Analgesic efficacy of paracetamol in children using tonsillectomy as a pain model

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.

Pharmacokinetics of single dose administration of three increasing doses of acetaminophen per os in 1-3-month-old foals

BACKGROUND

Acetaminophen is a common analgesic and antipyretic drug used in human medicine and might be an alternative to nonsteroidal anti-inflammatory drugs for treating pain and pyrexia in foals. The pharmacokinetics and safety of differing doses of acetaminophen have not been investigated in foals.

OBJECTIVES

To determine the plasma pharmacokinetics and any changes in haematology and biochemistry profiles following oral administration of single doses of acetaminophen at 10, 20, and 40 mg/kg to foals.

STUDY DESIGN

Randomised cross-over pharmacokinetic study.

METHODS

Six Quarter Horse (two colts and four fillies) foals received 10, 20, and 40 mg/kg acetaminophen orally once. Haematology and biochemistry profiles were performed before and 7 days after each drug administration. Blood samples were collected over 64 h after drug administration and were used to quantify plasma acetaminophen concentrations by liquid chromatography. Pharmacokinetic parameters were determined using compartmental analysis.

RESULTS

Median (range) acetaminophen plasma concentrations were 4.4 (1.8-5.1), 6.3 (2.6-12.6), and 14 (7.3-18) μg/ml for the 10, 20, and 40 mg/kg doses, respectively. Median acetaminophen area under the concentration versus time curve (AUC)0-∞ ranged from 25 (11-32), 41 (22-74), and 105 (82-142) h × μg/ml for the 10, 20, and 40 mg/kg doses, respectively. Dose-normalised maximal concentrations and AUC0-∞ values were similar across dose concentrations (p > 0.05). Median terminal half-life for all doses was 2.7-2.8 h. Haematology and biochemistry profiles were normal except for blood urea nitrogen and alkaline phosphatase concentrations.

MAIN LIMITATIONS

Foals were growing throughout the study, starting at 1 month and ending at 3 months. Deposition of drugs changes with age. The sample size was small and only single doses were evaluated. No liver biopsies were performed.

CONCLUSION

Plasma disposition of acetaminophen after a single oral dose of 10, 20, and 40 mg/kg to 1-3-month-old foals varies greatly with the dose. The analgesic and antipyretic effect in foals is unknown.

Pharmacokinetics of acetaminophen after a single Oral administration of 20 or 40 mg/kg to 7-9 Day-old foals

Background

Acetaminophen is utilized in human infants for pain management and fever. Neonatal foals might benefit from administration of acetaminophen but effective and safe dosage regimens for neonatal foals remains to be determined.

Objective

The objective was to determine the plasma pharmacokinetics of acetaminophen following oral administration of a single dose of 20 mg/kg or 40 mg/kg to neonatal foals. A secondary objective was to evaluate any changes in hematology and biochemistry profiles.

Study design

Randomized study.

Methods

Eight clinically healthy 7-9-day old Quarter Horse foals (3 colts and 5 fillies) received a single oral dose of acetaminophen either 20 (n = 4) or 40 (n = 4) mg/kg. Hematology and biochemistry profiles were evaluated before and 7 days after drug administration. Blood samples were collected before and 8 times after acetaminophen administration for 48 h to quantify plasma acetaminophen concentrations. Plasma pharmacokinetic parameters were estimated using non- compartmental analysis.

Results

The median peak plasma concentrations (and range) occurred at 1.5 (0.5-2) hours, and 1.0 (1-2) hours for the 20 and 40 mg/kg doses. The maximum plasma concentration (and range) was 12 (7.9-17.4) μg/mL for the 20 mg/kg dose and 14 (11-18) μg/mL for 40 mg/kg dose. The median AUC_0-∞ ranged from 46 to 100 and 79 to 160 h*-μg/mL for the 20 and 40 mg/kg dose, respectively. Hematology and biochemistry profiles remained within normal limits.

Conclusion

Plasma disposition of acetaminophen after oral administration of 20 and 40 mg/kg to neonates is comparable to adult horses. However, safety and the optimal dosage regimen of acetaminophen for treating pain and or pyrexia in neonates in this age group remains to be determined.

Unlocking the Optimal Analgesic Potential: A Systematic Review and Meta-Analysis Comparing Intravenous, Oral, and Rectal Paracetamol in Equivalent Doses

Paracetamol (acetaminophen) is an extensively used analgesic for acute and chronic pain management. Currently, paracetamol is manufactured for oral, rectal, and intravenous (IV) use. Research has shown varied results on the analgesic properties of IV paracetamol compared to oral and rectal paracetamol; however, research on the same doses of paracetamol is limited. Therefore, this review was constructed to explore the analgesic properties of IV paracetamol compared with oral and rectal paracetamol administered in equivalent doses. A broad and thorough literature search was performed on five electronic databases, including PubMed, ScienceDirect, Medline, Scopus, and Google Scholar. Statistical analysis of all outcomes in our review was then performed using the Review Manager software. Outcomes were categorized as primary (pain relief and time to request rescue analgesia) and secondary (adverse events after analgesia). An extensive quality appraisal was also done using the Review Manager software's Cochrane risk of bias tool. The literature survey yielded 2,945 articles, of which 12 were used for review and analysis. The pooled analysis for patients undergoing surgical procedures showed that IV paracetamol had statistically similar postoperative pain scores at two (mean difference (MD) = -0.14; 95% confidence interval (CI) -0.58-0.29; p = 0.51), 24 (MD = 0.09; 95% CI = -0.02-0.21; p = 0.12), and 48 (MD = 0.04; 95% CI = -0.08-0.16; p = 0.52) hours as oral paracetamol. Similarly, the data on time to rescue analgesia showed no considerable difference between the IV and oral paracetamol groups (MD = -1.58; 95% CI = -5.51-2.35; p = 0.43). On the other hand, the pooled analysis for patients presenting non-surgical acute pain showed no significant difference in the mean pain scores between patients treated with IV and oral paracetamol (MD = -0.35; 95% CI = -2.19-1.48; p = 0.71). Furthermore, a subgroup analysis of analgesia-related adverse events showed that the incidences of vomiting/nausea and pruritus did not differ between patients receiving IV and oral paracetamol (odds ratio (OR) = 0.71; 95% CI = 0.45-1.11; p = 0.13 and OR = 0.48; 95% CI = 0.18-1.29; p = 0.05, respectively). A review of information from two trials comparing equal doses of IV and rectal paracetamol suggested that the postoperative pain scores were statistically similar between the groups. IV paracetamol is not superior to oral or rectal paracetamol administered in equal doses. Therefore, we cannot recommend or refute IV paracetamol as the first-line analgesia for acute and postoperative pain.

The Three W's of Acetaminophen In Children: Who, Why, and Which Administration Mode

Acetaminophen is one of the oldest medications commonly administered in children. Its efficacy in treating fever and pain is well accepted among clinicians. However, the available evidence supporting the use of acetaminophen's different modes of administration remains relatively scarce and poorly known. This short report summarizes the available evidence and provides a framework to guide clinicians regarding a rational use of acetaminophen in children.

Paracetamol (acetaminophen) use in infants and children was never shown to be safe for neurodevelopment: a systematic review with citation tracking

Although widely believed by pediatricians and parents to be safe for use in infants and children when used as directed, increasing evidence indicates that early life exposure to paracetamol (acetaminophen) may cause long-term neurodevelopmental problems. Furthermore, recent studies in animal models demonstrate that cognitive development is exquisitely sensitive to paracetamol exposure during early development. In this study, evidence for the claim that paracetamol is safe was evaluated using a systematic literature search. Publications on PubMed between 1974 and 2017 that contained the keywords "infant" and either "paracetamol" or "acetaminophen" were considered. Of those initial 3096 papers, 218 were identified that made claims that paracetamol was safe for use with infants or children. From these 218, a total of 103 papers were identified as sources of authority for the safety claim.   Conclusion: A total of 52 papers contained actual experiments designed to test safety, and had a median follow-up time of 48 h. None monitored neurodevelopment. Furthermore, no trial considered total exposure to drug since birth, eliminating the possibility that the effects of drug exposure on long-term neurodevelopment could be accurately assessed. On the other hand, abundant and sufficient evidence was found to conclude that paracetamol does not induce acute liver damage in babies or children when used as directed. What is Known: • Paracetamol (acetaminophen) is widely thought by pediatricians and parents to be safe when used as directed in the pediatric population, and is the most widely used drug in that population, with more than 90% of children exposed to the drug in some reports. • Paracetamol is known to cause liver damage in adults under conditions of oxidative stress or when used in excess, but increasing evidence from studies in humans and in laboratory animals indicates that the target organ for paracetamol toxicity during early development is the brain, not the liver. What is New: • This study finds hundreds of published reports in the medical literature asserting that paracetamol is safe when used as directed, providing a foundation for the widespread belief that the drug is safe. • This study shows that paracetamol was proven to be safe by approximately 50 short-term studies demonstrating the drug's safety for the pediatric liver, but the drug was never shown to be safe for neurodevelopment. Paracetamol is widely believed to be safe for infants and children when used as directed, despite mounting evidence in humans and in laboratory animals indicating that the drug is not safe for neurodevelopment. An exhaustive search of published work cited for safe use of paracetamol in the pediatric population revealed 52 experimental studies pointing toward safety, but the median follow-up time was only 48 h, and neurodevelopment was never assessed.

A scoping review of randomized clinical trials for pain management in pediatric tonsillectomy and adenotonsillectomy

Objectives

To examine the volume, topics, and reporting trends in the published literature of randomized clinical trials for pharmacologic pain management of pediatric tonsillectomy and adenotonsillectomy and to identify areas requiring further research.

Data Sources

PubMed (National Library of Medicine and National Institutes of Health), Scopus (Elsevier), CINAHL (EBSCO), and Cochrane Library (Wiley).

Methods

A systematic search of four databases was conducted. Only randomized controlled or comparison trials examining pain improvement with a pharmacologic intervention in pediatric tonsillectomy or adenotonsillectomy were included. Data collected included demographics, pain-related outcomes, sedation scores, nausea/vomiting, postoperative bleeding, types of drug comparisons, modes of administration, timing of administration, and identities of the investigated drugs.

Results

One hundred and eighty-nine studies were included for analysis. Most studies included validated pain scales, with the majority using visual-assisted scales (49.21%). Fewer studies examined pain beyond 24 h postoperation (24.87%), and few studies included a validated sedation scale (12.17%). Studies have compared several different dimensions of pharmacologic treatment, including different drugs, timing of administration, modes of administration, and dosages. Only 23 (12.17%) studies examined medications administered postoperatively, and only 29 (15.34%) studies examined oral medications. Acetaminophen only had four self-comparisons.

Conclusion

Our work provides the first scoping review of pain and pediatric tonsillectomy. With drug safety profiles considered, the literature does not have enough data to determine which treatment regimen provides superior pain control in pediatric tonsillectomy. Even common drugs like acetaminophen and ibuprofen require further research for optimizing the treatment of posttonsillectomy pain. The heterogeneity in study design and comparisons weakens the conclusions of potential systematic reviews and meta-analyses. Future directions include more noninferiority studies of unique comparisons and more studies examining oral medications given postoperatively.

Could the analgesic drugs, paracetamol and indomethacin, function as quorum sensing inhibitors?

The current failure of antimicrobials in treating life-threatening diseases, the high rate of multidrug resistant pathogens and the slow progress in the development of new antibiotics directed scientists to develop antivirulence drugs that targets quorum sensing (QS). In many microbes, QS acts as a communication system which control pathogenicity of microbes. Analgesics can be beneficial in controlling virulence traits of microbes and hence they may augment the efficacy of antimicrobials. In this study, two analgesics were screened for the inhibition of QS in Chromobacterium violaceum CV026 and their effects on virulence production in Pseudomonas aeruginosa PAO1 strain and clinical isolates of Acinetobacter baumannii were evaluated. The traits investigated were biofilm formation, pyocyanin and rhamnolipid production, twitching, swarming or surface associated motilities, production of protease, phospholipase and gelatinase enzymes and sensitivity to oxidative stress. Relative expression of abaI gene was calculated by performing qRT-PCR. Docking analysis of paracetamol as QSI (quorum sensing inhibitor) of AbaI and AbaR proteins was performed. Paracetamol inhibited QS in CV026, but indomethacin devoids anti-QS activity. Paracetamol inhibited virulence factors of PAO1. It strongly inhibited biofilm formation, and swarming by 66.4% and 57.1%, respectively. While, it moderately to slightly inhibited rhamnolipid, pyocyanin, gelatinase, resistance to oxidative stress, protease and twitching motility by 33.3%, 33.1% 17.5%, 9.1%, 8.7% and 7.7%, respectively. For A. baumannii, paracetamol strongly inhibited biofilm by 39.7-93% and phospholipase enzyme by 8.7-100%, reduced twitching and surface motility by 6.7-82.5% and 7.7-29.4%, respectively, And slightly reduced sensitivity to oxidative stress by 3.3-36.4%. Paracetamol at sub-MIC suppressed the expression of abaI gene by 32% in A. baumannii. Docking studies suggested that paracetamol can bind to AbaR and AbaI proteins and bind more to AbaR, hence it may act by inhibiting AHL signal reception. As a conclusion, paracetamol, beside its analgesic activity, has anti-QS activity and could be used in the eradication of P. aeruginosa and A. baumannii infections in combination with antibiotics.

Enteral Acetaminophen Bioavailability in Pediatric Intensive Care Patients Determined With an Oral Microtracer and Pharmacokinetic Modeling to Optimize Dosing

OBJECTIVES

Decreasing morbidity and mortality by rationalizing drug treatment in the critically ill is of paramount importance but challenging as the underlying clinical condition may lead to large variation in drug disposition and response. New microtracer methodology is now available to gain knowledge on drug disposition in the intensive care. On the basis of studies in healthy adults, physicians tend to assume that oral doses of acetaminophen will be completely absorbed and therefore prescribe the same dose per kilogram for oral and IV administration. As the oral bioavailability of acetaminophen in critically ill children is unknown, we designed a microtracer study to shed a light on this issue.

DESIGN

An innovative microtracer study design with population pharmacokinetics.

SETTING

A tertiary referral PICU.

PATIENTS

Stable critically ill children, 0-6 years old, and already receiving IV acetaminophen.

INTERVENTIONS

Concomitant administration of an oral C radiolabeled acetaminophen microtracer (3 ng/kg) with IV acetaminophen treatment (15 mg/kg every 6 hr).

MEASUREMENTS

Blood was drawn from an indwelling arterial or central venous catheter up to 24 hours after C acetaminophen microtracer administration. Acetaminophen concentrations were measured by liquid chromatography-mass spectrometry and C concentrations by accelerated mass spectrometry.

MAIN RESULTS

In 47 patients (median age of 6.1 mo; Q1-Q3, 1.8-20 mo) the mean enteral bioavailability was 72% (range, 11-91%). With a standard dose (15 mg/kg 4 times daily), therapeutic steady-state concentrations were 2.5 times more likely to be reached with IV than with oral administration.

CONCLUSIONS

Microtracer studies present a new opportunity to gain knowledge on drug disposition in the intensive care. Using this modality in children in the pediatric intensive care, we showed that enteral administration of acetaminophen results in less predictable exposure and higher likelihood of subtherapeutic blood concentration than does IV administration. IV dosing may be preferable to ensure adequate pain relief.

Nonopioid analgesics for perioperative and cardiac surgery pain in children: Current evidence and knowledge gaps

Objective:

The purpose of this review is to present the available literature on the use of nonopioid analgesics such as nonsteroidal anti-inflammatory drugs in postcardiac surgery pediatric patients, mainly to focus on patients <1 year of age, and to provide the foundation for future research.

Materials and Methods:

Published studies that address the use on nonopioid medications for postoperative sedation and analgesia in infants and children undergoing cardiac surgery were identified from online sources. Studies were reviewed by two authors independently to assess the quality of the data as well as the evidence. Due to limited availability of such studies, the review was then expanded to include use in noncardiac procedures as well as to expanded age groups. All studies that met the primary objective were included.

Results/Data Synthesis:

Majority of the studies in the population of interest were related to use of ketorolac. Five studies specifically addressed ketorolac use in cardiac patients. In addition, studies were reviewed for nonopioid analgesia in noncardiac patients and included as a part of the available evidence as in the case of acetaminophen use. Newer agents as well as agents with very limited information were also acknowledged.

Conclusion:

Nonopioid medications appear to show promise for analgesia in infants undergoing cardiac surgery, with ketorolac being the most potent agent as a potential substitute for opioids. These agents demonstrate a reasonable safety profile even in the very young. There continue to be significant gaps in knowledge before their adoption becomes routine. However, gives the awareness regarding short-term and long-term impact of opioid use in this vulnerable population, and studies of such agents are an urgent need.

Managing Procedural Pain in the Neonate Using an Opioid-sparing Approach

PURPOSE

Pain in the neonate is often challenging to assess but important to control. Physicians often must balance the need for optimal pain control with the need to minimize oversedation and prolonged opioid use. Both inadequate pain control and overuse of opioids can have long-term consequences, including poor developmental outcomes. The aim of this review is to introduce a comprehensive approach to pain management for physicians, nurses, and surgeons caring for critically ill neonates, focusing on nonopioid alternatives to manage procedural pain.

FINDINGS

After review, categories of opioid-sparing interventions identified included (1) nonopioid pharmacologic agents, (2) local and regional anesthesia, and (3) nonpharmacologic alternatives. Nonopioid pharmacologic agents identified for neonatal use included acetaminophen, NSAIDs, dexmedetomidine, and gabapentin. Local and regional anesthesia included neuraxial blockade (spinals and epidurals), subcutaneous injections, and topical anesthesia. Nonpharmacologic agents uniquely available in the neonatal setting included skin-to-skin care, facilitated tucking, sucrose, breastfeeding, and nonnutritive sucking.

IMPLICATIONS

The use of various pharmacologic and interventional treatments for neonatal pain management allows for the incorporation of opioid-sparing techniques in neonates who are already at risk for poor neurodevelopmental outcomes. A multifactorial approach to pain control is paramount to optimize periprocedural comfort and to minimize the negative sequelae of uncontrolled pain in the neonate.

Analgesic effectiveness, pharmacokinetics, and safety of a paracetamol/ibuprofen fixed-dose combination in children undergoing adenotonsillectomy: A randomized, single-blind, parallel group trial

BACKGROUND

Pain following tonsillectomy is often poorly managed in the home setting. Multimodal analgesia with acetaminophen (paracetamol) and nonsteroidal anti-inflammatory drugs offers superior analgesia over monotherapy but may be difficult for caregivers to manage. A fixed-dose combination oral suspension product containing paracetamol and ibuprofen has been developed to facilitate pediatric dosing.

AIMS

The aims of this study are to determine the analgesic effectiveness, pharmacokinetics, and safety of the fixed-dose combination at two doses in the pediatric population.

METHODS

In this prospective, multicenter, randomized, single-blind, parallel group trial, 251 children aged 2-12 years undergoing day-stay (adeno)tonsillectomy were randomized to two dose groups of the fixed-dose combination. A doubled loading dose was given preoperatively, followed by treatment for up to 11 days (Higher dose: paracetamol 15 mg/kg + ibuprofen 4.5 mg/kg, Lower dose: paracetamol 12 mg/kg + ibuprofen 3.6 mg/kg). Blood samples were collected for pharmacokinetic analysis for up to 6 hours after the loading dose. The analgesic effectiveness was examined on the first day after surgery using both Parents Postoperative Pain Measurement and modified Wong-Baker Faces pain scales. Rescue medication consumption was recorded throughout the study.

RESULTS

Differences in maximum plasma concentration (C_max ) and total exposure (AUC_0→t ) between the treatment groups for both analytes were consistent with a 25% increase in dose; there was no difference in time to peak concentration (T_max ). On the first postoperative day, there was no difference in pain scores or rescue medication use between treatment groups (approximately 30% in both groups). The combination was well tolerated by both groups. The most common adverse events were vomiting and nausea. The incidence of postoperative bleeding was 4.4%.

CONCLUSION

The shallow dose-response relationship and good tolerability of the fixed-dose combination over an extended study period supports the utility of both doses of the fixed-dose combination in the home setting.

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.

Recent Advances in Pediatric Use of Oral Paracetamol in Fever and Pain Management

Paracetamol is a common analgesic and antipyretic drug for management of fever and mild-to-moderate pain in infants and children, and it is considered as first-line therapy for the treatment of both according to international guidelines and recommendations. The mechanism of action of paracetamol is complex and multifactorial, and several aspects of the pharmacology impact its clinical use, especially in the selection of the correct analgesic and antipyretic dose. A systematic literature search was performed by following procedures for transparent reporting of systematic reviews and meta-analyses. To maximize efficacy and avoid delays in effect, use of the appropriate dose of paracetamol is paramount. Older clinical studies using paracetamol at subtherapeutic doses of ≤10 mg/kg generally show that it is less effective than non-steroidal anti-inflammatory drugs (NSAIDs). However, recent evidence shows that when used at dose of 15 mg/kg for fever and pain management, paracetamol is significantly more effective than placebo, and at least as effective as NSAIDs. Paracetamol 15 mg/kg has a tolerability profile similar to that of placebo and NSAIDs such as ibuprofen and ketoprofen used for short-term treatment of fever. However, when used at repetitive doses for consecutive days, paracetamol shows lower risk of adverse events compared to NSAIDs. Also, unlike NSAIDs, paracetamol is indicated for use in children of all ages. Overall, clinical evidence qualifies paracetamol 15 mg/kg a safe and effective option for treatment of pain and fever in children.

Swedish guidelines for the treatment of pain in tonsil surgery in pediatric patients up to 18 years

BACKGROUND

Surgery of the tonsils often causes severe pain lasting for many days as been shown by data from the National Tonsil Surgery Register in Sweden. Tonsillotomy is associated with fewer readmissions due to bleeding, number of days requiring analgesics and health care contacts due to pain compared to tonsillectomy. The register data demonstrate the necessity of better-evidenced based pain treatment guidelines for tonsil-surgery.

OBJECTIVES

To develop evidenced based pain treatment guidelines for tonsil-surgery in Sweden.

METHODS

The evidence based guidelines were designed by an updated literature review and from the clinical expertise in the pediatric pain field, which thereafter were reviewed by ENT-doctors and anesthetists from each ENT-clinic in Sweden.

RESULTS

A multimodal pain treatment approach is advocated, including premedication and administration during anesthesia, with paracetamol (acetaminophen), clonidine and betamethasone. If not given as a premedication the combination can be administered intravenously in the initial phase of anesthesia. At the end of surgery, if no bleeding problems, cox-inhibitors can be given. After discharge from hospital, the recommendations for pain relief are paracetamol combined with cox-inhibitors (ibuprofen, diclofenac) and if needed oral clonidine in favor of opioids. When pain intensity decreases, discontinue the analgesic treatment in the following order: opioid, clonidine, paracetamol and at last ibuprofen. The need for analgesic treatment after tonsillectomy is usually 5-8 days, after tonsillotomy only 3-5 days. Parents are recommended to contact the hospital if the child has difficulties in drinking or eating adequately and/or suffers from pain despite taking the recommended medication regularly.

CONCLUSIONS

Swedish guidelines for tonsil-surgery provide practical evidence-based pain treatment recommendations.

Pharmacogenomics of acetaminophen in pediatric populations: a moving target

Acetaminophen (APAP) is widely used as an over-the-counter fever reducer and pain reliever. However, the current therapeutic use of APAP is not optimal. The inter-patient variability in both efficacy and toxicity limits the use of this drug. This is particularly an issue in pediatric populations, where tools for predicting drug efficacy and developmental toxicity are not well established. Variability in toxicity between age groups may be accounted for by differences in metabolism, transport, and the genetics behind those differences. While pharmacogenomics has been revolutionizing the paradigm of pharmacotherapy for many drugs, its application in pediatric populations faces significant challenges given the dynamic ontogenic changes in cellular and systems physiology. In this review we focused on the ontogenesis of the regulatory pathways involved in the disposition of APAP and on the variability between pediatric, adolescent, and adult patients. We also summarize important polymorphisms of the pharmacogenes associated with APAP metabolism. Pharmacogenetic studies in pediatric APAP treatment are also reviewed. We conclude that while a consensus in pharmacogenetic management of APAP in pediatric populations has not been achieved, a systems biology based strategy for comprehensively understanding the ontogenic regulatory pathway as well as the interaction between age and genetic variations are particularly necessary in order to address this question.

Effect of high-dose paracetamol on needle procedures in children with cancer--an RCT

AIM

The aim was to investigate whether children experience less pain, fear and/or distress when they receive high-dose paracetamol compared with placebo, using a needle insertion in a subcutaneously implanted intravenous port as a model.

METHODS

Fifty-one children ranging from 1 to 18 years of age being treated in a paediatric oncology setting were included consecutively when undergoing routine needle insertion into a subcutaneously implanted intravenous port. All children were subjected to one needle insertion following topical anaesthetic (EMLA) application in this double-blind, placebo-controlled RCT, comparing orally administered paracetamol (n = 24) 40 mg/kg body weight (max 2000 mg) with placebo (n = 27). The patients' pain, fear and distress were reported by parents, nurses and children (≥7 years of age) using 0- to 100-mm visual analogue scales (VAS). In addition, pain observation, procedure time and cortisol reduction were assessed.

RESULTS

No differences between the paracetamol and the placebo group were found with respect to demographic characteristics. According to VAS reports, paracetamol did not reduce pain, fear and distress compared with placebo. Pain observation, cortisol reduction and procedure time did not differ between the study groups.

CONCLUSION

Paracetamol provides no additive effect in reducing pain, fear and distress when combined with topical anaesthesia in children undergoing port needle insertion.

The analgesic efficacy of preoperative oral Ibuprofen and acetaminophen in children undergoing adenotonsillectomy: a randomized clinical trial

Background:

Adenotonsillectomy is one of the most common surgical procedures in children. Several complications and morbidities are common after nasal surgeries and the most common is pain. Several techniques have been employed to reduce the severity of postoperative pain. One of the preoperative techniques is pre-emptive analgesia through preventive central hypersensitization. This technique is performed by applying analgesic methods before the onset of nociceptive stimuli, consequently decreasing postoperative analgesics requirements.

Objectives:

Preoperative oral drug administration for pain analgesia is performed in several methods. The aim of this study was to compare the analgesic effects of preoperatively administration of oral acetaminophen and ibuprofen.

Patients and Methods:

In a double-blinded, randomized placebo-controlled study, sixty 4-12 years old ASA I or II children scheduled for elective adenotonsillectomy, were assigned to receive either acetaminophen 15 mg/kg, ibuprofen 10 mg/kg or placebo 30 minutes before the operation. Postoperative pain was assessed using the Children's Hospital of Eastern Ontario Pain Scale (CHEOPS), upon arrival to the post anesthetic care unit (PACU) and ward. Findings were analyzed by SPSS version 17 using variance analysis and Tukey’s test.

Results:

The average pain intensities were significantly lower in acetaminophen group based on the CHEOPS in both PACU and ward compared to ibuprofen or placebo groups; but there was no difference in pain intensity between the ibuprofen and placebo groups. Pain intensity in PACU in Acetaminophen group was 7.05 ± 0.64 vs. 8.38 ± 1.20 in placebo group and 8.14 ± 0.85 in ibuprofen group, pain intensity in ward in the acetaminophen group was 6.0.87 ± 0.85in the acetaminophen group, vs. 8.04 ± 1.02 in placebo group, and 7.78 ± 0.78 in ibuprofen group.

Conclusions:

This study showed that administration of oral acetaminophen 30 minutes preoperatively, resulted in significantly lower pain intensity in children undergoing adenotonsillectomy in PACU and ward, compared to ibuprofen and placebo.

Pre-emptive triple analgesia protocol for tonsillectomy pain control in children: double-blind, randomised, controlled, clinical trial

Introduction:

This double-blind, controlled, parallel-group study was designed to determine the efficacy of pre-emptive triple analgesia for paediatric post-tonsillectomy pain management.

Materials and methods:

One hundred and thirty-five children were randomised into two groups: pre-emptive triple analgesia (n = 55) and control (n = 80). Pain was assessed using a visual analogue scale (in hospital) and the Parent's Postoperative Pain Measure (at home), and scores recorded.

Results:

Visual analogue scale scores on awakening and for 6 hours post-surgery were significantly better in the study group than the control group (p < 0.05). The Parent's Postoperative Pain Measure scores of control group children were significantly higher within the first 3 post-operative days (p = 0.000), with a greater percentage of children experiencing significant pain and requiring more analgesia.

Conclusion:

The proposed multimodal, pre-emptive analgesia protocol for paediatric post-tonsillectomy pain results in less post-operative pain, both in hospital or at home.

Safety and population pharmacokinetic analysis of intravenous acetaminophen in neonates, infants, children, and adolescents with pain or Fever

OBJECTIVES

The administration of acetaminophen via the oral and rectal routes may be contraindicated in specific clinical settings. Intravenous administration provides an alternative route for fever reduction and analgesia. This phase 1 study of intravenous acetaminophen (Ofirmev, Cadence Pharmaceuticals, Inc., San Diego, CA) in inpatient pediatric patients with pain or fever requiring intravenous therapy was designed to assess the safety and pharmacokinetics of repeated doses over 48 hours.

METHODS

Neonates (full-term to 28 days) received either 12.5 mg/kg every 6 hours or 15 mg/kg every 8 hours. Infants (29 days to <2 years), children (2 to <12 years) and adolescents (≥12 years) received either 12.5 mg/kg every 4 hours or 15 mg/kg every 6 hours. Both noncompartmental and population nonlinear mixed-effects modeling approaches were used. Urinary metabolite data were analyzed, and safety and tolerability were assessed.

RESULTS

Pharmacokinetic parameters of acetaminophen were estimated using a two-compartment disposition model with weight allometrically expressed on clearances and central and peripheral volumes of distribution (Vds). Postnatal age, with a maturation function, was a significant covariate on clearance. Total systemic normalized clearance was 18.4 L/hr per 70 kg, with a plateau reached at approximately 2 years. Total central and peripheral Vds of acetaminophen were 16 and 59.5 L/70 kg, respectively. The drug was well tolerated based on the incidence of adverse events. The primary and minor pathways of elimination were acetaminophen glucuronidation, sulfation, and glutathione conjugate metabolites across all age groups.

CONCLUSIONS

Intravenous acetaminophen in infants, children, and adolescents was well tolerated and achieved plasma concentrations similar to those achieved with labeled 15 mg/kg body weight doses by oral or rectal administration.

Postoperative plasma paracetamol levels following oral or intravenous paracetamol administration: a double-blind randomised controlled trial

In day-case surgery paracetamol is commonly given orally preoperatively, or intravenously intraoperatively. In this double-blind randomised controlled trial we investigated which of these methods of administration achieved therapeutic plasma levels most effectively in the early postoperative period. Thirty patients undergoing day case arthroscopy of the knee were randomised to receive either 1.0 g oral paracetamol 30 to 60 minutes preoperatively (20 patients) or 1.0 g intravenous paracetamol intraoperatively (10 patients). Plasma paracetamol levels were measured 30 minutes after arrival in the recovery room. Secondary outcomes included postoperative pain scores, rescue analgesia requirements and duration of stay in the recovery room. All patients receiving the intravenous preparation had plasma levels above the analgesic level compared to less than half (7/20) in the oral group. Mean plasma paracetamol levels were 88.6 µmol/l for the intravenous group and 53.2 µmol/l for the oral group (P=0.0005). There were trends towards reduced rescue analgesia and duration of stay in the recovery room for the intravenous group although not reaching statistical significance. There was no difference in pain scores between groups. Intraoperative administration of 1.0 g of intravenous paracetamol more reliably achieved effective paracetamol levels in the early postoperative period compared to an equal dose given orally preoperatively. Only a minority of patients receiving the 1.0 g oral dose preoperatively had plasma levels in the therapeutic analgesic range.

Randomised controlled trial comparing oral and intravenous paracetamol (acetaminophen) plasma levels when given as preoperative analgesia

Gastric absorption of oral paracetamol (acetaminophen) may be unreliable perioperatively in the starved and stressed patient. We compared plasma concentrations of parenteral paracetamol given preoperatively and oral paracetamol when given as premedication. Patients scheduled for elective ear; nose and throat surgery or orthopaedic surgery were randomised to receive either oral or intravenous paracetamol as preoperative medication. The oral dose was given 30 minutes before induction of anaesthesia and the intravenous dose given pre-induction. All patients were given a standardised anaesthetic by the same specialist anaesthetist who took blood for paracetamol concentrations 30 minutes after the first dose and then at 30 minute intervals for 240 minutes. Therapeutic concentrations of paracetamol were reached in 96% of patients who had received the drug parenterally, and 67% of patients who had received it orally. Maximum median plasma concentrations were 19 mg.l(-1) (interquartile range 15 to 23 mg.l(-1)) and 13 mg.l(-1) (interquartile range 0 to 18 mg.l(-1)) for the intravenous and oral group respectively. The difference between intravenous and oral groups was less marked after 150 minutes but the intravenous preparation gave higher plasma concentrations throughout the study period. It can be concluded that paracetamol gives more reliable therapeutic plasma concentrations when given intravenously.

Pharmacotherapy for acute pain in children: current practice and recent advances

INTRODUCTION

Acute pain in children may be undertreated. Improved understanding of developmental neurobiology and paediatric pharmacokinetics should facilitate better management of pharmacotherapy. The objective of this review is to discuss current paediatric practice and recent advances with these analgesic agents by using an evidence-based approach.

AREAS COVERED

Using PubMed an extensive literature review was conducted on the commonly used analgesic agents in children from 2000 to April 2010.

EXPERT OPINION

A multimodal analgesic regimen provides better pain control and functional outcome in children. The choice of pharmacological treatment is determined by the severity and type of pain. However, more research and evidence is required to determine the optimal drug combinations.

Paracetamol for intravenous use in medium--and intensive care patients: pharmacokinetics and tolerance

PURPOSE

We studied the pharmacokinetics of paracetamol and determine the incidence of hypotension after intravenous administration in medium- (MCU) and intensive care (ICU) patients.

METHODS

All patients on the ICU/MCU starting with paracetamol i.v. were included, yielding 38 patients. Blood samples were collected at predetermined time points to determine paracetamol serum concentration. The number of patients with a clinically relevant reduction in systolic blood pressure (SBP) and the number of patients that needed intervention to regain an acceptable blood pressure level were assessed.

RESULTS

Overall, pharmacokinetic data were roughly comparable with earlier publications, but differences were noted in the subgroup ICU patients. Also, there was a trend to a larger peak serum concentration (p = 0.052) and a significantly smaller volume of distribution (p = 0.033) in MCU patients compared with ICU patients. Twenty-two percent (22%) and 33% of patients had a clinically relevant reduction in systolic blood pressure (SBP) 15 and 30 min after start of paracetamol infusion, respectively. In six patients (16%), an intervention was needed to correct blood pressure. Overall, SBP was significantly reduced at T = 15 min and 30 min postinfusion (p < 0.003 at both time points) when compared with SBP at the start of paracetamol infusion.

CONCLUSIONS

Further research on differences in paracetamol pharmacokinetics between ICU and MCU patients is warranted, as these differences might result in differences in efficacy. Furthermore, administration of paracetamol i.v. as potential cause of hypotension in the critically ill patient must not be overlooked.

[Therapy of perioperative pain in pediatric urology]

Difficulties in estimating the kind and intensity of pain as well as uncertainty in drug selection and dosing are often responsible for a suboptimal treatment of pain therapy in the various age groups in childhood. The following article will help to minimize these deficits by contributing full details of safe and effective concepts for perioperative pain therapy in childhood.

Pharmacokinetics and analgesic effects of intravenous propacetamol vs rectal paracetamol in children after major craniofacial surgery

BACKGROUND

The pharmacokinetics and analgesic effects of intravenous and rectal paracetamol were compared in nonventilated infants after craniofacial surgery in a double-blind placebo controlled study.

METHODS

During surgery all infants (6 months-2 years) received a rectal loading dose of 40 mg.kg(-1) paracetamol 2 h before anticipated extubation. On admittance to the pediatric surgical ICU, the children were randomized to receive either a 15 min intravenous infusion of 40 mg.kg(-1) propacetamol, a prodrug of paracetamol, or 20 mg.kg(-1) paracetamol rectally every 6 h. A population pharmacokinetic analysis of the paracetamol plasma concentration time-profiles was undertaken using nonlinear mixed effects models. The visual analogue scale (VAS) (score 0-10 cm) and COMFORT Behavior scale (score 6-30) were used to monitor analgesia in the 24-h period following surgery.

RESULTS

Twelve infants received intravenous propacetamol and 14 paracetamol suppositories. Paracetamol pharmacokinetics were described according to a two-compartmental model with linear disposition. Pharmacokinetic parameters were standardized to a 70 kg person using allometric '1/4 power' models. Parameter estimates were: absorption half-life from the rectum 4.6 h, propacetamol hydrolysis half-life 0.028 h, clearance 12 l.h(-1).70 kg(-1), intercompartmental clearance 116 l.h(-1).70 kg(-1), central and peripheral volume of distribution 7.9 and 44 l.70 kg(-1), respectively. During the 24-h study period 22 infants exhibited VAS scores <4 cm, which was considered a cutoff point. On single occasions four patients, two in each group, exhibited a VAS score >/=4 cm. Nine patients in the rectal treatment group and three patients in the intravenous treatment group received midazolam for COMFORT-B scores exceeding 17 (P < 0.05).

CONCLUSIONS

Intravenous propacetamol proved to be more effective than rectal paracetamol in infants after craniofacial surgery. Midazolam was more frequently administered to patients receiving paracetamol suppositories, indicating that these children experienced more distress, possibly caused by pain.

Randomized controlled trial of duration of analgesia following intravenous or rectal acetaminophen after adenotonsillectomy in children

BACKGROUND

Doses of acetaminophen 40 mg kg(-1) rectally and 15 mg kg(-1) i.v. produce similar effect-site concentrations. However, the clinical effectiveness of these routes has not been compared. The aim of this study was to compare duration and efficacy of analgesia in children following adenotonsillectomy after acetaminophen either 40 mg kg(-1) rectally or 15 mg kg(-1) i.v.

METHODS

Fifty children aged between 2 and 5 yr were recruited. They received a standardized anaesthetic, including 2 microg kg(-1) of fentanyl. Children were randomized to receive either rectal or i.v. acetaminophen. Postoperative pain was assessed regularly with the Children and Infants Postoperative Pain Scale score and rescue analgesia provided if scores were 4 or greater. The primary outcome measure was time to first analgesia. Results were plotted with a Kaplan-Meier analysis and median time to rescue analgesia compared between the groups.

RESULTS

The protocol was successfully completed in 46 children. Forty-five children required rescue medication. The time to first rescue analgesia was longer in children receiving rectal acetaminophen (median 10 h, inter-quartile range 9-11 h) compared with those receiving i.v. acetaminophen (7, 6-10 h) with a P-value of 0.01 by log-rank test for equality in survivor function. Few children in either group required rescue analgesia within the first 6 h with differences between the groups being most prominent in the period from 6 to 10 h.

CONCLUSIONS

Rectal acetaminophen 40 mg kg(-1) provides longer analgesia for moderately painful procedures when compared with 15 mg kg(-1) acetaminophen i.v.

Effects of intramuscular and peritonsillar injection of tramadol before tonsillectomy: a double blind, randomized, placebo-controlled clinical trial

BACKGROUND/AIMS

Our objective was to investigate the efficacy of intramuscular injection and peritonsillar infiltration of tramadol to prevent pain in children undergoing tonsillectomy.

METHODS

In a double-blinded trial, 45 children were randomized into three groups: infiltration anesthesia with tramadol (2 mgkg(-1)) to the peritonsillar area (INF group, n=15), intramuscular analgesia with tramadol (2 mgkg(-1)) (IM group, n=15), and the placebo controls (PL group, n=15). Visual analog scale (VAS) scores for pain assessment, heart rate (HR) and mean arterial pressure (MAP) during and after anesthesia were recorded.

RESULTS

Mean HR values were higher in INF than PL group at 10th, 20th, and 30th minutes of operation (P<0.05). Nine children required analgesics within the first hour after surgery in PL compared to 1 child in INF group (P=0.036). VAS scores on awakening were significantly better in INF than PL group (P=0.015). The difference between IM and PL groups was not significant for any of the parameters.

CONCLUSION

Peritonsillar infiltration with tramadol provided good intraoperative analgesia, less postoperative pain on awakening and lower analgesic requirement within the first hour after surgery.

Oral naproxen but not oral paracetamol reduces the need for rescue analgesic after adenoidectomy in children

BACKGROUND

Our aim was to show the efficacy of naproxen and paracetamol with and without pethidine on pain and nausea and vomiting after adenoidectomy. The primary outcome was the requirement of rescue analgesic for post-operative pain and the secondary outcome was post-operative nausea and vomiting (PONV).

METHODS

A randomized, double-blind, placebo-controlled study design was used. Thirty minutes before anaesthesia induction, patients (n= 180) received either a single oral dose analgesic (naproxen 10 mg/kg or paracetamol 20 mg/kg) or a placebo. Half of the children received pethidine 1 mg/kg intravenously (i.v.) at the induction of anaesthesia. Post-operative pain was evaluated using an objective behavioural pain scale (OPS 0-9) and rescue medication, i.v. fentanyl 1 mug/kg, was administered if the child suffered from moderate or severe pain (OPS > or = 4).

RESULTS

When pethidine was not used, 83% of the children in the naproxen group vs. 97% in the other two groups required rescue fentanyl (P < 0.05). The use of pethidine reduced the incidence of fentanyl requirement by 30% and the number of fentanyl doses by 50% (P < 0.001). It also equalized the effects of naproxen, paracetamol and the placebo making the pain model invalid for this kind of study. The drawback associated with better analgesia was a doubling of the incidence of PONV (P < 0.001).

CONCLUSIONS

Oral naproxen (10 mg/kg), but not oral paracetamol (20 mg/kg), reduces the need for rescue analgesic after adenoidectomy in children. The sensitivity of the pain model is crucial for these types of studies.

[Systemic analgesia adapted to the children's condition]

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.

Patterns of Pain and Analgesic Use in 3- to 7-Year-Old Children After Tonsillectomy

Tonsillectomy is a common surgical procedure usually associated with moderate to severe pain. Although self-report is the gold standard for pain assessment, researchers have not studied young children at home with self-report measures. The purpose of this study was to describe the patterns of self-reported pain intensity and analgesic administration in 3- to 7-year-old children undergoing tonsillectomy during the operative day in the hospital and the first 2 postoperative days at home in Iceland. As part of a larger study, 68 children undergoing tonsillectomy were taught to use the Wong-Baker FACES Pain Rating Scale. Pain intensity scores and data about administration of analgesics were collected from children, the medical record, and the parents over a 3-day period. Children received primarily acetaminophen or acetaminophen with codeine in the hospital. At home, 99% of doses administered were acetaminophen only. Most doses were administered rectally. Forty percent of children received 24-hour therapeutic doses in the hospital. Only 10% received a 24-hour therapeutic dose at home despite significant pain scores of 4 or 5 persisting through the second postoperative day. Younger children were less likely to receive acetaminophen with codeine. In the hospital, children with pain intensity scores of 4 or 5 received prescribed morphine only 13% of the time. Children experienced clinically significant pain through the second postoperative day and will probably require a change in protocol to provide more aggressive pain management earlier. This study extends to younger children the research evidence that current pain protocols are inadequate.

The Analgesic Efficacy of Acetaminophen, Ketoprofen, or Their Combination for Pediatric Surgical Patients Having Soft Tissue or Orthopedic Procedures

The combined use of acetaminophen and a nonsteroidal antiinflammatory drug has been shown to provide better postoperative analgesia than either drug alone in several adult studies. However, there are no pediatric studies analyzing similar effects when the currently recommended doses of acetaminophen are used. In a double-blind, placebo-controlled design we randomized 120 children, aged 1-9 yr, undergoing orthopedic or soft tissue surgery, into 3 groups to receive either acetaminophen 60 mg/kg rectally and 40 mg/kg orally, ketoprofen 2 mg/kg IV twice, or the combination of the active drugs. The first drug doses were given at anesthetic induction and the second doses 8 h thereafter. During anesthesia all children received sevoflurane and a continuous infusion of remifentanil. Postoperative pain was evaluated by the behavioral objective pain scale (0-9) for 24 h. The rescue medication was morphine 0.05 mg/kg IV. The primary outcome variable was morphine consumption. For statistical analysis, analysis of variance, chi2 test and Kaplan-Meier survival analysis were used. Morphine requirement was less in the combination than in the acetaminophen group both in the postanesthesia care unit (2.5 +/- 1.7 versus 3.9 +/- 2.1 morphine doses) and during the 24-h postoperative follow-up (4.1 +/- 2.5 versus 5.9 +/- 2.9 morphine doses) (P < 0.05). No differences existed between the ketoprofen and the acetaminophen groups. The objective pain scale scores were lowest in the combination group both in the postanesthesia care unit and in the postoperative ward (P < 0.05). When children were divided based on their surgery, opioid requirement and pain scores were less in the combination than in the parent drug groups only after orthopedic surgery. The combination of acetaminophen 100 mg/kg and ketoprofen 4 mg/kg in a day provided better analgesia and lower pain scores after orthopedic, but not soft tissue, surgery in children.

The pharmacokinetics of a single rectal dose of paracetamol (40 mg x kg(-1)) in children with liver disease

BACKGROUND

The aim of our study was to measure the serum paracetamol concentrations achieved following a single rectal loading dose of 40 mg x kg(-1) in children with chronic liver disease.

METHODS

We recruited 17 children (3-15 years, 10.6-75 kg) undergoing minor surgical procedures under general anesthesia. Paracetamol was administered at the end of surgery and blood samples were taken for analysis at 2, 3, 4, 6 and 8 h postdose.

RESULTS

The mean Cmax of 11.4 mg x l(-1) [coefficient of variation (CV) 66%] was achieved at a Tmax of 2.7 h (CV 42%). The relative bioavailability (F) of the suppository formulation was not estimated, but clearance (Cl/F) estimates 0.73 l x kg(-1) x h(-1) (CV 87%) and time-concentration profiles for these children were similar to the normal pediatric population.

CONCLUSIONS

There are currently no biologic markers available for monitoring possible hepatotoxicity in this cohort of patients with liver disease, but our data suggest that a single-dose suppository is a satisfactory analgesic alternative.

Systematic review on analgesics given for pain following tonsillectomy in children

In this systematic review effectiveness of analgesics for pain after tonsillectomy in children was evaluated and trial methodology of the included studies explored. Databases were searched for randomised, controlled studies on systemic paracetamol, NSAIDs and opioids. Eighty-four studies were evaluated for inclusion. Thirty-six studies were included and 48 excluded. Only in two studies investigated analgesics were given postoperatively for pain. All other studies investigated prophylactic administration of analgesics. Only five studies were truly placebo controlled. Trial methodology of the included studies varied greatly in respect to analgesics and doses used, duration of follow-up periods, methods of pain measurement, rescue analgesics and criteria for administrating rescue analgesia used. Sensitivity of studies was often unclear. Only 16 out of 36 studies were considered to be sensitive. Because of highly variable methodology and lack of sensitivity only limited conclusions on clinical efficacy of analgesics investigated can be drawn. No analgesic in single prophylactic dose provided analgesia for day of operation. Further studies are needed to find the optimal analgesic(s) for pain after tonsillectomy in children.

Equal antipyretic effectiveness of oral and rectal acetaminophen: a randomized controlled trial [ISRCTN11886401]

BACKGROUND

The antipyretic effectiveness of rectal versus oral acetaminophen is not well established. This study is designed to compare the antipyretic effectiveness of two rectal acetaminophen doses (15 mg/kg) and (35 mg/kg), to the standard oral dose of 15 mg/kg.

METHODS

This is a randomized, double-dummy, double-blind study of 51 febrile children, receiving one of three regimens of a single acetaminophen dose: 15 mg/kg orally, 15 mg/kg rectally, or 35 mg/kg rectally. Rectal temperature was monitored at baseline and hourly for a total of six hours. The primary outcome of the study, time to maximum antipyresis, and the secondary outcome of time to temperature reduction by at least 1 degrees C were analyzed by one-way ANOVA. Two-way ANOVA with repeated measures over time was used to compare the secondary outcome: change in temperature from baseline at times 1, 2, 3, 4, 5, and 6 hours among the three groups. Intent-to-treat analysis was planned.

RESULTS

No significant differences were found among the three groups in the time to maximum antipyresis (overall mean = 3.6 hours; 95% CI: 3.2-4.0), time to fever reduction by 1 degrees C or the mean hourly temperature from baseline to 6 hours following dose administration. Hypothermia (temperature < 36.5 degrees C) occurred in 11(21.6%) subjects, with the highest proportion being in the rectal high-dose group.

CONCLUSION

Standard (15 mg/kg) oral, (15 mg/kg) rectal, and high-dose (35 mg/kg) rectal acetaminophen have similar antipyretic effectiveness.

An evaluation of pain and postoperative nausea and vomiting following the introduction of guidelines for tonsillectomy

BACKGROUND

Tonsillectomy and adenotonsillectomy have a high incidence of postoperative pain, and postoperative nausea and vomiting (PONV). Pain is traditionally controlled with morphine but this increases the risk of PONV and may cause respiratory depression. Antiemetics reduce PONV but their routine use has been questioned on safety grounds.

METHOD

After determining the current anesthetic management of elective tonsillectomy and adenotonsillectomy patients in our hospital, guidelines were developed to avoid the routine use of morphine and antiemetics. The effect on pain and PONV was then evaluated over a 3 month period. Postoperative pain was scored using the Oucher visual analog scale and nausea scored using a five point scale.

RESULTS

We analysed 34 cases to determine our current practice and 37 cases to evaluate the effect of introducing guidelines. Postguidelines, the median Oucher pain score at 4 h was 10, and at 8, 12, 16 h was zero. Despite receiving no antiemetics, only two children vomited (5%) after introduction of guidelines.

CONCLUSION

Guidelines which use a combination of paracetamol, nonsteroidal anti-inflammatory drugs and fentanyl, provide excellent analgesia with minimal PONV after elective tonsillectomy and adenotonsillectomy. As a result the routine use of morphine and antiemetics can be avoided.

A systematic review of trial methodology, using the placebo groups of randomized controlled trials in paediatric postoperative pain

Trial methodology was evaluated in paediatric analgesic studies. Databases were searched for randomised, placebo controlled studies of systemic paracetamol, NSAIDs and opioids administered for acute postoperative pain in children. Eighty-three studies met the inclusion criteria and 40 were included for the analysis. Analgesics were administered for established postoperative pain in two studies only. In all other studies they were administered in a prophylactic manner. As study design and sensitivity are particularly demanding in studies using pre-emptive dosing of analgesics, the placebo groups were analysed for issues of study sensitivity. Postoperative pain outcomes included pain scores in 34, rescue analgesia in 36, time to first rescue analgesia in 15, pain on activity in eight, number of patients with pain in six, pain relief in three, global efficacy rating in two and analgesic consumption via PCA in four studies. Twenty of 36 studies reported criteria for rescue analgesia that varied from 20 to 77% of the maximum pain intensity. Need of rescue analgesia showed more often differences between study groups than time to first rescue analgesia or pain intensity. Rescue analgesia was administered to 21-100% of the patients in the placebo groups where no other analgesics were given perioperatively. Most patients in the placebo groups had pain that was greater than 30% of the maximum. In conclusion, analysis of the methodology showed several aspects of trial design that can be improved in future studies. Placebo control groups can be used in paediatric analgesic studies to demonstrate internal sensitivity.

Pre-emptive effects of ibuprofen syrup and lidocaine infiltration on post-operative analgesia in children undergoing adenotonsillectomy

We aimed to compare the effects of lidocaine and adrenaline with ibuprofen syrup (administered before adenotonsillectomy) on post-operative analgesia and initiation of oral feeding. One group of 20 children received 100 g/5 ml ibuprofen suspension (10 mg/kg) 1 h before anaesthesia; bleeding control was provided by pre-incisional administration of 1:200,000 adrenaline solution (10 ml). The same amount of 0.5% lidocaine solution plus 1:200,000 adrenaline was applied pre-incisionally in a similar manner in a second group of 20 children. No significant differences were observed between the two groups in terms of the duration of operation and anaesthesia, post-operative pain scores, paracetamol requirements, times to initiation of liquid and solid food intake, or adverse side-effects. We conclude that ibuprofen syrup applied pre-incisionally and local infiltration with lidocaine are equally effective for post-operative analgesia.

Temperament and pain in 3 to 7-year-old children undergoing tonsillectomy

The purpose of this study was to examine the relationships among temperament, self-reported pain, parent's report of children's pain behavior and pain intensity, amount of pain medication received, and parents' attitudes toward use of analgesics in 3- to 7-year-old children undergoing tonsillectomy. Sixty-eight child/parent dyads participated in the study. Correlations were found between some temperamental factors and child's self-reported pain intensity in the hospital and at home as well as parents' report of pain behavior at home. There was a significant positive relationship between the child's self-reported pain intensity and analgesic administration in the hospital and at home.

Valdecoxib versus rofecoxib in acute postsurgical pain: results of a randomized controlled trial

The analgesic efficacy of the cyclooxygenase-2 specific inhibitors, valdecoxib and rofecoxib, were evaluated in patients following oral surgery. In a randomized, double-blind, controlled trial, patients experiencing moderate or severe pain received single-dose valdecoxib 40 mg (n=99), rofecoxib 50 mg (n=101), or placebo (n=50) within 4 hours after multiple third molar extraction with bone removal. Onset of action was significantly faster with valdecoxib 40 mg (30 minutes) compared with rofecoxib 50 mg (45 minutes), as measured by pain intensity difference and pain relief scores (P <or= 0.05). Valdecoxib and rofecoxib provided a similar magnitude of analgesic effect, as measured by time-weighted sum of total pain relief, at 6 hours post dosing. However, valdecoxib was significantly superior to rofecoxib with respect to mean time-specific pain intensity difference and pain relief scores from 30 minutes to 1.5 hours post dose (P < 0.05). All treatments were well tolerated.