Photos Sculpt the Stories of Youth: Using Photovoice to Holistically Capture the Lived Experiences and Pain of Youth Who Underwent Spinal Fusion Surgery

Spinal fusion surgery is one of the most common major surgical procedures in youth. Adolescent idiopathic scoliosis (AIS) is the most frequent reason for corrective spinal fusion. AIS (∼25%-47% of cases) and spinal fusion surgeries are associated with pain, including the development of new onset chronic pain for up to 15% of youth. This research used photovoice approaches to explore the journeys of youth from before, during, and after spinal fusion surgery, to demonstrate their experiences both of and beyond pain. Twenty participants were recruited from a previous study conducted by the senior author's lab. Participants captured photos/videos in their daily life (Phase 1); collected previously taken photos/videos from before/during/after their surgery (Phase 2); and participated in individual interviews to reflexively discuss the meaning behind photos/videos (Phase 3). Before interviews, a questionnaire was administered to assess pain characteristics. Nineteen girls/women with scoliosis and one boy/man with kyphosis (12-19 years old, Mage = 16 years) participated; they identified as white (80%), other (15%), and Southeast Asian (5%). The researchers used a reflexive thematic analysis approach, which generated five themes: (1) body aesthetic versus machine; (2) expectations and anticipation of surgery/outcomes; (3) desire of normalcy and freedom; (4) navigating a hoped-for positive surgery experience; and (5) the journey sculpts identity formation and sense of self. Findings support youth advocacy, underscoring the need to validate youth concerns and inform healthcare professionals of the importance of individualized care. Youth perspectives highlighted opportunities for optimizing surgery/healthcare experiences and the psychosocial impacts of scoliosis on body image and appearance.

Perception of Pain Expression Among Surgical Patients and Families from Three Ethnic Groups of a Nation: A Multicenter Qualitative Study

Background

Despite its universal nature; perception, coping, responses, treatment options, and overall experiences of pain are influenced by biopsychosocial factors to various extents. Pain perception, expression, and control are progressively learned behaviors among members of a society and are culture-specific. Effects of ethnicity-related culture (ethnoculture) on pain experience in a broader context have increasingly been reported. However, evidence from ethnoculturally diverse groups of a nation, particularly based on surgical patients, is limited. Therefore, as a qualitative research effort of a broader project aimed at assessing ethnocultural determinants of surgical pain management, this study explored the perception of ethnoculturally diverse patients and families about expressing surgical disease-related pain.

Methods

This study follows subjectivist-interpretivist philosophical assumptions as an underpinning research paradigm. We purposively selected 11 patients for in-depth interviews and 12 patients' family members for focus group discussions in three hospitals of ethnic-based regions of Ethiopia. In the phenomenological frame, thematic analysis was employed.

Finding

Ethnocultural background influences how individuals express and respond to pain according to emergent themes of finding- Pain and overlooked cultural influence, Pain expressiveness in cultural context, Stereotypes of pain expressiveness, and Bravehood through stoic response. Pain feelings are commonly hidden where the domestic culture values stoic response to pain compared to ethnoculture where pain expressiveness is encouraged.

Conclusion

Individuals can express and respond to pain differently due to ethnocultural diversity within a nation. Researchers and clinicians should consider cultural context while applying the prevailing one-size-fits-all pain assessment tools among surgical patients of a nation with ethnocultural diversity.

Kinins' Contribution to Postoperative Pain in an Experimental Animal Model and Its Implications

Postoperative pain causes discomfort and disability, besides high medical costs. The search for better treatments for this pain is essential to improve recovery and reduce morbidity and risk of chronic postoperative pain. Kinins and their receptors contribute to different painful conditions and are among the main painful inflammatory mediators. We investigated the kinin's role in a postoperative pain model in mice and reviewed data associating kinins with this painful condition. The postoperative pain model was induced by an incision in the mice's paw's skin and fascia with the underlying muscle's elevation. Kinin levels were evaluated by enzyme immunoassays in sham or operated animals. Kinin's role in surgical procedure-associated mechanical allodynia was investigated using systemic or local administration of antagonists of the kinin B₁ receptor (DALBk or SSR240612) or B₂ receptor (Icatibant or FR173657) and a kallikrein inhibitor (aprotinin). Kinin levels increased in mice's serum and plantar tissue after the surgical procedure. All kinin B₁ or B₂ receptor antagonists and aprotinin reduced incision-induced mechanical allodynia. Although controversial, kinins contribute mainly to the initial phase of postoperative pain. The kallikrein-kinin system can be targeted to relieve this pain, but more investigations are necessary, especially associations with other pharmacologic targets.

Phenotype- and species-specific skin proteomic signatures for incision-induced pain in humans and mice

BACKGROUND

Acute pain after surgery is common and often leads to chronic post-surgical pain, but neither treatment nor prevention is currently sufficient. We hypothesised that specific protein networks (protein-protein interactions) are relevant for pain after surgery in humans and mice.

METHODS

Standardised surgical incisions were performed in male human volunteers and male mice. Quantitative and qualitative sensory phenotyping were combined with unbiased quantitative mass spectrometry-based proteomics and protein network theory. The primary outcomes were skin protein signature changes in humans and phenotype-specific protein-protein interaction analysis 24 h after incision. Secondary outcomes were interspecies comparison of protein regulation as well as protein-protein interactions after incision and validation of selected proteins in human skin by immunofluorescence.

RESULTS

Skin biopsies in 21 human volunteers revealed 119/1569 regulated proteins 24 h after incision. Protein-protein interaction analysis delineated remarkable differences between subjects with small (low responders, n=12) and large incision-related hyperalgesic areas (high responders, n=7), a phenotype most predictive of developing chronic post-surgical pain. Whereas low responders predominantly showed an anti-inflammatory protein signature, high responders exhibited signatures associated with a distinct proteolytic environment and persistent inflammation. Compared to humans, skin biopsies in mice habored even more regulated proteins (435/1871) 24 h after incision with limited overlap between species as assessed by proteome dynamics and PPI. Immunohistochemistry confirmed the expression of high priority candidates in human skin biopsies.

CONCLUSIONS

Proteome profiling of human skin after incision revealed protein-protein interactions correlated with pain and hyperalgesia, which may be of potential significance for preventing chronic post-surgical pain. Importantly, protein-protein interactions were differentially modulated in mice compared to humans opening new avenues for successful translational research.

What we know and what we don't know about the perioperative use of methadone in children and adolescents

Postoperative pain control is essential to optimizing patient outcomes, improving satisfaction, and allowing patients to resume their baseline functional activities. Methadone, a synthetic mu-opioid agonist, has multiple pharmacologic properties that may be optimal for perioperative use. Compared to other opioids, methadone has a longer duration of action, rapid onset, extended dosing intervals, high oral bioavailability, low cost, lack of active metabolites, and action on multiple receptors. The current literature examining the use of methadone in the perioperative care of children and adolescents is limited and most often reported within the context of spine or cardiothoracic surgery. Overall, these studies support the hypothesis that perioperative methadone in pediatric patients may decrease postoperative pain, opioid consumption, length-of-stay, and the incidence of some opioid-related side effects, like constipation and urinary retention. A variety of protocols for the perioperative use of methadone have been described, including a single intraoperative dose as well as multiple small doses within multimodal pain protocols. The superiority of these protocols has not been established. Like all opioids, methadone has a side effect profile which includes nausea, vomiting, reduced GI motility, sedation, and respiratory depression at high doses. There is also a concern that it can cause QTc prolongation in patients. The primary aim of this educational review is to examine the pharmacologic data, published perioperative protocols, dosing considerations, and risks and benefits associated with inclusion of methadone in analgesic regimens for surgical patients. A secondary aim is to introduce opportunities for research around the perioperative use of methadone in children and adolescents. Based on our review, we would prioritize establishing optimal procedure-specific methadone protocols, determining generalizability for use in routine pediatric surgeries, and investigating methadone safety and efficacy prospectively as the primary opioid for pain management in the postanesthesia care unit or postsurgical floors.

Effect of meditation music and comedy movie interventions on postoperative kinesiophobia and pain in patients undergoing total knee arthroplasty

BACKGROUND

This study aimed to investigate the effects of music and comedy movie interventions on postoperative pain and kinesiophobia in patients who underwent total knee arthroplasty.

METHODS

This randomized-controlled study was carried out with the participation of patients who underwent total knee arthroplasty. The patients were divided into three groups. To reduce surgical pain and kinesiophobia, the patients in group 1 watched a comedy movie, those in group 2 listened to music, and those in group 3 did not participate in any intervention other than the routine practices of the clinic.

RESULTS

The personal and medical characteristics of the patients in all groups were similar. The patients in all three groups were kinesiophobic, and their surgical pain levels were moderate despite pharmaceutical interventions. Groups 1 and 2 had a statistically significant decrease in kinesiophobia and pain scores after the interventions. The effects of having patients watch a comedy movie and having them listen to meditation music were not significantly different.

CONCLUSIONS

The results of the study showed that listening to meditation music or watching comedy movie scenes had significant positive effects in alleviating postoperative pain and kinesiophobia after TKA. Based on the results of this study, it is recommended that patients watch comedy movies and listen to meditation music to alleviate their postoperative pain and kinesiophobia.

TRIAL REGISTRATION

NCT, NCT05471778. The study was registered at ClinicalTrials.gov.

Effect of ondansetron for preventing postoperative nausea and vomiting after breast cancer surgery

OBJECTIVE

To evaluate the preventive effect of preoperative administration of ondansetron on postoperative nausea and vomiting (PONV) in patients receiving breast cancer surgery.

METHODS

Data from 225 patients who received modified radical mastectomy from January 2019 to December 2020 were retrospectively reviewed. The patients were divided into an ondansetron group and a control group according to whether they received preoperative ondansetron or not. The incidence of PONV, visual analog scale (VAS) score, the rescue analgesics use and rescue antiemetic use, as well as the patient satisfaction degree about their PONV were compared between the two groups.

RESULTS

The ondansetron group showed lower total incidence of PONV, lower VAS score at 6 h post-operation as well as less rescue antiemetic use than the control group (P<0.05). Patients in the ondansetron group were more satisfied with their PONV condition than those in the control group (P<0.05).

CONCLUSION

Preoperative administration of ondansetron can prevent PONV and relieve pain 2-24 hours after breast cancer surgery.

Electroacupuncture attenuates surgical pain-induced delirium-like behavior in mice via remodeling gut microbiota and dendritic spine

Surgical pain is associated with delirium in patients, and acupuncture can treat pain. However, whether electroacupuncture can attenuate the surgical pain-associated delirium via the gut-brain axis remains unknown. Leveraging a mouse model of foot incision-induced surgical pain and delirium-like behavior, we found that electroacupuncture stimulation at specific acupoints (e.g., DU20+KI1) attenuated both surgical pain and delirium-like behavior in mice. Mechanistically, mice with incision-induced surgical pain and delirium-like behavior showed gut microbiota imbalance, microglia activation in the spinal cord, somatosensory cortex, and hippocampus, as well as an enhanced dendritic spine elimination in cortex revealed by two-photon imaging. The electroacupuncture regimen that alleviated surgical pain and delirium-like behavior in mice also effectively restored the gut microbiota balance, prevented the microglia activation, and reversed the dendritic spine elimination. These data demonstrated a potentially important gut-brain interactive mechanism underlying the surgical pain-induced delirium in mice. Pending further studies, these findings revealed a possible therapeutic approach in preventing and/or treating postoperative delirium by using perioperative electroacupuncture stimulation in patients.

Critical evaluation of contrasting evidence on whether male circumcision has adverse psychological effects: A systematic review

OBJECTIVE

To conduct the first systematic review critically examining evidence on whether early male circumcision has short- and long-term adverse psychological effects.

METHODS

We searched PubMed, EMBASE, SCOPUS, Cochrane Library, and Google Scholar.

RESULTS

Twenty-four studies with original data met the inclusion criteria. These comprised 11,173 total males, 4340 circumcised in infancy and 6908 uncircumcised. Nineteen were rated 1+, 2++ or 2+, and 5 were rated 2- by SIGN criteria. Neonatal circumcision, particularly without anesthetic, increased vaccination pain response, but had little effect on breastfeeding or cognitive ability. Studies reporting associations with sudden infant death syndrome, autism, alexithymia and impaired sexual function and pleasure had design flaws and were rated 2-. Sexual arousal, touch, pain, and warmth thresholds measured by quantitative sensory testing were not diminished in neonatally circumcised men. Neonatal circumcision was not associated with empathy in men, contradicting the hypothesis that procedural pain causes central nervous system changes. After correcting all associations with socioaffective processing parameters for multiple testing only higher sociosexual desire, dyadic sexual libido/drive, and stress remained significant. The relatively greater sexual activity found in circumcised men might reflect reduced sexual activity in uncircumcised men overall owing to pain and psychological aversion in those with foreskin-related medical conditions (reverse causality). Most studies employed case-control designs with limited follow-up. Studies beyond childhood were prone to confounding.

CONCLUSION

The highest quality evidence suggest that neonatal and later circumcision has limited or no short-term or long-term adverse psychological effects.

Cannabinoids in the Management of Acute Pain: A Systematic Review and Meta-analysis

Objective: To synthesize the best evidence surrounding the efficacy of cannabinoids for acute pain in the clinical setting based on subjective pain scores and observed adverse effects. Design: Systematic review with meta-analysis. Data Sources: PubMed, Embase, Cochrane Databases, and Google Scholar. Eligibility Criteria: English-language randomized-controlled clinical trials comparing cannabinoids with placebo in patients with acute pain. Data Extraction and Synthesis: Study quality was assessed using the Cochrane risk of bias tool. All stages were conducted independently by a team of three reviewers. Data were pooled through meta-analysis and stratified by route of administration. Primary Outcomes and Measures: Patient-reported pain and adverse events (AEs). Results: Six trials (678 participants) were included examining oral (5 trials) and intramuscular (1 trial) cannabinoids. Overall, there was a small but statistically significant treatment effect favoring the use of cannabinoids over placebo (-0.90, 95% confidence interval [CI] -1.69 to -0.1, i 2=65%, p=0.03). When stratified by route of administration, intramuscular cannabinoids were found to have a significant reduction in pain relative to placebo (-2.98, 95% CI -4.09 to -1.87, i 2=0%, p<0.0001). No difference in effect was observed between oral cannabinoids and placebo (-0.21, 95% CI -0.64 to 0.22, i 2=3%, p=0.34). Serious AEs were rare, and similar across the cannabinoid (14/374, 3.7%) and placebo groups (8/304, 2.6%). Conclusions: There is low-quality evidence indicating that cannabinoids may be a safe alternative for a small but significant reduction in subjective pain score when treating acute pain, with intramuscular administration resulting in a greater reduction relative to oral. Higher quality, long-term randomized-controlled trials examining whether there may be a role for cannabinoids in treating acute pain are required.

Hydromorphone population pharmacokinetics in pediatric surgical patients

BACKGROUND

Hydromorphone is an opioid agonist used for pediatric analgesia. Due to lack of data, pediatric dosing (based on adult pharmacokinetic models) is not optimal.

AIM

This study characterizes hydromorphone population pharmacokinetics in pediatric surgical patients.

METHODS

In this prospective observational study, 34 children (4-18 years, bodyweight 23-89.6 kg) received multiple intravenous hydromorphone boluses followed by postoperative hydromorphone patient-controlled analgesia. Arterial blood samples were collected before and at 3, 10, 30, and 90 (and few samples at 1350) minutes after the first dose. Hydromorphone concentrations were measured by validated LC-MS/MS assay. Nonlinear mixed-effects modeling was used for pharmacokinetic model development. The final population pharmacokinetic model was evaluated by visual predictive check and bootstrap analysis. Monte Carlo simulations based on the final pharmacokinetic model determined optimal patient-controlled analgesia parameters to achieve a target of 20 ng/mL (as the median effective analgesic concentration), using minimum effective analgesic concentration of 4 ng/mL as a proxy for patient-controlled analgesia dose demand, and not exceeding the defined safe upper threshold of 40 ng/mL.

RESULTS

Hydromorphone pharmacokinetic profiles were adequately described by a two-compartmental model with first-order elimination. Bodyweight was found to be a significant covariate for hydromorphone clearance. Allometrically scaledpharmacokinetic parameter estimates (per 70 kg), systemic clearance (0.748 L/min), volume of distribution (33 L), peripheral clearance (1.57 L/min), and peripheral volume of distribution (146 L) were similar to reported adult parameter estimates. Sex, race, age, and type of surgery were not identified as significant covariates. To identify optimal patient-controlled analgesia dosing parameters, we simulated several initial loading doses, demand doses, and lockout intervals. Our simulations support an initial patient-controlled analgesia loading dose of 15 µg/kg followed by a demand dose of 6 µg/kg with lockout intervals of 20 minutes.

CONCLUSIONS

After intravenous hydromorphone, plasma pharmacokinetic profiles in children undergoing different surgeries were well described by a two-compartment population allometric pharmacokinetic model using bodyweight as the size descriptor. Model informed simulations identified patient-controlled analgesia parameters to inform initial settings, with adjustments as needed based on observed individual effects.

Narrative Summary of Recently Published Literature on Intravenous Ibuprofen

PURPOSE

This is a narrative review of the published literature on IV ibuprofen (IVIB) as one of the drugs used in multimodal pain management in inpatients and outpatients pre- and postoperatively and for nonsurgical pain or fever.

METHODS

The efficacy, concurrent opioid use, pharmacokinetic properties, tolerability, stress response, and postoperative recovery with IVIB, which were investigated in 9 clinical studies, are presented in this narrative review. In total, 1062 adult patients and healthy volunteers were included in these 9 studies; 757 of these subjects received IVIB, and the remaining 305 received either placebo or a comparator medication.

FINDINGS

The plasma ibuprofen level with IVIB was twice that with oral ibuprofen, and patients experienced less postoperative pain, decreased opioid use, improved quality of recovery, and reduced postsurgical fatigue and surgical stress response, and used less over-the-counter medication.

IMPLICATIONS

Overall, preemptive IVIB should be considered in the analgesic regimen for the management of pre- and postoperative pain, as it has a favorable safety profile, with fewer associated adverse events and serious adverse events, significantly lower levels of perioperative cytokines and catecholamines, and improved peri- and postoperative pain control with a decreased use of opioid medications.

Antinociceptive Effect of the Citrus Flavonoid Eriocitrinon Postoperative Pain Conditions

BACKGROUND

Postoperative pain remains a major clinical problem as there are limited analgesic strategies that have been proven to be effective in preventing and relieving this type of pain. Natural products, including flavonoids, have distinct pharmacological properties and play an important role in the discovery of analgesic drugs.

MATERIALS AND METHODS

In this study, the flavonoid eriocitrin (eriodictyol 7-O-rutinoside), which is the main flavonoid in lemon fruit (Citrus limon), was mechanistically investigated for its prospective antinociceptive effect in a mouse model of postoperative pain. The antinociceptive property was evaluated by utilizing both tonic (acetic acid-induced writhing behavior) and phasic (hot-plate) nociception modalities. The hindpaw incisional surgery was performed and hyperalgesia was assessed using von Frey filaments.

RESULTS

The tested doses of eriocitrin significantly attenuated (P<0.01, P<0.001) the chemically-induced tonic visceral nociception (5, 10, 15, and 30 mg/kg) and acute phasic thermal nociception (10, 15, and 30 mg/kg). A significant dose-dependent reduction in the incisional nociceptive hyperalgesia was exhibited by eriocitrin, with a marked antinociception observed at doses of 15 mg/kg (P<0.05 during 30-60 minutes) and 30 mg/kg (P<0.05, P<0.01 during 30-120 minutes).

CONCLUSION

The antinociceptive effect of eriocitrin (30 mg/kg) was strongly blocked by the antagonists of the opioid receptor, naltrexone, and GABAA receptor, bicuculline, thereby suggesting the involvement of opioidergic and GABAergic mechanisms in the nociception, reducing proclivity of eriocitrin during transmission of incisional nociception. These results concluded that eriocitrin has a potent antinociceptive effect in postoperative pain conditions, probably mediated through opioid and GABAA receptors.

An integrated safety analysis of combined acetaminophen and ibuprofen (Maxigesic /Combogesic®) in adults

INTRODUCTION

Acetaminophen (APAP) and ibuprofen (IBP) are two analgesic compounds with a long history of use. Both are considered safe at recommended over-the-counter daily doses. Chronic use, high doses, or concomitant medication can produce safety risks for both drugs. APAP is associated with increased risk of hepatic injury, while IBP can produce gastric bleeding and thromboembolic events. Using a combination of APAP and IBP provides superior analgesia without transgressing daily dose limits of each individual drug.

METHODS

The present study aimed to determine if treatment with a fixed-dose combination (FDC) containing APAP and IBP results in any unexpected adverse events (AEs) and/or changes in the safety profiles of its two ingredients compared to monotherapy. The analysis will examine clinical safety data obtained from either single dose trials, multiple dose trials, a long-term exposure trial, and post-marketing surveillance data of APAP/IBP FDC tablets (Maxigesic®/Combogesic®, AFT Pharmaceuticals Ltd). The largest dataset was obtained by pooling the four randomized-controlled, multiple-dose clinical studies with either APAP 325 mg + IBP 97.5 mg (FDC 325/97.5, three tablets per dose) or APAP 500 mg + IBP 150 mg (FDC 500/150, two tablets per dose). At maximum doses, the two FDCs are bioequivalent, permitting the pooling of data for the analysis of safety.

RESULTS

A safety population of 922 patients who received full doses of either FDC, APAP alone, IBP alone, or placebo was compiled from the four studies. A total of 521 AEs were experienced with the incidence of FDC AEs similar to or below either monotherapy group or placebo. The FDC did not alter the incidence and percentage of the most common AEs, including gastrointestinal events and postoperative bleeding.

CONCLUSION

Overall, the FDC is well tolerated and has a strong safety profile at single and multiple doses with improved efficacy over monotherapy.

Postoperative Pain Assessment Indices Based on Photoplethysmography Waveform Analysis

The purpose of this study was to derive parameters that might reflect postoperative pain from photoplethysmography (PPG) and verify the derived parameters in postoperative pain assessment. We obtained preoperative and postoperative PPG and 100-mm visual analog scale (VAS) from 65 surgical patients and extracted a total of 51 PPG morphology-based parameters and their normalized parameters from these PPGs obtained. Pain discrimination performances of these derived parameters were assessed by statistical analyses, including Wilcoxon signed rank test with Bonferroni correction, classification accuracy based on logistic regression, and 4-fold cross validation. After comparing these parameters derived from PPG in pre- and post-operative conditions, statistically significant difference was found in 36 of the 51 parameters. Using logistic classification, dynamic between-pulse parameters such as normalized systolic amplitude variation and normalized diastolic amplitude variation showed better pain classification performance than the static within-pulse parameters. VAS score was 0 in every pre-operation condition, but >60 VAS was observed in the post-operative condition. Systolic peak amplitude variation normalized by PPG AC amplitude showed the best performance in classifying post-operative pain, with accuracy, sensitivity, specificity, and positive predictivity values of 79.5, 74.0, 86.0, and 84.5%, respectively. These results are superior to those of the surgical pleth index (SPI, GE Healthcare, Chicago, IL, United States) at 65.9, 65.9, 66.5, and 66.5%, respectively.

Use of Methadone to Reverse Opioid Escalation in a Patient With Surgical Pain

Acute pain is a prevalent issue for patients recovering from surgical procedures. Methadone has been recognized as a unique option for treatment of surgical pain due to its multiple mechanisms of analgesia and its potential to decrease tolerance to other opioids. Studies of methadone use in postoperative settings are sparse in part due to safety concerns, such as complex pharmacokinetics, risk of respiratory depression, and association with arrhythmias. In this case study of a 70-year-old male with postsurgical abdominal pain, methadone utilization over a period of 9 days resulted in patient-reported analgesia and aided in de-escalating overall opioid use. More studies are needed to develop guidance on how methadone can be used to relieve pain following surgical procedures.

CYP2D6 pharmacogenetic and oxycodone pharmacokinetic association study in pediatric surgical patients

AIM

Oxycodone is partly metabolized to the active metabolite oxymorphone by hepatic CYP2D6 in the liver. Significant genetic variability in CYP2D6 activity affects oxymorphone formation. This study aimed to associate CYP2D6 genotype and oxycodone's metabolism.

METHODS

30 children were administered oral oxycodone postoperatively. Plasma levels of oxycodone and oxymorphone, and CYP2D6 genotype were analyzed. CYP2D6 genotype and oxycodone metabolism phenotype were determined based on CYP2D6 total activity score (TAS) and metabolism phenotype: poor metabolizer (PM), intermediate metabolizer (IM), extensive metabolizer (EM) or ultrarapid metabolizer (UM).

RESULTS

Compared with PM/IM subjects, significantly greater oxymorphone exposure was seen in EM subjects (p = 0.02 for C_max, p = 0.016 for AUC_0-6 and p = 0.026 for AUC_0-24). Similarly, higher TAS value was found to be associated with greater oxymorphone exposure. Higher conversion of oxycodone to oxymorphone was observed in EM subjects compared with PM/IM subjects (p = 0.0007 for C_max, p = 0.001 for AUC_0-6 and p = 0.004 for AUC_0-24).

CONCLUSION

CYP2D6 phenotypes explain metabolism of oxycodone in children, and oxymorphone exposure is higher in CYP2D6 EM phenotype. Further studies are needed to predict the occurrence of adverse event and tailor oxycodone dose for a specific CYP2D6 phenotype.

Sleep Deprivation and Recovery Sleep Prior to a Noxious Inflammatory Insult Influence Characteristics and Duration of Pain

STUDY OBJECTIVES

Insufficient sleep and chronic pain are public health epidemics. Sleep loss worsens pain and predicts the development of chronic pain. Whether previous, acute sleep loss and recovery sleep determine pain levels and duration remains poorly understood. This study tested whether acute sleep deprivation and recovery sleep prior to formalin injection alter post-injection pain levels and duration.

METHODS

Male Sprague-Dawley rats (n = 48) underwent sleep deprivation or ad libitum sleep for 9 hours. Thereafter, rats received a subcutaneous injection of formalin or saline into a hind paw. In the recovery sleep group, rats were allowed 24 h between sleep deprivation and the injection of formalin. Mechanical and thermal nociception were assessed using the von Frey test and Hargreaves' method. Nociceptive measures were performed at 1, 3, 7, 10, 14, 17 and 21 days post-injection.

RESULTS

Formalin caused bilateral mechanical hypersensitivity (allodynia) that persisted for up to 21 days post-injection. Sleep deprivation significantly enhanced bilateral allodynia. There was a synergistic interaction when sleep deprivation preceded a formalin injection. Rats allowed a recovery sleep period prior to formalin injection developed allodynia only in the injected limb, with higher mechanical thresholds (less allodynia) and a shorter recovery period. There were no persistent changes in thermal nociception.

CONCLUSION

The data suggest that acute sleep loss preceding an inflammatory insult enhances pain and can contribute to chronic pain. The results encourage studies in a model of surgical pain to test whether enhancing sleep reduces pain levels and duration.

An integrated safety analysis of intravenous ibuprofen (Caldolor(®)) in adults

Intravenous (IV) nonsteroidal anti-inflammatory drugs such as IV ibuprofen are increasingly used as a component of multimodal pain management in the inpatient and outpatient settings. The safety of IV ibuprofen as assessed in ten sponsored clinical studies is presented in this analysis. Overall, 1,752 adult patients have been included in safety and efficacy trials over 11 years; 1,220 of these patients have received IV ibuprofen and 532 received either placebo or comparator medication. The incidence of adverse events (AEs), serious AEs, and changes in vital signs and clinically significant laboratory parameters have been summarized and compared to patients receiving placebo or active comparator drug. Overall, IV ibuprofen has been well tolerated by hospitalized and outpatient patients when administered both prior to surgery and postoperatively as well as for nonsurgical pain or fever. The overall incidence of AEs is lower in patients receiving IV ibuprofen as compared to those receiving placebo in this integrated analysis. Specific analysis of hematological and renal effects showed no increased risk for patients receiving IV ibuprofen. A subset analysis of elderly patients suggests that no dose adjustment is needed in this higher risk population. This integrated safety analysis demonstrates that IV ibuprofen can be safely administered prior to surgery and continued in the postoperative period as a component of multimodal pain management.

ABCC3 and OCT1 genotypes influence pharmacokinetics of morphine in children

AIM

Large interindividual variability in morphine pharmacokinetics could contribute to variability in morphine analgesia and adverse events.

METHODS

Influence of weight, genetic polymorphisms, race and sex on morphine clearance and metabolite formation from 220 children undergoing outpatient adenotonsillectomy was studied. A nonlinear mixed effects model was developed in NONMEM to describe morphine and morphine glucuronide pharmacokinetics.

RESULTS

Children with ABCC3 -211C>T polymorphism C/C genotype had significantly higher levels of morphine-6-glucuronide and morphine-3-glucuronide formation (∼40%) than C/T+T/T genotypes (p < 0.05). In this extended cohort similar to our earlier report, OCT1 homozygous genotypes (n = 13, OCT1*2-*5/*2-*5) had lower morphine clearance (14%; p = 0.06), and in addition complementing lower metabolite formation (∼39%) was observed. ABCB1 3435C>T TT genotype children had lower levels of morphine-3-glucuronide formation though no effect was observed on morphine and morphine-6-glucuronide pharmacokinetics.

CONCLUSION

Our data suggest that besides bodyweight, OCT1 and ABCC3 genotypes play a significant role in the pharmacokinetics of intravenous morphine and its metabolites in children.

The shortened infusion time of intravenous ibuprofen, part 2: a multicenter, open-label, surgical surveillance trial to evaluate safety

PURPOSE

The literature and clinical data support the use of intravenous (IV) infusions of ibuprofen to control pain and reduce the opioid requirements associated with surgical pain. According to current guidelines, IV ibuprofen can be administered via a slow IV infusion performed during a 30-minute period. Although recent studies indicate that more rapid infusions may yield additional benefits for patients, the safety of such an approach needs further evaluation. The main purpose of this study was to determine the safety of single and multiple doses of IV ibuprofen (800 mg) administered over 5 to 10 minutes at the induction of anesthesia and after the surgical procedure for the treatment of postoperative pain.

METHODS

This was a Phase IV, multicenter, open-label, clinical surveillance study. It was conducted at 21 hospitals in the United States, and 300 adult hospitalized patients undergoing surgery were enrolled. The exclusion criteria for the study were: inadequate IV access; hypersensitivity to any component of IV ibuprofen, aspirin, or related products; and any active, clinically significant bleeding. Also excluded were patients who had taken NSAIDs <6 hours before administration of IV ibuprofen; pregnant or breastfeeding female patients; and patients in the perioperative period of coronary artery bypass graft surgery. Patients received 800 mg of IV ibuprofen administered over 5 to 10 minutes preoperatively. Vital signs, adverse events, and pain scores were assessed.

FINDINGS

Approximately 22% (65 of 300) of patients reported adverse events (serious and nonserious). The most common adverse event was infusion site pain (34 of 300 [11%]). No deaths were reported. Nine subjects reported serious adverse events, 8 of which occurred during the first 6 hours. All serious events reported were judged unrelated to ibuprofen. Of the 300 total patients, 2 (0.67%) discontinued the study drug due to an adverse event (1 patient discontinued the study because of infusion site pain, and 1 patient withdrew due to a hypersensitivity reaction after drug administration).

IMPLICATIONS

Our study found that IV ibuprofen infused over 5 to 10 minutes at induction of anesthesia is a safe administration option for surgical patients. ClinicalTrials.gov identifier: NCT01334957.

Genetic risk signatures of opioid-induced respiratory depression following pediatric tonsillectomy

Background: Respiratory depression is a clinically and economically important but preventable complication of opioids. Genetic factors can help identify patients with high risk for respiratory depression. Methods: In this prospective genotype blinded clinical study, we evaluated the effect of a panel of variants in candidate genes on opioid-related respiratory depression in 347 children following tonsillectomy. Results: Using unsupervised hierarchical clustering and a combination of candidate genotypes and clinical variables, we identified several distinct clusters of patients at high risk (36-38%) and low risk (10-17%) of respiratory depression; the relative risk of respiratory depression for high versus low risk clusters was 2.1-3.8 (p = 0.003). Conclusion: Genetic risk predictions (genetic signatures) along with clinical risk factors effectively identify children at higher and lower risks of opioid-induced respiratory depression. Genetic signatures of respiratory depression offer strategies for improved clinical decision support to guide clinicians to balance the risks of opioid adverse effects with analgesia. Original submitted 9 July 2014; Revision submitted 19 September 2014.