Alfred F. A. M. Schobben

Guidelines on Paediatric Dosing on the Basis of Developmental Physiology and Pharmacokinetic Considerations

The approach to paediatric drug dosing needs to be based on the physiological characteristics of the child and the pharmacokinetic parameters of the drug. This review summarises the current knowledge on developmental changes in absorption, distribution, metabolism and excretion and combines this knowledge with in vivo and in vitro pharmacokinetic data that are currently available. In addition, dosage adjustments based on practical problems, such as child-friendly formulations and feeding regimens, disease state, genetic make-up and environmental influences are presented.Modification of a dosage based on absorption, depends on the route of absorption, the physico chemical properties of the drug and the age of the child. For oral drug absorption, a distinction should be made between the very young and children over a few weeks old. In the latter case, it is likely that practical considerations, like appropriate formulations, have much greater relevance to oral drug absorption.The volume of distribution (Vd) may be altered in children. Hydrophilic drugs with a high Vd in adults should be normalised to bodyweight in young children (age <2 years), whereas hydrophilic drugs with a low Vd in adults should be normalised to body surface area (BSA) in these children. For drugs that are metabolised by the liver, the effect of the Vd becomes apparent in children <2 months of age. In general, only the first dose should be based on the Vd subsequent doses should be determined by the clearance. Pharmacokinetic studies on renal and liver function clarify that a distinction should be made between maturation and growth of the organs. After the maturation process has finished, the main influences on the clearance of drugs are growth and changes in blood flow of the liver and kidney. Drugs that are primarily metabolised by the liver should be administered with extreme care until the age of 2 months. Modification of dosing should be based on response and on therapeutic drug monitoring. At the age of 2–6 months, a general guideline based on bodyweight may be used. After 6 months of age, BSA is a good marker as a basis for drug dosing. However, even at this age, drugs that are primarily metabolised by cytochrome P450 2D6 and uridine diphosphate glucuronosyltransferase should be normalised to bodyweight.In the first 2 years of life, the renal excretion rate should be determined by markers of renal function, such as serum creatinine and p-aminohippuric acid clearance. A dosage guideline for drugs that are significantly excreted by the kidney should be based on the determination of renal function in first 2 years of life. After maturation, the dose should be normalised to BSA.These guidelines are intended to be used in clinical practice and to form a basis for more research. The integration of these guidelines, and combining them with pharmacodynamic effects, should be considered and could form a basis for further study.

Antipsychotic Drug Use and Risk of Pneumonia in Elderly People

OBJECTIVES: To investigate the association between antipsychotic drug use and risk of pneumonia in elderly people.

Linking Laboratory and medication data: new opportunities for pharmacoepidemiological research

Abstract Transfer of automated laboratory data collected during routine clinical care from the laboratory information system into a database format that enables linkage to other administrative (e.g., patient characteristics) or clinical (e.g., medication, diagnoses, procedures) data provides a valuable tool for clinical epidemiological research. It allows the investigation of biochemical characteristics of diseases, therapeutic effects and diagnostic and/or prognostic markers for disease with easy access and at relatively low cost. To this end, the Utrecht Patient Oriented Database (UPOD), an infrastructure of relational databases comprising data on patient characteristics, laboratory test results, medication orders, hospital discharge diagnoses and medical procedures for all patients treated at the University Medical Centre Utrecht since January 2004, was established. Current research within UPOD is focused on the innovative linkage of laboratory and medication data, which, for example, makes it possible to assess the quality of pharmacotherapy in clinical practice, to investigate interference between laboratory tests and drugs, to study the risk of adverse drug reactions, and to develop diagnostic and prognostic markers or algorithms for adverse drug reactions. Although recently established, we believe that UPOD broadens the opportunities for clinical pharmacoepidemiological research and can contribute to patient care from a laboratory perspective. Clin Chem Lab Med 2007;45:13–9.

Acceptability of different oral formulations in infants and preschool children

Objective Liquid medicines are easy to swallow. However, they may have disadvantages, such as a bad taste or refrigerated storage conditions. These disadvantages may be avoided by the use of oral solid medicines, such as powders or tablets. The aim of this study was to investigate the acceptability of and preference among four oral formulations in domiciliary infants and preschool children in The Netherlands. Methods Parents administered four oral placebo dosage forms that were aimed at a neutral taste, at home, to their child (1–4 years of age) twice on one day following a randomised cross-over design: small (4 mm) tablet, powder, suspension and syrup. They were asked to report the childs acceptability by a score on a 10 cm visual analogue scale (VAS score) and by the result of the intake. At the end of the study, they were asked to report the preference of the child and themselves. Results 183 children were included and 148 children were evaluated. The data revealed a period/cross-over effect. The estimate of the mean VAS score was significantly higher for the tablet than for the suspension (tablet 9.39/9.01; powder 8.84/8.20, suspension 8.26/7.90, syrup 8.35/8.19; data day 1/all days). The estimate of the mean number of intakes fully swallowed was significantly higher for the tablet than for the other formulations (all p values <0.05). Children and parents preferred the tablet and syrup over the suspension and the suspension over the powder (all p values <0.05). Conclusions All formulations were well accepted. The tablets were the best accepted formulation; the tablets and syrup the most preferred. Trial Registration number ISRCTN63138435.

Effect of Cytochrome P450 2D6 Genotype on Maternal Paroxetine Plasma Concentrations during Pregnancy

Background and ObjectiveIncreasing numbers of women in childbearing years are treated with antidepressants. Concerns regarding fetal exposure to medication has led to large studies on drug effects on birth outcome and on the risk of congenital anomalies. The risk of adverse effects due to paroxetine use during pregnancy has been associated with the extent of exposure. Nevertheless, few studies have covered dosing aspects in order to minimize fetal antidepressant exposure while limiting the risk of treatment failure. Essential pharmacokinetic data in pregnancy are lacking, even regarding paroxetine, one of the most commonly used antidepressants. We examined the changes of maternal paroxetine concentrations during pregnancy in relation to cytochrome P450 (CYP) 2D6 genotype.MethodAn observational cohort study was conducted in 74 pregnant women aged from 25 to 45 years treated with paroxetine during pregnancy. Blood samples and information on dosing, weight, smoking and mood were provided at 16–20, 27–31 and 36–40 weeks of pregnancy. Samples were analysed for paroxetine plasma concentrations and CYP2D6 genotype.ResultsWomen who were genotyped as extensive metabolizers (EMs) or ultra-rapid metabolizers (UMs) for CYP2D6 (EM n = 43; UM n=1) showed steadily decreasing plasma paroxetine concentrations during the course of pregnancy, with a decrease of 0.3 µg/L (95% CI −0.58, −0.07) for each week of pregnancy. In contrast, plasma paroxetine concentrations of intermediate metabolizers (IMs [n = 25]) and poor metabolizers (PMs [n = 5]) increased during pregnancy, resulting in an increase of 0.82 µg/L (95% CI 0.42, 1.22) for each week of pregnancy. Weight gain, maternal age or smoking did not influence plasma drug concentrations. Decreasing plasma concentrations in EMs are in accordance with induced CYP2D6 activity during pregnancy. Accumulation of paroxetine in women with impaired CYP2D6 metabolism may be explained by competition with an endogenous substrate. In EMs/UMs the depressive symptoms increased significantly during the course of pregnancy, while in the IM/PM group these did not change.ConclusionsDifferences in CYP2D6 genotype may have divergent effects on maternal plasma paroxetine concentrations during pregnancy, with therapeutic consequences. Accumulation of paroxetine in a considerable group of pregnant women will lead to unintended increased exposure of paroxetine to the unborn child. Knowledge about a patient’s CYP2D6 genotype is indispensable when prescribing paroxetine in pregnancy [trialregister.nl Identifier ISRCTN25383361].

Drug-induced thrombocytopenia: a population study.

AbstractBackground: Drug-induced immune thrombocytopenia, excluding heparin-induced thrombocytopenia, is a rare adverse drug reaction for which the evidence about frequency, relative risk and risk factors mainly originates from case reports and case studies. This study aims to quantify the risk for thrombocytopenia following exposure to drugs that are most often reported to cause thrombocytopenia in the general population. Methods: A retrospective, case-control study was conducted within the PHARMO record linkage system. Cases were defined as patients hospitalised for thrombocytopenia in the period 1 January 1990 to 31 December 2002. For each case, up to four controls were matched based on age, sex and geographical area. Exposure on the index date to anticonvulsants, β-lactam antibacterials, cinchona alkaloids, disease modifying antirheumatic drugs (DMARDs), diuretics, NSAIDs, sulfonamide antibacterials and tuberculostatics was assessed and categorised into mutually exclusive groups of current, recent, past and non-use. The risk was quantified with multivariate conditional logistic regression analysis. Results: The study population comprised 705 cases and 2658 controls. Current use of β-lactam antibacterials was associated with an increased risk for thrombocytopenia (adjusted odds ratio 7.4, 95% CI 1.8, 29.6). Increased risk estimates, although not significant, were found for current exposure to DMARDs and the sulfonamide antibacterial cotrimoxazole (trimethoprim/sulfamethoxazole). No increased risk was found for anticonvulsants, cinchona alkaloids, diuretics, NSAIDs or tuberculostatics. Conclusion: More evidence for an increased risk for thrombocytopenia in current use of β-lactam antibacterials in the general population was provided. The expected increase in risk could not be confirmed for the other drugs investigated, which is possibly a result of the limited statistical power. Future studies including more patients and with laboratory data should confirm our findings before drawing definite conclusions.

The availability and age‐appropriateness of medicines authorized for children in the Netherlands

AIM To study the number of medicines and active chemical entities that are authorized and commercially available for children in the Netherlands and to evaluate the age-appropriateness of the available paediatric medicines. METHODS The availability of paediatric medicines and active chemical entities was studied with the help of a Dutch medicines database and the Summary of Product Characteristics. Medicines were categorized with respect to their route of administration, type of oral dosage form and therapeutic category. The age-appropriateness was assessed on three aspects: dose capability, suitability of the dosage form and inclusion of potentially harmful excipients. RESULTS Three thousand five hundred and forty-two paediatric medicines containing 703 different active chemical entities were identified. This equalled half of all the medicines and chemical entities available for human use. The percentage of paediatric medicines increased with age and varied for the route of administration from 22% (dermal) to 81% (inhalation) and for the therapeutic category from 11% (uro-genital, sex hormones) to 89% (anti-parasites). The appropriateness of the paediatric medicines with respect to their authorization status, dose capability and dosage form increased with age from 27-88%. Fifty-two percent of all oral paediatric liquid formulations contained a potentially harmful excipient. CONCLUSION This study confirms the limited availability of paediatric medicines for a broad range of therapeutic areas and shows that paediatric medicines may not be age-appropriate, even if authorized. While confirming the need for a legislative incentive, the results also provide baseline information for an estimation of the effect of the European Paediatric Regulation in the near future.

Effects of the Pharmaceutical Technologic Aspects of Oral Pediatric Drugs on Patient-Related Outcomes: A Systematic Literature Review

BACKGROUND In view of the high rates of off-label and unlicensed prescribing of drugs in children, the US Food and Drug Administration and the European Union have implemented legislative regulations for the pharmaceutical industry to increase the number of drugs with approved pediatric labeling. However, the extent to which the effects of pharmaceutical technologic aspects of pediatric oral drugs (eg, taste, route and frequency of administration, user instructions) on patient-related outcomes (eg, efficacy, tolerability, preference, adherence) can be based on clinical evidence from the available literature is unknown. OBJECTIVE This systematic literature review aimed to identify the nature, volume, and quality of comparative studies that have assessed the effects of pharmaceutical technologic aspects of oral pediatric drugs on patient-related outcomes. METHODS The Cochrane, EMBASE, and MEDLINE databases were searched from their start through December 31, 2009. Studies were eligible for inclusion if they were published in English; included search terms for child, study design, medicine, formulation aspects, dosage form, routes of administration, patient acceptance, adherence, side effects and tolerability, and/or efficacy; reported on > or = 10 children aged 0 to <18 years; and described the effects of > or = 1 of 3 pharmaceutical technologic aspects of an oral pediatric drug (formulation and dosage form; route and frequency of administration; and/or packaging, administration device, and user instruction) on > or = 1 of 6 patient-related outcomes (clinical efficacy, side effects and tolerability, patient preference, patient acceptance, administration errors, and/or adherence). Studies were excluded if they concerned a nonallopathic drug (ie, homeopathic remedy, anthroposophic drug, herbal supplement, or food supplement); related to asthma (because modern asthma treatment protocols strongly favor the use of drug inhalation above oral medication); and/or related to analgesics. The characteristics of each of the included publications were assessed with respect to pharmaceutical technologic aspect studied; patient-related outcomes studied; pharmacotherapeutic indication; year of publication; geographic location; number and age of the included subjects; and sponsorship by industry and/or author affiliation with the pharmaceutical industry. The electronic search was supplemented with a manual search of the cited references. RESULTS Ninety-four publications were identified as eligible for inclusion. These publications reported on 176 assessments of the effects of > or = 1 pharmaceutical technologic aspect on > or = 1 patient-related outcome. Fifty-five percent of the studies were conducted in children aged 2 or 3 years, and 69% in children aged 4 or 5 years. Forty-three percent of the publications included > or = 100 patients. Fifty-one percent of the studies were conducted in the United States or Canada, and 29% in Europe. Antibacterials for systemic use were the subject of 30% of the included publications. Two of the 94 publications were of appropriate methodologic quality (Jadad score > or = 4). Forty-nine percent of the studies were sponsored by the pharmaceutical industry or were written by > or = 1 author affiliated with the industry. Sixty-eight percent of the included studies had Jadad scores of 0 or 1 (poor quality). The proportion of industry-sponsored or industry-authored studies with a Jadad score > or = 2 or in > or = 100 children was not significantly different from that of non-industry-sponsored or-authored studies. The proportion of industry-sponsored or industry-authored studies conducted in the United States/Canada (48 [51%]) was not significantly different from that of studies conducted elsewhere (46 [49%]). The distribution of technologic aspects assessed in the included studies were formulation and dosage form, 48%; route and frequency of administration, 44%; and packaging, administration device, and user instruction, 8%. Seventy-six assessments included > or = 100 patients. Twenty-one of these assessments addressed patient acceptance or patient preference; 17, clinical efficacy; and 14, side effects and tolerability. CONCLUSIONS This systematic review identified 94 articles on oral drugs for use in children and adolescents, which reported on a total 176 assessments of the effects of 3 pharmaceutical technologic aspects (formulation and dosage form; route and frequency of administration; and packaging, administration device, and user instruction) on 6 patient-related outcomes (clinical efficacy, side effects and tolerability, patient preference, patient acceptance, administration errors, and adherence). Only 2 of the 94 publications were of appropriate methodologic quality. These results suggest that published clinical evidence to support pharmaceutical development programs is limited.

Once-daily versus multiple-daily gentamicin in infants and children.

In this prospective randomized trial, the efficacy and safety of once-daily administration of gentamicin were compared with multiple-daily administration in infants and children. In addition, pharmacokinetic variables were calculated. Gentamicin therapy was started at a dose of 5 mg/kg per day under individual dose or dosage interval adjustments to achieve target levels. Fifty-two infants and children aged 1 month (postterm) to 16 years were enrolled. The duration of fever from the start of therapy, the percentage decline of C-reactive protein (CRP) on day 3 of treatment, and the clinical outcome were used as efficacy parameters. Nephrotoxicity was evaluated using creatinine serum levels. Basic characteristics in both groups were comparable. A good clinical response was observed in both groups. Fever may have resolved faster with multiple-daily administration, but this was not statistically significant. The percentage of decline of CRP was also comparable in both groups. Nephrotoxicity occurred in six patients, three per group. Many patients were too ill or too young to perform hearing tests, but no clinical signs of ototoxicity were observed. Mean doses of 6.8 mg/kg per day (multiple-daily administration) and 7.3 mg/kg per day (once-daily administration) were necessary to meet the target gentamicin levels. Triple-daily doses had to be reduced to a twice-daily regimen in 17 of 26 children. Dose and dosage interval adaptations can be performed by Bayesian forecasting using a one-compartment model with one set of K e and V d parameters. The authors consider both regimens equally effective, with a comparable incidence of nephrotoxicity. A starting dose of 6.5 mg/kg once daily is advised.

Methods of administering oral formulations and child acceptability

INTRODUCTION Children may be unable or unwilling to swallow medicines. In order to avoid or accommodate any such problems, parents may decide to administer medicines other than intended. The aim of this study was to investigate how parents administered four oral placebo formulations to infants and preschool children and how the applied methods correlated with child acceptability. METHODS Parents were asked to administer a 4 mm mini-tablet, powder, suspension and syrup to their child twice on one day and to report the child characteristics and administration details in a participant diary. RESULTS A 151 children were included. The tablet, syrup and suspension were mostly given on their own, whereas the powder was commonly given with food or drink. Generally, the higher the child acceptability (VAS-score) of the first administration of a specific formulation, the less frequently its method of administration was changed. A change in the method of administration of the same formulation involving (a larger quantity of) food or drink generally resulted in a higher VAS-score. CONCLUSIONS The joint administration of medicines with food or drink is an effective strategy to ensure swallowing. This study supports earlier findings that 4mm mini-tablets are a suitable dosage form from infant age.