Efficacy of different routes of acetaminophen administration for postoperative pain in children: a systematic review and network meta-analysis.

PURPOSE: Acetaminophen is the most common drug used to treat acute pain in the pediatric population, given its wide safety margin, low cost, and multiple routes for administration. We sought to determine the most efficacious route of acetaminophen administration for postoperative acute pain relief in the pediatric surgical population. METHODS: We conducted a systematic review of randomized controlled trials (RCTs) that included children aged between 30 days and 17 yr who underwent any type of surgical procedure and that evaluated the analgesic efficacy of different routes of administration of acetaminophen for the treatment of postoperative pain. We searched MEDLINE, CENTRAL, Embase, CINAHL, LILACs, and Google Scholar databases for trials published from inception to 16 April 2023. We assessed the risk of bias in the included studies using the Cochrane Risk of Bias 1.0 tool. We performed a frequentist network meta-analysis using a random-effects model. Our primary outcome was postoperative pain using validated pain scales. RESULTS: We screened 2,344 studies and included 14 trials with 829 participants in the analysis. We conducted a network meta-analysis for the period from zero to two hours, including six trials with 496 participants. There was no evidence of differences between intravenous vs rectal routes of administration of acetaminophen (difference in means, -0.28; 95% confidence interval [CI], -0.62 to 0.06; very low certainty of the evidence) and intravenous vs oral acetaminophen (difference in means, -0.60; 95% CI, -1.20 to 0.01; low certainty of the evidence). For the comparison of oral vs rectal routes, we found evidence favouring the oral route (difference in means, -0.88; 95% CI, -1.44 to -0.31; low certainty of the evidence). Few trials reported secondary outcomes of interest; when comparing the oral and rectal routes in the incidence of nausea and vomiting, there was no evidence of differences (relative risk, 1.20; 95% CI, 0.81 to 1.78). CONCLUSION: The available evidence on the effect of the administration route of acetaminophen on postoperative pain in children is very uncertain. The outcomes of postoperative pain control and postoperative vomiting may differ very little between the oral and rectal route. Better designed and executed RCTs are required to address this important clinical question. STUDY REGISTRATION: PROSPERO (CRD42021286495); first submitted 19 November 2021.

RéSUMé: OBJECTIF: Compte tenu de sa large marge de sécurité, de son faible coût et de ses multiples voies d'administration, l'acétaminophène est le médicament le plus couramment utilisé pour traiter la douleur aiguë dans la population pédiatrique. Nous avons cherché à déterminer la voie d'administration d'acétaminophène la plus efficace pour le soulagement de la douleur aiguë postopératoire dans la population chirurgicale pédiatrique. MéTHODE: Nous avons réalisé une revue systématique d'études randomisées contrôlées (ERC) qui ont inclus des enfants âgé·es de 30 jours à 17 ans ayant bénéficié de n'importe quel type d'intervention chirurgicale et qui ont évalué l'efficacité analgésique de différentes voies d'administration d'acétaminophène pour le traitement de la douleur postopératoire. Nous avons mené des recherches dans les bases de données MEDLINE, CENTRAL, Embase, CINAHL, LILAC et Google Scholar pour en tirer les études publiées depuis leur création jusqu'au 16 avril 2023. Le risque de biais dans les études incluses a été évalué à l'aide de l'outil de Risque de biais 1.0 de Cochrane. Nous avons réalisé une méta-analyse de réseau fréquentiste à l'aide d'un modèle à effets aléatoires. Notre critère d'évaluation principal était la douleur postopératoire mesurée à l'aide d'échelles de douleur validées. RéSULTATS: Nous avons passé en revue 2344 études et inclus 14 études incluant un total de 829 enfants dans l'analyse. Nous avons mené une méta-analyse en réseau pour une période allant de zéro à deux heures, comprenant six études avec 496 participant·es. Il n'y avait aucune preuve de différences entre les voies d'administraion intraveineuse vs rectale de l'acétaminophène (différence de moyennes, −0,28; intervalle de confiance [IC] à 95 %, −0,62 à 0,06; très faible certitude des données probantes) et entre les voies intraveineuse vs orale (différence de moyennes, −0,60; IC 95 %, −1,20 à 0,01; faible certitude des données probantes). Pour la comparaison des voies orale vs rectale, nous avons trouvé des données probantes en faveur de la voie orale (différence de moyennes, −0,88; IC 95 %, −1,44 à −0,31; faible degré de certitude des données probantes). Peu d'études ont rapporté des résultats secondaires d'intérêt; en comparant les voies orale et rectale dans l'incidence des nausées et des vomissements, il n'y avait aucune preuve de différences (risque relatif, 1,20; IC 95 %, 0,81 à 1,78). CONCLUSION: Les données probantes disponibles sur l'effet de la voie d'administration de l'acétaminophène sur la douleur postopératoire chez les enfants sont très incertaines. Les résultats de contrôle de la douleur postopératoire et de vomissements postopératoires peuvent différer très peu entre la voie orale et la voie rectale. Des ERC mieux conçues et mieux exécutées sont nécessaires pour répondre à cette importante question clinique. ENREGISTREMENT DE L'éTUDE: PROSPERO (CRD42021286495); première soumission le 19 novembre 2021.

Traumatic Spinal Injury in Children; Time to Revise Pre-Hospital and Diagnostic Protocols?

Background: Traumatic spinal injury in children is a rare but serious life event. Predicting pediatric patients at risk for spinal injury remains difficult. This study focuses on the cause of the injury and predictors to identify children at risk and appropriate diagnostic procedures. Methods: Retrospective chart review from the Landelijke Trauma Registratie of patients with spinal injury from 2010 to 2021 in a level 1 pediatric trauma center. Results: We included 114 children with spinal injury, 79.8% of whom were aged 12-17 years. In the overall trauma population, the incidence of spinal injury was 10% in children aged 12-17 years, 2.3% in children aged 6-11 years, and 0.4% in children 0-5 years of age. Neurological deficits were present in 27.2% of patients in the emergency department, with permanent deficits in 14.0%. Spinal fractures were present in 91.2% of 12-17-year-olds, 43.8% in 6-11-year-olds, and 71.4% in 0-5-year-olds. ISS was 23 (SD 14) in children with spinal injury compared to 8 (SD 9) for children without spinal injury. Conclusions: In children 0-11 years old, spinal injury is very rare compared to the overall trauma population, and there are more non-osseous injuries. Clinicians should consider MRI as the next step after conventional X-ray to diagnose or exclude spinal injuries in this group. In older children aged 12-17 years, the incidence of spinal injury is much higher, at 10%. Although ISS is higher in children with spinal injury, a low ISS does not exclude spinal injury. If one fracture is found, more fractures in other regions of the spine may be present.

Population pharmacokinetics of paracetamol across the human age-range from (pre)term neonates, infants, children to adults.

In order to characterize the variation in pharmacokinetics of paracetamol across the human age span, we performed a population pharmacokinetic analysis from preterm neonates to adults with specific focus on clearance. Concentration-time data obtained in 220 neonates (post-natal age 1-76 days, gestational age 27-42 weeks), infants (0.11-1.33 yrs), children (2-7 yrs) and adults (19-34 yrs) were analyzed using NONMEM 7.2. In the covariate analysis, linear functions, power functions, and a power function with a bodyweight-dependent exponent were tested. Between preterm neonates and adults, linear bodyweight functions were identified for Q2, Q3, V1, V2, and V3, while for CL a power function with a bodyweight-dependent exponent k was identified (CLi = CLp × (BW/70)(k) ). The exponent k was found to decrease in a sigmoidal manner with bodyweight from 1.2 to 0.75, with half the decrease in exponent reached at 12.2 kg. No other covariates such as age were identified. A pharmacokinetic model for paracetamol characterizing changes in pharmacokinetic parameters across the pediatric age-range was developed. Clearance was found to change in a nonlinear manner with bodyweight. Based on the final model, dosing guidelines are proposed from preterm neonates to adolescents resulting in similar exposure across all age ranges.

Predictive performance of a recently developed population pharmacokinetic model for morphine and its metabolites in new datasets of (preterm) neonates, infants and children.

BACKGROUND AND OBJECTIVE: Model validation procedures are crucial when models are to be used to develop new dosing algorithms. In this study, the predictive performance of a previously published paediatric population pharmacokinetic model for morphine and its metabolites in children younger than 3 years (original model) is studied in new datasets that were not used to develop the original model. METHODS: Six external datasets including neonates and infants up to 1 year were obtained from four different research centres. These datasets contained postoperative patients, ventilated patients and patients on extracorporeal membrane oxygenation (ECMO) treatment. Basic observed versus predicted plots, normalized prediction distribution error analysis, model refitting, bootstrap analysis, subpopulation analysis and a literature comparison of clearance predictions were performed with the new datasets to evaluate the predictive performance of the original morphine pharmacokinetic model. RESULTS: The original model was found to be stable and the parameter estimates were found to be precise. The concentrations predicted by the original model were in good agreement with the observed concentrations in the four datasets from postoperative and ventilated patients, and the model-predicted clearances in these datasets were in agreement with literature values. In the datasets from patients on ECMO treatment with continuous venovenous haemofiltration (CVVH) the predictive performance of the model was good as well, whereas underprediction occurred, particularly for the metabolites, in patients on ECMO treatment without CVVH. CONCLUSION: The predictive value of the original morphine pharmacokinetic model is demonstrated in new datasets by the use of six different validation and evaluation tools. It is herewith justified to undertake a proof-of-principle approach in the development of rational dosing recommendations - namely, performing a prospective clinical trial in which the model-based dosing algorithm is clinically evaluated.

Predictive Performance of a Recently Developed Population Pharmacokinetic Model for Morphine and its Metabolites in New Datasets of (Preterm) Neonates, Infants and Children.

BACKGROUND AND OBJECTIVE: Model validation procedures are crucial when models are to be used to develop new dosing algorithms. In this study, the predictive performance of a previously published paediatric population pharmacokinetic model for morphine and its metabolites in children younger than 3 years (original model) is studied in new datasets that were not used to develop the original model. METHODS: Six external datasets including neonates and infants up to 1 year were obtained from four different research centres. These datasets contained postoperative patients, ventilated patients and patients on extracorporeal membrane oxygenation (ECMO) treatment. Basic observed versus predicted plots, normalized prediction distribution error analysis, model refitting, bootstrap analysis, subpopulation analysis and a literature comparison of clearance predictions were performed with the new datasets to evaluate the predictive performance of the original morphine pharmacokinetic model. RESULTS: The original model was found to be stable and the parameter estimates were found to be precise. The concentrations predicted by the original model were in good agreement with the observed concentrations in the four datasets from postoperative and ventilated patients, and the model-predicted clearances in these datasets were in agreement with literature values. In the datasets from patients on ECMO treatment with continuous venovenous haemofiltration (CVVH) the predictive performance of the model was good as well, whereas underprediction occurred, particularly for the metabolites, in patients on ECMO treatment without CVVH. CONCLUSION: The predictive value of the original morphine pharmacokinetic model is demonstrated in new datasets by the use of six different validation and evaluation tools. It is herewith justified to undertake a proof-of-principle approach in the development of rational dosing recommendations - namely, performing a prospective clinical trial in which the model-based dosing algorithm is clinically evaluated.

Diclofenac and metabolite pharmacokinetics in children.

BACKGROUND: Data concerning metabolism of diclofenac in children are limited to intravenous and enteric coated oral formulations. There are no data examining diclofenac or its hydroxyl metabolite pharmacokinetics after rectal administration in children. METHODS: Infants (n = 26) undergoing tonsillectomy were given diclofenac 2 mg.kg(-1) followed by 1 mg.kg(-1) 8 h as suppository formulation for postoperative analgesia. Serum was assayed for diclofenac, 4'-hydroxydiclofenac and 5'-hydroxydiclofenac concentrations during the procedure and 1, 2 and 4 h postoperatively. The formation clearances of diclofenac to hydroxyl metabolites were estimated using nonlinear mixed effects models. A single compartment, first order absorption and first order elimination model was used to describe diclofenac pharmacokinetics. Published data from 11 children given enteric-coated diclofenac tablets were used to assess relative bioavailability. RESULTS: Mean (sd) age and weight of the patients were 4.5 (1.5) years and 20.5 (4.1) kg. The formation clearance to 4'-hydroxydiclofenac (% CV) and to 5'-hydroxydiclofenac were 8.41 (8.1) and 3.41 (113) l.h(-1) respectively, standardized to a 70 kg person using allometric '1/4 power' models. Clearance by other routes contributed 33.0 (64) l.h(-1) 70 kg(-1). Elimination clearance of hydroxyl metabolites was fixed at 27.5 l.h(-1) 70 kg(-1). The volumes of distribution of parent diclofenac and its hydroxyl metabolite were 22.8 (19.0) and 45.3 (l.70) kg(-1). The suppository formulation had an absorption half-life of 0.613 (33.2) h with a lag time of 0.188 (24.9) h. Interoccasion variability of formation clearance to 4'-hydroxydiclofenac, diclofenac volume of distribution, absorption half-time and lag time for the suppository was 36%, 55%, 14% and 119%, respectively. The relative bioavailability of the suppository compared with an enteric-coated tablet was 1.26. CONCLUSION: The formation clearance of the active metabolite 4'-hydroxydiclofenac contributed 19% of total clearance (44.82 l.h(-1) 70 kg(-1)). The rectum is a suitable route for administration of diclofenac in children 2-8 year of age and was associated with a higher relative bioavailabilty than enteric-coated tablets and an earlier maximum concentration (50 vs. 108 min). This pharmacokinetic profile renders diclofenac suppository a suitable formulation for short duration surgery.

Paracetamol and metabolite pharmacokinetics in infants.

BACKGROUND: Data concerning metabolism of paracetamol in infants are scant. Previous studies have examined urinary metabolite recovery rates after a single dose of paracetamol in either neonates (<6 weeks) or children (3-9 years). There are no studies investigating infants. METHODS: Infants ( n=47) undergoing major craniofacial surgery were given paracetamol 19-45 mg/kg 6-, 8-, or 12-hourly as either elixir or suppository formulation for postoperative analgesia, after a loading dose of 33-59 mg/kg rectally during the operation. Serum was assayed for paracetamol concentration in 40 of these infants at 5, 8, 11, 14, 17 and 20 h postoperatively. Urine samples were collected every 3 h for 24 h in 15 of these infants. The clearances of paracetamol to glucuronide and sulphate metabolites as well as the urinary clearance of unmetabolised paracetamol were estimated using non-linear, mixed-effects models. RESULTS: Mean (+/-SD) age and weight of the patients were 11.8+/-2.5 months and 9.1+/-1.9 kg. Clearances of paracetamol to paracetamol-glucuronide (%CV) and to paracetamol-sulphate were 6.6 (11.5) l/h and 7.5 (11.5) l/h respectively, standardised to a 70-kg person using allometric "1/4 power" models. Glucuronide formation clearance, but not sulphate formation, was related to age and increased with age from a predicted value in a neonate of 2.73 l/h/70 kg to a mature value of 6.6 l/h/70 kg with a maturation half-life of 8.09 months. Urine clearance of paracetamol-glucuronide, paracetamol-sulphate and unchanged paracetamol (%CV) were, respectively, 2.65, 3.03 and 0.55 (28) l/h/70 kg. The urine clearance of unchanged paracetamol and metabolites was related to urine volume flow rate. Clearance attributable to pathways other than these measured in urine was not identifiable. The glucuronide/sulphate formation clearance ratio was 0.69 at 12 months of age. Sulphate metabolism contributed 50% towards paracetamol clearance. CONCLUSION: Glucuronide formation clearance increases with age in the infant age range but sulphate formation does not. Renal clearance of paracetamol and its metabolites increases with urine flow rate. This and other studies show that paracetamol metabolism to glucuronide appears to be similar in infants and children, but in adults is increased in comparison with children. Oxidative pathways were undetectable in this infant study and may explain, in part, the reduced incidence of hepatotoxicity in infants.