Opioid-induced fragile-like regulatory T cells contribute to withdrawal.

Dysregulation of the immune system is a cardinal feature of opioid addiction. Here, we characterize the landscape of peripheral immune cells from patients with opioid use disorder and from healthy controls. Opioid-associated blood exhibited an abnormal distribution of immune cells characterized by a significant expansion of fragile-like regulatory T cells (Tregs), which was positively correlated with the withdrawal score. Analogously, opioid-treated mice also showed enhanced Treg-derived interferon-γ (IFN-γ) expression. IFN-γ signaling reshaped synaptic morphology in nucleus accumbens (NAc) neurons, modulating subsequent withdrawal symptoms. We demonstrate that opioids increase the expression of neuron-derived C-C motif chemokine ligand 2 (Ccl2) and disrupted blood-brain barrier (BBB) integrity through the downregulation of astrocyte-derived fatty-acid-binding protein 7 (Fabp7), which both triggered peripheral Treg infiltration into NAc. Our study demonstrates that opioids drive the expansion of fragile-like Tregs and favor peripheral Treg diapedesis across the BBB, which leads to IFN-γ-mediated synaptic instability and subsequent withdrawal symptoms.

Bias Factor and Therapeutic Window Correlate to Predict Safer Opioid Analgesics.

Biased agonism has been proposed as a means to separate desirable and adverse drug responses downstream of G protein-coupled receptor (GPCR) targets. Herein, we describe structural features of a series of mu-opioid-receptor (MOR)-selective agonists that preferentially activate receptors to couple to G proteins or to recruit ßarrestin proteins. By comparing relative bias for MOR-mediated signaling in each pathway, we demonstrate a strong correlation between the respiratory suppression/antinociception therapeutic window in a series of compounds spanning a wide range of signaling bias. We find that ßarrestin-biased compounds, such as fentanyl, are more likely to induce respiratory suppression at weak analgesic doses, while G protein signaling bias broadens the therapeutic window, allowing for antinociception in the absence of respiratory suppression.

Distinct µ-opioid ensembles trigger positive and negative fentanyl reinforcement.

Fentanyl is a powerful painkiller that elicits euphoria and positive reinforcement1. Fentanyl also leads to dependence, defined by the aversive withdrawal syndrome, which fuels negative reinforcement2,3 (that is, individuals retake the drug to avoid withdrawal). Positive and negative reinforcement maintain opioid consumption, which leads to addiction in one-fourth of users, the largest fraction for all addictive drugs4. Among the opioid receptors, µ-opioid receptors have a key role5, yet the induction loci of circuit adaptations that eventually lead to addiction remain unknown. Here we injected mice with fentanyl to acutely inhibit γ-aminobutyric acid-expressing neurons in the ventral tegmental area (VTA), causing disinhibition of dopamine neurons, which eventually increased dopamine in the nucleus accumbens. Knockdown of µ-opioid receptors in VTA abolished dopamine transients and positive reinforcement, but withdrawal remained unchanged. We identified neurons expressing µ-opioid receptors in the central amygdala (CeA) whose activity was enhanced during withdrawal. Knockdown of µ-opioid receptors in CeA eliminated aversive symptoms, suggesting that they mediate negative reinforcement. Thus, optogenetic stimulation caused place aversion, and mice readily learned to press a lever to pause optogenetic stimulation of CeA neurons that express µ-opioid receptors. Our study parses the neuronal populations that trigger positive and negative reinforcement in VTA and CeA, respectively. We lay out the circuit organization to develop interventions for reducing fentanyl addiction and facilitating rehabilitation.

Racial Inequality in Receipt of Medications for Opioid Use Disorder.

BACKGROUND: Since 2010, Black persons in the United States have had a greater increase in opioid overdose-related mortality than other groups, but national-level evidence characterizing racial and ethnic disparities in the use of medications for opioid use disorder (OUD) is limited. METHODS: We used Medicare claims data from the 2016-2019 period for a random 40% sample of fee-for-service beneficiaries who were Black, Hispanic, or White; were eligible for Medicare owing to disability; and had an index event related to OUD (nonfatal overdose treated in an emergency department or inpatient setting, hospitalization with injection drug use-related infection, or inpatient or residential rehabilitation or detoxification care). We measured the receipt of medications to treat OUD (buprenorphine, naltrexone, and naloxone), the receipt of high-risk medications (opioid analgesics and benzodiazepines), and health care utilization, all in the 180 days after the index event. We estimated differences in outcomes according to race and ethnic group with adjustment for beneficiary age, sex, index event, count of chronic coexisting conditions, and state of residence. RESULTS: We identified 25,904 OUD-related index events among 23,370 beneficiaries, with 3937 events (15.2%) occurring among Black patients, 2105 (8.1%) among Hispanic patients, and 19,862 (76.7%) among White patients. In the 180 days after the index event, patients received buprenorphine after 12.7% of events among Black patients, after 18.7% of those among Hispanic patients, and after 23.3% of those among White patients; patients received naloxone after 14.4%, 20.7%, and 22.9%, respectively; and patients received benzodiazepines after 23.4%, 29.6%, and 37.1%, respectively. Racial differences in the receipt of medications to treat OUD did not change appreciably from 2016 to 2019 (buprenorphine receipt: after 9.1% of index events among Black patients vs. 21.6% of those among White patients in 2016, and after 14.1% vs. 25.5% in 2019). In all study groups, patients had multiple ambulatory visits in the 180 days after the index event (mean number of visits, 6.6 after events among Black patients, 6.7 after events among Hispanic patients, and 7.6 after events among White patients). CONCLUSIONS: Racial and ethnic differences in the receipt of medications to treat OUD after an index event related to this disorder among patients with disability were substantial and did not change over time. The high incidence of ambulatory visits in all groups showed that disparities persisted despite frequent health care contact. (Funded by the National Institute on Drug Abuse and the National Institute on Aging.).

Unidirectional cross-activation of GRPR by MOR1D uncouples itch and analgesia induced by opioids.

Spinal opioid-induced itch, a prevalent side effect of pain management, has been proposed to result from pain inhibition. We now report that the µ-opioid receptor (MOR) isoform MOR1D is essential for morphine-induced scratching (MIS), whereas the isoform MOR1 is required only for morphine-induced analgesia (MIA). MOR1D heterodimerizes with gastrin-releasing peptide receptor (GRPR) in the spinal cord, relaying itch information. We show that morphine triggers internalization of both GRPR and MOR1D, whereas GRP specifically triggers GRPR internalization and morphine-independent scratching. Providing potential insight into opioid-induced itch prevention, we demonstrate that molecular and pharmacologic inhibition of PLCß3 and IP3R3, downstream effectors of GRPR, specifically block MIS but not MIA. In addition, blocking MOR1D-GRPR association attenuates MIS but not MIA. Together, these data suggest that opioid-induced itch is an active process concomitant with but independent of opioid analgesia, occurring via the unidirectional cross-activation of GRPR signaling by MOR1D heterodimerization.

Improving translation of animal models of addiction and relapse by reverse translation.

Critical features of human addiction are increasingly being incorporated into complementary animal models, including escalation of drug intake, punished drug seeking and taking, intermittent drug access, choice between drug and non-drug rewards, and assessment of individual differences based on criteria in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). Combined with new technologies, these models advanced our understanding of brain mechanisms of drug self-administration and relapse, but these mechanistic gains have not led to improvements in addiction treatment. This problem is not unique to addiction neuroscience, but it is an increasing source of disappointment and calls to regroup. Here we first summarize behavioural and neurobiological results from the animal models mentioned above. We then propose a reverse translational approach, whose goal is to develop models that mimic successful treatments: opioid agonist maintenance, contingency management and the community-reinforcement approach. These reverse-translated 'treatments' may provide an ecologically relevant platform from which to discover new circuits, test new medications and improve translation.

Analgesia and Sedation Use During Noninvasive Ventilation for Acute Respiratory Failure.

OBJECTIVES: To describe U.S. practice regarding administration of sedation and analgesia to patients on noninvasive ventilation (NIV) for acute respiratory failure (ARF) and to determine the association of this practice with odds of intubation or death. DESIGN: A retrospective multicenter cohort study. SETTING: A total of 1017 hospitals contributed data between January 2010 and September 2020 to the Premier Healthcare Database, a nationally representative healthcare database in the United States. PATIENTS: Adult (≥ 18 yr) patients admitted to U.S. hospitals requiring NIV for ARF. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We identified 433,357 patients on NIV of whom (26.7% [95% CI] 26.3%-27.0%) received sedation or analgesia. A total of 50,589 patients (11.7%) received opioids only, 40,646 (9.4%) received benzodiazepines only, 20,146 (4.6%) received opioids and benzodiazepines, 1.573 (0.4%) received dexmedetomidine only, and 2,639 (0.6%) received dexmedetomidine in addition to opioid and/or benzodiazepine. Of 433,357 patients receiving NIV, 50,413 (11.6%; 95% CI, 11.5-11.7%) patients underwent invasive mechanical ventilation on hospital days 2-5 or died on hospital days 2-30. Intubation was used in 32,301 patients (7.4%; 95% CI, 7.3-7.6%). Further, death occurred in 24,140 (5.6%; 95% CI, 5.5-5.7%). In multivariable analysis adjusting for relevant covariates, receipt of any medication studied was associated with increased odds of intubation or death. In inverse probability weighting, receipt of any study medication was also associated with increased odds of intubation or death (average treatment effect odds ratio 1.38; 95% CI, 1.35-1.40). CONCLUSIONS: The use of sedation and analgesia during NIV is common. Medication exposure was associated with increased odds of intubation or death. Further investigation is needed to confirm this finding and determine whether any subpopulations are especially harmed by this practice.

Pharmacokinetic and neuroimmune pharmacogenetic impacts on slow-release morphine cancer pain control and adverse effects.

The aim was to determine if opioid neuroimmunopharmacology pathway gene polymorphisms alter serum morphine, morphine-3-glucuronide and morphine-6-glucuronide concentration-response relationships in 506 cancer patients receiving controlled-release oral morphine. Morphine-3-glucuronide concentrations (standardised to 11 h post-dose) were higher in patients without pain control (median (interquartile range) 1.2 (0.7-2.3) versus 1.0 (0.5-1.9) µM, P = 0.006), whereas morphine concentrations were higher in patients with cognitive dysfunction (40 (20-81) versus 29 (14-60) nM, P = 0.02). TLR2 rs3804100 variant carriers had reduced odds (adjusted odds ratio (95% confidence interval) 0.42 (0.22-0.82), P = 0.01) of opioid adverse events. IL2 rs2069762 G/G (0.20 (0.06-0.52)), BDNF rs6265 A/A (0.15 (0.02-0.63)) and IL6R rs8192284 carrier (0.55 (0.34-0.90)) genotypes had decreased, and IL6 rs10499563 C/C increased (3.3 (1.2-9.3)), odds of sickness response (P ≤ 0.02). The study has limitations in heterogeneity in doses, sampling times and diagnoses but still suggests that pharmacokinetics and immune genetics co-contribute to morphine pain control and adverse effects in cancer patients.

Continuous Wound Irrigation and Intraoperative Methadone Decreases Opioid Use and Shortens Length of Stay After CRS/HIPEC.

BACKGROUND: Epidural analgesia is resource and labor intense and may limit postoperative management options and delay discharge. This study compared postoperative outcomes after cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) with epidural analgesia versus continuous wound infusion system (CWIS) with/without intraoperative methadone. METHODS: A single-institution, retrospective chart review was performed including all patients undergoing open CRS/HIPEC from 2018 to 2021. Patient demographics, surgical characteristics, length of stay, and in-hospital analgesic use were reviewed. In-hospital opioid exposure in morphine milligram equivalents (MME) was calculated. Multivariate analysis (MVA) for mean total and daily opioid exposure was conducted. RESULTS: A total of 157 patients were included. Fifty-three (34%) had epidural analgesia, 96 (61%) had CWIS, and 79 (50%) received methadone. Length of stay was significantly shorter with CWIS + methadone versus epidural (7 vs. 8 days, p < 0.01). MVA showed significantly lower mean total and daily opioid exposure with CWIS+methadone versus epidural (total: 252.8 ± 17.7 MME vs. 486.8 ± 86.6 MME; odds ratio [OR] 0.72, 95% confidence interval [CI] 0.52-0.98, p = 0.04; Daily: 32.8 ± 2.0 MME vs. 51.9 ± 5.7 MME, OR 0.72, 95% CI 0.52-0.99, p ≤ 0.05). The CWIS-only group (n = 17) had a significantly lower median oral opioid exposure versus epidural (135 MME vs. 7.5 MME, p < 0.001) and longer length of stay versus CWIS + methadone (9 vs. 7 days, p = 0.04), There were no CWIS or methadone-associated complications and one epidural abscess. CONCLUSIONS: CWIS + methadone safely offers better pain control with less in-hospital opioid use, shorter length of stay, and decreased resource utilization compared with epidural analgesia in patients undergoing CRS-HIPEC.

Improved Postoperative Pain Management Outcomes After Implementation of Enhanced Recovery After Surgery (ERAS) Protocol for Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy (CRS-HIPEC).

BACKGROUND: Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) for patients with peritoneal carcinomatosis is promising but has potential for significant morbidity and prolonged hospitalization. Enhanced Recovery After Surgery (ERAS) is a standardized protocol designed to optimize perioperative care. This study describes trends in epidural and opioid use after implementing ERAS for CRS-HIPEC at a tertiary academic center. METHODS: A retrospective analysis of patients undergoing CRS-HIPEC from January 2020 to September 2023 was conducted. ERAS was implemented in February 2022. Medication and outcomes data were compared before and after ERAS initiation. All opioids were converted to morphine milligram equivalents (MMEs). RESULTS: A total of 136 patients underwent CRS-HIPEC: 73 (54%) pre- and 63 (46%) post-ERAS. Epidural usage increased from 63% pre-ERAS to 87% post-ERAS (p = 0.001). Compared with those without epidurals, patients with epidurals had decreased total 7-day oral and intravenous (IV) opioid requirements (45 MME vs. 316 MME; p < 0.001). There was no difference in 7-day opioid totals between pre- and post-ERAS groups. After ERAS, more patients achieved early ambulation (83% vs. 53%; p < 0.001), early diet initiation (81% vs. 25%; p < 0.001), and early return of bowel function (86% vs. 67%; p = 0.012). CONCLUSIONS: ERAS implementation for CRS-HIPEC was associated with increased epidural use, decreased oral and IV opioid use, and earlier bowel function return. Our study demonstrates that epidural analgesia provides adequate pain control while significantly decreasing oral and IV opioid use, which may promote gastrointestinal recovery postoperatively. These findings support the implementation of an ERAS protocol for effective pain management in patients undergoing CRS-HIPEC.

Development and Verification of a Full Physiologically Based Pharmacokinetic Model for Sublingual Buprenorphine in Healthy Adult Volunteers that Accounts for Nonlinear Bioavailability.

Sublingual buprenorphine is used for opioid use disorder and neonatal opioid withdrawal syndrome. The study aimed to develop a full physiologically based pharmacokinetic (PBPK) model that can adequately describe dose- and formulation-dependent bioavailability of buprenorphine. Simcyp (v21.0) was used for model construction. Four linear regression models (i.e., untransformed or log transformed for dose or proportion sublingually absorbed) were explored to describe sublingual absorption of buprenorphine across dose. Published clinical trial data not used in model development were used for verification. The PBPK model's predictive performance was deemed adequate if the geometric means of ratios between predicted and observed (P/O) area under the curve (AUC), peak concentration (Cmax), and time to reach Cmax (Tmax) fell within the 1.25-fold prediction error range. Sublingual buprenorphine absorption was best described by a regression model with logarithmically transformed dose. By integrating this nonlinear absorption profile, the PBPK model adequately predicted buprenorphine pharmacokinetics (PK) following administration of sublingual tablets and solution across a dose range of 2-32 mg, with geometric mean (95% confidence interval) P/O ratios for AUC and Cmax equaling 0.99 (0.86-1.12) and 1.24 (1.09-1.40), respectively, and median (5th to 95th percentile) for Tmax equaling 1.11 (0.69-1.57). A verified PBPK model was developed that adequately predicts dose- and formulation-dependent buprenorphine PK following sublingual administration. SIGNIFICANCE STATEMENT: The physiologically based pharmacokinetic (PBPK) model developed in this study is the first to adequately predict dose- and formulation-dependent sublingual buprenorphine pharmacokinetics. Accurate prediction was facilitated by the incorporation of a novel nonlinear absorption model. The developed model will serve as the foundation for maternal-fetal PBPK modeling to predict maternal and fetal buprenorphine exposures to optimize buprenorphine treatment for neonatal opioid withdrawal syndrome.

Low dose of morphine to relieve dyspnea in acute respiratory failure: the OpiDys double-blind randomized controlled trial.

BACKGROUND: Morphine relieves dyspnea in various clinical circumstances. Whether or not this applies to patients admitted to intensive care units (ICUs) for acute respiratory failure (ARF) is unknown. We evaluated the efficacy and safety of low-dose morphine on dyspnea in patients admitted to the ICU for ARF. METHODS: In this single-center, double-blind, phase 2, randomized, controlled trial, we assigned non-intubated adults admitted to the ICU for ARF with severe dyspnea, defined by a visual analog scale for dyspnea (dyspnea-VAS) from zero (no dyspnea) to 100 mm (worst imaginable dyspnea) ≥40 mm, to receive a low dose of Morphine Hydrochloride (intravenous titration followed by subcutaneous relay) or Placebo. All patients received standard therapy, including etiological treatment and non-invasive respiratory support. RESULTS: Twenty-two patients were randomized, 11 in each group. The average dyspnea (median [interquartile range]) over 24 hours did not significantly differ between the two groups (40 [25 - 43] mm in the Morphine group vs. 40 [36 - 49] mm in the Placebo group, p=0.411). Dyspnea-VAS was lower in the Morphine group than in the Placebo group at the end of intravenous titration (30 [11 - 30] vs. 35 [30 - 44], p=0.044) and four hours later (18 [10 - 29] vs. 50 [30 - 60], p=0.043). The cumulative probability of intubation was higher in the Morphine group than in the Placebo group (p=0.046) CONCLUSION: In this phase 2 pilot trial, morphine did not improve 24-hour average dyspnea in adult patients with ARF, even though it had a statistically significant immediate effect. Of concern, Morphine use was associated with a higher intubation rate. TRIAL REGISTRATION: The protocol was declared on the ClinicalTrial.gov database (no. NCT04358133) and was published in September 2022.

Pregnancy Rates Among Women Treated with Medication for Opioid Use Disorder.

BACKGROUND: Treatment-seeking people with opioid use disorder (OUD) who are capable of pregnancy need accurate information about the potential impact of medication to treat OUD (MOUD) on fertility to make informed choices about treatment that are consistent with their reproductive wishes. There is a dearth of research on fertility associated with MOUD receipt in birthing people with OUD. OBJECTIVE: To estimate the association between treatment with MOUD and odds of conception among birthing people using national administrative claims. DESIGN: Retrospective case-crossover study using multi-state US administrative data (2006-2016). Dates of conception were estimated from delivery dates and served as "case" days for which MOUD exposures were compared to those on all other ("control") days of insurance enrollment. PARTICIPANTS: Treatment-seeking people with OUD with a delivery during the observation period. MAIN MEASURES: Odds ratios for conception from within-person fixed effects models were modeled as a function of exposure to MOUD (buprenorphine, methadone, extended-release depot naltrexone, or oral naltrexone) using conditional logistic regression. KEY RESULTS: A total of 21,928 births among 19,133 people with OUD were identified. In the sample, 5873 people received buprenorphine, 1825 methadone, 486 extended-release naltrexone, and 714 oral naltrexone. Participants could receive more than one type of MOUD. Mean age was 28.2 years (SD = 2.2; range = 16-45), with 76.2% having Medicaid. vs. commercial insurance. Compared to no MOUD, periods of methadone (aOR = 0.55 [95% CI = 0.48-0.63]) or buprenorphine receipt (aOR = 0.84 [0.77-0.91]) were associated with fewer conceptions. Treatment periods with extended-release depot naltrexone compared to no medication were associated with higher odds of conception (aOR = 1.75 [1.22-2.50]) and there was no significant difference in conception with oral naltrexone (aOR = 1.02 [0.67-1.54]). CONCLUSIONS: The association between MOUD and odds of conception among birthing people varied by type of MOUD, with extended-release naltrexone associated with higher odds of conceiving compared to no treatment. Clinical studies are urgently needed to investigate these findings further.

Safety and Efficacy of Vocacapsaicin for Management of Postsurgical Pain: A Randomized Clinical Trial.

BACKGROUND: Nonopioid management of postsurgical pain remains a major unmet need. Few studies have evaluated transient receptor potential vanilloid subfamily member 1 agonists for analgesia after surgery. This study examines intraoperative vocacapsaicin, a novel prodrug of the transient receptor potential vanilloid subfamily member 1 agonist capsaicin, in a validated model of postsurgical pain. METHODS: This was a triple-blinded, randomized, placebo-controlled, dose-ranging trial in patients undergoing bunionectomy. Patients were randomized 1:1:1:1 to surgical site administration of 14 ml of placebo or one of three vocacapsaicin concentrations: 0.30, 0.15, or 0.05 mg/ml. The prespecified primary endpoint was the area-under-the-curve of the numerical rating scale pain score at rest through 96 h for the 0.30 mg/ml group. Prespecified ordered, secondary endpoints for the 0.30 mg/ml group included the percentage of patients who did not require opioids from 0 to 96 h, total opioid consumption through 96 h, and the area-under-the-curve of the numerical rating scale pain score for the first week. RESULTS: The 147 patients were randomized. During the first 96 h, vocacapsaicin (0.30 mg/ml) reduced pain at rest by 33% versus placebo (primary endpoint, 95% CI [10%, 52%], effect size [Cohen's d] = 0.61, P = 0.005). Of patients receiving vocacapsaicin (0.30 mg/ml), 26% did not require postoperative opioids for analgesia (P = 0.025) versus 5% of patients receiving placebo. Vocacapsaicin (0.30 mg/ml) reduced opioid consumption over the first 96 h by 50% versus placebo (95% CI [26%, 67%], effect size = 0.76, P = 0.002). Vocacapsaicin (0.30 mg/ml) reduced pain over the first week by 37% versus placebo (95% CI [12%, 57%], effect size = 0.62, P = 0.004). The treatment effect persisted for at least 2 weeks. All study endpoints showed an administered concentration-versus-response relationship. Vocacapsaicin was well tolerated with no differences between groups in any safety parameter. CONCLUSIONS: A single, local administration of vocacapsaicin during surgery reduced pain and opioid consumption for at least 96 h after surgery compared to control.

Increased Postoperative Opioid Consumption in the Presence of Coadministration of 5-Hydroxytryptamine Type 3 Antagonists with Acetaminophen: A Hospital Registry Study.

BACKGROUND: Acetaminophen and 5-hydroxytryptamine type 3 (5-HT3) receptor antagonists are administered as standard prophylaxes for postoperative pain, nausea, and vomiting. Preclinical studies, however, suggest that 5-HT3 antagonists may compromise acetaminophen's analgesic effect. This hospital registry study investigates whether 5-HT3 antagonists mitigate the analgesic effect of prophylactic acetaminophen in a perioperative setting. METHODS: This study included 55,016 adult patients undergoing general anesthesia for ambulatory procedures at a tertiary healthcare center in Massachusetts from 2015 to 2022. Using binary exposure variables and a comprehensive selection of preplanned patient- and procedure-related covariates for confounder control, the authors investigated whether intraoperative 5-HT3 antagonists affected the association between pre- or intraoperative acetaminophen and postoperative opioid consumption, gauged by opioid dose in milligram oral morphine equivalents (OME) administered in the postanesthesia care unit. A multivariable, zero-inflated negative binomial regression model was applied. RESULTS: A total of 3,166 patients (5.8%) received only acetaminophen, 15,438 (28.1%) only 5-HT3 antagonists, 31,850 (57.9%) both drugs, and 4,562 (8.3%) neither drug. The median postanesthesia care unit opioid dose was 7.5 mg OME (interquartile range, 7.5 to 14.3 mg OME) among 16,640 of 55,016 (30.2%) patients who received opioids, and the mean opioid dose was 3.2 mg OME across all patients (maximum cumulative dose, 20.4 mg OME). Acetaminophen administration was associated with a -5.5% (95% CI, -9.6 to -1.4%; P = 0.009; adjusted absolute difference, -0.19 mg OME; 95% CI, -0.33 to -0.05; P = 0.009) reduction in opioid consumption among patients who did not receive a 5-HT3 antagonist, while there was no effect in patients who received a 5-HT3 antagonist (adjusted absolute difference, 0.00 mg OME; 95% CI, -0.06 to 0.05; P = 0.93; P for interaction = 0.013). CONCLUSIONS: A dose-dependent association of pre- or intraoperative acetaminophen with decreased postoperative opioid consumption was not observed when 5-HT3 antagonists were coadministered, suggesting that physicians might consider reserving 5-HT3 antagonists as rescue medication for postoperative nausea or vomiting when acetaminophen is administered for pain prophylaxis.

Impact of pharmacogenomic profiles on post-surgical pain following laparotomy for gynecologic pathology.

OBJECTIVES: The aim of this prospective study was to compare perioperative opioid use in women by status of CYP2D6, a highly polymorphic pharmacogene relevant to opioid metabolism. METHODS: Patients undergoing laparotomy were prospectively recruited and provided a preoperative saliva swab for a pharmacogenomic (PGx) gene panel. Postoperative opioid usage and pain scores were evaluated via chart review and a phone survey. Pharmacogenes known to be relevant to opioid metabolism were genotyped, and opioid metabolizing activity predicted by CYP2D6 genotyping. Patient and procedural factors were compared using Fisher's exact and Kruskal-Wallis tests. RESULTS: The 96 enrolled patients were classified as ultra-rapid (N = 3, 3%), normal (58, 60%), intermediate (27, 28%), and poor (8, 8%) opioid metabolizers. There was no difference in surgical complexity across CYP2D6 categories (p = 0.61). Morphine Milligram Equivalents (MME) consumed during the first 24 h after peri-operative suite exit were significantly different between groups: ultrarapid metabolizers had the highest median MME (75, IQR 45-88) compared to the other three groups (normal metabolizers 23 [8-45], intermediate metabolizers 48 [20-63], poor metabolizers 31 [12-53], p = 0.03). Opioid requirements were clinically greater in ultrarapid metabolizers during the second 24 h and last 24 h but were statistically similar (p = 0.07). There was no difference in MME prescribed at discharge (p = 0.22) or patient satisfaction with pain control (p = 0.64) between groups. CONCLUSIONS: A positive association existed between increased CYP2D6 activity and in-hospital opioid requirements, especially in the first 24 h after surgery. This provides important information to further individualize opioid prescriptions for patients undergoing laparotomy for gynecologic pathology.

A randomized, double-blind study to compare the efficacy and safety of nalbuphine nasal spray and injectable solution in patients after orthopaedic interventions and traumatological procedures.

AIMS: Our previous 3-period crossover study in healthy volunteers comparing the pharmacokinetics of nalbuphine nasal spray Apain with parenteral nalbuphine solution demonstrated high bioavailability of the nasal spray and close similarity of pharmacokinetic profiles after intranasal and intramuscular administration, especially within 30 min postdose. The aim of the present study was a noninferiority assessment of nalbuphine nasal spray vs. intramuscular injection for pain relief in postoperative patients. METHODS: Ninety orthopaedic and traumatology patients were enrolled in this double-blind, randomized study of the effectiveness and tolerance of a single 10.5 mg dose of nalbuphine nasal spray vs. 10 mg intramuscular injection. The summed pain intensity difference (SPID0-6) calculated using visual analogue scale scores was the primary study endpoint. RESULTS: Of 90 subjects enrolled, the per-protocol efficacy population comprised 79 patients; 6 patients in the reference group and 5 patients in the test group were excluded due to remedication. The mean values of study endpoints with 95% confidence interval were as follows in reference and test groups, respectively: SPID0-6 = 228.08 (205.73-250.43) vs. 248.73 9 (225.83-271.63), time to pain relief onset = 0.28 h (0.25-0.31) vs. 0.27 h (0.25-0.29), duration of analgesia = 5.55 h (5.17-5.93) vs. 5.51 h (5.10-5.92), area under the curve = 119.30 (91.17-147.43) vs. 99.81 (74.52-107.10). No statistically significant differences were revealed. CONCLUSION: Nalbuphine nasal spray Apain has been proven to be a safe, noninvasive alternative to intramuscular nalbuphine to relieve severe postoperative pain. Designed for self-administration and dose-adjusting, the noncontrolled opioid analgesic nalbuphine spray can be used for patient-controlled analgesia in out-of-hospital, field and home settings.

The association of pain impact and sleep disruption with opioid withdrawal during opioid-use disorder treatment.

AIMS: Persons with opioid-use disorder (OUD) often experience opioid withdrawal and opioid craving, which can drive continued opioid use and treatment discontinuation. In addition, hyperalgesia is common among persons with OUD, yet few studies have examined the role of pain impact during OUD treatment. The purpose of the present study was to test whether opioid withdrawal and craving were elevated in the context of greater pain impact (i.e. greater pain intensity and interference), and whether these associations changed throughout treatment. METHODS: Participants in residential OUD treatment (n = 24) wore wrist actigraphy to measure sleep and completed daily measures of pain impact, opioid withdrawal and opioid craving for up to 28 days. Mixed effects models were used to examine whether daily elevations in pain impact and sleep continuity were associated with withdrawal severity and opioid craving. RESULTS: Elevations in withdrawal, but not craving, occurred on days when individuals reported higher scores on the pain impact scale. Associations between pain impact and withdrawal were present throughout treatment, but stronger during early treatment. In contrast, both withdrawal and opioid craving were elevated following nights of greater wake after sleep onset and awakenings, but these findings were often more pronounced in early treatment. CONCLUSIONS: Pain impact and sleep disturbance are 2 factors associated with opioid withdrawal and opioid craving. Novel pharmacotherapies and scalable adjunctive interventions targeting sleep and pain impact should be tested in future work to improve OUD treatment outcomes.

A novel tramadol-polycaprolactone implant could palliate heroin conditioned place preference and withdrawal in rats: behavioral and neurochemical study.

Drug dependence is a chronic brain disease characterized by craving and recurrent episodes of relapse. Tramadol HCl is a promising agent for withdrawal symptoms management, considering its relatively low abuse potential and safety. Oral administration, however, is not preferred in abstinence maintenance programs. Introducing an implantable, long-lasting formula is suggested to help outpatient abstinence programs achieve higher rates of treatment continuation. Tramadol implants (T350 and T650) were prepared on polycaprolactone polymer ribbons by the wet method. Male Wistar rats were adapted to heroin-conditioned place preference (CPP) at escalating doses (3-30 mg/kg, intraperitoneally, for 14 days). Implants were surgically implanted in the back skin of rats. After 14 days, the CPP score was recorded. Naloxone (1 mg/kg, intraperitoneally) was used to induce withdrawal on day 15, and symptoms were scored. Elevated plus maze and open field tests were performed for anxiety-related symptoms. Striata were analyzed for neurochemical changes reflected in dopamine, 3,4-dihydroxyphenyl acetic acid, gamma-aminobutyric acid, and serotonin levels. Brain oxidative changes including glutathione and lipid peroxides were assessed. The tramadol implants (T350 and T650) reduced heroin CPP and limited naloxone-induced withdrawal symptoms. The striata showed increased levels of 3,4-dihydroxyphenyl acetic acid, and serotonin and decreased levels of gamma-aminobutyric acid and dopamine after heroin withdrawal induction, which were reversed after implanting T350 and T650. Implants restore the brain oxidative state. Nonsignificant low naloxone-induced withdrawal score after the implant was used in naive subjects indicating low abuse potential of the implants. The presented tramadol implants were effective at diminishing heroin CPP and withdrawal in rats, suggesting further investigations for application in the management of opioid withdrawal.

Comparing withdrawal- and anxiety-like behaviors following oral and subcutaneous oxycodone administration in C57BL/6 mice.

Excessive prescribing and misuse of prescription opioids, such as oxycodone, significantly contributed to the current opioid crisis. Although oxycodone is typically consumed orally by humans, parenteral routes of administration have primarily been used in preclinical models of oxycodone dependence. To address this issue, more recent studies have used oral self-administration procedures to study oxycodone seeking and withdrawal in rodents. Behavioral differences, however, following oral oxycodone intake versus parenteral oxycodone administration remain unclear. Thus, the goal of the current studies was to compare anxiety- and withdrawal-like behaviors using established opioid dependence models of either home cage oral intake of oxycodone (0.5 mg/ml) or repeated subcutaneous (s.c.) injections of oxycodone (10 mg/kg) in male and female mice. Here, mice received 10 days of oral or s.c. oxycodone administration, and following 72 h of forced abstinence, anxiety- and withdrawal-like behaviors were measured using elevated zero maze, open field, and naloxone-induced precipitated withdrawal procedures. Global withdrawal scores were increased to a similar degree following oral and s.c. oxycodone use, while both routes of oxycodone administration had minimal effects on anxiety-like behaviors. When examining individual withdrawal-like behaviors, mice receiving s.c. oxycodone exhibited more paw tremors and jumps during naloxone-induced precipitated withdrawal compared with oral oxycodone mice. These results indicate that both models of oxycodone administration are sufficient to elevate global withdrawal scores, but, when compared with oral consumption, s.c. oxycodone injections yielded more pronounced effects on some withdrawal-like behaviors.