Unlicensed and off-label drug use in children: implications for safety

A Comprehensive Physiologically Based Pharmacokinetic Model of Nadolol in Adults with Renal Disease and Pediatrics with Supraventricular Tachycardia

Nadolol is a long-acting non-selective β-adrenergic antagonist that helps treat angina and hypertension. The current study aimed to develop and validate the physiologically based pharmacokinetic model (PBPK) of nadolol in healthy adults, renal-compromised, and pediatric populations. A comprehensive PBPK model was established by utilizing a PK-Sim simulator. After establishing and validating the model in healthy adults, pathophysiological changes i.e., blood flow, hematocrit, and GFR that occur in renal failure were incorporated in the developed model, and the drug exposure was assessed through Box plots. The pediatric model was also developed and evaluated by considering the renal maturation process. The validation of the models was carried out by visual predictive checks, calculating predicted to observed (Rpre/obs) and the average fold error (AFE) of PK parameters i.e., the area under the concentration-time curve (AUC0-t), the maximum concentration in plasma (Cmax), and CL (clearance). The presented PBPK model successfully simulates the nadolol PK in healthy adults, renal-impaired, and pediatric populations, as the Rpre/obs values of all PK parameters fall within the acceptable range. The established PBPK model can be useful in nadolol dose optimization in patients with renal failure and children with supraventricular tachycardia.

The Potential Impact of Preemptive Pharmacogenetic Genotyping in the Neonatal Intensive Care Unit

OBJECTIVE

To evaluate the use of drugs with pharmacogenomic (PGx) guidelines from the Clinical Pharmacogenetics Implementation Consortium in early childhood.

STUDY DESIGN

A retrospective observational study of patients admitted to the neonatal intensive care (NICU) between 2005 and 2018 with at least 1 subsequent hospitalization at or after 5 years of age was performed to determine PGx drug exposure. Data regarding hospitalizations, drug exposures, gestational age, birth weight, and congenital anomalies and/or a primary genetic diagnosis were collected. Incidence of PGx drug and drug class exposures was determined and patient specific factors predictive of exposure were investigated.

RESULTS

During the study, 19 195 patients received NICU care and 4196 (22%) met study inclusion; 67% received 1-2, 28% 3-4, and 5% 5 or more PGx-drugs in early childhood. Preterm gestation, low birth weight (<2500 g), and the presence of any congenital anomalies and/or a primary genetic diagnosis were statistically significant predictors of Clinical Pharmacogenetics Implementation Consortium drug exposures (P < .01, P < .01, P < .01, respectively).

CONCLUSIONS

Preemptive PGx testing in patients in the NICU could have a significant impact on medical management during the NICU stay and throughout early childhood.

Predictive Models for Human Cytochrome P450 3A7 Selective Inhibitors and Substrates

Inappropriate use of prescription drugs is potentially more harmful in fetuses/neonates than in adults. Cytochrome P450 (CYP) 3A subfamily undergoes developmental changes in expression, such as a transition from CYP3A7 to CYP3A4 shortly after birth, which provides a potential way to distinguish medication effects on fetuses/neonates and adults. The purpose of this study was to build first-in-class predictive models for both inhibitors and substrates of CYP3A7/CYP3A4 using chemical structure analysis. Three metrics were used to evaluate model performance: area under the receiver operating characteristic curve (AUC-ROC), balanced accuracy (BA), and Matthews correlation coefficient (MCC). The performance varied for each CYP3A7/CYP3A4 inhibitor/substrate model depending on the data set type, model type, rebalancing method, and specific feature set. For the active inhibitor/substrate data set, the optimal models achieved AUC-ROC values ranging from 0.77 ± 0.01 to 0.84 ± 0.01. For the selective inhibitor/substrate data set, the optimal models achieved AUC-ROC values ranging from 0.72 ± 0.02 to 0.79 ± 0.04. The predictive power of the optimal models was validated by compounds with known potencies as CYP3A7/CYP3A4 inhibitors or substrates. In addition, we identified structural features significant for CYP3A7/CYP3A4 selective or common inhibitors and substrates. In summary, the top performing models can be further applied as a tool to rapidly evaluate the safety and efficacy of new drugs separately for fetuses/neonates and adults. The significant structural features could guide the design of new therapeutic drugs as well as aid in the optimization of existing medicine for fetuses/neonates.

The facial nerve palsy and cortisone evaluation (FACE) study in children: protocol for a randomized, placebo-controlled, multicenter trial, in a Borrelia burgdorferi endemic area

Background

Children with acute peripheral facial nerve palsy cannot yet be recommended corticosteroid treatment based on evidence. Adults with idiopathic facial nerve palsy are treated with corticosteroids, according to guidelines resulting from a meta-analysis comprising two major randomized placebo-controlled trials. Corresponding trials in children are lacking. Furthermore, acute facial nerve palsy in childhood is frequently associated with Lyme neuroborreliosis, caused by the spirochete Borrelia burgdorferi. The efficacy and safety of corticosteroid treatment of acute facial nerve palsy associated with Lyme neuroborreliosis, has not yet been determined in prospective trials in children, nor in adults.

Method

This randomized double-blind, placebo-controlled study will include a total of 500 Swedish children aged 1–17 years, presenting with acute facial nerve palsy of either idiopathic etiology or associated with Lyme neuroborreliosis. Inclusion is ongoing at 12 pediatric departments, all situated in Borrelia burgdorferi endemic areas. Participants are randomized into active treatment with prednisolone 1 mg/kg/day (maximum 50 mg/day) or placebo for oral intake once daily during 10 days without taper. Cases associated with Lyme neuroborreliosis are treated with antibiotics in addition to the study treatment. The House-Brackmann grading scale and the Sunnybrook facial grading system are used for physician-assessed evaluation of facial impairment at baseline, and at the 1- and 12-month follow-ups. Primary outcome is complete recovery, measured by House-Brackmann grading scale, at the 12-month follow-up. Child/parent-assessed questionnaires are used for evaluation of disease-specific quality of life and facial disability and its correlation to physician-assessed facial impairment will be evaluated. Furthermore, the study will evaluate factors of importance for predicting recovery, as well as the safety profile for short-term prednisolone treatment in children with acute facial nerve palsy.

Discussion

This article presents the rationale, design and content of a protocol for a study that will determine the efficacy of corticosteroid treatment in children with acute facial nerve palsy of idiopathic etiology, or associated with Lyme neuroborreliosis. Future results will attribute to evidence-based treatment guidelines applicable also in Borrelia burgdorferi endemic areas.

Trial registration

The study protocol was approved by the Swedish Medical Product Agency (EudraCT nr 2017–004187-35) and published at ClinicalTrials.gov (NCT03781700, initial release 12/14/2018).

Off-label Use in Ambulatory Paediatric Clinics in a Central South African Hospital

AIM

The aim of this article was to determine off-label (OL) use in paediatric ambulatory clinics in a South African central hospital.

PATIENTS AND METHODS

OL medicine events were documented in three paediatric clinics (general, highly specialized and dedicated HIV paediatric clinics) at Tygerberg Hospital, South Africa, and analysed according to South African medicine registration information.

RESULTS

There were 2167 medicine events for 658 children. Mean age was 5.6 years (interquartile range 1.8-8.8). There were 123 OL medicine events (6%). Extemporaneous OL use was most common (n = 58, 47%), followed by weight (n = 45, 37%) and lack of paediatric data (n = 38, 31%). Of note was OL use for weight for general paediatrics (n = 32, 78%, p < 0.001), lack of appropriate paediatric data for highly specialized paediatrics (n = 26, 61%, p = 0.004) and extemporaneous use for HIV-infected children (n = 34, 87%, p < 0.001), with significant less OL use for HIV-infected children (p = 0.009).

CONCLUSIONS

Of note is significant extemporaneous OL use in HIV-infected children.

Pharmacokinetics of rivaroxaban in children using physiologically based and population pharmacokinetic modelling: an EINSTEIN-Jr phase I study

BACKGROUND

The EINSTEIN-Jr program will evaluate rivaroxaban for the treatment of venous thromboembolism (VTE) in children, targeting exposures similar to the 20 mg once-daily dose for adults. A physiologically based pharmacokinetic (PBPK) model for pediatric rivaroxaban dosing has been constructed.

METHODS

We quantitatively assessed the pharmacokinetics (PK) of a single rivaroxaban dose in children using population pharmacokinetic (PopPK) modelling and assessed the applicability of the PBPK model. Plasma concentration-time data from the EINSTEIN-Jr phase I study were analysed by non-compartmental and PopPK analyses and compared with the predictions of the PBPK model. Two rivaroxaban dose levels, equivalent to adult doses of rivaroxaban 10 mg and 20 mg, and two different formulations (tablet and oral suspension) were tested in children aged 0.5-18 years who had completed treatment for VTE.

RESULTS

PK data from 59 children were obtained. The observed plasma concentration-time profiles in all subjects were mostly within the 90% prediction interval, irrespective of dose or formulation. The PopPK estimates and non-compartmental analysis-derived PK parameters (in children aged ≥6 years) were in good agreement with the PBPK model predictions.

CONCLUSIONS

These results confirmed the applicability of the rivaroxaban pediatric PBPK model in the pediatric population aged 0.5-18 years, which in combination with the PopPK model, will be further used to guide dose selection for the treatment of VTE with rivaroxaban in EINSTEIN-Jr phase II and III studies.

TRIAL REGISTRATION

ClinicalTrials.gov number, NCT01145859; registration date: 17 June 2010.

Validity of mobile electronic data capture in clinical studies: a pilot study in a pediatric population

BACKGROUND

Clinical studies in children are necessary yet conducting multiple visits at study centers remains challenging. The success of "care-at-home" initiatives and remote clinical trials suggests their potential to facilitate conduct of pediatric studies. This pilot aimed to study the feasibility of remotely collecting valid (i.e. complete and correct) saliva samples and clinical data utilizing mobile technology.

METHODS

Single-center, prospective pilot study in children undergoing elective tonsillectomy at the University of Basel Children's Hospital. Data on pain scores and concomitant medication and saliva samples were collected by caregivers on two to four inpatient study days and on three consecutive study days at home. A tailored mobile application developed for this study supported data collection. The primary endpoint was the proportion of complete and correct caregiver-collected data (pain scale) and saliva samples in the at-home setting. Secondary endpoints included the proportion of complete and correct saliva samples in the inpatient setting, subjective feasibility for caregivers, and study cost.

RESULTS

A total number of 23 children were included in the study of which 17 children, median age 6.0 years (IQR 5.0, 7.4), completed the study. During the at-home phase, 71.9% [CI = 64.4, 78.6] of all caregiver-collected pain assessments and 53.9% [CI = 44.2, 63.4] of all saliva samples were complete and correct. Overall, 64.7% [CI = 58.7, 70.4] of all data collected by caregivers at home was complete and correct. The predominant reason for incorrectness of data was adherence to the timing of predefined patient actions. Participating caregivers reported high levels of satisfaction and willingness to participate in similar trials in the future. Study costs for a potential sample size of 100 patients were calculated to be 20% lower for the at-home than for a traditional in-patient study setting.

CONCLUSIONS

Mobile device supported studies conducted at home may provide a cost-effective approach to facilitate conduct of clinical studies in children. Given findings in this pilot study, data collection at home may focus on electronic data capture rather than biological sampling.

Hospital pharmacists' perceived beliefs and responsibilities in indication-based off-label prescribing

Background Off-label prescribing is prevalent in healthcare. There is a lack of understanding of pharmacists' attitudes toward the practice of off-label prescribing, especially those that are prescribed for other indications than approved ones (termed as indication-based off-label prescribing). Objective Explore hospital pharmacists' attitudes toward and perceived responsibility in off-label and indication-based off-label prescribing in hospital pharmacy practice. Setting Pharmacists practicing in hospitals in the United States were investigated. Method Pharmacists were contacted via email through State affiliates of the American Society of Health-System Pharmacist. The survey described an indication-based off-label medication order for a hospitalized patient and the prescribing physician. Data were collected via Qualtrics. Main outcome measure Questions focused on awareness, beliefs, and responsibility-including, risk assessment and monitoring outcomes-related to off-label and indication-based offlabel prescribing. Results Of 107 pharmacist respondents, about 79% and 98% reported being familiar with offlabel and indication-based off-label prescribing, respectively. While 77.6% pharmacists believed that patients should be informed, only 37.4% agreed that they had responsibility of informing physicians; presence of policy was associated (p < 0.02) with pharmacist agreeing to inform physicians. Over 70% agreed that patients should be closely monitored for outcomes and 43.1% believed physicians had predominant responsibility of monitoring outcomes. Conclusion Pharmacists' perceived responsibility and beliefs regarding off-label prescribing are insightful that can be utilized for improving patient care.

Dose-Banding of Intravenous Piperacillin-Tazobactam in Pediatric Surgical Inpatients

BACKGROUND

Antimicrobial doses in children are often prescribed by using an individually calculated dose per weight (e.g., mg/kg) or based on body surface area. Dosing errors are the most commonly reported medication errors in children. A "dose-banding" strategy is frequently used for some over-the-counter drugs to prevent dosing errors. It could also lead to efficiencies by enabling batch preparation of intravenous (IV) medications in hospitals.

OBJECTIVES

To evaluate whether use of dose-banding for IV piperacillin-tazobactam results in acceptable dose variation from standard practice of individualized prescription of 100 mg/kg in children.

METHODS

We conducted a historically controlled intervention study comparing prescriptions of IV piperacillin-tazobactam before vs. after introduction of dose-banding prescribing guidance for surgical inpatients weighing >5 kg and <16 years of age at the tertiary referral pediatric hospital in Western Australia.

RESULTS

Dose-banding of IV piperacillin-tazobactam (with a maximum of 15% departure from the recommended milligram-per-weight dose of 100 mg/kg) resulted in similar overall variation of prescribed dose in comparison to individualized milligram-per-weight (non-dose-banded) prescribing. There was a trend toward fewer prescriptions with large variance (>30% variation from the 100-mg/kg dose) in the dose-banded compared to the non-dose-banded group (1/140 vs. 5/105; p = 0.09).

CONCLUSIONS

Our study showed dose-banding of IV piperacillin-tazobactam resulted in acceptable variation when compared to individualized milligram-per-weight dosing in children. Prospectively designed controlled trials are warranted to determine whether dose-banding could reduce medication errors and optimize use of hospital resources. Implications for future practice could include faster batch preparation, shorter checking and dispensing time, and reduction in drug wastage.

Recommended strategies for the oral administration of paediatric medicines with food and drinks in the context of their biopharmaceutical properties: a review

OBJECTIVES

This review focuses on the recommended strategies for the oral administration of paediatric medicines with food in the context of their biopharmaceutical properties.

KEY FINDINGS

Acceptability of oral medicines in young patients is more challenging than in adult patients. Mixing oral dosage forms with foods and drinks is sometimes suggested to administer a specific dose and enhance compliance in the paediatric population. In this review, the strategies for the co-administration of paediatric medicines with food and drinks are discussed. Current administration practices as reported by healthcare professionals and parents/carers are compared with the relevant guidelines. Differences in the type of vehicles recommended to be used and actually used in current practice were identified. Correlations of the type of food recommended, the type of formulation and the drug's biopharmaceutical classification system (BCS) class were performed and revealed that recommendations should be made on a case-by-case basis.

SUMMARY

The propensity for physiochemical or bioavailability changes that may occur from the co-administration of medicines with food and drinks in the paediatric population should be considered, and harmonisation of the recommended administration strategies is needed.

Off-label use and harmful potential of drugs in a NICU in Brazil: A descriptive study

Background

Neonates admitted to neonatal intensive care units (NICU) are exposed to a wide variety of drugs, most without any data on safety and efficacy. Objective: To describe the drugs prescribed to different groups of neonates hospitalized in a NICU, and to analyze off-label use and harmful potential of drugs, in terms of the potential risks.

Methods

This was a six-month retrospective cohort study of drug use in a NICU, with neonates who were inpatients for a period of over 24 hours, and using prescription data from electronic medical records. Drug information found in the package leaflets, in the British National Formulary for Children 2012–2013, and in the Thomson Micromedex database were compared. Drugs and excipients considered potentially harmful were evaluated according to the literature.

Results

One hundred ninety-two neonates were included in the study, with a mean gestational age (GA) of 33.3 weeks (SD ± 4.3), 75.0 % were preterm, with an average of 18.8 days of hospitalization (SD ± 18.1), and a total of 3617 neonates-day. 3290 prescriptions were registered, on average 17.1 prescriptions/neonate (SD ± 17.9) and 8.8 drugs/neonate (SD ± 5.9). The number of prescriptions and drugs was higher in neonates with GA <31 weeks (p <0.05). Anti-infectives for systemic use, blood, alimentary tract and metabolism drug groups were more frequent, varying according to the GA. Neonates (99.5 %) were exposed to unlicensed drugs (UL) and off label use (OL), more frequently in GA <28 weeks (p <0.05). Most OL drugs used were indicated for newborns. 15 potentially harmful drugs were used in more than 70 % of the neonates, and most were OL; exposure to harmful excipients occurred in 91.6 % of the neonates, a percentage even higher when considering immature neonates.

Conclusions

Immature neonates in a Brazilian NICU are exposed to a variety of OL, UL and potentially harmful drugs and excipients.

Pediatric drug safety signal detection: a new drug-event reference set for performance testing of data-mining methods and systems

BACKGROUND

Better evidence regarding drug safety in the pediatric population might be generated from existing data sources such as spontaneous reporting systems and electronic healthcare records. The Global Research in Paediatrics (GRiP)-Network of Excellence aims to develop pediatric-specific methods that can be applied to these data sources. A reference set of positive and negative drug-event associations is required.

OBJECTIVE

The aim of this study was to develop a pediatric-specific reference set of positive and negative drug-event associations.

METHODS

Considering user patterns and expert opinion, 16 drugs that are used in individuals aged 0-18 years were selected and evaluated against 16 events, regarded as important safety outcomes. A cross-table of unique drug-event pairs was created. Each pair was classified as potential positive or negative control based on information from the drug's Summary of Product Characteristics and Micromedex. If both information sources consistently listed the event as an adverse event, the combination was reviewed as potential positive control. If both did not, the combination was evaluated as potential negative control. Further evaluation was based on published literature.

RESULTS

Selected drugs include ibuprofen, flucloxacillin, domperidone, methylphenidate, montelukast, quinine, and cyproterone/ethinylestradiol. Selected events include bullous eruption, aplastic anemia, ventricular arrhythmia, sudden death, acute kidney injury, psychosis, and seizure. Altogether, 256 unique combinations were reviewed, yielding 37 positive (17 with evidence from the pediatric population and 20 with evidence from adults only) and 90 negative control pairs, with the remainder being unclassifiable.

CONCLUSION

We propose a drug-event reference set that can be used to compare different signal detection methods in the pediatric population.

Development of a paediatric population-based model of the pharmacokinetics of rivaroxaban

Background

Venous thromboembolism has been increasingly recognised as a clinical problem in the paediatric population. Guideline recommendations for antithrombotic therapy in paediatric patients are based mainly on extrapolation from adult clinical trial data, owing to the limited number of clinical trials in paediatric populations. The oral, direct Factor Xa inhibitor rivaroxaban has been approved in adult patients for several thromboembolic disorders, and its well-defined pharmacokinetic and pharmacodynamic characteristics and efficacy and safety profiles in adults warrant further investigation of this agent in the paediatric population.

Objective

The objective of this study was to develop and qualify a physiologically based pharmacokinetic (PBPK) model for rivaroxaban doses of 10 and 20 mg in adults and to scale this model to the paediatric population (0–18 years) to inform the dosing regimen for a clinical study of rivaroxaban in paediatric patients.

Methods

Experimental data sets from phase I studies supported the development and qualification of an adult PBPK model. This adult PBPK model was then scaled to the paediatric population by including anthropometric and physiological information, age-dependent clearance and age-dependent protein binding. The pharmacokinetic properties of rivaroxaban in virtual populations of children were simulated for two body weight-related dosing regimens equivalent to 10 and 20 mg once daily in adults. The quality of the model was judged by means of a visual predictive check. Subsequently, paediatric simulations of the area under the plasma concentration–time curve (AUC), maximum (peak) plasma drug concentration (C_max) and concentration in plasma after 24 h (C_24h) were compared with the adult reference simulations.

Results

Simulations for AUC, C_max and C_24h throughout the investigated age range largely overlapped with values obtained for the corresponding dose in the adult reference simulation for both body weight-related dosing regimens. However, pharmacokinetic values in infants and preschool children (body weight <40 kg) were lower than the 90 % confidence interval threshold of the adult reference model and, therefore, indicated that doses in these groups may need to be increased to achieve the same plasma levels as in adults. For children with body weight between 40 and 70 kg, simulated plasma pharmacokinetic parameters (C_max, C_24h and AUC) overlapped with the values obtained in the corresponding adult reference simulation, indicating that body weight-related exposure was similar between these children and adults. In adolescents of >70 kg body weight, the simulated 90 % prediction interval values of AUC and C_24h were much higher than the 90 % confidence interval of the adult reference population, owing to the weight-based simulation approach, but for these patients rivaroxaban would be administered at adult fixed doses of 10 and 20 mg.

Conclusion

The paediatric PBPK model developed here allowed an exploratory analysis of the pharmacokinetics of rivaroxaban in children to inform the dosing regimen for a clinical study in paediatric patients.

Electronic supplementary material

The online version of this article (doi:10.1007/s40262-013-0090-5) contains supplementary material, which is available to authorized users.

NIHR Medicines for Children Research Network: improving children's health through clinical research

The need to evaluate medicines for children is widely acknowledged due to pervasive unlicensed medicine use in the pediatric setting. The EU Paediatric Regulation was developed to address these considerations, which subsequently led to the establishment of the National Institute of Health Research (NIHR) Medicines for Children Research Network (MCRN) in England. MCRN supports public and industry studies, and facilitates feasibility, site setup, recruitment and other services. The MCRN and other networks are members of the European Network of Paediatric Research at the European Medicines Agency (Enpr-EMA). Enpr-EMA was established to foster and coordinate research, and develop collaborations across Europe. MCRN works with Enpr-EMA, industry and others to improve the conduct of research for the benefit of children's health.

Off-label medicine use in children and adolescents: results of a population-based study in Germany

Background

Population-based self-reported data on off-label medicine use independent from health care provisions are lacking. The purpose of this study is to investigate off-label medicine use in children and adolescents in Germany in a non-clinical setting and to identify prevalence, determinants and spectrum of off-label medicine use.

Methods

Data were obtained from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) conducted by the Robert Koch Institute (2003–2006). 17,450 randomly selected children aged 0–17 years took part in the drug interviews. Of those, 8,899 took at least one medicine during the 7 days preceding the interview. Off-label medicine use was defined as the discrepancy between actual use and the intended use described in the summary of product characteristics. Off-label medicine use was stratified into off-label indication, off-label age, off-label over-dosing, and off-label under-dosing.

Results

The prevalence rate of off-label medicine use among those who used medicines amount of is 40.2%. The prevalence rate is significantly higher in boys (41.4%), in children aged 3 to 6 years (48.7%), without migration background (40.9%), with high social status (42.5%), living in small (42.0%) and medium sized cities (41.6%), and with a poor parents rated health status (41.7%). 12,667 preparations (attributable in respect to off-label use) were taken by 8,899 children. 30% of the medicines have been used off-label. Off-label medicine use was highest in preparations of the ATC-class “C00 Cardiovascular System”. In all origins of medicine, all age groups and all ATC-classes under-dosing was the most frequent reason for off-label medicine use.

Conclusions

There is a considerable level of self-reported off-label medicines use in the general paediatric population. Further investigations are needed to examine in how far off-label medicine use is based on lack of knowledge or on empiricism in paediatric pharmacotherapy. Attention also needs to be paid to under-dosing which potentially exposes drug users to risks of side effects without the benefit of a therapeutic effect. Clinical trials for licensing of paediatric medicines, education of health care professionals, but also of parents and carers are needed to ensure the rational use of medicines.

Population pharmacokinetics of piperacillin using scavenged samples from preterm infants

OBJECTIVES

Piperacillin is often used in preterm infants for intra-abdominal infections; however, dosing has been derived from small single-center studies excluding extremely preterm infants at a highest risk for these infections. We evaluated the population pharmacokinetics (PK) of piperacillin using targeted sparse sampling and scavenged samples obtained from preterm infants ≤ 32 weeks of gestational age at birth and <120 postnatal days.

MATERIALS AND METHODS

A 5-center study was performed. A population PK model using nonlinear mixed effect modeling was developed. Covariate effects were evaluated based on the estimated precision and clinical significance.

RESULTS

Fifty-six preterm infants were evaluated and had a median (range) gestational age at birth of 25 (22-32) weeks, a postnatal age of 17 (1-77) days, a postmenstrual age of 29 (23-40) weeks, and a weight of 867 (400-2580) g. The final PK data set contained 211 samples; 202/211 (96%) were scavenged from the discarded clinical specimens. Piperacillin population PK was best described by a 1-compartment model. The population mean clearance (CL) was derived by the equation CL (L/h) = 0.479 × (weight)(0.75) × 0.5/serum creatinine and using a volume of distribution (V) (L) of 2.91 × (weight). The relative standard errors around parameter estimates ranged from 13.7% to 32.2%. A trend toward increased CL was observed with increasing gestational age at birth; infants with serum creatinine ≥ 1.2 mg/dL had a 60% reduction in piperacillin CL. The majority (>70%) of infants did not meet predefined pharmacodynamic efficacy targets.

CONCLUSIONS

Scavenged PK sampling is a minimal-risk approach that can provide meaningful information related to the development of PK models but not dosing recommendations for piperacillin. The utility of scavenged sampling in providing definitive dosing recommendations may be drug dependent and needs to be further explored.

Patterns of Drug Utilization in a Neonatal Intensive Care Unit

The objective of this study was to determine drug use in newborns at an inborn tertiary care neonatal intensive care unit, serving a predominantly African American population, to identify educational/research priorities in neonatal drug therapy. Data on demographics and exposure rates to all drugs from 6839 neonates born between January 1997 and June 2004 were analyzed. Number of drugs used was correlated with race, gender, gestational age, birthweight, and survival status. The contribution of these factors to mean drug use was predicted by multivariate regression analysis. In this population of 80% African Americans, mean drug use was 3.6/infant, with the highest use in the 24- to 27-week gestational age group (11.7/infant). Ampicillin and cefotaxime had the highest exposure rates. Premature infants had high use of surfactant, pressor agents, and diuretics. Caucasians, males, gestational age<28 weeks, and birthweight<1000 g were the risk factors for higher drug exposure. Future research/education must emphasize these therapeutic areas with priority assigned to low-birthweight infants.

Ethical considerations for pharmacogenomic testing in pediatric clinical care and research

The information gained from pharmacogenomic testing is becoming increasingly recognized as an opportunity to improve our current dosing strategies for children. The identification of gene polymorphisms that influence drug disposition and effect can be used to help predict a child's susceptibility to toxicity and/or response to a particular drug or therapeutic regimen. However, the potential consequences of performing genomic analysis in children raise important ethical considerations. Although the level of risk introduced remains partially hypothetical, awareness of the ethical concerns and protective legislation will be an important part of fully informing patients, families, clinicians, and researchers about the risks and benefits of pharmacogenomic testing in children. Where it can be done without loss of benefit, risk reduction is a moral imperative, and so the ethical complexities related to pharmacogenomics must be addressed in an ongoing way as we continue to learn more about the value of the technology to children.

Innovative clinical trial design for pediatric therapeutics

Until approximately 15 years ago, sponsors rarely included children in the development of therapeutics. US and European legislation has resulted in an increase in the number of pediatric trials and specific label changes and dosing recommendations, although infants remain an understudied group. The lack of clinical trials in children is partly due to specific challenges in conducting trials in this patient population. Therapeutics in special populations, including premature infants, obese children and children receiving extracorporeal life support, are even less studied. National research networks in Europe and the USA are beginning to address some of the gaps in pediatric therapeutics using novel clinical trial designs. Recent innovations in pediatric clinical trial design, including sparse and scavenged sampling, population pharmacokinetic analyses and 'opportunistic' studies, have addressed some of the historical challenges associated with clinical trials in children.

Presentation of the French Network of Paediatric Clinical Investigation Centres (CIC.P)

The network of Paediatric Clinical Investigation Centres (CIC.P) consists of eight research centres integrated into teaching hospitals. They collaborate with all medical and surgical departments, medico-technical departments, INSERM research units, and with university research units. The aims of the network were to conduct paediatric clinical research in the areas of drug evaluation and pathophysiology (primarily growth and neurosciences) and contribute to technical innovations. The CIC.P Network provides support to investigators, from design through the conduct of investigator-initiated or industrially sponsored clinical research protocols. It also provides physicians, pharmacists and nurses with specific training in paediatric clinical research. It has facilities specifically designed for the conduct of research in children. In accordance with Good Clinical Practice (GCP) guidelines, the CIC Network also supports parents and their children during participation in medical research.

Managing the risks of off-licence prescribing in pregnancy

The dearth of randomised controlled trials confirming the efficacy, quality and safety of drugs used in pregnant women means that off-licence prescribing in this vulnerable patient population is commonplace. If a licenced drug harms a patient, the responsibility lies with the manufacturer. When an off-licence drug causes harm, the responsibility lies with the doctor. In theory, a doctor could be exposed to a claim of negligence solely for using an off-licence drug if harm was caused and if a licenced alternative was available. However, it is more likely that a failure to provide adequate information on which a patient can give informed consent will result in litigation. Off-licence prescribing is an important aspect of patient care. However, the doctor must ensure that the patient fully understands the relative risks and benefits of the treatment, what is meant by off-licence drug use, that a licenced alternative is available and the reasons why the particular course of action was chosen. The entire consenting process must be fully documented. Off-licence drugs are frequently given on grounds of cost, but cost constraints are not a defence to a claim of negligence. Sensible prescribing is key to managing the risks of using off-licence drugs. Whenever possible, licenced drugs supported by extensive clinical trial programs undertaken for regulatory approval should be used in preference to off-licence, unproven alternatives, particularly when both are equivalent in efficacy and no additional benefits are associated with use of the off-licence drug. Absence of evidence of harm is not the same as evidence of absence of harm.

Ethical challenges in neonatal research: Summary report of the ethics group of the newborn drug development initiative

BACKGROUND

The Newborn Drug Development Initiative (NDDI) was established to address the lack of substantive data supporting efficacy and safety of drugs in the neonate.

OBJECTIVE

This commentary summarizes some of the ethical issues involved in neonatal drug development.

METHODS

At the NDDI workshop held March 29 and 30, 2004, in Baltimore, Maryland, members of the Ethics Group were dispersed among the subspecialty groups before convening to discuss common ethical themes. The Ethics Group then met together to identify and discuss those ethical themes that were both important and shared among the groups. These themes are discussed and illustrated with the other NDDI group reports. This workshop was cosponsored by the National Institute of Child Health and Human Development and the US Food and Drug Administration.

RESULTS

Neonatal drug research is scientifically and ethically necessary to establish the efficacy and safety of drugs widely used in newborn medicine. However, research involving neonates must be carefully designed to balance potential risks and benefits, with consideration given to the component analysis of risk. The protocols proposed by the NDDI groups would be considered greater than minimal risk and offering prospect for direct benefit, thus adhering to the Department of Health and Human Services' pediatric research regulations (Subpart D). The NDDI groups all proposed randomized controlled clinical trials, with careful attention to scientifically and ethically appropriate control groups. Multiple regulatory bodies have affirmed that in the absence of proven effective treatment or when a proven treatment offers marginal benefits, study designs with placebo controls are ethical. Obtaining parental permission is a complex issue, with a paucity of evidence describing the feasibility of informed and voluntary consent under conditions of duress and a short therapeutic window. The Subpart D regulations offer sufficient protection to critically ill neonates. The application of the revised Subpart B regulations would restrict the use of a waiver of consent for minimal risk research and for emergency research, and would not allow research that offers no direct benefit and no more than a minor increase over minimal risk.

CONCLUSIONS

Multisite collaboration involving standards of care and institutional review board procedures may be important for establishing scientific and ethical consistency. Ongoing dialogue among researchers, clinicians, parents, and other interested parties is essential to promoting ethically and scientifically sound neonatal clinical research.

Off-label prescribing in a French hospital

OBJECTIVE

In contrast to paediatrics patients, data concerning the extent of off-label prescribing for adult patients are limited. The aim of our study was to investigate the frequency of off-label drug use for adult patients in a French general hospital.

METHOD

The study was conducted on a Wednesday in November 2004. Prescribing was prospectively assessed on the basis of conformity with the marketing authorizations.

RESULTS

A total of 1341 prescriptions for 192 hospitalized patients were analysed. Twenty three per cent of the prescriptions were off-label. Among all patients, 70% received at least one off-label medicine. Most off-label prescriptions were related to an unapproved indication (75%). The main other reasons were dosage (14%) and dosing schedule (9%). Anti-thrombotic and anti-ulcer agents were found on more than 40% of the off-label prescriptions.

CONCLUSION

Off-label prescriptions occur frequently in the hospital and often alternatives with the proper marketing authorizations are available. An increased involvement of hospital pharmacists should reduce the incidence of off-label prescribing and thus contribute to patient safety and possibly cost reduction.

A Mechanistic Approach for the Scaling of Clearance in Children

BACKGROUND AND OBJECTIVE

Clearance is an important pharmacokinetic concept for scaling dosage, understanding the risks of drug-drug interactions and environmental risk assessment in children. Accurate clearance scaling to children requires prior knowledge of adult clearance mechanisms and the age-dependence of physiological and enzymatic development. The objective of this research was to develop and evaluate ontogeny models that would provide an assessment of the age-dependence of clearance.

METHODS

Using in vitro data and/or in vivo clearance values for children for eight compounds that are eliminated primarily by one process, models for the ontogeny of renal clearance, cytochrome P450 (CYP) 3A4, CYP2E1, CYP1A2, uridine diphosphate glucuronosyltransferase (UGT) 2B7, UGT1A6, sulfonation and biliary clearance were developed. Resulting ontogeny models were evaluated using six compounds that demonstrated elimination via multiple pathways. The proportion of total clearance attributed to each clearance pathway in adults was delineated. Each pathway was individually scaled to the desired age, inclusive of protein-binding prediction, and summed to generate a total plasma clearance for the child under investigation. The paediatric age range included in the study was premature neonates to sub-adults.

RESULTS

There was excellent correlation between observed and predicted clearances for the model development (R2 = 0.979) and test sets (Q2 = 0.927). Clearance in premature neonates could also be well predicted (development R2 = 0.951; test Q2 = 0.899).

CONCLUSION

Paediatric clinical trial development could greatly benefit from clearance scaling, particularly in guiding dosing regimens. Furthermore, since the proportion of clearance via different elimination pathways is age-dependent, information could be gained on the developmental extent of drug-drug interactions.

Development and Evaluation of a Generic Physiologically Based Pharmacokinetic Model for Children

BACKGROUND

Clinical trials in children are being encouraged by regulatory authorities in light of the immense off-label and unlicensed use of drugs in the paediatric population. The use of in silico techniques for pharmacokinetic prediction will aid in the development of paediatric clinical trials by guiding dosing regimens, ensuring efficient blood sampling times, maximising therapeutic effect and potentially reducing the number of children required for the study. The goal of this study was to extend an existing physiologically based pharmacokinetic (PBPK) model for adults to reflect the age-related physiological changes in children from birth to 18 years of age and, in conjunction with a previously developed age-specific clearance model, to evaluate the accuracy of the paediatric PBPK model to predict paediatric plasma profiles.

METHODS

The age-dependence of bodyweight, height, organ weights, blood flows, interstitial space and vascular space were taken from the literature. Physiological parameters that were used in the PBPK model were checked against literature values to ensure consistency. These included cardiac output, portal vein flow, extracellular water, total body water, lipid and protein. Five model compounds (paracetamol [acetaminophen], alfentanil, morphine, theophylline and levofloxacin) were then examined by gathering the plasma concentration-time profiles, volumes of distribution and elimination half-lives from different ages of children and adults. First, the adult data were used to ensure accurate prediction of pharmacokinetic profiles. The model was then scaled to the specific age of children in the study, including the scaling of clearance, and the generated plasma concentration profiles, volumes of distribution and elimination half-lives were compared with literature values.

RESULTS

Physiological scaling produced highly age-dependent cardiac output, portal vein flow, extracellular water, total body water, lipid and protein values that well represented literature data. The pharmacokinetic profiles in children for the five compounds were well predicted and the trends associated with age were evident. Thus, young neonates had plasma concentrations greater than the adults and older children had concentrations less than the adults. Eighty-three percent, 97% and 87% of the predicted plasma concentrations, volumes of distribution and elimination half-lives, respectively, were within 50% of the study reported values. There was no age-dependent bias for term neonates to 18 years of age when examining volumes of distribution and elimination half-lives.

CONCLUSION

This study suggests that the developed paediatric PBPK model can be used to scale pharmacokinetics from adults. The accurate prediction of pharmacokinetic parameters in children will aid in the development of dosing regimens and sampling times, thus increasing the efficiency of paediatric clinical trials.

Off label and unlicensed drugs use in paediatric cardiology

OBJECTIVES

The use of drugs in an off label or unlicensed manner to treat children is a widespread phenomenon in Europe and the United States. The incidence of unlicensed and off label prescribing in paediatric cardiology practice has not been studied to date. This study was designed to assess the extent and nature of off label and unlicensed drug use in paediatric cardiology inpatients.

METHODS

In a prospective study, drug prescriptions in a paediatric cardiology ward were reviewed during a 2-year period. Data were collected and analyzed by special software created for this purpose.

RESULTS

The children (n = 544) studied varied in age from 4 h to 18 years. One or more off label and unlicensed prescriptions were given to 414 (76%) patients. Of the 2,130 prescriptions given during the 2-year period, more than one-half were unlicensed (11%) or off label (47%). While children aged 2-11 years received most of the unlicensed drug prescriptions (17%), neonates, who did not receive unlicensed drugs, led (64%) in the use of off label drugs. CONCLUSIONS. This study showed that the problem of off label and unlicensed drug use also exists in paediatric cardiology. The findings imply that the phenomenon of off label and unlicensed use of drugs in children can be correlated with the deficiency of paediatric drug formulations on the global market and insufficient data from clinical studies which must be performed to confirm the efficacy and safety of drugs in the paediatric population. Therefore, efforts to improve paediatric labelling are important and need the full support of all involved.