Newborns and drug studies: the NICHD/FDA newborn drug development initiative

Advocating for the inclusion of kidney health outcomes in neonatal research: best practice recommendations by the Neonatal Kidney Collaborative

Acute kidney injury (AKI) occurs in nearly 30% of sick neonates. Chronic kidney disease (CKD) can be detected in certain populations of sick neonates as early as 2 years. AKI is often part of a multisystem syndrome that negatively impacts developing organs resulting in short- and long-term pulmonary, neurodevelopmental, and cardiovascular morbidities. It is critical to incorporate kidney-related data into neonatal clinical trials in a uniform manner to better understand how neonatal AKI or CKD could affect an outcome of interest. Here, we provide expert opinion recommendations and rationales to support the inclusion of short- and long-term neonatal kidney outcomes using a tiered approach based on study design: (1) observational studies (prospective or retrospective) limited to data available within a center's standard practice, (2) observational studies involving prospective data collection where prespecified kidney outcomes are included in the design, (3) interventional studies with non-nephrotoxic agents, and (4) interventional studies with known nephrotoxic agents. We also provide recommendations for biospecimen collection to facilitate ancillary kidney specific research initiatives. This approach balances the costs of AKI and CKD ascertainment with knowledge gained. We advocate that kidney outcomes be included routinely in neonatal clinical study design. Consistent incorporation of kidney outcomes across studies will increase our knowledge of neonatal morbidity.

Cangrelor PK/PD analysis in post-operative neonatal cardiac patients at risk for thrombosis

Essentials An optimal therapeutic strategy has yet to be established to prevent early shunt thrombosis. A phase 1 study of cangrelor was performed in neonates after palliation of congenital heart disease. PD endpoint of >90% platelet inhibition in 60% of patients was achieved at 0.5 µg/kg/min dosing. No serious adverse events related to drug administration were observed, including bleeding. ABSTRACT: Background Systemic-to-pulmonary artery shunt thrombosis is a significant cause of early postoperative mortality in neonates after palliation of congenital heart disease. In the context of thromboprophylaxis, an optimal therapeutic strategy has yet to be established before aspirin administration. Cangrelor, a fast-acting, reversible P2Y12 inhibitor, may fill this unmet need. Objectives To evaluate the pharmacokinetics (PK), pharmacodynamics (PD), and safety of cangrelor in neonates undergoing stage 1 palliation. Methods This prospective, open-label, single-arm study evaluated two cangrelor dosing cohorts following placement of a systemic-to-pulmonary artery shunt, right ventricle-to-pulmonary artery shunt, or ductal stent. Drug concentrations and platelet reactivity, assessed by light transmission aggregometry and in microfluidic assays (MF), were measured. Results Twenty-two patients were consented and 15 received a 1-hour infusion of cangrelor at either 0.5 µg/kg/min (cohort 1) or 0.25 µg/kg/min (cohort 2). Whereas the primary PD endpoint was achieved at the higher dose (ie, reduction in maximal platelet aggregation by ≥90% in 60% of participants), only 29% of those in cohort 2 attained this goal. Comparable and statistically significant results were obtained in MF assays (P < .0001 vs. baseline). Drug levels during infusion were 3-fold higher in cohort 1 vs. cohort 2 (P < .001). Most participants (70%) had undetectable drug levels by 10 minutes postinfusion with full recovery in platelet function at 1 hour. No drug-related bleeding events occurred. Conclusions Favorable PK/PD properties of cangrelor 0.5 µg/kg/min dosing and safety profile warrant further evaluation in neonates following palliative cardiac procedures.

The Utility of Pharmacometric Models in Clinical Pharmacology Research in Infants

Purpose of commentary

Acquiring knowledge on drug disposition and action in infant is challenging because of the problem of sparse and unbalanced data obtained for each individual infant due to the limited blood volume as well as the issue of extensive inter-subject and intra-subject variability in drug exposure and response due to the fast growth and dynamic maturation changes in infants. This commentary highlights the importance of using population-based pharmacometric models to improve knowledge on drug disposition and action in infants.

Recent findings

Pharmacometric modeling remains to be critical in clinical pharmacology research in infants. Many pediatric covariate models developed for scaling of drug clearance use a combination of allometric weight scaling to account for size change and a sigmoid function of antenatal development and postnatal maturation to characterize the age-related maturation. To expedite the development of safe and effective dosing regimens in infants, a number of strategies have been proposed recently, including the use of pediatric covariate model obtained from one drug for extrapolation to other drugs undergoing similar elimination pathways, as well as the combination of opportunistic clinical studies and population-based pharmacometrics models.

Summary

Population-based pharmacometric modeling plays a pivotal role in clinical pharmacology research in infants. Most of the covariate models reported so far focus on antibiotics undergoing renal elimination. Novel modeling strategies have been proposed recently to facilitate clinical pharmacology research and expedite the dose optimization process in infants.

New Horizons in Pediatric Psychopharmacology

Preclinical Research Recent advances in pediatric psychopharmacology have been rather uneven. Increased use of psychotropic drugs among the pediatric population has raised concerns regarding their inappropriate use and safety. While clinical trials have been conducted on various pediatric psychopharmacological drugs, there has been an insignificant amount of importance to innovation in holistic treatment. A rational approach toward elucidating the various challenges would be contingent on the convergence of the development of novel efficacious psychotropic drugs with concrete conceptual frameworks and guidelines fostering enhanced outcomes. A research infrastructure concerning the relevance of the clinician's perspective, combining drugs with alternative therapies, the need for pediatric specific formulations and relevance of these in developing countries provides a basis on which innovative treatment/development can be constructed. The current commentary highlights these comprehensive and targeted treatment guidelines as aspects necessary for building the future of the field. Drug Dev Res 77 : 474-478, 2016. © 2016 Wiley Periodicals, Inc.

Clinical trials of medicines in neonates: the influence of ethical and practical issues on design and conduct

In the past, there has been a perception that ethical and practical problems limit the opportunities for research in neonates. This perception is no longer appropriate. It is now clear that research about the medicines used in neonates is an ethical requirement. It is possible to conduct high quality research in neonates if the research team adapt to the characteristics of this population. Good practice involves respecting the specific needs of newborn babies and their families by adopting relevant approaches to study design, recruitment, pharmacokinetic studies and safety assessment. Neonatal units have a unique culture that requires careful development in a research setting. Clinical investigators need to recognize the clinical and ethical imperative to conduct rigorous research. Industry needs to engage with neonatal networks early in the process of drug development, preferably before contacting regulatory agencies. Follow-up over 3-5 years is essential for the evaluation of medicines in neonates and explicit funding for this is required for the assessment of the benefit and risk of treatments given to sick newborn babies. The views of parents must be central to the development of studies and the research agenda. Ethical and practical problems are no longer barriers to research in neonates. The current challenges are to disseminate good practice and maximize capacity in order to meet the need for research among newborn babies.

Dopamine and dobutamine use in preterm or low birth weight neonates in the premier 2008 database

BACKGROUND

Dobutamine and dopamine are off-patent drugs prioritized by the National Institute of Child Health and Human Development and US Food and Drug Administration for further study under the Best Pharmaceuticals for Children Act. Both agents are used to manage cardiac insufficiency in preterm neonates and are subject to controversy among neonatologists. Among the controversies are outcome measures (blood pressure vs end organ perfusion) and long-term effects.

OBJECTIVES

We analyzed retrospective hospitalization data to (1) describe the use of dopamine and dobutamine in low birth weight (LBW) or preterm infants in a large sample and (2) explore the potential of using observational data to describe outcomes in LBW or preterm infants treated with dopamine or dobutamine.

METHODS

Inpatient data were extracted from the Premier database to calculate the prevalence of use of dopamine and dobutamine among neonates in 2008. Prevalence of use was calculated by categorizing patients as ever or never having received dopamine or dobutamine. We compared mortality in the neonates by using Cox proportional hazards models to identify variables associated with survival and to control for their effects.

RESULTS

Out of 877,201 pediatric hospitalizations in 2008, 65,216 were neonates and had data available about dopamine and dobutamine use. Of these, 7459 were preterm or LBW and included 1143 very LBW (VLBW) neonates. Dopamine alone was given to 194 VLBW neonates, dobutamine alone was given to 14, and both dopamine and dobutamine were given to 79 neonates. For the VLBW neonates, probability of treatment with dopamine or dobutamine varied almost 10-fold from 4.4% to 38.4% at 11 hospitals and did not differ by 3M APR-DRG (all patient refined diagnosis related group) severity of illness or 3M APR-DRG risk of mortality.

CONCLUSIONS

Our data suggest the prevalence of dopamine or dobutamine use was 4.9% in preterm or LBW neonates and 25.1% in VLBW neonates. Treatment with dopamine alone was more common than treatment with dobutamine alone. There was no difference in mortality between neonates treated with dopamine compared with treatment with dobutamine, but access to charts and clinical details are required to conduct a comparative effectiveness study.

Estimates of pediatric medication use in the United States: current abilities and limitations

BACKGROUND

Resources are available for measuring adult medication use, but similar resources have not been fully developed for measuring pediatric use. Policy decisions require an understanding of the population affected, the number of children, their ages, sex, geographic distribution, race and ethnicity, and insurance status, as well as trends over time.

OBJECTIVE

In this article, databases providing information about prescription drugs used in the United States are reviewed with respect to pediatric populations.

METHODS

A series of searches were conducted in MEDLINE using these terms: frequency, prevalence, drug utilization, children, pediatric, drug usage, medications, and prescriptions. Authors of selected articles were interviewed to identify salient issues in the measurement of pediatric medication use. Preliminary analysis of several databases followed within the context of government implementation of the Best Pharmaceuticals for Children Act. This was followed by further MEDLINE searches and synthesis of the literature.

RESULTS

Databases with information about pediatric population medication use included 7 with outpatient data and 4 with inpatient data. Outpatient data were available from government and private sources, but inpatient data were available from private sources only. Three of the government and 1 of the private databases with outpatient data had sample sizes of several thousand, too small to allow analysis of frequency trends in pediatric populations or subpopulations, in which many drugs are used by fewer than 0.01% of patients.

CONCLUSIONS

Sample size needs are greater when measuring pediatric medication use because the overall level of use is lower among children than adults. Databases resulting from hospital quality efforts, conglomeration of pharmacy benefit records, and standardization of state Medicaid records offer opportunities to describe prescription medication use in samples of several hundred thousand to several million children but will require dedicated resources.

The National Institutes of Health and the Best Pharmaceuticals for Children Act

The majority of drugs used to treat children are not labeled for use in children. The Best Pharmaceuticals for Children Act of 2002, re-authorized as the US FDA Amendments Act of 2007, directs the National Institutes of Health (NIH) to sponsor pediatric clinical trials of drugs lacking patent protection, if the FDA request for studies has been declined. The NIH is currently sponsoring 17 clinical studies. Challenges encountered include a paucity of investigators who are trained in pediatric clinical pharmacology; inadequate knowledge of the mechanisms of drug action in a growing child; and lack of pediatric formulations.

Adaptive designs for dose-finding in non-cancer phase II trials: influence of early unexpected outcomes

BACKGROUND

In non-cancer phase II trials, dose-finding trials are usually carried out using fixed designs, in which several doses including a placebo are randomly distributed to patients. However, in certain vulnerable populations, such as neonates or infants, there is an heightened requirement for safety, precluding randomization.

PURPOSE

To estimate the minimum effective dose of a new drug from a non-cancer phase II trial, we propose the use of adaptive designs like the Continual Reassessment Method (CRM). This approach estimates the dose closest to some target response, and has been shown to be unbiased and efficient in cancer phase I trials.

METHODS

Based on a motivating example, we point out the individual influence of first outliers in this setting. A weighted version of the CRM is proposed as a theoretical benchmark to control for these outliers. Using simulations, we illustrate how this approach provides further insight into the behavior of the CRM.

RESULTS

When dealing with low targets like a 10% failure rate, the CRM appears unable to rapidly overcome an early unexpected outcome. This behavior persisted despite changing the inference (Bayesian or likelihood), underlying dose-response model (though slightly improved using the power model), and the number of patients enrolled at each dose level.

LIMITATIONS

The choices for initial guesses of failure rates, the vague prior for the model parameter, and the log-log shape of weights can appear somewhat arbitrary.

CONCLUSIONS

In phase II dose-finding studies in which failure targets are below 20%, the CRM appears quite sensitive to first unexpected outcomes. Using a power model for dose-response improves some behavior if the trial is started at the first dose level and includes at least three to five patients at the starting dose before applying the CRM allocation rule.

Off-label prescribing to children in the United States outpatient setting

OBJECTIVE

The aim of this study was to determine the frequency of off-label prescribing to children at United States outpatient visits and to determine how drug class, patient age, and physician specialty relate to off-label prescribing.

METHODS

Data from the 2001 through 2004 National Ambulatory Medical Care Surveys (NAMCS) consisted of a sample of 7901 outpatient visits by children aged 0 through 17 years in which prescriptions were given, representative of an estimated 312 million visits. We compared FDA-approved age and indication to the child's age and diagnoses. We used multivariate logistic regression to determine adjusted differences in probabilities of off-label prescribing.

RESULTS

Sixty-two percent of outpatient pediatric visits included off-label prescribing. Approximately 96% of cardiovascular-renal, 86% of pain, 80% of gastrointestinal, and 67% of pulmonary and dermatologic medication prescriptions were off label. Visits by children aged <6 years had a higher probability of off-label prescribing (P < .01), especially visits by children aged <1 year (74% adjusted probability). Visits to specialists also involved a significantly increased probability (68% vs 59% for general pediatricians, P < .01) of off-label prescribing.

CONCLUSIONS

Despite recent studies and labeling changes of pediatric medications, the majority of pediatric outpatient visits involve off-label prescribing across all medication categories. Off-label prescribing is more frequent for younger children and those receiving care from specialist pediatricians. Increased dissemination of pediatric studies and label information may be helpful to guide clinical practice. Further research should be prioritized for the medications most commonly prescribed off label and to determine outcomes, causes, and appropriateness of off-label prescribing to children.

Selected Proceedings of the NICHD/FDA newborn drug development initiative: Part II

BACKGROUND

In February 2003, the National Institute of Child Health and Human Development (NICHD) and the US Food and Drug Administration (FDA) created the Newborn Drug Development Initiative (NDDI), an ongoing program to determine gaps in knowledge in neonatal therapeutics and to explore clinical study designs for use in the newborn population. Working groups were established in 3 therapeutic areas: the central nervous, pulmonary, and cardiovascular systems. Three additional groups discussed pain control, drug prioritization, and ethics in neonatal clinical trials.

OBJECTIVE

The purpose of this article was to provide an overview of the 5 articles written by members of the Neurology, Cardiology, Drug Prioritization, and Ethics Groups.

METHODS

Information for the current article, as well as the 5 articles presented in this supplemental section, was gathered from the proceedings of a workshop cosponsored by the NICHD and the FDA. This workshop took place March 29 and 30, 2004, in Baltimore, Maryland.

RESULTS

The Neurology Group addressed the treatment of 2 common and interrelated conditions in the newborn population: neonatal seizures and hypoxic-ischemic encephalopathy. The unsubstantiated clinical preference for using phenobarbital to treat neonatal seizures, coupled with the development of several newer antiepileptic drugs with application in children, dictates the need for rigorous clinical trials of these drugs in the neonatal population. A number of pharmacologic agents currently undergoing extensive investigations in experimental animals and adult humans may have application in the newborn population. The Cardiology Group reviewed controversial approaches to the diagnosis and treatment of cardiovascular instability of preterm infants and identified gaps in knowledge. The group discussed issues of study design and developed 2 study proposals: (1) a placebo-controlled trial with a rescue arm for symptomatic infants; and (2) a targeted blood pressure (BP) trial. The Drug Prioritization Group focused on the fact that the uniqueness of the newborn population is due to distinctive and changing physiologic characteristics, conditions, and diseases that are different from those affecting older children, as well as the large differences in developmental patterns between 23 weeks of gestation and term. All of these factors help explain the lack of adequate trials and the sparseness of evidence regarding efficacy and toxicity risks of most drugs used in the newborn population. Unfortunately, the frequency of drug use and polypharmacy is highest in very-low-birth-weight infants. The large number of drugs requiring study and the uniqueness of the indications for those drugs preclude the use of the prioritization process used in older children. The focus of the Drug Prioritization Group was the determination of factors that identify which drugs are most important for study. The Ethics Group was unique in that its members were integrated into the therapeutic groups. This approach allowed for the identification of similarities and dissimilarities in the proposed clinical trial design framework. The summary report included here identifies common themes voiced in the various NDDI reports and deliberations.

CONCLUSIONS

The 5 articles included in this issue address different issues but share common themes: the need to develop innovative trial designs and biomarkers of efficacy, consideration of ethical concerns, and selection of appropriate drugs for study.