Challenges Associated with Route of Administration in Neonatal Drug Delivery

Examining safety and efficacy of a fixed concentration heparin dosing strategy for anticoagulation in neonatal extracorporeal membrane oxygenation

OBJECTIVES

The paediatric intensive care unit changed heparin infusion dosing from a variable weight-based concentration to a fixed concentration strategy, when smart pump-based drug library was introduced. This change meant significantly lower rates of infusion were needed for the same dose of heparin in the neonatal population. We performed a safety and efficacy assessment of this change.

METHODS

We performed a retrospective single-centre evaluation based on data from respiratory VA-extracorporeal membrane oxygenation (ECMO) patients weighing ≤5 kg, pre and post the change to fixed strength heparin infusion. Efficacy was analysed by distribution of activated clotting times (ACT) and heparin dose requirements between the groups. Safety was analysed using thrombotic and haemorrhagic event rates. Continuous variables were reported as median, interquartile ranges, and non-parametric tests were used. Generalised estimating equations (GEE) were used to analyse associations of heparin dosing strategy with ACT and heparin dose requirements in the first 24 h of ECMO. Incidence rate ratios of circuit related thrombotic and haemorrhagic events between groups were analysed using Poisson regression with offset for run hours.

RESULTS

33 infants (20 variable weight-based, 13 fixed concentration) were analysed. Distribution of ACT ranges and heparin dose requirements were similar between the two groups during the ECMO run and this was confirmed by GEE. Incidence rate ratios of thrombotic (fixed v weight-based) (1.9 [0.5-8], p = .37), and haemorrhagic events (0.9 [0.1-4.9], p = .95) did not show statistically significant differences.

CONCLUSIONS

Fixed concentration dosing of heparin was at least equally effective and safe compared to a weight-based dosing.

Physiologically Based Pharmacokinetic Modeling in Neonates: Current Status and Future Perspectives

Rational drug use in special populations is a clinical problem that doctors and pharma-cists must consider seriously. Neonates are the most physiologically immature and vulnerable to drug dosing. There is a pronounced difference in the anatomical and physiological profiles be-tween neonates and older people, affecting the absorption, distribution, metabolism, and excretion of drugs in vivo, ultimately leading to changes in drug concentration. Thus, dose adjustments in neonates are necessary to achieve adequate therapeutic concentrations and avoid drug toxicity. Over the past few decades, modeling and simulation techniques, especially physiologically based pharmacokinetic (PBPK) modeling, have been increasingly used in pediatric drug development and clinical therapy. This rigorously designed and verified model can effectively compensate for the deficiencies of clinical trials in neonates, provide a valuable reference for clinical research design, and even replace some clinical trials to predict drug plasma concentrations in newborns. This review introduces previous findings regarding age-dependent physiological changes and pathological factors affecting neonatal pharmacokinetics, along with their research means. The application of PBPK modeling in neonatal pharmacokinetic studies of various medications is also reviewed. Based on this, we propose future perspectives on neonatal PBPK modeling and hope for its broader application.

Pediatric Drug Development: Reviewing Challenges and Opportunities by Tracking Innovative Therapies

The paradigm of pediatric drug development has been evolving in a "carrot-and-stick"-based tactic to address population-specific issues. However, the off-label prescription of adult medicines to pediatric patients remains a feature of clinical practice, which may compromise the age-appropriate evaluation of treatments. Therefore, the United States and the European Pediatric Formulation Initiative have recommended applying nanotechnology-based delivery systems to tackle some of these challenges, particularly applying inorganic, polymeric, and lipid-based nanoparticles. Connected with these, advanced therapy medicinal products (ATMPs) have also been highlighted, with optimistic perspectives for the pediatric population. Despite the results achieved using these innovative therapies, a workforce that congregates pediatric patients and/or caregivers, healthcare stakeholders, drug developers, and physicians continues to be of utmost relevance to promote standardized guidelines for pediatric drug development, enabling a fast lab-to-clinical translation. Therefore, taking into consideration the significance of this topic, this work aims to compile the current landscape of pediatric drug development by (1) outlining the historic regulatory panorama, (2) summarizing the challenges in the development of pediatric drug formulation, and (3) delineating the advantages/disadvantages of using innovative approaches, such as nanomedicines and ATMPs in pediatrics. Moreover, some attention will be given to the role of pharmaceutical technologists and developers in conceiving pediatric medicines.

Nanocarriers in Tuberculosis Treatment: Challenges and Delivery Strategies

The World Health Organization identifies tuberculosis (TB), caused by Mycobacterium tuberculosis, as a leading infectious killer. Although conventional treatments for TB exist, they come with challenges such as a heavy pill regimen, prolonged treatment duration, and a strict schedule, leading to multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains. The rise of MDR strains endangers future TB control. Despite these concerns, the hunt for an efficient treatment continues. One breakthrough has been the use of nanotechnology in medicines, presenting a novel approach for TB treatment. Nanocarriers, such as lipid nanoparticles, nanosuspensions, liposomes, and polymeric micelles, facilitate targeted delivery of anti-TB drugs. The benefits of nanocarriers include reduced drug doses, fewer side effects, improved drug solubility, better bioavailability, and improved patient compliance, speeding up recovery. Additionally, nanocarriers can be made even more targeted by linking them with ligands such as mannose or hyaluronic acid. This review explores these innovative TB treatments, including studies on nanocarriers containing anti-TB drugs and related patents.

Clinical pharmacological considerations in an early intravenous to oral antibiotic switch: are barriers real or simply perceived?

BACKGROUND

Traditionally, there has been a common belief that ongoing i.v. antibiotic therapy is superior to an early i.v. to oral switch, especially for severe infections. However, this may be at least partly based on early observations rather than robust, high-quality data and contemporary clinical studies. It is important to examine whether these traditional views align with clinical pharmacological considerations, or conversely, if these considerations may support the broader application of an early i.v. to oral switch under appropriate circumstances.

OBJECTIVES

To examine the rationale for an early i.v. to oral antibiotic switch in the context of clinical pharmacokinetic and pharmacodynamic principles and to discuss whether commonly encountered pharmacological barriers are real or simply perceived.

SOURCES

We conducted PubMed searches on barriers and clinicians' perceptions about an early i.v. to oral switch, clinical studies comparing switching with i.v.-only dosing, and pharmacological factors affecting oral antimicrobials.

CONTENT

We focused on general pharmacological and clinical pharmacokinetic and pharmacodynamic principles and considerations that are relevant when clinicians ponder whether to switch from i.v. to oral antimicrobial dosing. The main focus of this review was on antibiotics. The discussion of the general principles is accompanied by specific examples from the literature.

IMPLICATIONS

Clinical pharmacological considerations and an imposing and increasing number of clinical studies, including randomized clinical trials, support an early i.v. to oral switch for the treatment of a number of infection types, under appropriate circumstances. We hope that the information provided here will add to calls for a critical examination of the role of i.v. to oral switching for many infections that are currently treated almost exclusively with i.v.-only therapy, and that it will inform health policy and guideline development by infectious diseases organizations.

Analytical and Non-Analytical Variation May Lead to Inappropriate Antimicrobial Dosing in Neonates: An In Silico Study

BACKGROUND

Therapeutic drug monitoring (TDM) of aminoglycosides and vancomycin is used to prevent oto- and nephrotoxicity in neonates. Analytical and nonanalytical factors potentially influence dosing recommendations. This study aimed to determine the impact of analytical variation (imprecision and bias) and nonanalytical factors (accuracy of drug administration time, use of non-trough concentrations, biological variation, and dosing errors) on neonatal antimicrobial dosing recommendations.

METHODS

Published population pharmacokinetic models and the Australasian Neonatal Medicines Formulary were used to simulate antimicrobial concentration-time profiles in a virtual neonate population. Laboratory quality assurance data were used to quantify analytical variation in antimicrobial measurement methods used in clinical practice. Guideline-informed dosing recommendations based on drug concentrations were applied to compare the impact of analytical variation and nonanalytical factors on antimicrobial dosing.

RESULTS

Analytical variation caused differences in subsequent guideline-informed dosing recommendations in 9.3-12.1% (amikacin), 16.2-19.0% (tobramycin), 12.2-45.8% (gentamicin), and 9.6-19.5% (vancomycin) of neonates. For vancomycin, inaccuracies in drug administration time (45.6%), use of non-trough concentrations (44.7%), within-subject biological variation (38.2%), and dosing errors (27.5%) were predicted to result in more dosing discrepancies than analytical variation (12.5%). Using current analytical performance specifications, tolerated dosing discrepancies would be up to 14.8% (aminoglycosides) and 23.7% (vancomycin).

CONCLUSIONS

Although analytical variation can influence neonatal antimicrobial dosing recommendations, nonanalytical factors are more influential. These result in substantial variation in subsequent dosing of antimicrobials, risking inadvertent under- or overexposure. Harmonization of measurement methods and improved patient management systems may reduce the impact of analytical and nonanalytical factors on neonatal antimicrobial dosing.

Developmental Pharmacokinetics of Antibiotics Used in Neonatal ICU: Focus on Preterm Infants

Neonatal Infections are among the most common reasons for admission to the intensive care unit. Neonatal sepsis (NS) significantly contributes to mortality rates. Empiric antibiotic therapy of NS recommended by current international guidelines includes benzylpenicillin, ampicillin/amoxicillin, and aminoglycosides (gentamicin). The rise of antibacterial resistance precipitates the growth of the use of antibiotics of the Watch (second, third, and fourth generations of cephalosporines, carbapenems, macrolides, glycopeptides, rifamycins, fluoroquinolones) and Reserve groups (fifth generation of cephalosporines, oxazolidinones, lipoglycopeptides, fosfomycin), which are associated with a less clinical experience and higher risks of toxic reactions. A proper dosing regimen is essential for effective and safe antibiotic therapy, but its choice in neonates is complicated with high variability in the maturation of organ systems affecting drug absorption, distribution, metabolism, and excretion. Changes in antibiotic pharmacokinetic parameters result in altered efficacy and safety. Population pharmacokinetics can help to prognosis outcomes of antibiotic therapy, but it should be considered that the neonatal population is heterogeneous, and this heterogeneity is mainly determined by gestational and postnatal age. Preterm neonates are common in clinical practice, and due to the different physiology compared to the full terms, constitute a specific neonatal subpopulation. The objective of this review is to summarize the evidence about the developmental changes (specific for preterm and full-term infants, separately) of pharmacokinetic parameters of antibiotics used in neonatal intensive care units.

What babies need: accelerating access to current and novel antiretroviral drugs in neonates through pharmacokinetic studies

Although 23 antiretroviral drugs are approved for use in adults, only six are approved by regulatory authorities for use in term neonates born to women with HIV, with even fewer options for preterm neonates. A major hurdle for approvals is the delay in the generation of pharmacokinetic and safety data for antiretrovirals in neonates. The median time between the year of approval from the US Food and Drug Administration of an antiretroviral agent for adults and the first publication date for pharmacokinetic data in neonates less than 4 weeks old is 8 years (range 2-23 years). In this Viewpoint, we address pharmacokinetic research gaps and priorities for current and novel antiretroviral use in neonates. We also consider the challenges and provide guidance on neonatal clinical pharmacology research on antiretroviral agents with the goal of stimulating research and expediting the availability of safe medications for the prevention and treatment of HIV in this vulnerable population.

Off-label use of combined antiretroviral therapy, analysis of data collected by the Italian Register for HIV-1 infection in paediatrics in a large cohort of children

BACKGROUND

Early start of highly active antiretroviral therapy (HAART) in perinatally HIV-1 infected children is the optimal strategy to prevent immunological and clinical deterioration. To date, according to EMA, only 35% of antiretroviral drugs are licenced in children < 2 years of age and 60% in those aged 2-12 years, due to the lack of adequate paediatric clinical studies on pharmacokinetics, pharmacodynamics and drug safety in children.

METHODS

An observational retrospective study investigating the rate and the outcomes of off-label prescription of HAART was conducted on 225 perinatally HIV-1 infected children enrolled in the Italian Register for HIV Infection in Children and followed-up from 2001 to 2018.

RESULTS

22.2% (50/225) of included children were receiving an off-label HAART regimen at last check. Only 26% (13/50) of off-label children had an undetectable viral load (VL) before the commencing of the regimen and the 52.0% (26/50) had a CD4 + T lymphocyte percentage > 25%. At last check, during the off label regimen, the 80% (40/50) of patients had an undetectable VL, and 90% (45/50) of them displayed CD4 + T lymphocyte percentage > 25%. The most widely used off-label drugs were: dolutegravir/abacavir/lamivudine (16%; 8/50), emtricitbine/tenofovir disoproxil (22%; 11/50), lopinavir/ritonavir (20%; 10/50) and elvitegravir/cobicistat/emtricitabine/ tenofovir alafenamide (10%; 10/50). At logistic regression analysis, detectable VL before starting the current HAART regimen was a risk factor for receiving an off-label therapy (OR: 2.41; 95% CI 1.13-5.19; p = 0.024). Moreover, children < 2 years of age were at increased risk for receiving off-label HAART with respect to older children (OR: 3.24; 95% CI 1063-7.3; p = 0.001). Even if our safety data regarding off-label regimens where poor, no adverse event was reported.

CONCLUSION

The prescription of an off-label HAART regimen in perinatally HIV-1 infected children was common, in particular in children with detectable VL despite previous HAART and in younger children, especially those receiving their first regimen. Our data suggest similar proportions of virological and immunological successes at last check among children receiving off-label or on-label HAART. Larger studies are needed to better clarify efficacy and safety of off-label HAART regimens in children, in order to allow the enlargement of on-label prescription in children.

Pediatric Antiretroviral Therapy

Human immunodeficiency virus (HIV) is one of the most serious pediatric infectious diseases, affecting around 3 million children and adolescents worldwide. Lifelong antiretroviral treatment (ART) provides multiple benefits including sustained virologic suppression, restoration and preservation of immune function, decreased morbidity and mortality, and improved quality of life. However, access to ART, particularly among neonates and young infants, continues to be challenging due to limited number of suitable formulations and limited access to pediatric ARV drug. Moreover, children and adolescents living with HIV may experience long-term HIV- and ART-associated comorbidities including cardiovascular, renal, neurological, and metabolic complications. We provide an overview of currently available formulations, dosing, and safety considerations for pediatric antiretroviral drugs by drug classes and according to the three age groups including neonates, children, and adolescents.

Physiological and Pharmaceutical Considerations for Rectal Drug Formulations

Although the oral route is the most convenient route for drug administration, there are a number of circumstances where this is not possible from either a clinical or pharmaceutical perspective. In these cases, the rectal route may represent a practical alternative and can be used to administer drugs for both local and systemic actions. The environment in the rectum is considered relatively constant and stable and has low enzymatic activity in comparison to other sections of the gastrointestinal tract. In addition, drugs can partially bypass the liver following systemic absorption, which reduces the hepatic first-pass effect. Therefore, rectal drug delivery can provide significant local and systemic levels for various drugs, despite the relatively small surface area of the rectal mucosa. Further development and optimization of rectal drug formulations have led to improvements in drug bioavailability, formulation retention, and drug release kinetics. However, despite the pharmaceutical advances in rectal drug delivery, very few of them have translated to the clinical phase. This review will address the physiological and pharmaceutical considerations influencing rectal drug delivery as well as the conventional and novel drug delivery approaches. The translational challenges and development aspects of novel formulations will also be discussed.

Neonatal pharmacology and clinical implications

During the neonatal period, there is physiological immaturity of organs, systems and metabolic pathways that influences the pharmacokinetics and pharmacodynamics of administered drugs, the dosage of which should be constantly amended, considering the progressive increase in weight and the maturation of the elimination pathways. In this article, we analyse the main pharmacokinetic aspects (absorption, distribution, metabolism and excretion) that exist during the neonatal period, to offer a description of the physiological background for variability in pharmacological dosing.

Making Medicines Baby Size: The Challenges in Bridging the Formulation Gap in Neonatal Medicine

The development of age-appropriate formulations should focus on dosage forms that can deliver variable yet accurate doses that are safe and acceptable to the child, are matched to his/her development and ability, and avoid medication errors. However, in the past decade, the medication needs of neonates have largely been neglected. The aim of this review is to expand on what differentiates the needs of preterm and term neonates from those of the older paediatric subsets, in terms of environment of care, ability to measure and administer the dose (from the perspective of the patient and carer, the routes of administration, the device and the product), neonatal biopharmaceutics and regulatory challenges. This review offers insight into those challenges posed by the formulation of medicinal products for neonatal patients in order to support the development of clinically relevant products.

Safety, dosing, and pharmaceutical quality for studies that evaluate medicinal products (including biological products) in neonates

The study of medications among pediatric patients has increased worldwide since 1997 in response to new legislation and regulations, but these studies have not yet adequately addressed the therapeutic needs of neonates. Additionally, extant guidance developed by regulatory agencies worldwide does not fully address the specificities of neonatal drug development, especially among extremely premature newborns who currently survive. Consequently, an international consortium from Canada, Europe, Japan, and the United States was organized by the Critical Path Institute to address the content of guidance. This group included neonatologists, neonatal nurses, parents, regulators, ethicists, clinical pharmacologists, specialists in pharmacokinetics, specialists in clinical trials and pediatricians working in the pharmaceutical industry. This group has developed a comprehensive, referenced White Paper to guide neonatal clinical trials of medicines - particularly early phase studies. Key points include: the need to base product development on neonatal physiology and pharmacology while making the most of knowledge acquired in other settings; the central role of families in research; and the value of the whole neonatal team in the design, implementation and interpretation of studies. This White Paper should facilitate successful clinical trials of medicines in neonates by informing regulators, sponsors, and the neonatal community of existing good practice.

Clinical research in neonates and infants: Challenges and perspectives

To date, up to 65% of drugs used in neonates and infants are off-label or unlicensed, as they were implemented in clinical care without the usual regulatory phases of pharmacological drug development. Pharmacotherapy in this age group is still mainly based on the individual clinical expertise of specialized pediatricians. Pharmacological trials involving neonates are indeed more difficult to perform: appropriate dosing is hampered by the rapid physiological changes occurring at this stage of development, and the selection of proper end-points and biomarkers is complicated by the limited knowledge of the pathophysiology of the specific diseases of infancy. Moreover, there are many ethical challenges in planning and conducting drug studies in pediatric patients (especially in newborns and infants). In the current review, we address some challenges and discuss possible perspectives to stimulate scientific and clinical pharmacological research in neonates and infants. We hereby aim to illustrate the add on value of the regulatory framework for model-based neonatal medicinal development currently used in Europe and the United States. We provide several examples of successful recent pharmacological trials performed in neonates and infants. In these examples, success was ensured by the implementation of specific pharmacokinetic assessments, thanks to accurate drug dosing achieved with a combination of dose validation, population pharmacokinetics and mathematical models of drug clearance and distribution; moreover, age-specific pharmacodynamics was considered via appropriate evaluations of drug efficacy with end-points adapted to the peculiar pathophysiology of diseases in this age group. These "pharmacological" challenges add to the ethical challenges that are always present in planning and conducting clinical studies in neonates and infants and support the opinion that clinical research in pediatrics should be evaluated by ad hoc ethical committees with specific expertise.