Comparison of analgesic efficacy of tramadol, morphine and methadone in cats undergoing ovariohysterectomy.

OBJECTIVES: The aim of this study was to compare the analgesic efficacy and the effect on physiological variables and behavior of the use of tramadol, methadone and morphine as preoperative analgesia in healthy cats undergoing elective ovariohysterectomy. METHODS: Cats undergoing ovariohysterectomy were randomly assigned to receive one of the following premedication treatments intramuscularly: methadone (0.2 mg/kg; n = 10); morphine (0.2 mg/kg; n = 10); or tramadol (3 mg/kg; n = 10). Induction of anesthesia was done with propofol, and maintenance of anesthesia was done with isoflurane. Intraoperative heart rate, arterial blood pressure, respiratory rate, end-tidal isoflurane concentration and frequency of rescue analgesia (fentanyl 2.5 µg/kg) were compared between groups. Postoperative analgesia was assessed using the UNESP-Botucatu Multidimensional Composite Pain Scale, and perioperative serum glucose, cortisol concentrations and postoperative rescue analgesia were evaluated. RESULTS: Intraoperative rescue analgesia was required in 76.5% of cats at some time during surgery, and 27% of cats required postoperative rescue analgesia up to 6 h after extubation. There were no significant differences between groups with respect to intraoperative and postoperative rescue analgesia, pain scale scores and end-tidal isoflurane concentrations. In the immediate postoperative period, after extubation, most of the patients presented with hypothermia; however, 1-6 h postoperatively, hyperthermia was observed in most of the patients, and was most common in the tramadol group. CONCLUSIONS AND CLINICAL RELEVANCE: Under the conditions of this study, methadone, morphine and tramadol produced satisfactory postoperative analgesia in most of the cats undergoing ovariohysterectomy, and the effects lasted up to 6 h postoperatively. Intraoperative analgesia was not sufficient in most cases. Significant cardiovascular or respiratory effects contraindicating the use of these drugs were not found. Postanesthetic hyperthermia occurred with all opioids studied and was more frequent in the tramadol group.

Evaluation of urinary trace element levels in patients with opioid use disorder undergoing methadone treatment in western Iran.

The monitoring of essential and toxic elements in patients with Opioid Use Disorder (OUD) undergoing methadone treatment (MT) is important, and there is limited previous research on the urinary levels of these elements in MT patients. Therefore, the present study aimed to analyze certain elements in the context of methadone treatment compared to a healthy group. In this study, patients with opioid use disorder undergoing MT (n = 67) were compared with a healthy group of companions (n = 62) in terms of urinary concentrations of some essential elements (selenium (Se), zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), calcium (Ca)) and toxic elements (lead (Pb), cadmium (Cd), arsenic (As), and chromium (Cr)). Urine samples were prepared using the acid digestion method with a mixture of nitric acid and perchloric acid and assessed using the ICP-MS method. Our results showed that the two groups had no significant differences in terms of gender, education level, occupation, and smoking status. Urinary concentrations of Se, Cu, and Fe levels were significantly lower in the MT group compared to the healthy subjects. However, the concentrations of Pb, Cd, As, Mn, Cr, and Ca in the MT group were higher than in the healthy group (p < 0.05). No significant difference was established between the levels of Zn in the two groups (p = 0.232). The results of regression analysis revealed that the differences between the concentration levels of all metals (except Zn) between two groups were still remained significant after adjusting for all variables (p < 0.05). The data obtained in the current study showed lower urinary concentrations of some essential elements and higher levels of some toxic elements in the MT group compared to the healthy subjects. These findings should be incorporated into harm-reduction interventions.

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.

The effects of OPRM1 118A>G on methadone response in pain management in advanced cancer at end of life.

Cancer pain is the most feared symptom at end of life. Methadone has advantages over other opioids but is associated with significant variability in clinical response, making dosing challenging in practice. OPRM1 is the most studied pharmacogene associated with the pharmacodynamics of opioids, however reports on the association of the A118G polymorphism on opioid dose requirements are conflicting, with no reports including methadone as the primary intervention. This association study on OPRM1 A118G and response to methadone for pain management, includes a review of this genetic factor's role in inter-patient variability. Fifty-four adult patients with advanced cancer were recruited in a prospective, multi-centre, open label dose individualization study. Patient characteristics were not shown to influence methadone response, and no significant associations were observed for methadone dose or pain score. The findings of our review of association studies for OPRM1 A118G in advanced cancer pain demonstrate the importance of taking ancestry into account. While our sample size was small, our results were consistent with European populations, but in contrast to studies in Chinese patients, where carriers of the A118G polymorphism were associated with higher opioid dose requirements. Pharmacogenetic studies in palliative care are challenging, continued contribution will support future genotype-based drug dosing guidelines.

Perioperative methadone for posterior spinal fusion in adolescents: Results from a double-blind randomized-controlled trial.

BACKGROUND: Posterior spinal fusion is the most common surgical procedure performed for correction of adolescent idiopathic scoliosis in the United States. Intraoperative methadone has been shown to improve pain control in adult patients undergoing complex spine surgery, and current pediatric studies show encouraging results; however, prospective randomized-controlled trials are lacking in the pediatric literature. AIMS: We conducted a single-center double-blind randomized-controlled trial to compare intraoperative use of methadone to morphine in pediatric patients undergoing posterior spinal fusion. METHODS: A total of 47 adolescents undergoing posterior spinal fusion were randomized (stratified by sex) to either a methadone (n = 25) or morphine (n = 22) group. The primary outcome was postoperative opioid consumption. Secondary outcomes included postoperative pain severity, opioid-related side effects, and ratio of patient-controlled analgesia injections: attempts as a behavioral index of uncontrolled pain. RESULTS: Patients in the methadone group consumed less total opioid postoperatively (median [interquartile range], 0.3 mg/kg [0.1, 0.5]) than patients in the morphine group (0.3 mg/kg [0.2, 0.6]), median difference [95% confidence interval] -0.07 [-0.2 to 0.02]; (p = .026). Despite the lower amount of opioid used postoperatively, pain scores for the methadone group (3.5 [3.0, 4.3]) were not significantly different from those in the morphine group (4.0 [3.2, 5.0]; p = .250). Groups did not differ on opioid-related side effects. CONCLUSIONS: A two-dose intraoperative methadone regimen resulted in decreased opioid consumption compared to morphine. Although the clinical significance of these results may be limited, the analgesic equipoise without increased opioid-related side effects and potential for a lower incidence of chronic pain may tip the balance in favor of routine methadone use for adolescents undergoing posterior spinal fusion.

Cancer pain management: long-term maintenance therapy.

This is a case report regarding a patient on maintenance therapy with methadone wth cancer pain. Minimal increase in methadone dose and a better modulation of administration intervals were effective, allowing the achievement of an optimal analgesia in a short time. This effect was maintained at home after discharge up the last follow-up 3 weeks after discharge. Existing literature is discussed and it is suggested to use the same drug, methadone, in increased doses.

DRD2 TaqIA polymorphism-related functional connectivity between anterior insula and dorsolateral prefrontal cortex predicts the retention time in heroin-dependent individuals under methadone maintenance treatment.

BACKGROUND: Dopamine receptor D2 (DRD2) TaqIA polymorphism has an influence on addiction treatment response and prognosis by mediating brain dopaminergic system efficacy. Insula is crucial for conscious urges to take drugs and maintain drug use. However, it remains unclear about the contribution of DRD2 TaqIA polymorphism to the regulation of insular on addiction behavioral and its relation with the therapeutic effect of methadone maintenance treatment (MMT). METHODS: 57 male former heroin dependents receiving stable MMT and 49 matched male healthy controls (HC) were enrolled. Salivary genotyping for DRD2 TaqA1 and A2 alleles, brain resting-state functional MRI scan and a 24-month follow-up for collecting illegal-drug-use information was conducted and followed by clustering of functional connectivity (FC) patterns of HC insula, insula subregion parcellation of MMT patients, comparing the whole brain FC maps between the A1 carriers and non-carriers and analyzing the correlation between the genotype-related FC of insula sub-regions with the retention time in MMT patients by Cox regression. RESULTS: Two insula subregions were identified: the anterior insula (AI) and the posterior insula (PI) subregion. The A1 carriers had a reduced FC between the left AI and the right dorsolateral prefrontal cortex (dlPFC) relative to no carriers. And this reduced FC was a poor prognostic factor for the retention time in MMT patients. CONCLUSION: DRD2 TaqIA polymorphism affects the retention time in heroin-dependent individuals under MMT by mediating the functional connectivity strength between left AI and right dlPFC, and the two brain regions are promising therapeutic targets for individualized treatment.

Negative Urgency Linked to Craving and Substance Use Among Adults on Buprenorphine or Methadone.

Despite the effectiveness of medication-assisted treatment (MAT), adults receiving MAT experience opioid cravings and engage in non-opioid illicit substance use that increases the risk of relapse and overdose. The current study examines whether negative urgency, defined as the tendency to act impulsively in response to intense negative emotion, is a risk factor for opioid cravings and non-opioid illicit substance use. Fifty-eight adults (predominately White cis-gender females) receiving MAT (with buprenorphine or methadone) were recruited from online substance use forums and asked to complete self-report questionnaires on negative urgency (UPPS-P Impulsive Behavior Scale), past 3-month opioid cravings (ASSIST-Alcohol, Smoking, and Substance Involvement Screening Test), and non-opioid illicit substance use (e.g., amphetamines, cocaine, benzodiazepines). Results revealed that negative urgency was associated with past 3-month opioid cravings, as well as past month illicit stimulant use (not benzodiazepine use). These results may indicate that individuals high in negative urgency would benefit from receiving extra intervention during MAT.

Comparison of the Effects of OPRM1 A118G Polymorphism Using Different Opioids: A Prospective Study.

CONTEXT: µ-opioid receptor gene (OPRM1) A118G polymorphism (rs1799971) causes loss of N-glycosylation sites at the extracellular domain of µ-opioid receptors. G-allele carriers show a limited response to morphine; however, studies investigating the impact of A118G polymorphism on the efficacy of opioids other than morphine are limited. OBJECTIVE: To compare the impact of A118G polymorphism on the efficacy of various opioids. METHODS: This prospective cohort study enrolled 222 in-patients administered one of the following opioid therapies for cancer pain as part of an opioid introduction or rotation strategy: tapentadol extended-release tablets, methadone tablets, hydromorphone controlled-release tablets, oxycodone controlled-release tablets, or transdermal fentanyl patches. The impact of A118G polymorphism on the difference in the Brief Pain Inventory-Short Form score on days three, seven, and 14 from baseline was compared among the groups. RESULTS: Overall, 81, 74, and 67 patients had the AA, AG, and GG genotypes, respectively, with an OPRM1 A118G G-allele variant frequency of 0.47. The reduction in the Brief Pain Inventory-Short Form score after opioid therapy initiation did not differ significantly among the patients with the three A118G genotypes treated with tapentadol (p = 0.84) or methadone (p = 0.97), whereas it was significantly smaller in G-allele carriers than that in AA homozygous patients treated with hydromorphone (p < 0.001), oxycodone (p = 0.031), or fentanyl (p < 0.001). CONCLUSION: Tapentadol and methadone may be more suitable than hydromorphone, oxycodone, and fentanyl for G-allele carriers due to their dual mechanism of action and low susceptibility to OPRM1 A118G polymorphism.

A Survey of the Status of Methadone Switching in Japan Using a Hospital-Based Administrative Claims Database.

Methadone is generally used for the management of cancer pain in patients who cannot obtain adequate analgesia from other strong opioids; however, it has a complicated and inconsistent conversion ratio from pre-switching opioid dosage to methadone. This issue may be pronounced in Japan because only oral tablets are commercially available. We aimed to elucidate the status of methadone switching in Japan, focusing on its dosage. Using a Japanese hospital-based administrative claims database, we included patients who switched to methadone between April 2008 and January 2021. The proportion of methadone switching completion that required more than the defined conversion ratio in the Japanese package insert (called "high-dose methadone switching") was evaluated as a primary endpoint. Other endpoints included "the duration from initiation to completion of methadone switching" and "factors affecting high-dose methadone switching by using multivariate logistic regression analysis". Of 1585 patients who received methadone, 370 were enrolled. Among those, 130 (35.1%) received high-dose methadone switching. The median duration of methadone switching completion (12 days) was longer in the high-dose methadone switching group than in other patients. Four variables were identified as factors affecting high-dose methadone switching. Younger age and outpatient status increased the risk of requiring high-dose methadone switching, whereas the concomitant use of nonsteroidal anti-inflammatory drugs and fentanyl as a pre-switching opioid decreased the risk. In conclusion, more than 30% of the patients underwent high-dose methadone switching and required long completion periods, suggesting that methadone switching remains challenging in Japan.

Finding predictors for successful opioid response in cancer patients: An analysis of data from four randomized controlled trials.

CONTEXT: There is no consensus on which "strong" (or step 3 WHO analgesic ladder) opioid to prescribe to a particular patient with cancer-related pain. A better understanding of opioid and patient characteristics on treatment response will contribute to a more personalized opioid treatment. OBJECTIVES: Assessment of potential predictors for successful opioid treatment response in patients with cancer pain. METHODS: An international partnership between four cancer pain research groups resulted in a combined individual-level database from four relevant randomized controlled trials (RCTs; n = 881). Together, these RCTs investigated the short-term (1 week) and medium-term (4 or 5 weeks) treatment responses for morphine, buprenorphine, methadone, oxycodone, and fentanyl. Candidate predictors for treatment response were sex, age, pain type, pain duration, depression, anxiety, Karnofsky performance score, opioid type, and use of anti-neuropathic drug. RESULTS: Opioid type and pain type were found statistically significant predictors of short-term treatment success. Sex, age, pain type, anxiety, and opioid type were statistically, significantly associated with medium-term treatment success. However, these models showed low discriminative power. CONCLUSION: Fentanyl and methadone, and mixed pain were found to be statistically significant predictors of treatment success in patients with cancer-related pain. With the predictors currently assessed our data did not allow for the creation of a clinical prediction model with good discriminative power. Additional - unrevealed - predictors are necessary to develop a future prediction model.

Quality of life and associated factors of heroin-dependent patients receiving methadone and buprenorphine maintenance treatment.

AIM: Although studies in Western countries have investigated the quality of life (QoL) of heroin users, limited research on this topic has been conducted in Asia. The present study assessed QoL in patients with heroin dependence receiving medications to treat opioid use disorder. METHODS: We performed a cross-sectional study of patients with heroin dependence receiving methadone and buprenorphine treatment. The demographic and substance use variables of patients receiving methadone and buprenorphine were compared. The Chinese Health Questionnaire (CHQ-12), Obsessive Compulsive Drug Use Scale (OCDUS), and World Health Organization Quality of Life Short Form Taiwan version (WHOQOL-BREF-T) were administered to measure patient mental health problems, addiction severity, and QoL, respectively. Multivariate regression was used to identify the factors associated with QoL. RESULTS: A total of 149 patients receiving methadone and 31 receiving buprenorphine completed the questionnaires. Individuals in the buprenorphine group were more likely to be married (p = 0.024) or employed (p = 0.024), have a higher educational level (p = 0.013), have lower drug craving (OCDUS: p = 0.035), or have higher QoL (WHOQOL-BREF-T: p = 0.004) than those in the methadone group. After adjustment for other variables, employment was positively associated with the physical, psychological, and environmental domains of QoL. Receiving buprenorphine treatment (p = 0.032) and longer treatment duration (p = 0.016) were associated with higher psychological QoL. CONCLUSION: Several factors were associated with QoL in patients with heroin dependence. Some measures may improve their QoL, such as reducing employment barriers, improving treatment adherence, or increasing accessibility to buprenorphine treatment.

Methadone maintenance treatment and impulsivity: premature responding.

INTRODUCTION: Previous research showed that methadone maintenance treatment (MMT) is linked to impulsivity, with higher impulsivity levels being associated with for example, increased drug use. One aspect of impulsivity, most commonly studied in rodent research, is premature responding, the failure to wait for a starting signal. Premature responding is of high translational significance since it predicts the development of addiction-like behaviors in rodents. METHODS: We assessed 45 MMT patients and 46 demographically matched (age, sex, education, and handedness) healthy volunteers (HVs) on premature responding alongside action and inhibition of instructed and intentional trials using the Intentional Hand Task (IHT). RESULTS: The results showed markedly enhanced premature responses in the MMT vs. the HV group, which correlated positively with methadone dosage in the MMT patients. Throughout the task, MMT patients were faster across all trial parts and less accurate in response to instructed trials compared to HVs. CONCLUSIONS: The increase in premature motor reactions during variable waiting periods alongside increased motion speed and lower accuracy might reflect a specific motor inhibition deficit in MMT, a subcomponent of impulsivity not previously assessed in MMT. Incorporating an experimentally defined measure of impulsivity, such as premature responding, into existing test batteries used by clinicians might enable more tailored treatments addressing the increased impulsivity levels and associated dysfunctional behaviors in MMT.

Metabolic and functional substrates of impulsive decision-making in individuals with heroin addiction after prolonged methadone maintenance treatment.

Elevated impulsivity has been frequently reported in individuals with opioid addiction receiving methadone maintenance therapy (MMT), but the underlying neural mechanisms and cognitive subprocesses are not fully understood. We acquired functional magnetic resonance imaging (fMRI) data from 37 subjects with heroin addiction receiving long-term MMT and 33 healthy controls who performed a probabilistic reversal learning task, and measured their resting-state brain glucose using fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET). Subjects receiving MMT exhibited significantly elevated self-reported impulsivity, and computational modeling revealed a marked impulsive decision bias manifested as switching more frequently without available evidence. Moreover, this impulsive decision bias was associated with the dose and duration of methadone use, irrelevant to the duration of heroin use. During the task, the switch-related hypoactivation in the left rostral middle frontal gyrus was correlated with the impulsive decision bias while the function of reward sensitivity was intact in subjects receiving MMT. Using prior brain-wide receptor density data, we found that the highest variance of regional metabolic abnormalities was explained by the spatial distribution of µ-opioid receptors among 10 types of neurotransmitter receptors. Heightened impulsivity in individuals receiving prolonged MMT is manifested as atypical choice bias and noise in decision-making processes, which is further driven by deficits in top-down cognitive control, other than reward sensitivity. Our findings uncover multifaceted mechanisms underlying elevated impulsivity in subjects receiving MMT, which might provide insights for developing complementary therapies to improve retention during MMT.

Towards adherence monitoring using breath or oral fluid as a matrix in a methadone maintenance treatment program for patients with a chronic heroin use disorder: Issues and interpretation of the results.

Urine has been the preferred matrix for monitoring heroin and methadone adherence due to its large detection window. Drawbacks such as privacy concerns and adulteration however require other matrices. The study aims to determine if oral fluid and exhaled breath are suitable alternatives for heroin and methadone monitoring and to assess the detection time in exhaled breath. Forty-three participants, all on methadone and heroin-assisted treatment, were studied. Participants were monitored after the first and right before the second dosage of heroin. At both time points, oral fluid and exhaled breath samples were collected with urine at the second time point. All samples were screened for opiates, methadone and other drugs using immunoassay and LC-MS-MS. At the second time point, 98% of oral fluid samples and all exhaled breath samples tested positive for 6-monoacetylmorphine (6-MAM). Regarding morphine detection, the findings were reversed (100% in oral fluid, 98% in exhaled breath). Methadone-related results were 100% positive across all matrices, as expected. Notable is the detection of the heroin marker acetylcodeine in oral fluid and exhaled breath samples, which resulted in relatively low negative predictive value (average 54.6%). Oral fluid and exhaled breath are suitable alternatives for heroin and methadone maintenance monitoring. Clinicians should consider ease of collection, adulteration risk, costs, turn-around time and the substance of interest while choosing a matrix. In addition, even in cases when medicinal heroin is used, medical professionals should be aware of the presence of acetylcodeine in these alternate matrices.

Sedation Weaning Initiative Targeting Methadone Exposure: Single Center Improvements in Withdrawal Symptoms and Hospital Length of Stay for Pediatric Cardiac Critical Care.

OBJECTIVES: Sedation and pain medications are necessary in the management of postoperative pediatric cardiac patients. Prolonged exposure to these medications can lead to negative side effects including withdrawal. We hypothesized that standardized weaning guidelines would decrease exposure to sedation medications and decrease withdrawal symptoms. The primary aim was to decrease average days of methadone exposure to within goal for moderate- and high-risk patients within 6 months. DESIGN: Quality improvement methods were used to standardize sedation medication weaning in a pediatric cardiac ICU. SETTING: This study took place at Duke Children's Hospital Pediatric Cardiac ICU in Durham, North Carolina from January 1, 2020, to December 31, 2021. PATIENTS: Children less than 12 months old admitted to the pediatric cardiac ICU who underwent cardiac surgery. INTERVENTIONS: Sedation weaning guidelines were implemented over the course of 12 months. Data were tracked every 6 months and compared with the 12 months pre-intervention. Patients were stratified into low, moderate, and high risk withdrawal categories based on duration of opioid infusion exposure. MEASUREMENTS AND MAIN RESULTS: Total sample size was 94 patients in the moderate and high risk categories. Process measures included documentation of Withdrawal Assessment Tool scores and appropriate methadone prescription in patients which increased to 100% post-intervention. For outcome measures, we observed decreased dexmedetomidine infusion duration, decreased methadone wean duration, decreased frequency of elevated Withdrawal Assessment Tool scores, and decreased hospital length of stay post-intervention. For the primary aim, methadone wean duration consistently decreased after each study period. Our intervention did not adversely impact balancing measures. CONCLUSIONS: A quality improvement initiative to standardize sedation weaning in a Pediatric Cardiac ICU was successfully implemented and was correlated with decreased duration of sedation medications, decreased withdrawal scores, and decreased length of stay.