Paracetamol to induce ductus arteriosus closure: is it valid?

Clinical and echocardiography predictors of response to first-line acetaminophen treatment in preterm infants with hemodynamically significant patent ductus arteriosus

OBJECTIVE

To assess clinical and echocardiography predictors of acetaminophen response for the treatment of patent ductus arteriosus (PDA) in preterm neonates.

STUDY DESIGN

Retrospective cohort study of preterm infants born <30 weeks, with a diagnosis of hemodynamically significant PDA, who received 1st line treatment with intravenous acetaminophen during the first 2 postnatal weeks. Response was defined by PDA closure or improvement in PDA score of >50%.

RESULTS

A total of 100 infants were included whose median weight and gestational age at birth were 663 grams and 24.6 weeks respectively. In total, 66 infants were classified as responders and were more likely to have intrauterine growth restriction, exposure to maternal hypertension and chorioamnionitis. Non-response was more common among infants with thrombocytopenia and anemia.

CONCLUSION

Responders were more likely to be IUGR with echocardiography indices of lower preload. Response to 1st line intravenous acetaminophen therapy is comparable to non-steroidal drugs in preterm infants. Relationship of response to acetaminophen to perinatal characteristics requires further characterization.

Evaluation of the Closure of Patent Ductus Arteriosus With Ibuprofen Compared to Indomethacin

OBJECTIVE

Limited data exist comparing indomethacin and ibuprofen for the treatment of patent ductus arteriosus (PDA). The objective was to compare the safety and efficacy of indomethacin and ibuprofen for treatment of PDA closure.

METHODS

This single-center, pre-test/post-test quasi-experiment included preterm infants admitted to the neonatal intensive care unit who received indomethacin (July 1, 2013-September 30, 2015) or ibuprofen (December 1, 2015-July 31, 2019) for PDA. Patients were excluded if they were thrombocytopenic, had existing kidney injury, unresolved intraventricular hemorrhage (IVH) or necrotizing enterocolitis (NEC) at treatment initiation. Data were obtained from the electronic health record. Study outcomes were complete PDA closure, degree of PDA closure, resolution of symptoms, and new-onset acute kidney injury (AKI), IVH, or NEC.

RESULTS

A total of 114 patients were included: 44 (39%) received indomethacin and 70 (61%) received -ibuprofen. Twenty-one (21%) patients experienced successful PDA closure within 1 week: 13 (32%) indomethacin patients and 8 (13%) ibuprofen patients (p = 0.023). PDA size reduction occurred in 43 (46%) patients with 29 (25%) experiencing complete symptom resolution. Significantly more indomethacin patients compared with ibuprofen patients experienced new-onset AKI (48% vs 17%; p < 0.001) and received concomitant nephrotoxins (68% vs 39%; p = 0.002). There were no significant differences in new-onset IVH or NEC.

CONCLUSIONS

Indomethacin administration successfully closed the PDA in more neonates than ibuprofen but resulted in higher rates of AKI. However, this was confounded by more frequent administration of concomitant nephrotoxins. Larger trials are needed to help elucidate the optimal drug for closure of the PDA in neonates.

Combination pharmacotherapy for patent ductus arteriosus: Rationale and evidence

While cyclooxygenase inhibitors have been the most common medications used to facilitate earlier closure of patent ductus arteriosus in preterm infants, adverse effects and low efficacy in extremely low gestational age neonates (ELGANs) have highlighted a need for alternative options. Combination therapy with acetaminophen and ibuprofen is a novel strategy for PDA treatment in ELGANs, as it may facilitate higher ductal closure rates via additive action on two separate pathways inhibiting prostaglandin production. Initial small observational studies and pilot randomized clinical trials indicate potentially higher efficacy of the combination regime to induce ductal closure in comparison to treatment with ibuprofen alone. In this review, we examine the potential clinical impact of treatment failure in ELGANs with significant PDA, highlight the biological rationale in support of studying combination therapy, and review the randomized and non-randomized studies to date. With the rising number of ELGANs receiving neonatal intensive care, who are vulnerable to PDA-related morbidities, there is an urgent need for adequately powered clinical trials to systematically investigate the efficacy and safety of combination therapy for PDA treatment.

The Association of Patent Ductus Arteriosus with Inflammation: A Narrative Review of the Role of Inflammatory Biomarkers and Treatment Strategy in Premature Infants

Patent ductus arteriosus (PDA) is a common cardiovascular complication that complicates clinical care in the intensive care of premature infants. Prenatal and postnatal infections and the inflammation process can contribute to PDA, and intrauterine inflammation is a known risk factor of PDA. A variety of inflammatory biomarkers have been reported to be associated with PDA. Chorioamnionitis induces the fetal inflammatory process via several cytokines that have been reported to be associated with the presence of PDA and may have a role in the vascular remodeling process or vessel dilation of the ductus. On the other hand, anti-inflammatory agents, such as antenatal steroids, decrease PDA incidence and severity in patients born to those with chorioamnionitis. Proinflammatory cytokines, which are expressed more significantly in preterm neonates and chorioamnionitis, are associated with the presence of PDA. In this review, we focus on the pathogenesis of PDA in preterm infants and the role of biomarkers associated with the perinatal inflammatory process.

Different approaches for patent ductus arteriosus in premature infants using acetaminophen

BACKGROUND

Acetaminophen use for pharmacological treatment of hemodynamically significant patent ductus arteriosus (hsPDA) in preterm infants is becoming more popular with emerging evidence that it is effective as well as safe alternative for other agents used to close hsPDA.

DATA SOURCES

We performed a narrative review of literature about pharmacological treatment of PDA using acetaminophen.

RESULTS

Acetaminophen was used as a prophylaxis, symptomatic, targeted, and a rescue approach.

CONCLUSIONS

It appears that acetaminophen could be used in different approaches to close the hsPDA. Long-term outcomes of acetaminophen exposure early in life still lack certainty.

Qual Deve Ser o Tratamento de Primeira Linha para o Fechamento de Persistência de Canal Arterial Hemodinamicamente Significativo em Bebês Prematuros?

Fundamento

É importante saber qual medicamento usar como tratamento de primeira linha para fechar o duto.

Objetivos

O objetivo deste estudo é comparar a eficácia e os efeitos colaterais das formas intravenosas (IV) de ibuprofeno e paracetamol e contribuir para a literatura investigando o primeiro medicamento selecionado no tratamento clínico da persistência do canal arterial (PCA).

Métodos

Nosso estudo foi realizado entre janeiro de 2017 e dezembro de 2019. Foram incluídos no estudo bebês prematuros com peso ao nascer (PN) ≤1500 g e idade gestacional (IG) ≤32 semanas. No período do estudo, todos os bebês com persistência do canal arterial hemodinamicamente significativa (hsPCA) receberam ibuprofeno intravenoso (IV) como resgate como tratamento clínico primário ou tratamento com paracetamol IV se houvesse contraindicações para o ibuprofeno. Os pacientes foram divididos em dois grupos: pacientes que receberam ibuprofeno IV e pacientes que receberam paracetamol IV.

Resultados

Desses pacientes, 101 receberam paracetamol IV e 169 receberam ibuprofeno IV. A taxa de sucesso do fechamento da PCA com o primeiro curso do tratamento foi de 74,3% no grupo de paracetamol IV e 72,8% no grupo de ibuprofeno IV (p=0,212).

Conclusões

Nossos resultados mostram que o paracetamol IV é tão eficaz quanto o ibuprofeno IV no tratamento de primeira linha de hsPCA, podendo se tornar o tratamento preferencial para o controle de hsPCA.

Population pharmacokinetic-pharmacodynamic modeling of acetaminophen in preterm neonates with hemodynamically significant patent ductus arteriosus

BACKGROUND

Pharmacokinetics (PK) of intravenous acetaminophen has not been assessed in preterm neonates with hemodynamically significant patent ductus arteriosus (PDA). Moreover, there is a lack of data evaluating the association between PK and pharmacodynamics (PD) of acetaminophen in hemodynamically significant PDA. Hence, we performed a population PK-PD modeling of acetaminophen in preterm neonates with hemodynamically significant PDA.

METHODS

A prospective, observational study was carried out in preterm neonates with hemodynamically significant PDA receiving intravenous acetaminophen (15 mg/kg six hourly) for maximum of nine days. The diameter of the ductus arteriosus was measured using General Electric Vivid 7® (echocardiography) and was the PD measure. The PK-PD modeling was performed using Monolix 2019R2. We performed Monte Carlo (MC) simulations to determine the probability of ductus arteriosus closure from first to the ninth day of acetaminophen treatment.

RESULTS

Fifty-five neonates were recruited. A one-compartment model with first-order elimination described well the PK of acetaminophen. Clearance (CL) and volume of distribution (Vd) for typical neonate weighing 0.98 kg was 0.0452 L/h and 1.18 L, respectively. A combination of an Imax model with effect compartment and an exponential disease progression model described well the PD of acetaminophen. The average baseline diameter of the ductus arteriosus (E0) was 2.53 mm while IC₅₀ was 0.477 µg/mL. The disease progression rate constant (Kprog) and effect compartment transfer rate constant (ke0) were 0.00425 h^-1 and 0.000103 h^-1, respectively. MC simulations of the current dosing regimen revealed a probability of 73.7% ductus arteriosus closure compared to 83.8% with 20 mg/kg six hourly dose.

CONCLUSION

The PK-PD model developed can be used for dosing acetaminophen in premature neonates with hemodynamically significant PDA. Intravenous dose of 20 mg/kg intravenously every six hours is likely to provide a better therapeutic effect than the existing dosing regimen.

Pharmacokinetics of Intravenous Paracetamol (Acetaminophen) and Ductus Arteriosus Closure After Premature Birth

In preterm infants, a high risk of hemodynamically significant patent ductus arteriosus (PDA) exists and its persistence is associated with an increased risk of severe morbidity. Current pharmacological options include ibuprofen or indomethacin. However, treatment by indomethacin or ibuprofen of a large PDA was shown to reduce early pulmonary hemorrhage and later medical treatment but had no effect on neonatal death or morbidity. Early prophylactic treatment of ductus arteriosus by paracetamol seems to be an attractive opportunity to reduce life-threatening morbidity. However, there are currently no data regarding the pharmacokinetics (PK) and pharmacodynamics of paracetamol in preterm neonates in this potential new indication. In this study, we aimed to develop a population PK model for paracetamol and investigate the relationship between paracetamol exposure levels and time to contraction of the ductus. Data were modeled using Monolix software. A one-compartment model adequately described the paracetamol concentration-time course. A Weibull model adequately described the time to contraction of the ductus. Our results suggest that the dosage used in this study (i.e., first day 42.5 mg/kg, then 30 mg/kg/day) allows for reaching the maximum inhibition response from paracetamol regarding the time to close the ductus. However, this study pointed out a lower effect of paracetamol on extremely preterm neonates (below 27 weeks). Therefore, a dose-finding study focusing specifically on extremely preterm neonates with treatment efficacy and toxicity is strongly needed.

Premature closure of ductus arteriosus after a single dose of diclofenac during pregnancy

A male term neonate was admitted to the neonatal intensive care unit in the first hours of life with central cyanosis. Echocardiogram showed severe biventricular hypertrophy, markedly right-sided, tricuspid regurgitation, a patent foramen ovale and a closed ductus arteriosus (CDA). The mother recalled being treated with a single dose of intravenous diclofenac for low back pain 2 weeks earlier. The newborn was started on propranolol with symptomatic improvement and was discharged on day 10. At 1-month follow-up, he showed complete resolution of ventricular hypertrophy and suspended propranolol. In the literature, of the 22 cases of CDA after intrauterine exposure to diclofenac, 11 resolved in utero, 3 required ventilatory and inotropic support and 1 evolved to persistent pulmonary hypertension. In this case, a thorough anamnesis was key to identify the probable cause of an otherwise unexplained transient ventricular hypertrophy. This case also alerts to the fetal risks of non-steroidal anti-inflammatory drugs during the third trimester, requiring close monitoring.

Intravenous acetaminophen (at 15 mg/kg/dose every 6 hours) in critically ill preterm neonates with patent ductus arteriosus: A prospective study

WHAT IS KNOWN AND OBJECTIVES

Acetaminophen has been increasingly used in treating patent ductus arteriosus (PDA) in preterm neonates. Variations were observed in the dosing regimen of acetaminophen across the studies. There is hardly any data available for a relatively higher dose of intravenous acetaminophen (15 mg/kg/dose every 6 hours) in the preterm population. We present here the results of a prospective study with this dose of intravenous acetaminophen for treating PDA in critically ill preterm neonates.

METHODS

Preterm neonates (≤37 weeks of gestational age) with haemodynamically significant PDA were enrolled. Intravenous acetaminophen at 15 mg/kg/dose every 6 hours was administered. Echocardiographic monitoring, liver and renal function tests were carried out. Standard definitions were adhered for defining acute kidney injury (AKI) and hepatotoxicity.

RESULTS

Fifty-five neonates were recruited. Following the first dose, less than half had their serum acetaminophen concentrations in the therapeutic range. Extreme preterm neonates were less likely to have a sustained therapeutic acetaminophen concentration after the first dose. Following multiple doses and at steady state, 97.2% and 98.8% respectively were in the therapeutic range. Forty-three (78.2%) neonates had successful closure of the ductus arteriosus of which 22 were extreme preterm, 17 were very preterm and 4 were late preterm neonates; and considering their birthweights, 21 were extremely low, 16 were very low and 6 were low birthweight categories. Ten neonates had elevated alanine aminotransferase levels with three in the low-to-moderate risk of hepatotoxicity category. Eight neonates had altered renal function tests indicating AKI.

WHAT IS NEW AND CONCLUSION

Intravenous acetaminophen at 15 mg/kg/dose every 6 hours was efficacious in 78.2% of the preterm neonates with PDA. We observed a lower incidence of hepatotoxicity, and AKI in the study population. No association was observed between the serum acetaminophen concentrations and PDA closure.

Molecular and Mechanical Mechanisms Regulating Ductus Arteriosus Closure in Preterm Infants

Failure of ductus arteriosus closure after preterm birth is associated with significant morbidities. Ductal closure requires and is regulated by a complex interplay of molecular and mechanical mechanisms with underlying genetic factors. In utero patency of the ductus is maintained by low oxygen tension, high levels of prostaglandins, nitric oxide and carbon monoxide. After birth, ductal closure occurs first by functional closure, followed by anatomical remodeling. High oxygen tension and decreased prostaglandin levels mediated by numerous factors including potassium channels, endothelin-1, isoprostanes lead to the contraction of the ductus. Bradykinin and corticosteroids also induce ductal constriction by attenuating the sensitivity of the ductus to PGE2. Smooth muscle cells of the ductus can sense oxygen through a mitochondrial network by the role of Rho-kinase pathway which ends up with increased intracellular calcium levels and contraction of myosin light chains. Anatomical closure of the ductus is also complex with various mechanisms such as migration and proliferation of smooth muscle cells, extracellular matrix production, endothelial cell proliferation which mediate cushion formation with the interaction of blood cells. Regulation of vessel walls is affected by retinoic acid, TGF-β1, notch signaling, hyaluronan, fibronectin, chondroitin sulfate, elastin, and vascular endothelial cell growth factor (VEGF). Formation of the platelet plug facilitates luminal remodeling by the obstruction of the constricted ductal lumen. Vasa vasorum are more pronounced in the term ductus but are less active in the preterm ductus. More than 100 genes are effective in the prostaglandin pathway or in vascular smooth muscle development and structure may affect the patency of ductus. Hemodynamic changes after birth including fluid load and flow characteristics as well as shear forces within the ductus also stimulate closure. Current pharmacological treatment for the closure of a patent ductus is based on the blockage of the prostaglandin pathway mainly through COX or POX inhibition, albeit with some limitations and side effects. Further research for new agents aiming ductal closure should focus on a clear understanding of vascular biology of the ductus.

Use of combination therapy with acetaminophen and ibuprofen for closure of the patent ductus arteriosus in preterm neonates

Objective

To compare effectiveness and safety of combination therapy (acetaminophen and ibuprofen) to monotherapy (ibuprofen, indomethacin, or acetaminophen alone) in treatment of the patent ductus arteriosus (PDA) in premature neonates.

Methods

This was a retrospective cohort study of neonates admitted to a tertiary-level neonatal intensive care unit. Included neonates were born at <32 weeks gestation and received pharmacotherapy for PDA closure. Based on the primary therapy received, our cohort was divided into the following four groups: indomethacin alone, ibuprofen alone, acetaminophen alone, and ibuprofen and acetaminophen (in combination). Baseline characteristics, effectiveness, safety, neonatal mortality, and morbidities rates between these groups were compared.

Results

One hundred and forty neonates were analyzed; 17 received combination therapy, and 123 neonates received monotherapy: 22 (17.9%) ibuprofen, 29 (23.6%) acetaminophen, and 72 (58.5%) indomethacin. The PDA closure rates were 41.7% for indomethacin, 41.2% for combination therapy, 37.9% for acetaminophen, and 31.8% for ibuprofen (P=0.100). Rates of adverse effects were comparable between the groups.

Conclusion

The rate of ductal closure was not different between combination therapy and monotherapy. The study did not demonstrate any increased adverse effects in the combination group. Future well-designed prospective clinical trials are needed to guide clinical practice.

A Physiology-Based Pharmacokinetic Framework to Support Drug Development and Dose Precision During Therapeutic Hypothermia in Neonates

Therapeutic hypothermia (TH) is standard treatment for neonates (≥36 weeks) with perinatal asphyxia (PA) and hypoxic-ischemic encephalopathy. TH reduces mortality and neurodevelopmental disability due to reduced metabolic rate and decreased neuronal apoptosis. Since both hypothermia and PA influence physiology, they are expected to alter pharmacokinetics (PK). Tools for personalized dosing in this setting are lacking. A neonatal hypothermia physiology-based PK (PBPK) framework would enable precision dosing in the clinic. In this literature review, the stepwise approach, benefits and challenges to develop such a PBPK framework are covered. It hereby contributes to explore the impact of non-maturational PK covariates. First, the current evidence as well as knowledge gaps on the impact of PA and TH on drug absorption, distribution, metabolism and excretion in neonates is summarized. While reduced renal drug elimination is well-documented in neonates with PA undergoing hypothermia, knowledge of the impact on drug metabolism is limited. Second, a multidisciplinary approach to develop a neonatal hypothermia PBPK framework is presented. Insights on the effect of hypothermia on hepatic drug elimination can partly be generated from in vitro (human/animal) profiling of hepatic drug metabolizing enzymes and transporters. Also, endogenous biomarkers may be evaluated as surrogate for metabolic activity. To distinguish the impact of PA versus hypothermia on drug metabolism, in vivo neonatal animal data are needed. The conventional pig is a well-established model for PA and the neonatal Göttingen minipig should be further explored for PA under hypothermia conditions, as it is the most commonly used pig strain in nonclinical drug development. Finally, a strategy is proposed for establishing and fine-tuning compound-specific PBPK models for this application. Besides improvement of clinical exposure predictions of drugs used during hypothermia, the developed PBPK models can be applied in drug development. Add-on pharmacotherapies to further improve outcome in neonates undergoing hypothermia are under investigation, all in need for dosing guidance. Furthermore, the hypothermia PBPK framework can be used to develop temperature-driven PBPK models for other populations or indications. The applicability of the proposed workflow and the challenges in the development of the PBPK framework are illustrated for midazolam as model drug.

Patent ductus arteriosus in preterm infants: is early transcatheter closure a paradigm shift?

The optimal management approach of the patent ductus arteriosus (PDA) in premature infants remains uncertain owing the lack of evidence for long-term benefits and the limited analyses of the complications of medical and surgical interventions to date. In recent years, devices suitable to plug the PDA of premature infants (including extremely low birthweight, <1000 g) have become available and several trials have demonstrated successful and safe transcatheter PDA closure (TCPC) in this population. Whether TCPC represents a paradigm shift in PDA management that will result in improved short- and long-term outcomes, less bronchopulmonary dysplasia, improved neurodevelopment, or better long term renal function remains to be seen. Careful rigorous study of the potential benefits of TCPC in this highly vulnerable population in the context of well-designed adequately powered trials is needed prior to widespread adoption of this approach.

Understanding the pathobiology in patent ductus arteriosus in prematurity-beyond prostaglandins and oxygen

The ductus arteriosus (DA) is probably the most intriguing vessel in postnatal hemodynamic transition. DA patency in utero is an active state, in which prostaglandin E₂ (PGE₂) and nitric monoxide (NO), play an important role. Since the DA gets programmed for postnatal closure as gestation advances, in preterm infants the DA frequently remains patent (PDA). PGE₂ exposure programs functional postnatal closure by inducing gene expression of ion channels and phosphodiesterases and anatomical closure by inducing intimal thickening. Postnatally, oxygen inhibits potassium and activates calcium channels, which ultimately leads to a rise in intracellular calcium concentration consequently inducing phosphorylation of the myosin light chain and thereby vasoconstriction of the DA. Since ion channel expression is lower in preterm infants, oxygen induced functional vasoconstriction is attenuated in comparison with full term newborns. Furthermore, the preterm DA is more sensitive to both PGE₂ and NO compared to the term DA pushing the balance toward less constriction. In this review we explain the physiology of DA patency in utero and subsequent postnatal functional closure. We will focus on the pathobiology of PDA in preterm infants and the (un)intended effect of antenatal exposure to medication on both fetal and neonatal DA vascular tone.

Comparative effectiveness of drugs used to constrict the patent ductus arteriosus: a secondary analysis of the PDA-TOLERATE trial (NCT01958320)

OBJECTIVE

To evaluate the effectiveness of drugs used to constrict patent ductus arteriosus (PDA) in newborns < 28 weeks.

METHODS

We performed a secondary analysis of the multi-center PDA-TOLERATE trial (NCT01958320). Infants with moderate-to-large PDAs were randomized 1:1 at 8.1 ± 2.1 days to either Drug treatment (n = 104) or Conservative management (n = 98). Drug treatments were assigned by center rather than within center (acetaminophen: 5 centers, 27 infants; ibuprofen: 7 centers, 38 infants; indomethacin: 7 centers, 39 infants).

RESULTS

Indomethacin produced the greatest constriction (compared with spontaneous constriction during Conservative management): RR (95% CI) = 3.21 (2.05-5.01)), followed by ibuprofen = 2.03 (1.05-3.91), and acetaminophen = 1.33 (0.55-3.24). The initial rate of acetaminophen-induced constriction was 27%. Infants with persistent moderate-to-large PDA after acetaminophen were treated with indomethacin. The final rate of constriction after acetaminophen ± indomethacin was 60% (similar to the rate in infants receiving indomethacin-alone (62%)).

CONCLUSION

Indomethacin was more effective than acetaminophen in producing ductus constriction.

Tratamiento farmacológico del conducto arterioso permeable en recién nacidos prematuros

Introducción. Por lo general, el manejo farmacológico del conducto arterioso permeable (CAP) comprende inhibidores no selectivos de la enzima ciclooxigenasa, en especial indometacina e ibuprofeno. En años recientes también se ha sugerido al acetaminofén como alternativa terapéutica.Objetivo. Realizar una revisión narrativa de la literatura acerca del manejo farmacológico del CAP.Materiales y métodos. Se realizó una búsqueda estructurada de la literatura en las bases de datos ProQuest, EBSCO, ScienceDirect, PubMed, LILACS, Embase, Trip Database, SciELO y Cochrane Library con los términos “Ductus Arteriosus, patent AND therapeutics”; “Ductus Arteriosus, patent AND indometacin”; “Ductus Arteriosus, Patent AND ibuprofen”, y “Ductus Arteriosus, patent AND acetaminophen”. La búsqueda se hizo en inglés con sus equivalentes en español.Resultados. Se encontraron 69 artículos con información relevante para llevar a cabo la presente revisión.Conclusiones. En neonatos prematuros, la base del tratamiento farmacológico del CAP continúa siendo los inhibidores no selectivos de la ciclooxigenasa, indometacina e ibuprofeno, ambos con perfiles similares de seguridad y eficacia. La evidencia disponible sugiere que el acetaminofén podría constituir una alternativa útil para el manejo, pero resulta insuficiente para realizar recomendaciones definitivas respecto a la eficacia y seguridad de este medicamento.

Efficacy and Safety of Oral Paracetamol vs. Oral Ibuprofen in the Treatment of Symptomatic Patent Ductus Arteriosus in Premature Infants

BACKGROUND

The ductus arteriosus (DA) is situated between the aortic arch and the pulmonary artery in fetal circulation, and its closure is one of the most important changes required for the transition to extrauterine life. Prolonged duration of patent DA (PDA) impairs hemodynamics and contributes both to morbidity associated with prematurity and to mortality. Therefore, when best to initiate treatment and what drug to use as first-line treatment to close the ductus is important.

OBJECTIVE

The aim of this study was to compare the efficacy and side effects of the oral forms of ibuprofen and paracetamol and to contribute to the literature investigating the first drug to be selected in the medical treatment of PDA.

METHODS

This observational, retrospective cohort study was conducted in infants born at ≤ 28 weeks' gestation and admitted to our Neonatal Intensive Care Unit (Manisa Merkezefendi State Hospital, Manisa, Turkey) between February 2015 and April 2018. Included infants were born at ≤ 28 weeks' gestation, had PDA-related clinical findings and hemodynamically significant PDA on echocardiography, and received oral ibuprofen or oral paracetamol therapy as the closure treatment.

RESULTS

The most common clinical findings for the diagnosis of PDA were hyperdynamic circulation, tachycardia, and increased oxygen requirement. In total, 43 of the 51 (84.3%) premature infants in the ibuprofen group and 32 of the 36 (88.8%) in the paracetamol group achieved PDA closure after the first treatment cycle. There was no statistically significant difference between the two groups in terms of respiratory morbidity, renal and liver function, intraventricular hemorrhage, necrotizing enterocolitis, bronchopulmonary dysplasia, retinopathy of prematurity, length of hospital stay, and mortality.

CONCLUSIONS

Our results indicate that oral paracetamol was as effective as oral ibuprofen in the medical treatment of PDA. In addition, both drugs were considered well-tolerated in terms of effects on kidney, liver, and intestinal functions. Our results demonstrate that oral paracetamol can be used effectively and safely as the first-line treatment of PDA.

Maternal paracetamol intake and fetal ductus arteriosus constriction or closure: a case series analysis

Recent case reports describe an association between maternal paracetamol intake and fetal ductus arteriosus constriction or closure. To put these cases into perspective and explore causality, a structured literature search was conducted. The World Health Organization Uppsala Monitoring Centre (WHO-UMC) causality tool was applied to the cases retrieved. The search resulted in 12 papers with 25 case descriptions, of which one case was classified as unlikely, nine as possible, 11 as probable and four as certain. Consequently, we concluded that a causal relationship between maternal paracetamol intake and fetal ductus arteriosus constriction or closure is likely. These findings suggest that pharmacovigilance studies on paracetamol safety during pregnancy are warranted to quantify the event and put the current findings into clinical perspective. Although analgesia during pregnancy and during the peripartum period is of obvious relevance, alternative analgesics such as opioids or other nonsteroidal anti-inflammatory drugs also have side effects.

Efficacy and Safety of Paracetamol for Patent Ductus Arteriosus Closure in Preterm Infants: An Updated Systematic Review and Meta-Analysis

Background: Indomethacin and ibuprofen, two commonly used prostaglandin inhibitors, are the drugs of choice for patent ductus arteriosus. However, paracetamol is an alternative choice when these drugs are ineffective or contraindicated. This study aimed to confirm paracetamol's efficacy and safety compared with those of other drugs or placebos for patent ductus arteriosus closure in premature infants. Methods: We conducted a literature search using the Cochrane Library, PubMed, CINAHL, and EMBASE databases for randomized controlled trials and quasi-randomized controlled trials. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to direct the process and PICO (P, population; I, intervention/interest; C, comparator; O, outcome) principle to constitute the theme. We combined the research data through qualitative summaries or meta-analyses. Results: The final analyses included 15 trials (N = 1,313). No significant differences were noted between paracetamol and ibuprofen except for shorter mean days needed for patent ductus arteriosus closure, lower risk of gastrointestinal bleeding, and hyperbilirubinemia. No significant difference existed between paracetamol and indomethacin. Oral paracetamol was more effective than placebo in infants weighing 1,501-2,500 g. Conclusions: Our study findings tentatively conclude that paracetamol can induce early patent ductus arteriosus closure without significant side effects but that its efficacy is not superior to that of indomethacin.

Acetaminophen in low doses for closure of the ductus arteriosus of the premature

Objective

The objective of the study is to report the experience with acetaminophen in low doses as an alternative to the treatment of the ductus arteriosus of the preterm newborn.

Materials and Methods

Retrospective study including preterm newborns with patent ductus arteriosus who received oral acetaminophen because treatment with indomethacin had failed or is contraindicated. A dosage consisted of a first dose of 25 mg/kg and maintenance doses of 30 mg/kg/day, for 3 to 7 days. A second cycle was administered in cases of reopening of the ductus arteriosus. The rates of ductal closure and surgery were calculated. Patients were categorized into responder and nonresponder groups for acetaminophen, and the average values of ductal diameter, weight, gestational age, and postnatal age were compared.

Results

Eighty-seven preterm newborns, with a postnatal age from 3 to 27 days, with average values of ductus arteriosus equal to 2.5 ± 0.8 mm/kg, gestational age 27.2 ± 1.9 weeks, and birth weight 888.9 ± 241 g, received acetaminophen for 3 to 7 days. A second cycle was administered in 15 preterm newborns. The ductus closure rate, after one or two cycles, was 74.7%, and the recommendations for surgical closure were progressively reduced from 50% in the 1^st year to 6.2% in the past year. Lower ductal closure rate occurred in the group of newborns with the lowest average weight (P = 0.018), the highest average ductal diameter (P = 0.002), and the lowest average gestational age (P = 0.09). Postnatal age at the start of acetaminophen use was shown to be irrelevant regarding the treatment (P = 0.591).

Conclusions

Acetaminophen in low doses showed to be an effective alternative for the closure of the ductus arteriosus for preterm newborns in whom treatment with indomethacin or ibuprofen failed or was contraindicated.

Early treatment versus expectative management of patent ductus arteriosus in preterm infants: a multicentre, randomised, non-inferiority trial in Europe (BeNeDuctus trial)

BACKGROUND

Much controversy exists about the optimal management of a patent ductus arteriosus (PDA) in preterm infants, especially in those born at a gestational age (GA) less than 28 weeks. No causal relationship has been proven between a (haemodynamically significant) PDA and neonatal complications related to pulmonary hyperperfusion and/or systemic hypoperfusion. Although studies show conflicting results, a common understanding is that medical or surgical treatment of a PDA does not seem to reduce the risk of major neonatal morbidities and mortality. As the PDA might have closed spontaneously, treated children are potentially exposed to iatrogenic adverse effects. A conservative approach is gaining interest worldwide, although convincing evidence to support its use is lacking.

METHODS

This multicentre, randomised, non-inferiority trial is conducted in neonatal intensive care units. The study population consists of preterm infants (GA < 28 weeks) with an echocardiographic-confirmed PDA with a transductal diameter > 1.5 mm. Early treatment (between 24 and 72 h postnatal age) with the cyclooxygenase inhibitor (COXi) ibuprofen (IBU) is compared with an expectative management (no intervention intended to close a PDA). The primary outcome is the composite of mortality, and/or necrotising enterocolitis (NEC) Bell stage ≥ IIa, and/or bronchopulmonary dysplasia (BPD) defined as the need for supplemental oxygen, all at a postmenstrual age (PMA) of 36 weeks. Secondary outcome parameters are short term sequelae of cardiovascular failure, comorbidity and adverse events assessed during hospitalization and long-term neurodevelopmental outcome assessed at a corrected age of 2 years. Consequences regarding health economics are evaluated by cost effectiveness analysis and budget impact analysis.

DISCUSSION

As a conservative approach is gaining interest, we investigate whether in preterm infants, born at a GA less than 28 weeks, with a PDA an expectative management is non-inferior to early treatment with IBU regarding to the composite outcome of mortality and/or NEC and/or BPD at a PMA of 36 weeks.

TRIAL REGISTRATION

This trial is registered with the Dutch Trial Register NTR5479 (registered on 19 October 2015), the registry sponsored by the United States National Library of Medicine Clinicaltrials.gov NCT02884219 (registered May 2016) and the European Clinical Trials Database EudraCT 2017-001376-28 .

The dark side of ibuprofen in the treatment of patent ductus arteriosus: could paracetamol be the solution?

INTRODUCTION

Patent ductus arteriosus (PDA) persistence is associated, in prematures, to several complications. The optimal PDA management is still under debate, especially regarding the best therapeutic approach and the time to treat. The available drugs are not exempt from contraindications and side effects; ibuprofen itself, although representing the first-choice therapy, can show nephrotoxicity and other complications. Paracetamol seems a valid alternative to classic nonsteroidal anti-inflammatory Drugs, with a lower toxicity. Areas covered: Through an analysis of the published literature on ibuprofen and paracetamol effects in preterm neonates, this review compares the available treatments for PDA, analyzing the mechanisms underlining ibuprofen-associated nephrotoxicity and the eventual paracetamol-induced hepatic damage, also providing an update of what has been yet demonstrated and a clear description of the still open issues. Expert Opinion: Paracetamol is an acceptable alternative in case of contraindication to ibuprofen; its toxicity, in this setting, is very low. Lower doses may be effective, with even fewer risks. In the future, paracetamol could represent an efficacious first-line therapy, although its safety, optimal dosage, and global impact have to be fully clarified through long-term trials, also in the perspective of an individualized and person-based therapy taking into account the extraordinary individual variability.

Paracetamol Serum Concentrations in Neonates Treated Enterally for Ductal Closure: A Pilot Study

We determined serum paracetamol concentrations 4 hours after the eighth dose in infants treated enterally for ductal closure. Serum paracetamol concentrations correlated (P = .0026) with ductal response. No patent ductus arteriosus in a baby with paracetamol levels <20 mg/L closed in response to treatment. Paracetamol levels also correlated (P = .046) with postnatal age.

Acetaminophen for Patent Ductus Arteriosus in Extremely Low-Birth-Weight Neonates

OBJECTIVE

Although non-steroidal anti-inflammatory drugs (NSAIDs) are the current standard therapy for the treatment of patent ductus arteriosus (PDA), many neonates have contraindications to receiving or may fail NSAID therapy. To avoid surgical ligation, these patients may benefit from an alternative therapy. The objective of this research is to report the efficacy and safety of acetaminophen for the treatment of PDA in a cohort of premature neonates.

METHODS

Demographics and clinical course were retrospectively evaluated for all neonates admitted during the study period who received acetaminophen for the treatment of PDA. Initial acetaminophen dosing was 15 mg/kg every 6 hours (88% intravenous). Efficacy was analyzed from ductal constriction on echocardiogram as well as need for further PDA treatment. Markers of hepatic and renal function as well as respiratory support and neonatal morbidities were evaluated to describe the safety of acetaminophen.

RESULTS

Forty-one neonates were identified with a median birth weight of 760 g (IQR 614-948 g) and median gestational age of 25 weeks (IQR 24-27 weeks). Treatment was initiated at a median postnatal age of 15 days (IQR 8-19 days) for a median duration of 7 days (IQR 6-10 days). Twenty-seven neonates (66%) required no further PDA treatment, with echocardiographic PDA closure documented in 10 neonates (24%) and reduced ductal size in 15 neonates (37%). No clinically significant adverse effects attributable to acetaminophen therapy were detected.

CONCLUSIONS

Most patients in this study responded to acetaminophen treatment for PDA, indicating that this therapy may be an option for extremely low-birth-weight neonates in order to avoid surgical ligation.

Efficacy of Paracetamol in Closure of Ductus Arteriosus in Infants under 32 Weeks of Gestation

BACKGROUND

Standard medical treatment for patent ductus arteriosus (PDA) closure has been indomethacin/ibuprofen or surgical ligation. Up to date, new strategies have been reported with paracetamol. The aim of this study was to present our experience with intravenous paracetamol for closing PDA in preterm neonates presenting contraindication to ibuprofen or ibuprofen had failed and no candidates for surgical ligation because of huge instability.

MATERIALS AND METHODS

We conducted a retrospective case series study in a neonatal intensive care unit from a tertiary hospital. 9 preterm infants ≤32 weeks of gestational age with hemodynamically significant PDA (hsPDA) were enrolled. They received 15 mg/kg/6h intravenous paracetamol for ductal closure. Demographic data and transaminase levels before and after treatment were collected.

RESULTS

30 preterm babies were diagnosed of hsPDA. 11/30 received ibuprofen with closure in 81.1%. 9 received intravenous paracetamol mainly due to bleeding disorders or thrombocytopenia. Successful closure on paracetamol was achieved in seven of nine babies (77.7%). There was a significant increase in transaminase levels in two patients. They required no treatment for normalization.

CONCLUSION

Paracetamol is an effective option in closure PDA. It should be a first-line therapeutic option when there are contraindications for ibuprofen treatment. Transaminases must be checked during treatment.

Exposure to acetaminophen and all its metabolites upon 10, 15, and 20 mg/kg intravenous acetaminophen in very-preterm infants

BackgroundExposure to acetaminophen and its metabolites in very-preterm infants is partly unknown. We investigated the exposure to acetaminophen and its metabolites upon 10, 15, or 20 mg/kg intravenous acetaminophen in preterm infants.MethodsIn a randomized trial, 59 preterm infants (24-32 weeks' gestational age, postnatal age <1 week) received 10, 15, or 20 mg/kg acetaminophen intravenously. Plasma concentrations of acetaminophen and its metabolites (glucuronide, sulfate, cysteine, mercapturate, and glutathione) were determined in 293 blood samples. Area under the plasma concentration-time curves (AUC_0-500 min) was related to dose and gestational age.ResultsBetween 10 and 20 mg/kg dose, median AUCs of acetaminophen, glucuronide, sulfate, and cysteine increased significantly resulting in unchanged ratios of AUC of metabolite to acetaminophen. The AUC ratio of glucuronide to acetaminophen increased with gestational age, that of sulfate decreased, and the ratio of cysteine and mercapturate remained unchanged.ConclusionWe found a gestational-age-dependent increase in glucuronidation but no evidence for saturation of a specific pathway as there was a proportional increase in exposure of acetaminophen and all metabolites. Compared with adults, very low exposure to glucuronide but higher exposure to sulfate, cysteine, and mercapturate metabolites was found, of which the relevance is not yet known.

Paracetamol in Patent Ductus Arteriosus Treatment: Efficacious and Safe?

In preterm infants, failure or delay in spontaneous closure of Ductus Arteriosus (DA), resulting in the condition of Patent Ductus Arteriosus (PDA), represents a significant issue. A prolonged situation of PDA can be associated with several short- and long-term complications. Despite years of researches and clinical experience on PDA management, unresolved questions about the treatment and heterogeneity of clinical practices in different centers still remain, in particular regarding timing and modality of intervention. Nowadays, the most reasonable strategy seems to be reserving the treatment only to hemodynamically significant PDA. The first-line therapy is medical, and ibuprofen, related to several side effects especially in terms of nephrotoxicity, is the drug of choice. Administration of oral or intravenous paracetamol (acetaminophen) recently gained attention, appearing effective as traditional nonsteroidal anti-inflammatory drugs (NSAIDs) in PDA closure, with lower toxicity. The results of the studies analyzed in this review mostly support paracetamol efficacy in ductal closure, with inconstant low and transient elevation of liver enzymes as reported side effect. However, more studies are needed to confirm if this therapy shows a real safety profile and to evaluate its long-term outcomes, before considering paracetamol as first-choice drug in PDA treatment.

Paracetamol and morphine for infant and neonatal pain; still a long way to go?

INTRODUCTION

Pharmacologic pain management in newborns and infants is often based on limited scientific data. To close the knowledge gap, drug-related research in this population is increasingly supported by the authorities, but remains very challenging. This review summarizes the challenges of analgesic studies in newborns and infants on morphine and paracetamol (acetaminophen). Areas covered: Aspects such as the definition and multimodal character of pain are reflected to newborn infants. Specific problems addressed include defining pharmacodynamic endpoints, performing clinical trials in this population and assessing developmental changes in both pharmacokinetics and pharmacodynamics. Expert commentary: Neonatal and infant pain management research faces two major challenges: lack of clear biomarkers and very heterogeneous pharmacokinetics and pharmacodynamics of analgesics. There is a clear call for integral research addressing the multimodality of pain in this population and further developing population pharmacokinetic models towards physiology-based models.

Oral paracetamol vs. oral ibuprofen in the treatment of symptomatic patent ductus arteriosus in premature infants: A randomized controlled trial

The aim of the present study was to analyze the changes of plasma and urinary prostaglandin E₂ (PGE₂) levels in preterm infants with symptomatic patent ductus arteriosus (sPDA) treated with oral ibuprofen and acetaminophen. A total of 87 preterm infants with sPDA admitted to the Neonatal Ward of the Affiliated Xuzhou Hospital of Medical College of Southeast University from October, 2012 to June, 2015 were selected and randomly divided into the ibuprofen group (n=43, 10 mg/kg ibuprofen administered orally as initial dose, followed by 5 mg/kg during the first 24 and 48 h later) and acetaminophen group (n=44, 15 mg/kg acetaminophen administered orally once every 6 h for three days). The levels of plasma and urinary PGE₂ in the two groups were estimated before and after treatment. The treatment of sPDA infants with ibuprofen (ibuprofen group) or acetaminophen (acetaminophen group) caused a significant decrease in the plasma and urinary PGE₂ levels in comparison with plasma and urinary PGE₂ levels before treatment (P<0.05). Furthermore, plasma and urinary PGE₂ levels in the acetaminophen group (45.0±36.9 ng/l) were significantly lower than those in the ibuprofen group (73.5±44.8 ng/l, P=0.002). The arterial duct closure rate was similar between the acetaminophen [31 (70.5%)] and ibuprofen groups [33 (76.7%), P=0.506]. The incidence of oliguria was less among sPDA infants of the acetaminophen group [1 (2.3%)] than observed among the sPDA infants of the ibuprofen group [6 (14.0%)]; however, this difference was not statistically significant (P=0.108). Additionally, the incidences of fecal occult blood positive rate, intraventricular hemorrhage, neonatal necrotizing enterocolitis and bronchopulmonary dysplasia were distributed similarly in the ibuprofen and acetaminophen groups (P>0.05). The levels of platelet, serum creatinine and alanine transaminase showed no significant changes between the ibuprofen and acetaminophen groups (P>0.05). Following treatment with ibuprofen or acetaminophen, the extent of decrease of plasma and urinary PGE₂ was significantly higher among sPDA infants with oliguria (135.0±38.0 ng/l) than that observed in sPDA infants without oliguria (52.5±37.0 ng/l) (P=0.01). The study also found a significant correlation between plasma and urinary PGE₂ levels (r=0.648, P=0.01) and the coefficient of variation of urinary PGE₂ (0.427) was less than that of plasma PGE₂ (0.539). The clinical efficacy of oral ibuprofen and acetaminophen in the treatment of preterm infants with sPDA was similar with low adverse events, whereas acetaminophen-induced PGE₂ levels were less than the levels observed in the ibuprofen-treated group. The incidence of oliguria was also lower in the acetaminophen group compared to the ibuprofen group. In addition, monitoring urinary PGE₂ levels was more suitable because of its non-invasiveness in the clinical setting than monitoring of plasma PGE₂ in preterm infants with sPDA.

Acetaminophen to avoid surgical ligation in extremely low gestational age neonates with persistent hemodynamically significant patent ductus arteriosus

OBJECTIVE

The objective of this study was to evaluate the effectiveness of rescue oral acetaminophen in improving echocardiography (echo) indices of patent ductus arteriosus (PDA) shunt volume and avoiding surgical ligation in extremely low gestational age (GA) neonates (ELGANs, <28 weeks) with persistent PDA.

STUDY DESIGN

Retrospective cohort study of ELGANs with moderate or severe PDA at risk for ligation after a practice change introducing oral acetaminophen (60 mg kg(-1) day(-1) for 3 to 7 days) to facilitate ductal constriction after indomethacin failure.

RESULTS

Twenty-six infants (median GA 24.4 weeks at birth) with persistent PDA under consideration for surgical ligation were treated with oral acetaminophen at a mean of 27 days of life. Echo indices of shunt volume improved in 12 (46%) infants (3 closed and 9 reduced to mild shunt), all of whom avoided ligation. There was no echo improvement in 14 (54%) infants, of which 8/14 underwent ligation, and ligation was deferred in 6/14 infants, mostly owing to improvement in respiratory stability. Fewer responders than non-responders underwent ligation (0% vs 57%, P<0.01), though there were no differences in other neonatal outcomes.

CONCLUSIONS

In ELGANs with persistent significant PDA, rescue therapy with oral acetaminophen was associated with improvement in echo indices of shunt volume and avoidance of ligation in nearly half of infants.

Intravenous paracetamol for PDA closure in the preterm: a single-center experience

Increasing recent evidence favors paracetamol use for patent ductus arteriosus (PDA) closure in preterms. Our study aims were (1) to assess efficacy and safety of intravenous (i.v.) paracetamol for PDA closure in a 23-32-week preterm population, as "first-line" (when traditional ibuprofen treatment was contraindicated) or "rescue" treatment (after ibuprofen failed), and (2) to identify predictors of PDA closure. The cumulative efficacy of consecutive cycles of i.v. paracetamol on PDA closure was confirmed after both "first-line" and "rescue" treatment, the overall PDA closure rates being, respectively, 56.7 and 61.1 % (p = 0.7624) after two cycles and 63.3 and 77.8 % (p = 0.2959) after three cycles. No toxicity was apparent after either "first-line" or "rescue" i.v. paracetamol treatment. On multivariate analysis, gestational age (GA) emerged as an independent predictor of PDA closure in the "first-line" i.v. paracetamol treatment group, while clinical risk index for babies (CRIB) score (a patient risk index based on birth weight, GA at birth, sex, patient's temperature on admission, and maximum base excess in first 12 h of life) was an independent predictor of PDA closure failure in the "rescue" group.

CONCLUSION

I.V. paracetamol proved effective in our study population. Randomized control trials (RCTs) are warranted to further investigate the efficacy and safety of i.v. paracetamol for PDA closure in preterms.

WHAT IS KNOWN

• Oral paracetamol has been judged as effective as oral ibuprofen for PDA closure in the preterm. • To date, only a handful of non-randomized studies exist to support the effectiveness of i.v. paracetamol in PDA closure. What is New: • Our observations confirm the clinical efficacy of i.v. paracetamol for PDA closure in a very low birth weight (VLBW)/extremely low birth weight (ELBW) preterm population. • Gestational age and CRIB score emerge as independent predictors of PDA closure.

The impact of a dedicated patent ductus arteriosus ligation team on neonatal health-care outcomes

OBJECTIVE

The decision to perform patent ductus arteriosus (PDA) ligation is controversial. Patient selection is oftentimes poorly standardized, leading to delays in referral and inappropriate intervention. A system for PDA ligation categorization and triaging process was introduced in 2006 at a quaternary hospital in Canada to streamline referrals and enhance perioperative care. We aimed to evaluate the impact of this dedicated PDA ligation triaging system comparing pre- and postimplementation of this system.

STUDY DESIGN

We performed a retrospective chart review. Demographic and cardiorespiratory data of neonates ⩽30 weeks gestation age at birth, who were referred for and/or had a PDA ligation performed during two distinct epochs (EPOCH 1 (2003 to 2005) and EPOCH 2 (2010 to 2012)), were analyzed. All surgeries were performed at The Hospital for Sick Children, the regional referral center for PDA ligation. The primary outcome was incidence of PDA ligation and procedural cancellations. Secondary outcomes included postoperative need for cardiovascular or respiratory support. Subgroup analysis was performed in neonates <1000 vs >1000 g at the time of surgery during both epochs.

RESULT

A total of 198 neonates underwent surgery with no difference in baseline demographics between epochs. The incidence of PDA ligation as a proportion of total live births under 30 weeks in Central East Region of Ontario was lower in the second epoch (EPOCH 1: 117/1092 (10.7%) vs EPOCH 2: 81/1520 (5.3%)). During the second epoch, 24% of referrals for surgery were canceled after review by our PDA ligation team. There were no overall differences in the proportion of neonates with oxygenation failure, ventilation failure or Post-Ligation Cardiac Syndrome (PLCS), after surgery, between epochs. The proportion of neonates who developed systemic hypotension was higher in patients <1000 g (n=34 (34%) vs n=17 (17.4%), P=0.01) at the time of surgery. In addition, we identified a reduction in the proportion of neonates <1000 g who developed PLCS in EPOCH 2. On the contrary, there was an increase in the proportion of neonates >1000 g who developed ventilation failure in EPOCH 2.

CONCLUSION

The presence of dedicated triaging and management system enhances efficiency of referral process through careful selection of patients for PDA ligation and optimizes perioperative management. We demonstrated a reduction in the incidence of PDA ligation without any negative impact on short-term neonatal morbidity. The use of targeted neonatal echocardiography in the assessment of PDA shunt volume and guiding postoperative decision making is likely to have contributed to these findings.

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.

Drug-induced renal damage in preterm neonates: state of the art and methods for early detection

Only a small fraction of drugs widely used in neonatal intensive care units (NICU) are specifically authorized for this population. Even if unlicensed or off-label use is necessary, it is associated with increased adverse drug reactions, which must be carefully weighed against expected benefits. In particular, renal damage is frequent among preterm babies, and is considered a predisposing factor for the development of chronic kidney disease in adulthood. Apart from specific conditions affecting premature neonates (e.g. respiratory distress syndrome, perinatal asphyxia), drugs play an important role in impairing renal function because of well-known nephrotoxicity and/or interaction with renal developmental factors. From a review of the available studies on drug use in NICU patients, we identified and described the most commonly administered drugs that are correlated to renal damage. Early detection of kidney injury is becoming an essential aspects for clinicians because of the limited number of biomarkers applicable in the neonatal population. Postnatal changes of biochemical processes that influence pharmacokinetic and pharmacodynamic aspects need to be further investigated in order to better understand the mechanisms of drug toxicity in this population. The most promising strategies for dose adjustment and therapeutic schemes are discussed. The purpose of this review was to describe current knowledge on drug use among premature babies and their implication in kidney injury development, as well as to highlight available strategies for early detection of renal damage.

Oral medications regarding their safety and efficacy in the management of patent ductus arteriosus

Patent ductus arteriosus (PDA) is a common clinical condition in preterm infants which is inversely related to birth weight and gestational age. Cyclooxygenase inhibitors such as indomethacin and ibuprofen which block the prostaglandin conversion from arachidonic acid are the most commonly used drugs for ductal closure. This review focuses on the safety and efficacy oral medications in the management of PDA in preterm infants. Ibuprofen seems to be the first choice due to its higher safety profile, as it is associated with fewer gastrointestinal and renal side effects when compared to indomethacin. PDA closure rates are better with oral than with intravenous ibuprofen probably due to the pharmacokinetic of the drug. However, these medications were reported to be associated with several adverse including transient renal failure, gastrointestinal bleeding and perforation, hyperbilirubinemia and platelet dysfunction. Paracetamol seems be an alternative to PDA therapy with lower adverse events and side effects.

Clinical pharmacology of paracetamol in neonates: a review

Paracetamol is commonly used to control mild-to-moderate pain or to reduce opioid exposure as part of multimodal analgesia, and is the only compound recommended to treat fever in neonates. Paracetamol clearance is lower in neonates than in children and adults. After metabolic conversion, paracetamol is subsequently eliminated by the renal route. The main metabolic conversions are conjugation with glucuronic acid and with sulphate. In the urine of neonates sulphated paracetamol concentration is higher than the glucuronidated paracetamol level, suggesting that sulfation prevails over glucuronidation in neonates. A loading dose of 20 mg/kg followed by 10 mg/kg every 6 hours of intravenous paracetamol is suggested to achieve a compartment concentration of 11 mg/L in late preterm and term neonates. Aiming for the same target concentration, oral doses are similar with rectal administration of 25 to 30 mg/kg/d in preterm neonates of 30 weeks' gestation, 45 mg/kg/d in preterm infants of 34 weeks' gestation, and 60 mg/kg/d in term neonates are suggested. The above-mentioned paracetamol doses for these indications (pain, fever) are well tolerated in neonates, but do not result in a significant increase in liver enzymes, and do not affect blood pressure and have limited effects on heart rate. In contrast, the higher doses suggested in extreme preterm neonates to induce closure of the patent ductus arteriosus have not yet been sufficiently evaluated regarding efficacy or safety. Moreover, focussed pharmacovigilance to explore the potential causal association between paracetamol exposure during perinatal life and infancy and subsequent atopy is warranted.

Natural History of Patent Ductus Arteriosus in Very Low Birth Weight Infants after Discharge

Data on the natural history of infants discharged with patent ductus arteriosus is sparse. We report on the 36-months follow-up after hospitalization in 68 infants discharged with an open ductus arteriosus. Notwithstanding a high spontaneous closure rate, catheter intervention in 5 infants illustrates a critical need for cardiologic follow-up.

[Paracetamol (acetaminophen) use in neonatology: a (re)appreciation of an old drug]

In neonates, paracetamol is mainly used for its analgesic action. This drug is actually preferred by neonatologists because of its broad therapeutic index. Recently, it has been demonstrated that paracetamol is also an anti-cyclooxygenase (COX) medication through its inhibitory action on the peroxidase arm of central and peripheral COX (Boutaud et al., 2002; Toussaint et al., 2010; Graham et al., 2013; Hinz et al., 2008; Hinz and Brune, 2011). As such, this drug interferes with the synthesis of prostaglandins. This inhibition of peroxidase is, however, limited to a low concentration of arachidonic acid (AA) (around 2μM, in vitro) when the plasmatic concentration of paracetamol is experimentally 10μM, actually within the same range as compared to the therapeutic concentrations in vivo. This may partly explain its low anti-inflammatory effect as compared to ibuprofen and indomethacin, which exert their inhibition on COX whatever the AA concentrations are. This new well-demonstrated action of paracetamol on peripheral COX-2 of intact cells could explain recent observations making this drug a potential alternative in treating patent ductus arteriosus. However, the higher dosages that have been claimed by some authors in this indication still remain to be validated. This inhibition that paracetamol shows on the physiological synthesis of prostaglandins E2 (PGE2) could also explain some long-term immune deviations because the physiological concentration of PGE2 is a well-known actor in the genesis of immune homeostasis in the submucosal area. Indeed, recent epidemiology studies have pointed out immune deviations in children repeatedly exposed to paracetamol earlier in life. Consequently, this is actually the new discovery of an old drug. From these new data on paracetamol, a more focused pharmacovigilance on the long-term effects of paracetamol repeatedly given in the early stage should be urgently initiated.