The placebo (I shall please)--is it so pleasing in children?

Pharmacokinetic and pharmacodynamic considerations of general anesthesia in pediatric subjects

Introduction: The target concentration strategy uses PKPD information for dose determination. Models have also quantified exposure-response relationships, improved understanding of developmental pharmacokinetics, rationalized dose prescription, provided insight into the importance of covariate information, explained drug interactions and driven decision-making and learning during drug development.Areas covered: The prime PKPD consideration is parameter estimation and quantification of variability. The main sources of variability in children are age (maturation) and weight (size). Model use is mostly confined to pharmacokinetics, partly because anesthesia effect models in the young are imprecise. Exploration of PK and PD covariates and their variability hold potential to better individualize treatment.Expert opinion: The ability to model drugs using computer-based technology is hindered because covariate data required to individualize treatment using these programs remain lacking. Target concentration intervention strategies remain incomplete because covariate information that might better predict individualization of dose is absent. Pharmacogenomics appear a valuable area for investigation for pharmacodynamics and pharmacodynamics. Effect measures in the very young are imprecise. Assessment of the analgesic component of anesthesia is crude. While neuromuscular monitoring is satisfactory, depth of anaesthesia EEG interpretation is inadequate. Closed loop anesthesia is possible with better understanding of EEG changes.

A randomised, double-blind, placebo-controlled clinical trial assessing the efficacy of bedtime buddy® for the treatment of nocturnal enuresis in children

BACKGROUND

Nocturnal enuresis (NE), or 'bedwetting', is a form of night-time urinary incontinence occurring in younger children. A diagnosis of NE can be socially disruptive and psychologically stressful for a child. The most common strategies used by parents to manage NE are waking the child during the night to use the bathroom and limiting the child's water intake before going to bed. Behavioural or educational therapies for NE such as urotherapy or bladder retraining are widely accepted and considered as a mainstream treatment option for non-neurogenic lower urinary tract dysfunction in children. Pharmacotherapy also plays an ancillary role. However, there is no gold standard therapy or intervention to effectively manage NE.

METHODS

This study aims to determine the efficacy of a herbal combination in the treatment of NE in children. The target population for this study is 80 children aged between 6 and 14 years old (males and females) who have primary nocturnal enuresis ≥3 per week (wet nights). The active group will receive one or two capsules per day containing 420 mg of a proprietary blend of Urox® (Seipel Group, Brisbane, Australia) containing Cratevox™ (Crataeva nurvala L; Capparidaceae; Varuna) stem bark extract standardised for 1.5% lupeol: non-standardised Equisetum arvense L. (Equisetaceae; Horsetail) stem extract; and, non-standardised Lindera aggregata Sims. The primary outcome for this study is the frequency of nocturia. Secondary outcomes include safety, quality of life, and daytime incontinence. Each participation will be involved in the trial for 32 weeks including contact with the research team every 2 weeks for the first 8 weeks and then every 8 weeks until trial completion.

DISCUSSION

This study examines a novel treatment for an under-researched health condition affecting many children. Despite the availability of several therapies for NE, there is insufficient evidence to support the use of any one intervention and as such this randomised placebo-controlled phase II trial will be an important contribution to understanding potential new treatments for this condition.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registration Number: 12618000288224.

PROTOCOL

23 February 2018, version 1.1.

Pharmacokinetics and analgesic effectiveness of intravenous parecoxib for tonsillectomy ± adenoidectomy

BACKGROUND

Few pharmacokinetic (PK) and pharmacodynamic (PD) data exist for COX-2 selective inhibitors in children. We wished to characterize the PKPD of parecoxib and its active metabolite, valdecoxib, in this population.

METHODS

Children (n = 59) were randomized to parecoxib 0.25 mg·kg^-1 , 1 mg·kg^-1 , and 2 mg·kg^-1 during tonsillectomy ± adenoidectomy. Samples (4-6 per child) were obtained from indwelling cannula over 6 h. A second group of inpatient children (n = 15) given 1 mg·kg^-1 contributed PK data from 6 to 24 h. Pain scores and rescue medication for the first group were recorded postoperatively for up to 24 h. PK data were pooled with those (10 samples/24 h) from a published study of children (n = 38) who underwent surgery. A three-compartment parent and one-compartment metabolite model with first-order elimination was used to describe data using nonlinear mixed effects models. An E_MAX model described the relationship between dose and rescue morphine equivalents during recovery.

RESULTS

Parecoxib PK parameter estimates were CL_PARECOXIB 19.1 L·h^-1 ·70 kg^-1 , V1_PARECOXIB 4.2 L·70 kg^-1 , Q2_PARECOXIB 6.29 L·h^-1 ·70 kg^-1 , V2_PARECOXIB 130 L·70 kg^-1 , Q3_PARECOXIB 6.02 L·h^-1 ·70 kg^-1 , and V3_PARECOXIB 2.03 L·70 kg^-1 . We assumed all parecoxib was metabolized to valdecoxib with CL_VALDECOXIB 9.53 L·h^-1 ·70 kg^-1 and V_VALDECOXIB 51 L·70 kg^-1 . There was no maturation of clearance over the age span studied. There were no differences in pain scores between groups on waking, discharge, 12 h, or 24 h. There were no differences in analgesia consumption over 24 h between groups for tramadol, fentanyl, and morphine rescue use. Fentanyl and morphine consumption, expressed as morphine equivalents (0.13 mg·kg^-1 ) in the 0.25 mg·kg^-1 group, was greater than that observed in the 1 or 2 mg·kg^-1 groups (0.095 mg·kg^-1 ) in PACU.

CONCLUSIONS

Parecoxib 0.9 mg·kg^-1 in a 2-year-old, 0.75 mg·kg^-1 in a 7-year-old, and 0.65 mg·kg^-1 in a 12-year-old child achieves dose equivalence of 40 mg in a standard 70 kg person. Clearance maturation may occur in infants younger than the current cohort. Parecoxib doses above 1 mg·kg^-1 add no additional analgesia.

Structured intervention for management of pain following day surgery in children

BACKGROUND

Ambulatory surgery forms a large part of pediatric surgical practice. Several studies indicate that postoperative pain is poorly managed with more than 30% of children having moderate to severe pain. In a busy outpatient clinic contact between healthcare professionals and the family is increasingly limited calling for a global and efficient pain management regime.

OBJECTIVE

The aim of this prospective observational cohort study was to determine postoperative pain intensity following day surgery in children after our structured intervention for pain management.

METHODS

A number of interventions in an effort to address barriers to effective postoperative pain management after day surgery were identified in the literature. By introducing our concept structured intervention, we aimed to address the majority if not all these barriers. Accordingly, we adapted postoperative pain management to each child using a multimodal approach consisting of surgery-specific analgesia with weight appropriate doses of acetaminophen and ibuprofen. Analgesics were handed out to the parents in formulations accepted by child and parent and after thorough information to the parents.

RESULTS

Two hundred and forty-five children were scheduled for surgery during the 3-month period of which 149 children were available for analysis. The postoperative pain as assessed by the parents with a the Short Form of the Parents' Postoperative Pain Measure (PPPM-SF) was well managed exhibiting a median pain score of 4 on postoperative day 0 (POD0) and median 1 on postoperative day 1 (POD1) and a numeric rating scale (NRS) median pain score of 2 on POD0 and median 1 on POD1. We found a highly significant correlation between the PPPM-SF and the NRS scores.

CONCLUSION

After thorough information of the parents we have successfully implemented a surgery-specific regime of primarily around-the-clock dosing of drug formulations acceptable for the specific child with dispensed medication ready available for the family.

Considerations when using pharmacokinetic/pharmacodynamic modeling to determine the effectiveness of simple analgesics in children

INTRODUCTION

Assessment of analgesic drugs includes comparative studies to other analgesics and local anesthesia blockade, number needed to treat estimates and opioid sparing descriptions. An additional methodology is to define the concentration-response relationship using pharmacokinetic/pharmacodynamic (PK/PD) modeling.

AREAS COVERED

A concentration-response relationship allows analgesic effect comparison between drugs for different acute pain types. Covariates such as size, age and organ function impact greatly on PK in children. The cumulative effect of confounding factors (e.g., pharmacogenetics, placebo and changes in baseline pain over time) complicates PD. Other factors (outcome measures, method of measurement, failure to account for study attrition) impact on outcome. Population PK/PD modeling approaches allow us to account for these various factors to some extent.

EXPERT OPINION

Nonlinear mixed effects models help interpret analgesic data and their use is increasing. The PK is relatively well understood. The next investigative step will involve investigation into covariate effects for PD. Mathematical functions for both placebo models and dropout models are well described and should be incorporated into analgesic effectiveness studies that investigate a range of doses. Improvements in pain assessment tools and a greater understanding of pharmacogenomics factors will help individualize analgesic therapy.

Postoperative analgesia using diclofenac and acetaminophen in children

BACKGROUND

Diclofenac dosing in children for analgesia is currently extrapolated from adult data. Oral diclofenac 1.0 mg·kg(-1) is recommended for children aged 1-12 years. Analgesic effect from combination diclofenac/acetaminophen is unknown.

METHODS

Children (n = 151) undergoing tonsillectomy (c. 1995) were randomized to receive acetaminophen elixir 40 mg·kg(-1) before surgery and 20 mg·kg(-1) rectally at the end of surgery with diclofenac suspension 0.1 mg·kg(-1) , 0.5 mg·kg(-1) , or 2.0 mg·kg(-1) before surgery or placebo. A further 93 children were randomized to receive diclofenac 0.1 mg·kg(-1) , 0.5 mg·kg(-1) , or 2.0 mg·kg(-1) only. Postoperative pain was assessed (visual analogue score, VAS 0-10) at half-hourly intervals from waking until discharge. Data were pooled with those from a further 222 children and 30 adults. One-compartment models with first-order absorption and elimination described the pharmacokinetics of both medicines. Combined drug effects were described using a modified EMAX model with an interaction term. An interval-censored model described the hazard of study dropout.

RESULTS

Analgesia onset had an equilibration half-time of 0.496 h for acetaminophen and 0.23 h for diclofenac. The maximum effect (EMAX ) was 4.9. The concentration resulting in 50% of EMAX (C50 ) was 1.23 mg·l(-1) for diclofenac and 13.3 mg·l(-1) for acetaminophen. A peak placebo effect of 6.8 occurred at 4 h. Drug effects were additive. The hazard of dropping out was related to pain (hazard ratio of 1.35 per unit change in pain). Diclofenac 1.0 mg·kg(-1) with acetaminophen 15 mg·kg(-1) achieves equivalent analgesia to acetaminophen 30 mg·kg(-1) .

CONCLUSIONS

Combination therapy can be used to achieve similar analgesia with lower doses of both drugs.

Intranasal sufentanil/ketamine analgesia in children

BACKGROUND

The management of procedural pain in children ranges from physical restraint to pharmacological interventions. Pediatric formulations that permit accurate dosing, are accepted by children and a have a rapid onset of analgesia are lacking.

OBJECTIVES

To investigate a pediatric formulation of intranasal sufentanil 0.5 mcg·kg(-1) and ketamine 0.5 mg·kg(-1) for procedural pain and to characterize the pharmacokinetic (PK) profile.

METHODS

Fifty children (≥10 kg) scheduled for a painful procedure were included in this prospective nonrandomized open-label clinical trial. Thirteen of these children had central venous access for drug assay sampling; enabling a compartmental PK analysis using nonlinear mixed-effects models. Pain intensity before and during the procedure was measured using age-appropriate pain scales. Heart rate, oxygen saturation and sedation were recorded.

RESULTS

Children had a mean age of 8.8 (sd 4.9) years and weight 35.2 (sd 20.1) kg. Sufentanil/ketamine nasal spray was effective (procedural pain intensity scores ≤5 (0-10)) in 78% of the painful procedures. The spray was well accepted by 94% of the children. Oxygen saturation and heart rate remained stable, and sedation was minimal. The bioavailability of sufentanil and ketamine was 24.6% and 35.8%, respectively. Maximum plasma concentration (Cmax) of sufentanil was 0.042 mcg·l(-1) (coefficient of variation (CV) 12.9%) at 13.8 min (CV 12.4%) (Tmax). Cmax for ketamine was 0.102 mg·l(-1) (CV 10.8%), and Tmax was 8.5 min (CV 17.3%).

CONCLUSION

Sufentanil/ketamine nasal spray provided rapid onset of analgesia for a variety of painful procedures with few adverse effects and has promising features for use in pediatric procedural pain management.

Psychological interventions for needle-related procedural pain and distress in children and adolescents

BACKGROUND

This review is an updated version of the original Cochrane review published in Issue 4, 2006. Needle-related procedures are a common source of pain and distress for children. Our previous review on this topic indicated that a number of psychological interventions were efficacious in managing pediatric needle pain, including distraction, hypnosis, and combined cognitive behavioural interventions. Considerable additional research in the area has been published since that time.

OBJECTIVES

To provide an update to our 2006 review assessing the efficacy of psychological interventions for needle-related procedural pain and distress in children and adolescents.

SEARCH METHODS

Searches of the following databases were conducted for relevant randomized controlled trials (RCTs): Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; EMBASE; PsycINFO; the Cumulative Index to Nursing and Allied Health Literature (CINAHL); and Web of Science. Requests for relevant studies were also posted on various electronic list servers. We ran an updated search in March 2012, and again in March 2013.

SELECTION CRITERIA

Participants included children and adolescents aged two to 19 years undergoing needle-related procedures. Only RCTs with at least five participants in each study arm comparing a psychological intervention group with a control or comparison group were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data and assessed trial quality and a third author helped with data extraction and coding for one non-English study. Included studies were coded for quality using the Cochrane Risk of bias tool. Standardized mean differences with 95% confidence intervals were computed for all analyses using Review Manager 5.2 software.

MAIN RESULTS

Thirty-nine trials with 3394 participants were included. The most commonly studied needle procedures were venipuncture, intravenous (IV) line insertion, and immunization. Studies included children aged two to 19 years, with the most evidence available for children under 12 years of age. Consistent with the original review, the most commonly studied psychological interventions for needle procedures were distraction, hypnosis, and cognitive behavioural therapy (CBT). The majority of included studies (19 of 39) examined distraction only. The additional studies from this review update continued to provide strong evidence for the efficacy of distraction and hypnosis. No evidence was available to support the efficacy of preparation and information, combined CBT (at least two or more cognitive or behavioural strategies combined), parent coaching plus distraction, suggestion, or virtual reality for reducing children's pain and distress. No conclusions could be drawn about interventions of memory alteration, parent positioning plus distraction, blowing out air, or distraction plus suggestion, as evidence was available from single studies only. In addition, the Risk of bias scores indicated several domains with high or unclear bias scores (for example, selection, detection, and performance bias) suggesting that the methodological rigour and reporting of RCTs of psychological interventions continue to have considerable room for improvement.

AUTHORS' CONCLUSIONS

Overall, there is strong evidence supporting the efficacy of distraction and hypnosis for needle-related pain and distress in children and adolescents, with no evidence currently available for preparation and information or both, combined CBT, parent coaching plus distraction, suggestion, or virtual reality. Additional research is needed to further assess interventions that have only been investigated in one RCT to date (that is, memory alteration, parent positioning plus distraction, blowing out air, and distraction plus suggestion). There are continuing issues with the quality of trials examining psychological interventions for needle-related pain and distress.

The effect of a 3 : 1 volume mixture of propofol 1% and thiopental 2.5% in reducing the pain on injection of propofol in children

BACKGROUND

In this prospective, randomized, double-blind, controlled trial, our primary objective was to assess the effect of a 3 : 1 mixture of propofol and thiopental in reducing pain on injection in children. Our hypothesis was that a 3 : 1 mixture of propofol and thiopental (treatment) would reduce the incidence of pain on injection to 20% compared to the expected incidence of 40% in the control group of an 11 : 1 mixture of propofol and 2% lidocaine.

METHODS

Study subjects were patients 12-17 years old who were scheduled to undergo surgery and general anesthesia. Pain was assessed by a single-blinded observer present in the operating room. The major statistical method used in the analysis was multiple logistic regression.

RESULTS

Among the 164 children analyzed, 96 patients (58.5%) were male. The average age was 14.3 (sd = 1.65). The incidence of pain in the control group was 32.1% (26/81), compared to 25.3% (21/83) in the treatment group. The logistic regression analysis showed that there was not sufficient evidence that the treatment group was better than control group in reducing pain (P = 0.24). There were no significant differences in postoperative recovery time, nausea, vomiting, or blood pressure between the two groups (all P values >0.10).

CONCLUSION

There was not sufficient evidence to show that a 3 : 1 mixture of propofol and thiopental was better than an 11 : 1 volume admixture of propofol and lidocaine in reducing the incidence of pain on injection to 20%.

Combined acetaminophen and ibuprofen for pain relief after oral surgery in adults: a randomized controlled trial

Background

Acetaminophen is often used with a non-steriodal anti-inflammatory drug for acute pain. Hitherto, these drugs have had to be given separately, typically at different time intervals. Maxigesic^® tablets combine acetaminophen and ibuprofen in clinically appropriate doses to simplify administration and dosage regimen. We compared this combination with each of the constituent drugs for the relief of pain after extraction of third molar teeth.

Methods

Adults (more than 16 yr) having one or more wisdom teeth removed under general or local anaesthesia were instructed to take two tablets before operation, then two tablets every 6 h for up to 48 h of: (i) a combination of acetaminophen 500 mg and ibuprofen 150 mg per tablet (Maxigesic^®); (ii) acetaminophen 500 mg per tablet alone; or (iii) ibuprofen 150 mg per tablet alone. The primary outcome measure was the area under the curve (AUC) of the 100 mm visual analogue scale pain measurements taken for up to 48 h after surgery, divided by time, at rest and on activity. Pharmacokinetic data were collected in a subset of patients.

Results

The mean (sem) time-corrected AUC on rest and activity, respectively, were: combination group 22.3 (3.2) and 28.4 (3.4); acetaminophen group 33.0 (3.1) and 40.4 (3.3); and ibuprofen group 34.8 (3.2) and 40.2 (3.4); P<0.01 for each of the four comparisons of combination vs constituent drug. There was no pharmacokinetic interaction between acetaminophen and ibuprofen administered together.

Conclusions

Maxigesic^® tablets provide superior pain relief after oral surgery to acetaminophen or ibuprofen alone.

Ethics and medical research in children

The ethics of clinical research is based on several well-known guidelines and documents. The guidelines vary between countries, but the principles of respect for persons, beneficence, and justice are constant. These principles are reflected in requirements to obtain free and informed consent, to minimize risk or harm, and to not overly burden or disadvantage particular populations. For research to be ethical, it must also be of such a standard, and be conducted in such a manner that it will generate knew and useful knowledge. Children have limited capacity for understanding and may be more open to coercion. Therefore, they are regarded as a particularly vulnerable population, and specific clauses regarding children are incorporated into many guidelines. A key concept in these clauses is the degree of risk acceptable for children involved in research. While it is generally agreed that children require particular attention because of their vulnerability, there is also increasing concern that children in general should not be disadvantaged by lack of knowledge due to reduced research activity. Finally, an increasingly active area of research in children involves genetics and biobanking. Research in these areas raises new and challenging ethical issues.