology of Ureaplasma species, the difficulties involved in diagnosis and establishing pathogenicity, and the challenges in defining appropriate treatment.

Parenteral antibiotics for the treatment of serious neonatal bacterial infections in developing country settings

BACKGROUND

A number of special issues must be considered when selecting simple, safe, inexpensive, and effective antimicrobial regimens for treatment of neonatal sepsis in developing country community settings.

METHODS

We reviewed available data regarding pharmacologic profiles of parenteral antibiotics with specific attention to properties relevant to their use in the treatment of neonatal infections in developing country communities.

RESULTS

For community-based management of neonatal infections, particularly attractive properties include efficacy and safety of extended-interval, intramuscular dosing regimens. The penicillins and cephalosporins have relatively favorable efficacy and safety profiles. Although the aminoglycosides have narrow therapeutic indices, when used appropriately, they are safe and effective. Although inexpensive and effective, the potential for significant life-threatening toxicity among neonates associated with chloramphenicol makes it the least preferred of the parenteral agents for empiric therapy.

CONCLUSIONS

The preferred parenteral regimens for community and first-level facility use are a combination of procaine penicillin G and gentamicin, or ceftriaxone given alone, which are safe and retain efficacy when dosed at extended intervals (> or =24 hours) by intramuscular administration.

Mycoplasma hominis Meningitis in a 24 Week Premature Neonate: Case Report and Short Literature Review

Over the last 20-year period there have been fewer than 10 reported cases of Mycoplasma hominis central nervous system infection in either premature or full term infants. The optimum management of M hominis infection in premature infants is still unclear. We report the case of a premature infant with persistent central nervous system infection caused by M hominis treated successfully with intravenous chloramphenicol. Previous reports of M hominis central nervous infection and its management are reviewed.

Developing paediatric medicines: identifying the needs and recognizing the challenges

There is a significant need for research and development into paediatric medicines. Only a small fraction of the drugs marketed and utilized as therapeutic agents in children have been clinically evaluated. The majority of marketed drugs are either not labelled, or inadequately labelled, for use in paediatric patients. The absence of suitable medicines or critical safety and efficacy information poses significant risks to a particularly vulnerable patient population. However, there are many challenges associated with developing medicines for the paediatric population and this review paper is intended to highlight these. The paediatric population is made up of a wide range of individuals of substantially varied physical size, weight and stage of physiological development. Experimentation on children is considered by many to be unethical, resulting in difficulties in obtaining critical safety data. Clinical trials are subject to detailed scrutiny by the various regulatory bodies who have recently recognized the need for pharmaceutical companies to invest in paediatric medicines. The costs associated with paediatric product development could result in poor or negative return on investment and so incentives have been proposed by the EU and US regulatory bodies. Additionally, some commonly used excipients may be unsuitable for use in children; and some dosage forms may be undesirable to the paediatric population.

Human milk biomonitoring data: interpretation and risk assessment issues

Biomonitoring data can, under certain conditions, be used to describe potential risks to human health (for example, blood lead levels used to determine children's neurodevelopmental risk). At present, there are very few chemical exposures at low levels for which sufficient data exist to state with confidence the link between levels of environmental chemicals in a person's body and his or her risk of adverse health effects. Human milk biomonitoring presents additional complications. Human milk can be used to obtain information on both the levels of environmental chemicals in the mother and her infant's exposure to an environmental chemical. However, in terms of the health of the mother, there are little to no extant data that can be used to link levels of most environmental chemicals in human milk to a particular health outcome in the mother. This is because, traditionally, risks are estimated based on dose, rather than on levels of environmental chemicals in the body, and the relationship between dose and human tissue levels is complex. On the other hand, for the infant, some information on dose is available because the infant is exposed to environmental chemicals in milk as a "dose" from which risk estimates can be derived. However, the traditional risk assessment approach is not designed to consider the benefits to the infant associated with breastfeeding and is complicated by the relatively short-term exposures to the infant from breastfeeding. A further complexity derives from the addition of in utero exposures, which complicates interpretation of epidemiological research on health outcomes of breastfeeding infants. Thus, the concept of "risk assessment" as it applies to human milk biomonitoring is not straightforward, and methodologies for undertaking this type of assessment have not yet been fully developed. This article describes the deliberations of the panel convened for the Technical Workshop on Human Milk Surveillance and Biomonitoring for Environmental Chemicals in the United States, held at the Hershey Medical Center, Pennsylvania State College of Medicine, on several issues related to risk assessment and human milk biomonitoring. Discussion of these topics and the thoughts and conclusions of the panel are described in this article.

Incorporating pharmacokinetic differences between children and adults in assessing children's risks to environmental toxicants

Children's risks from environmental toxicant exposure can be affected by pharmacokinetic factors that affect the internal dose of parent chemical or active metabolite. There are numerous physiologic differences between neonates and adults that affect pharmacokinetics including size of lipid, and tissue compartments, organ blood flows, protein binding capacity, and immature function of renal and hepatic systems. These factors combine to decrease the clearance of many therapeutic drugs, which can also be expected to occur with environmental toxicants in neonates. The net effect may be greater or lesser internal dose of active toxicant depending upon how the agent is distributed, metabolized, and eliminated. Child/adult pharmacokinetic differences decrease with increasing postnatal age, but these factors should still be considered in any children's age group, birth through adolescence, for which there is toxicant exposure. Physiologically based pharmacokinetic (PBPK) models can simulate the absorption, distribution, metabolism, and excretion of xenobiotics in both children and adults, allowing for a direct comparison of internal dose and risk across age groups. This review provides special focus on the development of hepatic cytochrome P-450 enzymes (CYPs) in early life and how this information, along with many factors unique to children, can be applied to PBPK models for this receptor population. This review describes a case study involving the development of neonatal PBPK models for the CYP1A2 substrates caffeine and theophylline. These models were calibrated with pharmacokinetic data in neonates and used to help understand key metabolic differences between neonates and adults across these two drugs.

Physiologically based pharmacokinetic (PBPK) modeling of caffeine and theophylline in neonates and adults: implications for assessing children's risks from environmental agents

Children's risks can differ from those in adults for numerous reasons, one being differences in the pharmacokinetic handling of chemicals. Immature metabolism and a variety of other factors in neonates can affect chemical disposition and clearance. These factors can be incorporated into physiologically based pharmacokinetic (PBPK) models that simulate the fate of environmental toxicants in both children and adults. PBPK models are most informative when supported by empirical data, but typically pediatric pharmacokinetic data for toxicants are not available. In contrast, pharmacokinetic data in children are readily available for therapeutic drugs. The current analysis utilizes data for caffeine and theophylline, closely related xanthines that are both cytochrome P-450 (CYP) 1A2 substrates, in developing PBPK models for neonates and adults. Model development involved scale-up of in vitro metabolic parameters to whole liver and adjusting metabolic function for the ontological pattern of CYP1A2 and other CYPs. Model runs were able to simulate the large differences in half-life and clearance between neonates and adults. Further, the models were able to reproduce the faster metabolic clearance of theophylline relative to caffeine in neonates. This differential between xanthines was found to be due primarily to an extra metabolic pathway available to theophylline, back-methylation to caffeine, that is not available to caffeine itself. This pathway is not observed in adults exemplifying the importance of secondary or novel routes of metabolism in the immature liver. Greater CYP2E1 metabolism of theophylline relative to caffeine in neonates also occurs. Neonatal PBPK models developed for these drugs may be adapted to other CYP1A2 substrates (e.g., arylamine toxicants). A stepwise approach for modeling environmental toxicants in children is proposed.

Incorporating children's toxicokinetics into a risk framework

Children's responses to environmental toxicants will be affected by the way in which their systems absorb, distribute, metabolize, and excrete chemicals. These toxicokinetic factors vary during development, from in utero where maternal and placental processes play a large role, to the neonate in which emerging metabolism and clearance pathways are key determinants. Toxicokinetic differences between neonates and adults lead to the potential for internal dosimetry differences and increased or decreased risk, depending on the mechanisms for toxicity and clearance of a given chemical. This article raises a number of questions that need to be addressed when conducting a toxicokinetic analysis of in utero or childhood exposures. These questions are organized into a proposed framework for conducting the assessment that involves problem formulation (identification of early life stage toxicokinetic factors and chemical-specific factors that may raise questions/concerns for children); data analysis (development of analytic approach, construction of child/adult or child/animal dosimetry comparisons); and risk characterization (evaluation of how children's toxicokinetic analysis can be used to decrease uncertainties in the risk assessment). The proposed approach provides a range of analytical options, from qualitative to quantitative, for assessing children's dosimetry. Further, it provides background information on a variety of toxicokinetic factors that can vary as a function of developmental stage. For example, the ontology of metabolizing systems is described via reference to pediatric studies involving therapeutic drugs and evidence from in vitro enzyme studies. This type of resource information is intended to help the assessor begin to address the issues raised in this paper.

Joining the DoTS: new approach to classifying adverse drug reactions

A new classification system for adverse drug reactions based on time course and susceptibility as well as dose responsiveness should improve drug development and management of adverse reactions

Antibiotics in neonatal infections: a review

The bacteria most commonly responsible for early-onset (materno-fetal) infections in neonates are group B streptococci, enterococci, Enterobacteriaceae and Listeria monocytogenes. Coagulase-negative staphylococci, particularly Staphylococcus epidermidis, are the main pathogens in late-onset (nosocomial) infections, especially in high-risk patients such as those with very low birthweight, umbilical or central venous catheters or undergoing prolonged ventilation. The primary objective of the paediatrician is to identity all potential cases of bacterial disease quickly and begin antibacterial treatment immediately after the appropriate cultures have been obtained. Combination therapy is recommended for initial empirical treatment in the neonate. In early-onset infections, an effective first-line empirical therapy is ampicillin plus an aminoglycoside (duration of treatment 10 days). An alternative is ampicillin plus a third-generation cephalosporin such as cefotaxime, a combination particularly useful in neonatal meningitis (mean duration of treatment 14 to 21 days), in patients at risk of nephrotoxicity and/or when therapeutic monitoring of aminoglycosides is not possible. Another potential substitute for the aminoglycoside is aztreonam. Triple combination therapy (such as amoxicillin plus cefotaxime and an aminoglycoside) could also be used for the first 2 to 3 days of life, followed by dual therapy after the microbiological results. In late-onset infections the combination oxacillin plus an aminoglycoside is widely recommended. However, vancomycin plus ceftazidime (+/- an aminoglycoside for the first 2 to 3 days) may be a better choice. Teicoplanin may be a substitute for vancomycin. However, the initial approach should always be modified by knowledge of the local bacterial epidemiology. After the microbiological results, treatment should be switched to narrower spectrum agents if a specific organism has been identified, and should be discontinued if cultures are negative and the neonate is in good clinical condition. Penicillins and third-generation cephalosporins are generally well tolerated in neonates. There is controversy regarding whether therapeutic drug monitoring of aminoglycosides will decrease toxicity (particularly renal damage) in neonates, and on the efficacy and safety of a single daily dose versus multiple daily doses of these drugs. Toxic effects caused by vancomycin are uncommon, but debate still exists over the need for therapeutic drug monitoring of this agent. When antibacterials are used in neonates, accurate determination of dosage is required, particularly for compounds with a low therapeutic index and in patients with renal failure. Very low birthweight infants are also particularly prone to antibacterial-induced toxicity.

Laboratory guidelines for monitoring of antimicrobial drugs

Few antimicrobial drugs meet the requirements for therapeutic drug monitoring. Those that are monitored include the aminoglycosides (gentamicin, tobramycin, and amikacin), chloramphenicol, and in some cases, vancomycin. For these drugs, there is evidence of a relationship between serum concentration, efficacy, and/or the incidence of adverse or toxic events. Monitoring begins with the appropriate timing of collection and continues through the analytical process to the integration of all data used to guide the clinician’s next decision.

Neonatal meningitis in Harare, Zimbabwe: a 2-year review

A 2-year review of neonatal meningitis was undertaken at a referral hospital in Zimbabwe to determine the pattern of bacterial isolates from the cerebrospinal fluid, the clinical presentation and the immediate outcome. During the study period, 94 cases were identified and the overall mortality was 41%. Group B Streptococcus was the predominant organism isolated (61%) and was associated with 42% mortality. Low-birthweight babies and babies with Gram-negative meningitis had mortality rates of 71 and 62%, respectively.

Antimicrobial therapy in neonates, infants and children

Many antimicrobial medications may be administered to paediatric patients with a degree of impunity because they are relatively non-toxic and have a wide therapeutic margin. However, because of different pharmacokinetics from those in adults, the potential for toxicity exists with the use of some of these agents. Drug absorption in paediatric patients, either orally or parenterally, is generally similar to that in adults, except among neonates and, particularly, premature neonates. Similarly, in neonates, drug distribution is altered, plasma protein binding is decreased and hepatic metabolism and renal excretory capacity are limited by physiological immaturity. Thus, in neonates, only drugs that have pharmacokinetically derived dosage schedules should be used, and therapeutic monitoring of plasma drug concentrations is recommended during therapy with aminoglycosides, vancomycin and chloramphenicol. In older infants and children, the pharmacokinetics of antimicrobial drugs generally approximate those in adults, and recommended dosages have been determined relative to bodyweight. Therapeutic monitoring of plasma drug concentrations may be important in certain patients, such as those with major organ failure, and may be useful in cases of suspected noncompliance. Additional pharmacokinetic considerations concerning antimicrobial medication and paediatric patients are the extent to which drug therapy penetrates the cerebrospinal fluid in meningitis, and the potential for and implications of exposure of infants to antimicrobial medications excreted in breast milk.

Chloramphenicol in paediatrics: current prescribing practice and the need to monitor

Two hundred and fifty-five neonates, infants and children, from 45 hospitals, who were receiving chloramphenicol therapy for serious infections were the subject of this study. Samples of serum and cerebrospinal fluid (CSF) were assayed for chloramphenicol and the patients' treatment regimens analysed. Less than 50% of neonates and 25% of infants received the "recommended" dose of chloramphenicol. In older children the recommended dose was used. Only 34% babies under 1 year of age and 50% older children had serum concentrations within the therapeutic range (15-25 mg/l). Thirty-one percent of neonates and infants had potentially toxic serum concentrations. Forty-three percent of neonates receiving chloramphenicol every 6 h had subtherapeutic peak serum levels compared to 20% of those receiving the antibiotic every 12 h. Concomitant administration of phenobarbitone or phenytoin had no effect on mean serum chloramphenicol levels. Serum concentrations of chloramphenicol were significantly higher in patients also receiving penicillin. CSF levels in 77 samples (39 patients) ranged from 1-60 mg/l. CSF from 44% patients contained less than 4 mg/l. Twelve neonates and infants (5.5%) suffered toxic side effects, four died. A further eight babies received an accidental 2- to 10-fold overdose and in three others an overdose was assumed following assay. No overdoses or toxic effects were reported in children over 1 year of age. Eight patients with impaired renal function had elevated serum levels and three showed toxic effects. In 22% patients dosage regimens were altered following assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical toxicology in the neonatal intensive care unit

The role of the clinical toxicologist in the neonatal nursery may be an extremely important one in the evaluation of epidemic-like toxic reactions occurring from: (a) the inappropriate use of medications; (b) the accidental contamination of parenterals; and (c) the introduction of relatively new products into the nursery environment. The newborn with high respiratory demands, thin epidermis with a large surface area to body mass ratio, and nutritional support being derived completely from parenteral sources provides a great number of routes of entry for the introduction of toxins. In approaching these problems, the clinician needs a structured approach in considering the impact of the route of administration, the contents of the product and the ability of the newborn to eliminate the toxin in question. In addition, some knowledge of the specialised structures and diseases of the newborn is required to adequately analyse the impact of a potential toxin on newborn disease processes. What we normally consider as adverse drug reactions are extremely rare in the neonate. Hypersensitivity phenomenon and the classic non-dose-related side effects described in adults are rare occurrences. This makes it a challenge for the clinical toxicologist to analyse and attempt to identify a toxic substance in the nursery. Having identified a toxin in the newborn, treatment may be complicated by the inability to use many of the standard forms of therapy, e.g. activated charcoal, diuresis, and extracorporeal removal. The lack of practicality of these procedures increases the necessity for good supportive care. Exchange transfusion, rarely considered in older children and adults, may offer the only viable option for rapid removal of a drug.

Bacterial meningitis. Rational selection and use of antibacterial drugs

Bacterial meningitis is a continuing challenge. This applies especially to infections in the neonate and the elderly, and to those which are hospital acquired. Factors which maintain the high morbidity and significant mortality from this disease include microbial virulence, a limited host response to infection within the cerebrospinal fluid (CSF), where phagocyte function is often impaired and complement and opsonic antibody activity are deficient, as well as delays in diagnosis and treatment. Added to these adverse factors is the pharmacokinetic hurdle of the 'blood-brain barrier', which limits drug concentrations achievable within the CSF. Inflammatory changes certainly improve the penetration of many agents, especially the penicillins and cephalosporins, but it must be remembered that with resolution of inflammation, achievable concentrations decline. Hence, the necessity for continuing parenteral administration of antibiotics throughout the treatment period. Although penicillin G (benzylpenicillin) remains the drug of choice for both pneumococcal and meningococcal infections, increasing resistance to ampicillin among Haemophilus influenzae has lead to greater reliance on alternative agents. Chloramphenicol is widely used, yet is potentially toxic, so that therapy with cefuroxime and the newer cephalosporins has been increasingly advocated. The advent of these potent, broad spectrum cephalosporins has induced a reappraisal of the treatment of Gram-negative bacillary meningitis, where ampicillin resistance and poor CSF penetration by the aminoglycosides have contributed to an unsatisfactory impact on outcome. Agents such as cefotaxime and ceftazidime have proved effective, although greater controlled experience is required. Finally, the contagious nature of meningococcal and H. influenzae infections justifies offering chemoprophylaxis to selected contacts, with rifampicin (or minocycline for contacts of patients with meningococcal infections).