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

Pharmacokinetic and Pharmacodynamic Analysis of Acetaminophen and Ibuprofen Dual Therapy for Patent Ductus Arteriosus Closure in Preterm Neonates at Less Than 29 Weeks of Gestation

Patent ductus arteriosus (PDA) is a blood vessel that critically supports fetal circulation. The ductus naturally closes within a few days after birth. However, it can stay open in premature neonates for an extended period of time, which is associated with increased mortality and various co-morbidities. Ibuprofen and indomethacin are currently the only 2 drugs approved for inducing PDA closure, but both have been associated with adverse renal and bleeding events. Clinical evidence suggests that combining acetaminophen (APAP) and ibuprofen treatments can decrease the need for surgical ligation. The objective of this study was to establish a disease-drug-trial model to characterize and predict PDA closure following single and combination drug therapy with ibuprofen and/or APAP in children at less than 29 weeks of gestation. The model was informed by a comprehensive literature review. The results of our analysis suggest that ibuprofen and APAP achieve therapeutic synergy. They further suggest that the younger the preterm neonates, the higher the treatment benefit. A 5-day oral dosing regimen consisting of ibuprofen (20 mg/kg Q24h on day 1, followed by 10 mg/kg Q24h on days 2-5) plus APAP (15 mg/kg Q6h) was deemed appropriate to achieve at least 90% PDA in all preterm neonates evaluated within 1 month of life. The model can now be used to design prospective pediatric trials to evaluate optimal drug combinations for PDA closure in preterm neonates and to refine optimal dosing regimens in cohorts of differing gestational age.

Gentamicin in Neonates with Hemodynamically Significant Patent Ductus Arteriosus

Background

Gentamicin has been shown to cause vasodilation in preclinical studies. Hemodynamically significant patent ductus arteriosus (hsPDA) is a commonly observed congenital heart disorder in preterm neonates. Concomitant gentamicin theoretically shall delay the closure/result in nonclosure of ductus arteriosus (DA). Similarly, hsPDA can alter the pharmacokinetics of gentamicin and so trough gentamicin concentrations. We carried out the present study to evaluate the association between gentamicin use and closure of hsPDA (treated with acetaminophen) as well as the effect of hsPDA on trough concentrations.

Methods

This study was a prospective, observational study that included 60 neonates diagnosed with hsPDA by echocardiography and 102 neonates without hsPDA. Demographic details, size of DA as per echocardiography at the end of treatment with acetaminophen, gentamicin-dosing regimen, and trough concentrations were collected. Standard definitions were adhered in classifying the gestational age, birth weights, and size of DA. The numerical values are reported in median (range).

Results

Neonates with hsPDA had significantly lower daily doses of gentamicin [4.5 (2.5-10), 7 (3.2-13) mg; P < 0.001] but longer duration of therapy [8 (3-14), 5 (3-7) days; P < 0.001] than those without hsPDA in very preterm neonates. No significant differences were observed in the trough concentrations of gentamicin between the groups. No association was observed between gentamicin use and closure of DA. However, those with successful closure of DA received gentamicin for a longer duration [6 (3-10), 4 (3-14) days; P < 0.05] that was independent of acetaminophen duration and had received higher cumulative doses of gentamicin.

Conclusion

In conclusion, we observed a significantly longer duration of gentamicin therapy in neonates with hsPDA compared to those without hsPDA. No significant differences were observed in the rates of closure of DA with concomitant gentamicin administration and gentamicin trough concentrations.

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.

Evaluation of urinary acetaminophen metabolites and its association with the genetic polymorphisms of the metabolising enzymes, and serum acetaminophen concentrations in preterm neonates with patent ductus arteriosus

Acetaminophen is gaining importance as a first-line drug for treating patent ductus arteriosus (PDA) in neonates. Predominant metabolites of acetaminophen in preterm neonates vary from that of adults; and the drug is predominantly metabolised by conjugation and partly by Cytochrome P450 (CYP) enzymes.We carried out the present study to identify the principal urine metabolites of acetaminophen (glucuronide/sulphate) in preterm neonates with hemodynamically significant PDA receiving intravenous acetaminophen, and to evaluate the prevalence of single nucleotide polymorphisms (SNPs) in the key CYP enzymes (CYP1A2*3, CYP1A2*4, CYP1A2*1C, CYP1A2*1K, CYP1A2*6, CYP2D6*10, CYP2E1*2, CYP2E1*5B, CYP3A4*1B, CYP3A4*2, CYP3A4*3, CYP3A5*3, CYP3A5*7, and CYP3A5*11) and their effect on urinary metabolites and serum acetaminophen concentrations.Nineteen (32.8%) neonates had heterozygous CYP1A2*1C, two (3.3%) with heterozygous CYP1A2*1K, 15 (27.8%) and two (3.7%) had heterozygous and homozygous CYP2D6*10, two (3.7%) had heterozygous CYP2E1*5B, seven (12.3%) and three (5.3%) had heterozygous and homozygous CYP3A4*1B, and three (5.5%) had CYP3A5*7 amongst the study population. Acetaminophen sulphate predominated over glucuronide metabolite at all time points. Postnatal days of life was significantly associated with an increase in the urine acetaminophen metabolites with decreased serum acetaminophen concentrations.A significant prevalence of SNPs in the key CYP enzymes related to acetaminophen metabolism was observed in our neonatal population. Population pharmacokinetic-pharmacodynamic modelling incorporating genetic and metabolite data is urgently needed for implementation of precision medicine in this vulnerable population.