Dataset Information

Pharmacokinetic/Pharmacodynamic Modelling of Allopurinol, its Active Metabolite Oxypurinol, and Biomarkers Hypoxanthine, Xanthine and Uric Acid in Hypoxic-Ischemic Encephalopathy Neonates.

ABSTRACT:

Background

Allopurinol, an xanthine oxidase (XO) inhibitor, is a promising intervention that may provide neuroprotection for neonates with hypoxic-ischemic encephalopathy (HIE). Currently, a double-blind, placebo-controlled study (ALBINO, NCT03162653) is investigating the neuroprotective effect of allopurinol in HIE neonates.

Objective

The aim of the current study was to establish the pharmacokinetics (PK) of allopurinol and oxypurinol, and the pharmacodynamics (PD) of both compounds on hypoxanthine, xanthine, and uric acid in HIE neonates. The dosage used and the effect of allopurinol in this population, either or not undergoing therapeutic hypothermia (TH), were evaluated.

Methods

Forty-six neonates from the ALBINO study and two historical clinical studies were included. All doses were administered on the first day of life. In the ALBINO study (n = 20), neonates received a first dose of allopurinol 20 mg/kg, and, in the case of TH (n = 13), a second dose of allopurinol 10 mg/kg. In the historical cohorts (n = 26), neonates (all without TH) received two doses of allopurinol 20 mg/kg in total. Allopurinol and oxypurinol population PK, and their effects on inhibiting conversions of hypoxanthine and xanthine to uric acid, were assessed using nonlinear mixed-effects modelling.

Results

Allopurinol and oxypurinol PK were described by two sequential one-compartment models with an autoinhibition effect on allopurinol metabolism by oxypurinol. For allopurinol, clearance (CL) was 0.83 L/h (95% confidence interval [CI] 0.62-1.09) and volume of distribution (V_d) was 2.43 L (95% CI 2.25-2.63). For metabolite oxypurinol, CL and V_d relative to a formation fraction (f_m) were 0.26 L/h (95% CI 0.23-0.3) and 11 L (95% CI 9.9-12.2), respectively. No difference in allopurinol and oxypurinol CL was found between TH and non-TH patients. The effect of allopurinol and oxypurinol on XO inhibition was described by a turnover model of hypoxanthine with sequential metabolites xanthine and uric acid. The combined allopurinol and oxypurinol concentration at the half-maximal XO inhibition was 0.36 mg/L (95% CI 0.31-0.42).

Conclusion

The PK and PD of allopurinol, oxypurinol, hypoxanthine, xanthine, and uric acid in neonates with HIE were described. The dosing regimen applied in the ALBINO trial leads to the targeted XO inhibition in neonates treated with or without TH.

SUBMITTER: Chu WY

PROVIDER: S-EPMC8813842 | biostudies-literature | 2022 Feb

REPOSITORIES: biostudies-literature

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Publications

Pharmacokinetic/Pharmacodynamic Modelling of Allopurinol, its Active Metabolite Oxypurinol, and Biomarkers Hypoxanthine, Xanthine and Uric Acid in Hypoxic-Ischemic Encephalopathy Neonates.

Chu Wan-Yu WY Annink Kim V KV Nijstad A Laura AL Maiwald Christian A CA Schroth Michael M Bakkali Loubna El LE van Bel Frank F Benders Manon J N L MJNL van Weissenbruch Mirjam M MM Hagen Anja A Franz Axel R AR Dorlo Thomas P C TPC Allegaert Karel K Huitema Alwin D R ADR

Clinical pharmacokinetics 20211007 2

<h4>Background</h4>Allopurinol, an xanthine oxidase (XO) inhibitor, is a promising intervention that may provide neuroprotection for neonates with hypoxic-ischemic encephalopathy (HIE). Currently, a double-blind, placebo-controlled study (ALBINO, NCT03162653) is investigating the neuroprotective effect of allopurinol in HIE neonates.<h4>Objective</h4>The aim of the current study was to establish the pharmacokinetics (PK) of allopurinol and oxypurinol, and the pharmacodynamics (PD) of both compou ...[more]

PMID: 34617261

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Project description:Previously, we developed a pharmacokinetic-pharmacodynamic model of allopurinol, oxypurinol, and biomarkers, hypoxanthine, xanthine, and uric acid, in neonates with hypoxic-ischemic encephalopathy, in which high initial biomarker levels were observed suggesting an impact of hypoxia. However, the full pharmacodynamics could not be elucidated in our previous study. The current study included additional data from the ALBINO study (NCT03162653) placebo group, aiming to characterize the dynamics of hypoxanthine, xanthine, and uric acid in neonates with hypoxic-ischemic encephalopathy. Neonates from the ALBINO study who received allopurinol or placebo mannitol were included. An extended population pharmacokinetic-pharmacodynamic model was developed based on the mechanism of purine metabolism, where synthesis, salvage, and degradation via xanthine oxidoreductase pathways were described. The initial level of the biomarkers was a combination of endogenous turnover and high disease-related amounts. Model development was accomplished by nonlinear mixed-effects modeling (NONMEM®, version 7.5). In total, 20 neonates treated with allopurinol and 17 neonates treated with mannitol were included in this analysis. Endogenous synthesis of the biomarkers reduced with 0.43% per hour because of precursor exhaustion. Hypoxanthine was readily salvaged or degraded to xanthine with rate constants of 0.5 1/h (95% confidence interval 0.33-0.77) and 0.2 1/h (95% confidence interval 0.09-0.31), respectively. A greater salvage was found in the allopurinol treatment group consistent with its mechanism of action. High hypoxia-induced initial levels of biomarkers were quantified, and were 1.2-fold to 2.9-fold higher in neonates with moderate-to-severe hypoxic-ischemic encephalopathy compared with those with mild hypoxic-ischemic encephalopathy. Half-maximal xanthine oxidoreductase inhibition was achieved with a combined allopurinol and oxypurinol concentration of 0.68 mg/L (95% confidence interval 0.48-0.92), suggesting full xanthine oxidoreductase inhibition during the period studied. This extended pharmacokinetic-pharmacodynamic model provided an adequate description of the complex hypoxanthine, xanthine, and uric acid metabolism in neonates with hypoxic-ischemic encephalopathy, suggesting a positive allopurinol effect on these biomarkers. The impact of hypoxia on their dynamics was characterized, underlining higher hypoxia-related initial exposure with a more severe hypoxic-ischemic encephalopathy status.

Project description:BackgroundHypoxic-ischemic encephalopathy (HIE) is one of the major complications that can lead to death or disability in neonates. We assessed the effect of citicoline as a neuroprotector in neonates with moderate and severe HIE.MethodsThis clinical trial was carried on 80 neonates with moderate to severe HIE who were not candidates for therapeutic cooling. They were subdivided randomly into two groups; citicoline treatment group which included 40 neonates who received citicoline 10 mg / kg /12 h IV for 4 weeks plus other supportive measures and the control group which included 40 neonates who were managed with placebo and the same supportive measures. All patients were evaluated for duration of mechanical ventilation (MV), need for inotropes, seizures (type, frequency, and duration), and duration of NICU. Cranial ultrasounds and brain magnetic resonance image (MRI) were performed for all included neonates after 4 weeks of treatment. Follow- ups of all neonates for the neurodevelopmental outcomes were done at 3, 6, 9, and 12 months.ResultsThere was a significant reduction in the number of neonates having seizures after discharge in the citicoline-treated group (2 neonates) compared to the control group (11 neonates). Cranial ultrasound and MRI findings at 4 weeks were significantly better in the treatment group compared to the control group. Moreover, neurodevelopmental outcome showed significant improvement at 9 and 12 months in the citicoline treated neonates compared to the control group. There was statistically significant reduction in the duration of seizures, NICU stay, inotrope use, and MV in the treatment group compared to the control group. Citicoline was well tolerated with no remarkable side effects.ConclusionCiticoline could be a promising neuroprotector drug in neonates with HIE.Trial registrationThe study was registered at ClinicalTrials.gov (NCT03949049). Registered at 14 May 2019, https://clinicaltrials.gov/ct2/show/NCT03949049.

Dataset Information

Pharmacokinetic/Pharmacodynamic Modelling of Allopurinol, its Active Metabolite Oxypurinol, and Biomarkers Hypoxanthine, Xanthine and Uric Acid in Hypoxic-Ischemic Encephalopathy Neonates.

Background

Objective

Methods

Results

Conclusion

Publications

Pharmacokinetic/Pharmacodynamic Modelling of Allopurinol, its Active Metabolite Oxypurinol, and Biomarkers Hypoxanthine, Xanthine and Uric Acid in Hypoxic-Ischemic Encephalopathy Neonates.

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