Tramadol-paracetamol for postoperative pain after spine surgery - A randomized, double-blind, placebo-controlled study.

OBJECTIVES: Multimodal pain management is one component in enhanced recovery after surgery protocol. Here we evaluate the efficacy of tramadol-paracetamol in acute postoperative pain and pain outcome at 12 months after spine surgery in randomized, double-blind, placebo-controlled trial. METHODS: We randomized 120 patients undergoing spine surgery to receive, for add-on pain management, two tramadol-paracetamol 37.5 mg/325 mg (n = 61) or placebo tablets (n = 59) twice a day for 5 postoperative days. In the hospital, multimodal pain management consisted of dexketoprofen and oxycodone. After discharge, patients were prescribed ibuprofen 200 mg, maximum 1,200 mg/day. Pain, analgesic use, and satisfaction with pain medication were followed up with the Brief Pain Inventory questionnaire before surgery and at 1 and 52 weeks after surgery. The primary outcome was patients' satisfaction with pain medication 1 week after surgery. RESULTS: At 1 week after surgery, patients' satisfaction with pain medication was similarly high in the two groups, 75% [interquartile range, 30%] in the placebo group and 70% [40%] in the tramadol-paracetamol group (p = 0.949) on a scale: 0% = not satisfied, 100% = totally satisfied. At 1 week, ibuprofen dose was lower in the placebo group 200 mg [1,000] compared to the tramadol-paracetamol group, 800 mg [1,600] (p = 0.016). There was no difference in the need for rescue oxycodone. Patients in the tramadol-paracetamol group had more adverse events associated with analgesics during the first postoperative week (relative risk = 1.8, 95% confidence interval, 1.2-2.6). CONCLUSION: Add-on pain treatment with tramadol-paracetamol did not enhance patients' satisfaction with early pain management after back surgery.

Opioid-induced respiratory depression suspected of drug interaction in a prostate cancer patient: a case report.

BACKGROUND: Many of the drugs used for the treatment and alleviation of symptoms in cancer patients are known to inhibit or induce cytochrome P450 (CYP). Therefore, it is important to pay attention to the drug interactions of opioid analgesics that are metabolized by CYPs, because for example when using oxycodone metabolized by CYP3A4, it is possible that the effect will be attenuated or enhanced by the concomitant use of drugs that induce or inhibit CYP3A4. Aprepitant, an antiemetic drug used in many patients receiving anticancer drugs, is known as a moderate competitive inhibitor of CYP3A4. We experienced a case of respiratory depression caused by opioids, which was suspected to be caused by a drug interaction with antiemetics especially aprepitant. CASE DESCRIPTION: The patient was a 72-year-old man. He had been treated with continuous oxycodone infusion for perianal pain associated with the rectal invasion of prostate cancer. No comorbidities other than renal dysfunction were observed. Oxycodone treatment was started at 48 mg/day, and was increased to 108 mg/day, and then the pain decreased. Once the pain was controlled, chemotherapy was planned. Antiemetics (dexamethasone, palonosetron, and aprepitant) were administered before anticancer drug administration. Approximately 3 hours after antiemetics administration and before the administration of the anticancer drugs, a ward nurse noticed that oversedation and respiratory depression had occurred. When the patient was called, he immediately woke up and was able to talk normally, so the anticancer drugs were administered as scheduled. About 2 hours after the nurse noticed oversedation, the attending physician reduced the dose of oxycodone infusion to 48 mg/day. After that, his drowsiness persisted, but his respiratory condition improved. Despite reducing the dose of oxycodone to less than half, the pain remained stable at numeric rating scale (NRS) 0-1, without the use of a rescue dose. The patient was discharged from the hospital 36 days after the administration of anticancer drugs, without any problems. CONCLUSIONS: The cause of respiratory depression in this case was thought to be a combination of factors, including drug interactions between oxycodone and antiemetics, and oxycodone accumulation due to renal dysfunction.

Simultaneous quantification and confirmation of oxycodone and its metabolites in equine urine using ultra-high performance liquid chromatography-tandem mass spectrometry.

Oxycodone, an opioid commonly used to treat pain in humans, has the potential to be abused in racehorses to enhance their performance. To understand the pharmacokinetics of oxycodone and its metabolites in horses, as well as to detect the illegal use of oxycodone in racehorses, a method for quantification and confirmation of oxycodone and its metabolites is needed. In this study, we developed and validated an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method that can simultaneously quantify and confirm oxycodone and eight metabolites in equine urine. Samples were subjected to enzymatic hydrolysis and then liquid-liquid extraction using ethyl acetate. The analyte separation was achieved on a Hypersil Gold C18 sub-2 µm column and analytes were detected on a triple quadrupole mass spectrometer. The limit of detection (LOD) and lower limit of quantification (LLOQ) were 25-50 pg/mL and 100 pg/mL, respectively. Excellent linearity of the calibration curves was observed over a range of 100-10000 pg/mL for all nine analytes. Retention time, signal-to-noise ratio, and product ion ratios were utilized as confirmation criteria, with the limits of confirmation (LOC) ranging from 100 to 250 pg/mL. The data from a pilot pharmacokinetic (PK) study suggested that oxycodone metabolites have longer detection periods in equine urine compared to oxycodone itself; thus, the detection of metabolites in equine urine extends the ability to detect oxycodone exposure in racehorses.

Genetic background and sex influence somatosensory sensitivity and oxycodone analgesia in the Hybrid Rat Diversity Panel.

Opioid use disorder (OUD) is an ongoing public health concern in the United States, and relatively little work has addressed how genetic background contributes to OUD. Understanding the genetic contributions to oxycodone-induced analgesia could provide insight into the early stages of OUD development. Here, we present findings from a behavioral phenotyping protocol using several inbred strains from the Hybrid Rat Diversity Panel. Our behavioral protocol included a modified "up-down" von Frey procedure to measure inherent strain differences in the sensitivity to a mechanical stimulus on the hindpaw. We also performed the tail immersion assay, which measures the latency to display tail withdrawal in response to a hot water bath. Initial withdrawal thresholds were taken in drug-naïve animals to record baseline thermal sensitivity across the strains. Oxycodone-induced analgesia was measured after administration of oxycodone over the course of 2 h. Both mechanical and thermal sensitivity are shaped by genetic factors and display moderate heritability (h2 = 0.23-0.40). All strains displayed oxycodone-induced analgesia that peaked at 15-30 min and returned to baseline by 2 h. There were significant differences between the strains in the magnitude and duration of their analgesic response to oxycodone, although the heritability estimates were quite modest (h2 = 0.10-0.15). These data demonstrate that genetic background confers differences in mechanical sensitivity, thermal sensitivity, and oxycodone-induced analgesia.

Comparative safety of tramadol and other opioids following total hip and knee arthroplasty.

BACKGROUND: Tramadol is increasingly used to treat acute postoperative pain among older adults following total hip and knee arthroplasty (THA/TKA). However, tramadol has a complex pharmacology and may be no safer than full opioid agonists. We compared the safety of tramadol, oxycodone, and hydrocodone among opioid-naïve older adults following elective THA/TKA. METHODS: This retrospective cohort included Medicare Fee-for-Service beneficiaries ≥ 65 years with elective THA/TKA between January 1, 2010 and September 30, 2015, 12 months of continuous Parts A and B enrollment, 6 months of continuous Part D enrollment, and no opioid use in the 6 months prior to THA/TKA. Participants initiated single-opioid therapy with tramadol, oxycodone, or hydrocodone within 7 days of discharge from THA/TKA hospitalization, regardless of concurrently administered nonopioid analgesics. Outcomes of interest included all-cause hospitalizations or emergency department visits (serious adverse events (SAEs)) and a composite of 10 surgical- and opioid-related SAEs within 90-days of THA/TKA. The intention-to-treat (ITT) and per-protocol (PP) hazard ratios (HRs) for tramadol versus other opioids were estimated using inverse-probability-of-treatment-weighted pooled logistic regression models. RESULTS: The study population included 2,697 tramadol, 11,407 oxycodone, and 14,665 hydrocodone initiators. Compared to oxycodone, tramadol increased the rate of all-cause SAEs in ITT analyses only (ITT HR 1.19, 95%CLs, 1.02, 1.41; PP HR 1.05, 95%CLs, 0.86, 1.29). Rates of composite SAEs were not significant across comparisons. Compared to hydrocodone, tramadol increased the rate of all-cause SAEs in the ITT and PP analyses (ITT HR 1.40, 95%CLs, 1.10, 1.76; PP HR 1.34, 95%CLs, 1.03, 1.75), but rates of composite SAEs were not significant across comparisons. CONCLUSIONS: Postoperative tramadol was associated with increased rates of all-cause SAEs, but not composite SAEs, compared to oxycodone and hydrocodone. Tramadol does not appear to have a superior safety profile and should not be preferentially prescribed to opioid-naïve older adults following THA/TKA.

Refractory Hypoglycemia Due to Sulfonylurea Contamination of Illicit Opioid Medications.

Illicit drug supply adulteration can heighten the risk for adverse health outcomes. Sulfonylurea medications are widely used in the treatment of diabetes mellitus (DM). Unintentional or intentional overdose of sulfonylureas can cause refractory hypoglycemia. This case report describes a 62-year-old male patient who presented to the emergency department (ED) after being found on the ground with signs of mild trauma. He was noted to be persistently hypoglycemic despite boluses of intravenous dextrose, a dextrose infusion, and oral nutrition. The patient did report purchase and oral ingestion of pills sold as oxycodone and that the pill shape and color were different from his usual supply. The patient was empirically treated with octreotide resulting in normalization of his serum glucose. Testing demonstrated a serum glipizide concentration six times the reporting range. This case represents unintentional sulfonylurea exposure in the setting of non-prescribed oxycodone use, resulting in hypoglycemia refractory to intravenous dextrose and oral nutrition. Octreotide is an additional potential treatment for this condition. As in this case, ingestion of street drugs may present a potential source of sulfonylurea exposure. Opioid contamination with sulfonylureas has not been widely reported in the literature and knowledge about this potential exposure is important for the prompt recognition and treatment of these patients by emergency physicians.

Pharmacological prevention and treatment of opioid-induced constipation in cancer patients: A systematic review and meta-analysis.

BACKGROUND: Cancer-related pain often requires opioid treatment with opioid-induced constipation (OIC) as its most frequent gastrointestinal side-effect. Both for prevention and treatment of OIC osmotic (e.g. polyethylene glycol) and stimulant (e.g. bisacodyl) laxatives are widely used. Newer drugs such as the peripherally acting µ-opioid receptor antagonists (PAMORAs) and naloxone in a fixed combination with oxycodone have become available for the management of OIC. This systematic review and meta-analysis aims to give an overview of the scientific evidence on pharmacological strategies for the prevention and treatment of OIC in cancer patients. METHODS: A systematic search in PubMed, Embase, Web of Science and the Cochrane Library was completed from inception up to 22 October 2022. Randomized and non-randomized studies were systematically selected. Bowel function and adverse drug events were assessed. RESULTS: Twenty trials (prevention: five RCTs and three cohort studies; treatment: ten RCTs and two comparative cohort studies) were included in the review. Regarding the prevention of OIC, three RCTs compared laxatives with other laxatives, finding no clear differences in effectivity of the laxatives used. One cohort study showed a significant benefit of magnesium oxide compared with no laxative. One RCT found a significant benefit for the PAMORA naldemedine compared with magnesium oxide. Preventive use of oxycodone/naloxone did not show a significant difference in two out of three other studies compared to oxycodone or fentanyl. A meta-analysis was not possible. Regarding the treatment of OIC, two RCTs compared laxatives, of which one RCT found that polyethylene glycol was significantly more effective than sennosides. Seven studies compared an opioid antagonist (naloxone, methylnaltrexone or naldemedine) with placebo and three studies compared different dosages of opioid antagonists. These studies with opioid antagonists were used for the meta-analysis. Oxycodone/naloxone showed a significant improvement in Bowel Function Index compared to oxycodone with laxatives (MD -13.68; 95 % CI -18.38 to -8.98; I2 = 58 %). Adverse drug event rates were similar amongst both groups, except for nausea in favour of oxycodone/naloxone (RR 0.51; 95 % CI 0.31-0.83; I2 = 0 %). Naldemedine (NAL) and methylnaltrexone (MNTX) demonstrated significantly higher response rates compared to placebo (NAL: RR 2.07, 95 % CI 1.64-2.61, I2 = 0 %; MNTX: RR 3.83, 95 % CI 2.81-5.22, I2 = 0 %). With regard to adverse events, abdominal pain was more present in treatment with methylnaltrexone and diarrhea was significantly more present in treatment with naldemedine. Different dosages of methylnaltrexone were not significantly different with regard to both efficacy and adverse drug event rates. CONCLUSIONS: Magnesium oxide and naldemedine are most likely effective for prevention of OIC in cancer patients. Naloxone in a fixed combination with oxycodone, naldemedine and methylnaltrexone effectively treat OIC in cancer patients with acceptable adverse events. However, their effect has not been compared to standard (osmotic and stimulant) laxatives. More studies comparing standard laxatives with each other and with opioid antagonists are necessary before recommendations for clinical practice can be made.

Harmonising IV Oxycodone with Paediatric Perioperative Medications: A Compatibility Study Through Y-Type Connectors.

Purpose: Co-administering multiple intravenous (IV) agents via Y-connectors is a common practice in hospitalised and fasting surgical patients. However, there is a lack of reliable data confirming the physical compatibility of some combinations including IV oxycodone, a drug that is gaining increasing popularity in the perioperative period. Concern regarding physical drug incompatibilities precludes concurrent coadministration with other common drugs through a single lumen. This can result in the cessation of infusions to allow the administration of other medications, resulting in exacerbation of acute pain. This study aims to evaluate the physical compatibility of IV oxycodone with some commonly co-administered drugs and IV fluids. Methods: Mixtures of oxycodone (1mg.mL-1) and the tested drugs and IV fluids were prepared in a ratio of 1:1. The mixtures were examined at 0 and 60 minutes from mixing and assessed using the European Conference Consensus Standards. This involved visual inspection (precipitation, turbidity, colour change, gas formation), spectrophotometry, and pH change. The tested drugs included ketamine, tramadol, clonidine, vancomycin, piperacillin/tazobactam, dexmedetomidine, cefotaxime, gentamicin, and paracetamol. In addition, the commonly used IV fluids tested included glucose 5% + sodium chloride 0.9% + 60 mmol potassium chloride, plasmalyte + dextrose 5%;plasmalyte + dextrose 5% + 55 mmol potassium chloride, plasmalyte + dextrose 5% + 55mmol potassium acetate, plasmalyte + dextrose 5% + 55mmol potassium dihydrogen phosphate, Hartmann's solution, Standard pediatric Total Parenteral Nutrition (TPN) 20/100 and TPN 25/150. Results: IV oxycodone (1 mg.mL-1) showed no visual changes; no spectrophotometric absorption variability at 350, 410, or 550nm; and no pH changes of >0.5 at 0 or 60 minutes with any of the tested drugs or fluids in the concentrations tested. Conclusion: According to European Consensus Conference Standards, IV Oxycodone at 1 mg.mL-1 is physically compatible in a ratio of 1:1 v/v with all investigated drugs and fluids tested for at least 60 minutes.

Interpectoral and Pectoserratus Plane Block vs. Local Anesthetic Infiltration for Partial Mastectomy: A Prospective Randomized Trial.

Background: Patients undergoing breast surgery are at risk of severe postoperative pain. Several opioid-sparing strategies exist to alleviate this condition. Regional anesthesia has long been a part of perioperative pain management for these patients. Aim: This randomized study examined the benefits of interpectoral and pectoserratus plane block (IPP/PSP), also known as pectoralis nerve plain block, compared with advanced local anesthetic infiltration. Methods: We analyzed 57 patients undergoing partial mastectomy with sentinel node dissection. They received either an ultrasound-guided IPP/PSP block performed preoperatively by an anesthetist or local anesthetic infiltration performed by the surgeon before and during the surgery. Results: Pain measured with the numerical rating scale (NRS) indicated no statistically significant difference between the groups (IPP/PSP 1.67 vs. infiltration 1.97; p value 0.578). Intraoperative use of fentanyl was significantly lower in the IPP/PSP group (0.18 mg vs 0.21 mg; p value 0.041). There was no statistically significant difference in the length of stay in the PACU (166 min vs 175 min; p value 0.51). There were no differences in reported postoperative nausea and vomiting (PONV) between the groups. The difference in postoperative use of oxycodone in the PACU (p value 0.7) and the use of oxycodone within 24 hours postoperatively (p value 0.87) was not statistically significant. Conclusions: Our study showed decreased intraoperative opioid use in the IPP/PSP group and no difference in postoperative pain scores up to 24 hours. Both groups reported low postoperative pain scores. This trial is registered with NCT04824599.

State-level variation in distribution of oxycodone and opioid-related deaths from 2000 to 2021: an ecological study of ARCOS and CDC WONDER data in the USA.

OBJECTIVES: This study aims to characterise oxycodone's distribution and opioid-related overdoses in the USA by state from 2000 to 2021. DESIGN: This is an observational study. SETTING: More than 80 000 Americans died of an opioid overdose in 2021 as the USA continues to struggle with an opioid crisis. Prescription opioids play a substantial role, introducing patients to opioids and providing a supply of drugs that can be redirected to those seeking to misuse them. METHODS: The Drug Enforcement Administration annual summary reports from the Automation of Reports and Consolidated Orders System provided weights of oxycodone distributed per state by business type (pharmacies, hospitals and practitioners). Weights were converted to morphine milligram equivalents (MME) per capita and normalised for population. The Centers for Disease Control and Prevention Wide-ranging ONline Data for Epidemiologic Research provided mortality data for heroin, other opioids, methadone, other synthetic narcotics and other/unspecified narcotics. RESULTS: There was a sharp 280.13% increase in total MME/person of oxycodone from 2000 to 2010, followed by a slower 54.34% decrease from 2010 to 2021. Florida (2007-2011), Delaware (2003-2020) and Tennessee (2012-2021) displayed consistent and substantial elevations in combined MME/person compared with other states. In the peak year (2010), there was a 15-fold difference between the highest and lowest states. MME/person from only pharmacies, which constituted >94% of the total, showed similar results. Hospitals in Alaska (2000-2001, 2008, 2010-2021), Colorado (2008-2021) and DC (2000-2011) distributed substantially more MME/person over many years compared with other states. Florida stood out in practitioner-distributed oxycodone, with an elevation of almost 15-fold the average state from 2006 to 2010. Opioid-related deaths increased +806% from 2000 to 2021, largely driven by heroin, other opioids and other synthetic narcotics. CONCLUSIONS: Oxycodone distribution across the USA showed marked differences between states and business types over time. Investigation of opioid policies in states of interest may provide insight for future actions to mitigate opioid misuse.

Clinical evaluation of PF614, a novel TAAP prodrug of oxycodone, versus OxyContin in a multi-ascending dose study with a bioequivalence arm in healthy volunteers.

PF614, a trypsin-activated abuse protection oxycodone prodrug designed to reduce recreational drug abuse, was compared to OxyContin for safety and pharmacokinetics (PKs) of plasma oxycodone following oral administration. This study was a two-part design including a multi-ascending dose (part A) and a bioequivalence (BE) study (part B) in healthy volunteers. In part A, 24 subjects were randomized 3:1 to receive PF614 (50, 100, or 200 mg, n = 6/cohort) or OxyContin (20, 40, or 80 mg; n = 2/cohort) in ascending cohorts, delivered every 12 h for a total of nine doses. In part B, 60 subjects randomized in a four-way crossover to evaluate BE, received PF614 100 mg and OxyContin 40 mg in fasted and fed (high-fat diet) states. All subjects were naltrexone blocked prior to first study drug administration to protect against opioid-related adverse effects; repeat doses were provided on days 1-5. In part A, PF614 was well-tolerated following twice daily doses of up to 200 mg for 5 days. Plasma oxycodone maximal plasma concentration and area under the concentration time curve increased linearly with increasing doses. Part B showed that plasma oxycodone BE was achieved following 100 mg PF614 or 40 mg OxyContin under both fasted and fed conditions. Additionally, PF614 provided similar oxycodone exposures following both fasted and fed states. This study confirms findings from our single-ascending dose study, showing that PF614 100 mg releases oxycodone with a PK profile comparable to 40 mg OxyContin under both fasted and fed conditions and with a similar safety profile under naltrexone-blocked conditions.

Chronic Pain Management in a CYP2D6 Poor Metabolizer: A Case Report for Oxycodone.

The objective of this case report is to illustrate pharmacogenomics (PGx)-guided oxycodone treatment, given the conflicting data on the analgesic response from oxycodone in Cytochrome P450 (CYP)2D6 poor metabolizers (PMs). PGx-guided therapy can help improve treatment outcomes. This case report describes a 58-year-old patient who was prescribed oxycodone for chronic pain management. The patient presented with a history of inadequate pain control despite analgesic treatment with oxycodone (morphine milliequivalent [MME] = 22.5). Pharmacogenetic testing revealed that the patient was a CYP2D6 Poor Metabolizer (PM), which may shed light on the observed lack of analgesic response to oxycodone. The clinical pharmacist recommended switching to an alternative opioid not metabolized via the CYP2D6 pathway. The patient was subsequently switched to hydromorphone (MME = 16), resulting in improved pain control and fewer side effects. The newer hydromorphone dose accounted for a 30% MME dose reduction. The patient's initial average and worst pain score were 7 and 9 out of 10, respectively, per the numeric rating scale (NRS). Upon follow-up with the patient in two weeks, her average and worst pain scores improved to 3 and 3.5 out of 10, respectively, per the NRS. Further PGx testing results led to an overall positive outcome, such as her willingness to participate in physical therapy as a result of improved pain scores. This case highlights the importance of considering individual variability in drug metabolism when prescribing medications, particularly opioids such as oxycodone, to ensure optimal therapeutic outcomes and minimize the risk of adverse events in CYP2D6 PMs.

The effect of opioid use on traffic fatalities.

We use a difference-in-differences design to study the effect of opioid use on traffic fatalities. Following Alpert et al., we focus on the 1996 introduction and marketing of OxyContin, and we examine its long-term impacts on traffic fatalities involving Schedule II drugs or heroin. Based on the national fatal vehicle crash database, we find that the states heavily targeted by the initial marketing of OxyContin (i.e., non-triplicate states) experienced 2.4 times more traffic fatalities (1.6 additional deaths per million individuals) involving Schedule II drugs or heroin during 2011-2019, when overdose deaths from heroin and fentanyl became more prominent. We find no difference in traffic fatalities until after the mid-2000s between states with and without a triplicate prescription program. The effect is mainly concentrated in fatal crashes with drug involvement of drivers ages between 25 and 44. Our results highlight additional long-term detrimental consequences of the introduction and marketing of OxyContin.

Bioinspired composite packed in blunt needles, integrated microextraction and determination of oxycodone and naloxone in saliva by substrate spray mass spectrometry.

BACKGROUND: Opioids are effective painkillers used for medical purposes. Their prolonged ingestion can provoke some side effects (including overdose or constipation) that are minimized by using opioid antagonists (e.g., naloxone). The rapid determination of opioids and their antagonists in biosamples is essential for an effective medical treatment. The direct combination of sample preparation and mass spectrometry (MS) fits well in this scenario. It can speed up the analysis achieving a good selectivity, which relies on the sample preparation and MS, and sensitivity levels. RESULTS: This article presents a novel substrate-spray mass spectrometry interface based on a polydopamine-cotton (PDA-Cel) composite hosted inside the inner diameter of a 14-gauge blunt needle to determine oxycodone and naloxone in saliva samples. The needle is used as a microextraction device and a substrate for mass spectrometric analysis. The lack of sharpness of the 14-gauge (14G) blunt needles challenges the formation of the electrospray (ESI), and a commercial 10 µL pipette tip is proposed as a simple solution to this shortcoming. Under the optimum parameters, the proposed method was validated, obtaining limits of detection lower than 0.6 µg L-1, linear range up to 200 µg L-1, and linearity better than 0.9915. Relative standard deviation (RSD) and relative recoveries (RR) were studied at three different concentration levels (2, 40, and 200 µg L-1). RSD values were better than 20.7 %, and RR ranged from 90 to 114 %. Finally, a positive sample from a patient under medical treatment was analyzed. SIGNIFICANCE AND NOVELTY: 14G blunt needles have been demonstrated as effective extraction devices due to their low price (<0.15 € per extraction unit), their better safety (avoiding finger pricking), and their higher hosting capacity (up to 8 mg of sorbent). The conductivity of stainless steel permits their use as electrospray emitters, making their direct combination to MS easier. The large variety of fibrous sorbents makes this approach versatile enough to be adapted to other analytical problems.

Paradoxical potentiation of the exercise pressor reflex by endomorphin 2 in the presence of naloxone.

When contracting muscles are freely perfused, the acid-sensing ion channel 3 (ASIC3) on group IV afferents plays a minor role in evoking the exercise pressor reflex. We recently showed in isolated dorsal root ganglion neurons innervating the gastrocnemius muscles that two mu opioid receptor agonists, namely endomorphin 2 and oxycodone, potentiated the sustained inward ASIC3 current evoked by acidic solutions. This in vitro finding prompted us to determine whether endomorphin 2 and oxycodone, when infused into the arterial supply of freely perfused contracting hindlimb muscles, potentiated the exercise pressor reflex. We found that infusion of endomorphin 2 and naloxone in decerebrated rats potentiated the pressor responses to contraction of the triceps surae muscles. The endomorphin 2-induced potentiation of the pressor responses to contraction was prevented by infusion of APETx2, an ASIC3 antagonist. Specifically, the peak pressor response to contraction averaged 19.3 ± 5.6 mmHg for control (n = 10), 27.2 ± 8.1 mmHg after naloxone and endomorphin 2 infusion (n = 10), and 20 ± 8 mmHg after APETx2 and endomorphin 2 infusion (n = 10). Infusion of endomorphin 2 and naloxone did not potentiate the pressor responses to contraction in ASIC3 knockout rats (n = 6). Partly similar findings were observed when oxycodone was substituted for endomorphin 2. Oxycodone infusion significantly increased the exercise pressor reflex over its control level, but subsequent APETx2 infusion failed to restore the increase to its control level (n = 9). The peak pressor response averaged 23.1 ± 8.6 mmHg for control (n = 9), 33.2 ± 11 mmHg after naloxone and oxycodone were infused (n = 9), and 27 ± 8.6 mmHg after APETx2 and oxycodone were infused (n = 9). Our data suggest that after opioid receptor blockade, ASIC3 stimulation by the endogenous mu opioid, endomorphin 2, potentiated the exercise pressor reflex.NEW & NOTEWORTHY This paper provides the first in vivo evidence that endomorphin 2, an endogenous opioid peptide, can paradoxically increase the magnitude of the exercise pressor reflex by an ASIC3-dependent mechanism even when the contracting muscles are freely perfused.

Breast milk oxycodone concentrations in mothers given oxycodone for post-Caesarean delivery pain management.

AIMS: Both effective analgesia and early breastfeeding play an important role in maternal and neonatal well-being after Caesarean delivery. We studied controlled-release oxycodone tablet treatment for postoperative pain management and determined the excretion of oxycodone into breast milk. METHODS: Controlled-release oxycodone/naloxone 10/5-mg tablets (n = 21) or controlled-release oxycodone 10-mg tablets (n = 22) were administered to mothers twice a day for the first 3 days after elective Caesarean delivery as a part of multimodal analgesia. Maternal plasma and breast milk samples were collected daily. Oxycodone, noroxycodone, oxymorphone and noroxymorphone concentrations were analysed with ultra-performance liquid chromatography-mass spectrometry. Maternal pain intensity was recorded with an 11-point Numeric Rating Scale (0-10). Neonatal oxycodone exposure was estimated by simulating five different exposure scenarios, including the highest possible exposure through breast milk. RESULTS: The mean oxycodone and noroxycodone milk-to-maternal plasma ratios were 3.2 and 3.0, respectively. A strong correlation was found between plasma and breast milk oxycodone (R2 = 0.87) and noroxycodone concentrations (R2 = 0.91). In the simulated highest neonatal exposure scenario, the neonate's maximum plasma concentration was estimated to be 5.4 ng/mL and the estimated weight-adjusted infant oxycodone dose was less than 10% of the maternal dose. Pain intensities were similarly low between the two treatment groups. CONCLUSIONS: The oxycodone dose received from colostrum and breast milk during the first three postoperative days after Caesarean delivery is assumed safe for healthy, term neonates, but in extreme cases it is possible for the neonate to receive a dose through breast milk that may elicit opioid effects.

Analgesic effect of the ultrasound-guided thoracolumbar paravertebral block in patients undergoing robot-assisted laparoscopic nephrectomy: a randomized controlled trial.

BACKGROUND: Paravertebral block has similar effect as epidural anesthesia, and has good somatic and visceral analgesic effect. Paravertebral block is widely used in thoracic surgery, but rarely used in abdominal surgery. AIMS: This study aimed to evaluate the analgesic effect of thoracolumbar paravertebral block in patients undergoing robot-assisted laparoscopic nephrectomy. METHODS: One hundred patients undergoing elective robot-assisted laparoscopic nephrectomy were included in this study. Based on whether the thoracolumbar paravertebral block was performed, the patients were randomly divided into the thoracolumbar paravertebral block combined with general anesthesia group (TL-PVB group) and simple general anesthesia group (NO-PVB group). Oxycodone was administered for patient-controlled intravenous analgesia (PCIA). The primary outcomes included the amount of remifentanil used during surgery, the amount of oxycodone used in 24 and 48 h after surgery. Secondary outcomes included the changes of heart rate (HR) and mean arterial pressure (MAP), time for the first analgesia administration, visual analog score (VAS) of pain during rest and movement, and time of postoperative recovery. RESULTS: Compared to the NO-PVB group, the amount of remifentanil used during surgery in patients with TL-PVB group was significantly reduced (1.78 ± 0.37 mg vs. 3.09 ± 0.48 mg, p < 0.001), the amount of oxycodone used 24 h after surgery was significantly reduced (8.70 ± 1.70 mg vs. 13.79 ± 2.74 mg, p < 0.001), and the amount of oxycodone used 48 h after surgery was remarkably reduced (21.83 ± 4.28 mg vs. 27.27 ± 4.76 mg, p < 0.001). There were significant differences in the changes of HR and MAP between the two groups (p < 0.001). The first analgesic requirement time of TL-PVB group was significantly longer than that of NO-PVB group (468.56 ± 169.60 min vs. 113.48 ± 37.26 min, p < 0.001). The postoperative VAS during rest and movement of TL-PVB group were significantly lower than that of NO-PVB group (p < 0.01). Compared with NO-PVB group, patients in TL-PVB group needed shorter time to awaken from anesthesia, leave the operating room, anal exhaust, get out of bed, and had shorter length of postoperative hospital stay (p < 0.001). The incidence of postoperative adverse reactions were lower in the TL-PVB group than that in the NO-PVB group (p < 0.05). CONCLUSIONS: Ultrasound-guided thoracolumbar paravertebral block significantly reduces intraoperative and postoperative opioid consumption, and provides better analgesia in patients undergoing robot-assisted laparoscopic nephrectomy, which is a recommendable combined anesthesia technique. TRIAL REGISTRATION: ChiCTR2200061326, 21/06/2022.

Stellate Ganglion Destruction With Alcohol Versus Thermal Ablation for Chronic Post-Mastectomy Pain: A Randomized Trial.

BACKGROUND: Post-mastectomy pain syndrome (PMPS) is a persistent post-surgical neuropathic pain. Stellate ganglion (SG) block is used for diagnosis, prognosis, and treatment of pain syndrome. OBJECTIVES: We aimed to evaluate the efficacy of SG destruction with alcohol versus thermal ablation for PMPS management. STUDY DESIGN: Randomized, double-blind clinical trial. SETTING: National Cancer Institute, Cairo University, Egypt. METHODS: Female patients aged 20-65 years who underwent breast cancer surgery and suffered moderate to severe pain for more than 6 months were categorized equally into 2 groups. SG destruction was with ultrasound (US) guidance and C7 level confirmation by fluoroscopy either by alcohol injection in Group A or thermal ablation with a time of 60 seconds at 80ºC repeated twice in Group B. Follow-up was at 1, 4, 8, and 12 weeks. RESULTS: Visual analog scale (VAS) measurements after 1, 4, 8, and 12 weeks were significantly lower than pre-procedure measurements in both groups (P value < 0.001). There was a significant reduction in VAS score after 4 and 8 weeks in Group A than in Group B (P value = 0.003 and 0.018). Oxycodone and pregabalin consumption after 4 and 8 weeks were significantly lower in Group A than in Group B. Physical health, mental health, and satisfaction scores were comparable. There were no significant complications in both groups. LIMITATIONS: The relatively small sample size and short follow-up period are limitations to our study. CONCLUSION: US-guided SG destruction with alcohol was more effective than thermal radiofrequency for managing acute postoperative pain by decreasing pain score, oxycodone, and pregabalin consumption, which were consumed before the block.