Using part of the initial analgesic dose as the epidural test dose did not delay the onset of labor analgesia: a randomized controlled clinical trial.

BACKGROUND: Epidural test dose for labor analgesia is controversial and varies widely in clinical practice. It is currently unclear whether using a portion of the initial dose for analgesia as the test dose delays the onset time of analgesia, compared to the traditional test dose. METHODS: One hundred and twenty-six parturients who chose epidural analgesia during labor were randomly assigned to two groups. The first dose in group L was 3 ml 1.5% lidocaine, and in the RF group was 10 ml 0.1% ropivacaine combined with 2 µg/ml fentanyl. After 3 min of observation, both groups received 8 ml 0.1% ropivacaine combined with 2 µg/ml fentanyl. The onset time of analgesia, motor and sensory blockade level, numerical pain rating scale, patient satisfaction score, and side effects were recorded. RESULTS: The onset time of analgesia in group RF was similar to that in group L (group RF vs group L, 7.0 [5.0-9.0] minutes vs 8.0 [5.0-11.0] minutes, p = 0.197). The incidence of foot numbness (group RF vs group L, 34.9% vs 57.1%, p = 0.020) and foot warming (group RF vs group L, 15.9% vs 47.6%, p < 0.001) in group RF was significantly lower than that in group L. There was no difference between the two groups on other outcomes. CONCLUSIONS: Compared with 1.5% lidocaine 3 ml, 0.1% ropivacaine 10 ml combined with 2 µg/ml fentanyl as an epidural test dose did not delay the onset of labor analgesia, and the side effects were slightly reduced. CLINICAL TRIAL REGISTRATION: http://www.chictr.org.cn (ChiCTR2100043071).

Physiologically based modeling reveals different risk of respiratory depression after fentanyl overdose between adults and children.

Despite a rapid increase in pediatric mortality rate from prescription and illicit opioids, there is limited research on the dose-dependent impact of opioids on respiratory depression in children, the leading cause of opioid-associated death. In this article, we extend a previously developed translational model to cover pediatric populations by incorporating age-dependent pharmacokinetic, pharmacodynamic, and physiological changes compared to adults. Our model reproduced previous perioperative clinical findings that adults and children have similar risk of respiratory depression at the same plasma fentanyl concentration when specific endpoints (minute ventilation, CO2 tension in the blood) were used. However, our model points to a potential caveat that, in a perioperative setting, routine use of mechanical ventilation and supplemental oxygen maintained the blood and tissue oxygen partial pressures in patients and prevented the use of oxygen-related endpoints to evaluate the consequences of respiratory depression. In a community setting when such oxygenation procedures are not immediately available, our model suggests that the higher oxygen demand and reduced cerebrovascular reactivity could make children more susceptible to severe hypoxemia and brain hypoxia, even with the same plasma fentanyl concentration as adults. Our work indicates that when developing intervention strategies to protect children from opioid overdose in a community setting, these pediatric-specific factors may need to be considered.

A confirmed case of xylazine-induced skin ulcers in a person who injects drugs in Miami, Florida, USA.

BACKGROUND: Xylazine is an alpha-2 adrenergic receptor agonist that has emerged as a contaminant in the illicit drug supply of fentanyl. Xylazine use may be suspected in naloxone-resistant overdoses and atypical, chronic wounds in people who use drugs (PWUD). This case is unique because it is the first case to our knowledge describing wound care for a xylazine-induced wound with a confirmatory xylazine test strip (XTS) in the setting of a syringe services program (SSP) and in the state of Florida. CASE PRESENTATION: A 43-year-old woman with a past medical history of severe opioid use disorder and stimulant use disorder presented to a student-run clinic at a Miami SSP for wound care. She had multiple ulcerations diffusely over her bilateral forearms with surrounding erythema and warmth. Seven weeks later, she presented to clinic again for wound care because her wounds had progressed. At this visit, a XTS was used to confirm the presence of xylazine in her urine. Wound care management and harm reduction strategies employed at both visits were informed by best clinical judgement due to lack of formal guidelines at the time. Wound outcomes are unknown as the patient has not returned to clinic. CONCLUSIONS: Many PWUD at highest risk for acute and chronic health consequences of xylazine-adulterated fentanyl do not have access to healthcare outside of low barrier clinics and SSPs due to lack of insurance or mistrust of the traditional healthcare system due to stigma. There is an urgent need for access to XTS for PWUD and clinical practice guidelines for the treatment of xylazine-related wounds in outpatient clinics.

Efficacy and safety of esketamine combined with propofol for curative endoscopic resection in colorectum: a prospective, randomized controlled trial.

BACKGROUND: Curative endoscopic resection is widely used to treat colonic polyps and early stage cancers. The anesthetic strategy commonly involves the use of propofol combined with a small dose of opioids for sedation. Adverse respiratory or cardiovascular events such as hypotension often occur when attempting to achieve the necessary level of sedation. Several studies have suggested its advantages owing to the anesthetic, analgesic, and sympathomimetic properties of esketamine. However, there are no reports on curative colorectal endoscopic resection. We designed this randomized controlled trial to assess the efficacy and safety of esketamine combined with propofol for sedation in patients undergoing curative colorectal endoscopic resection. METHODS: A total of 166 patients who underwent curative colorectal endoscopic resection were randomly assigned to groups A (propofol + fentanyl) or E (propofol + esketamine). Ideal sedation was assessed using the MOAA/S scale and was achieved using TCI-propofol with different doses of fentanyl and esketamine. The propofol consumption and vasoactive drug dosages were recorded. Sedation-related times, adverse events, and satisfaction were recorded. RESULTS: Of the 160 patients, the total propofol consumption was significantly lower in group E (n = 81) (300 mg) than in group A (n = 79) (350 mg). Hypotension and bradycardia were significantly lower in Group E than in Group A. The groups showed no significant differences in other adverse events, induction time, recovery time, or patient or endoscopist satisfaction. CONCLUSION: Compared to fentanyl, esketamine helps decrease propofol consumption and increases cardiovascular stability during curative colorectal endoscopic resection in American Society of Anesthesiologists Class I-III patients without affecting anesthesia, patient and endoscopist satisfaction, or other adverse events. TRIAL REGISTRATION: The study was retrospectively registered at the Chinese Clinical Trial Registry ( www.chictr.org.cn ; registration number: ChiCTR2300069014 on 03/03/2023).

Implementing physics-based digital patient twins to tailor the switch of oral morphine to transdermal fentanyl patches based on patient physiology.

Fentanyl transdermal patches are widely implemented for cancer-induced pain treatment due to the high potency of fentanyl and gradual drug release. However, transdermal fentanyl up-titration for opioid-naïve patients is difficult, which is why opioid treatment is often started with oral/iv morphine. Based on the daily dose of morphine, the initial dose of the fentanyl patch is decided upon. After reaching a stable level of pain, the switch is made from oral/iv morphine to transdermal fentanyl. There are standard calculation tools for transferring from oral/iv morphine to transdermal fentanyl, which is the same for all patients. By considering the variations in the physiology of the patients, a unique switching strategy cannot meet the needs of different patients. This study explores the outcome in terms of pain relief and minute ventilation during opioid therapy. For this, we used physics-based simulations on a virtually-generated population of patients, and we applied the same therapy to all patients. We could show that patients' physiology, such as gender, age, and weight, greatly impact the outcome of the therapy; as such, the correlation coefficient between pain intensity and age is 0.89, and the correlation coefficient between patient's weight and maximum plasma concentration of morphine and fentanyl is -0.98 and -0.97. Additionally, a different combination of the duration of overlap between morphine and fentanyl therapy with different doses of fentanyl was considered for the virtual patients to find the best opioid-switching strategy for each patient. We explored the impact of combining physiological features to determine the best-suited strategy for virtual patients. Our findings suggest that tailoring morphine and fentanyl therapy only based on a limited number of features is insufficient, and increasing the number of impactful physiological features positively influences the outcome of the therapy.

Routes of Drug Use Among Drug Overdose Deaths - United States, 2020-2022.

Preliminary reports indicate that more than 109,000 drug overdose deaths occurred in the United States in 2022; nearly 70% of these involved synthetic opioids other than methadone, primarily illegally manufactured fentanyl and fentanyl analogs (IMFs). Data from the western United States suggested a transition from injecting heroin to smoking IMFs. CDC analyzed data from the State Unintentional Drug Overdose Reporting System to describe trends in routes of drug use in 27 states and the District of Columbia among overdose deaths that occurred during January 2020-December 2022, overall and by region and drugs detected. From January-June 2020 to July-December 2022, the percentage of overdose deaths with evidence of injection decreased 29.1%, from 22.7% to 16.1%, whereas the percentage with evidence of smoking increased 73.7%, from 13.3% to 23.1%. The number of deaths with evidence of smoking increased 109.1%, from 2,794 to 5,843, and by 2022, smoking was the most commonly documented route of use in overdose deaths. Trends were similar in all U.S. regions. Among deaths with only IMFs detected, the percentage with evidence of injection decreased 41.6%, from 20.9% during January-June 2020 to 12.2% during July-December 2022, whereas the percentage with evidence of smoking increased 78.9%, from 10.9% to 19.5%. Similar trends were observed among deaths with both IMFs and stimulants detected. Strengthening public health and harm reduction services to address overdose risk related to diverse routes of drug use, including smoking and other noninjection routes, might reduce drug overdose deaths.

Guidelines for Rational Clinical Use of Fentanyl Transdermal Patch.

Pain is one of the most common clinical symptoms of cancer patients, seriously affecting the quality of life of patients and bringing heavy mental and economic burden to families and society. The treatment of cancer pain in China is facing numerous challenges, one of which includes the irrational usage of analgesic drugs in clinical practice. As a strong opioid analgesic, transdermal fentanyl patch has been widely used due to its convenient clinical application and obvious therapeutic effect. Several basic-level hospitals and even general hospitals in China fail to appropriate the application of drugs in clinical application due to the lack of understanding of the pharmacological characteristics and clinical application of fentanyl transdermal patch by medical staff, seriously affecting the treatment quality. Therefore, it is imperative to strengthen the rational use and management of fentanyl transdermal patches. Accordingly, the initiation by the Cancer Rehabilitation and Palliative Treatment Professional Committee of the Hubei Anti-cancer Association launched the compilation of the "Guidelines for Rational Clinical Use of Fentanyl Transdermal Patch" (from now on referred to as the "Guidelines") in Hubei Province, China. The experts in the preparation group are experts in many disciplines, such as medicine, pharmacy, and nursing. The expert group determines the outline, prepares the required regulations, and revises it repeatedly. Moreover, these experts put forward suggestions for revision to strictly control the accuracy and scientific authenticity of the contents of the "Guide". Finally, all experts of the preparation team certify and finalize the draft. This "Guide" prepared by experts of the Cancer Rehabilitation and Palliative Treatment Professional Committee of the Hubei Anti-cancer Association and the expert advisory group with joint efforts, aims to play a positive role in promoting the rational clinical use of fentanyl transdermal patch, reducing the mental and economic burden of patients, and ensuring medical quality and medical safety.

A scoping review of law enforcement drug seizures and overdose mortality in the United States.

BACKGROUND: Leveraging law enforcement drug seizure data to better respond to the overdose crisis requires an understanding of available evidence and knowledge gaps regarding relationships between drug seizures and overdose mortality. OBJECTIVE: This scoping review summarized peer-reviewed literature on associations between law enforcement drug seizures and drug-related mortality in the United States (US) in the era of illicitly-manufactured fentanyl, comparing study data sources, measures, methodologies, settings, and findings. METHODS: We identified 388 non-duplicate records from three online databases searched on May 23, 2023. After title/abstract and full-text screening by two independent reviewers, 14 studies met the criteria for inclusion. The included studies tested the association between a measure related to law enforcement drug seizures and an overdose mortality outcome in the US and were published in English, in peer-reviewed journals, during or after 2013. RESULTS: Four of 14 studies (29%) included data from the entire US, while the remaining studies focused on an individual state/city/county or a group of states/cities/counties. Synthetic opioid/fentanyl seizures represented the most frequently examined drug seizure category, and overdose deaths overall (involving any drugs) represented the most frequently examined outcome. Most studies used counts/rates of drug seizures, with fewer studies examining dosage/weight, drug combinations, the proportion of drug seizures involving a specific drug, or spatiotemporal distribution. The majority (86%) of studies reported at least one statistically significant positive association between a law enforcement drug seizure measure and an overdose mortality outcome, most consistently for fentanyl-related seizures. Results were relatively less consistent for seizures involving stimulants and other drugs. CONCLUSIONS: Studies in this review provided consistent evidence that fentanyl-related seizure measures are positively associated with overdose mortality outcomes, despite the limitations inherent in drug seizure data, even in the absence of available information regarding seizure weight or dosage.

Opioids in geriatric units in 14 Belgian hospitals: prevalence, dosage and associated factors.

Introduction: Adverse effects of opioids are common among older individuals, and undertreatment as well as overuse can be an issue. Epidemiological data on opioid use in older individuals are available, but scarce in hospitalized patients.Aims: The aim of this study is to examine the one-day prevalence of opioid use among older inpatients and identify the factors associated with both opioid use and dosage.Materials and methods: One-day cross-sectional study with data collected from geriatric units across 14 Belgian hospitals. The primary focus of the study is to assess the prevalence of opioid use and dosage, along with identifying associated factors. To achieve this, a multiple binary logistic regression model was fitted for opioid use, and a multiple linear regression model for opioid dose.Results: Opioids were used in 24.4% of 784 patients, of which 57.9% was treated with tramadol, 13.2% with oxycodone or morphine and 28.9% with transdermal buprenorphine or fentanyl. The odds for opioid use were 4.2 times higher in patients in orthogeriatric units compared to other patients (OR=4.2, 95% CI=2.50-7.05). The prevalence of opioid use was 34% higher in patients without dementia compared to patients with dementia (OR=0.66, 95% CI=0.46-0.95). The overall mean daily dosage was 14.07mg subcutaneous morphine equivalent. After adjustment for age, gender and dementia, dosage was only associated with type of opioid: the estimated mean opioid dose was 70% lower with tramadol (mean ratio=0,30,95% CI=0,23-0,39) and 67% lower with oxycodone and morphine (mean ratio=0,33, 95% CI=0,22-0,48) compared to transdermal buprenorphine and transdermal fentanyl.Conclusions: One in four patients received opioid treatment. It is not clear whether this reflects under- or overtreatment, but these results can serve as a benchmark for geriatric units to guide future pain management practices. The utilization of transdermal fentanyl and buprenorphine, resulting in higher doses of morphine equivalent, poses significant risks for side effects.

Ketamine for treatment-resistant major depressive disorder: Double-blind active-controlled crossover study.

BACKGROUND: The N-methyl-D-aspartate antagonist ketamine has rapid onset antidepressant activity in treatment-resistant depression (TRD). AIMS: To evaluate mood rating, safety and tolerability data from patients with TRD treated with ketamine and the psychoactive control fentanyl, as part of a larger study to explore EEG biomarkers associated with mood response. METHODS: We evaluated the efficacy and safety of intramuscular racemic ketamine in 25 patients with TRD, using a double-blind active-controlled randomized crossover design. Ketamine doses were 0.5 and 1 mg/kg, and the psychoactive control was fentanyl 50 mcg, given at weekly intervals. RESULTS/OUTCOMES: Within 1 h of ketamine dosing, patients reported reduced depression and anxiety ratings, which persisted for up to 7 days. A dose-response profile for ketamine was noted for dissociative side effects, adverse events and changes in blood pressure; however, changes in mood ratings were broadly similar for both ketamine doses. Overall, 14/25 patients (56%) were responders (⩾50% reduction at 24 h compared with baseline) for either ketamine dose for the Hospital Anxiety and Depression Scale (HADS), and 18/25 (72%) were responders for the HADS-anxiety scale. After fentanyl, only 1/25 (HADS-depression) and 3/25 (HADS-anxiety) were responders. Ketamine was generally safe and well tolerated in this population. CONCLUSIONS: Our findings add to the literature confirming ketamine's activity against depressive and anxiety symptoms in patients with TRD.

Characterizing Opioid Withdrawal Experiences and Consequences Among a Community Sample of People Who Use Opioids.

BACKGROUND: Opioid withdrawal symptoms are a highly salient and consequential health condition experienced by people who use opioids (PWUO). This study utilized qualitative interviews to explore opioid withdrawal experiences and consequences among PWUO in Los Angeles County, USA. METHODS: Semi-structured qualitative interviews were conducted with 22 PWUO (aged 27-63 years) between May 2021 and May 2022. Participants self-reported opioid and injection drug use in the last 30 days. We employed an inductive thematic approach to systematically code and synthesize textual interview data. RESULTS: Participants experienced withdrawal symptoms frequently, with many going to great lengths to avoid them. Withdrawal pain was described as incapacitating and interfered with PWUO's ability to sustain regular employment and ensure stable housing. Avoiding withdrawal was described as influential in driving decisions to continue using opioids. Mechanisms for managing withdrawal included using other substances to the point of sedation. PWUO who transitioned from heroin to fentanyl use revealed more frequent, painful, and faster onset of withdrawal symptoms. Adverse withdrawal experiences and fear of precipitated withdrawal from buprenorphine were barriers to treatment initiation and continuation. CONCLUSION: Withdrawal symptoms among PWUO increase health risk. Improved strategies to treat opioid withdrawal are urgently needed. Solutions such as safe supply and intentional opioid withdrawal interventions (educational trainings, withdrawal comfort kits) are needed to improve withdrawal management and reduce opioid-related harm.

Reduced side effects and improved pain management by continuous ketorolac infusion with patient-controlled fentanyl injection compared with single fentanyl administration in pelviscopic gynecologic surgery: a randomized, double-blind, controlled study.

BACKGROUND: A combination of opioids and adjunctive drugs can be used for intravenous patient-controlled analgesia (PCA) to minimize opioid-related side effects. We investigated whether two different analgesics administered separately via a dual-chamber PCA have fewer side effects with adequate analgesia than a single fentanyl PCA in gynecologic pelviscopic surgery. METHODS: This prospective, double-blind, randomized, and controlled study included 68 patients who underwent pelviscopic gynecological surgery. Patients were allocated to either the dual (ketorolac and fentanyl delivered by a dual-chamber PCA) or the single (fentanyl alone) group. Postoperative nausea and vomiting (PONV) and analgesic quality were compared between the two groups at 2, 6, 12, and 24 h postoperatively. RESULTS: The dual group showed a significantly lower incidence of PONV during postoperative 2-6 h (P = 0.011) and 6-12 h (P = 0.009). Finally, only two patients (5.7%) in the dual group and 18 (54.5%) in the single group experienced PONV during the entire postoperative 24 h and could not maintain intravenous PCA (odds ratio: 0.056, 95% CI [0.007, 0.229], P < 0.001). Despite the administration of less fentanyl via intravenous PCA during the postoperative 24 h in the dual group than in the single group (66.0 ± 77.8 vs. 383.6 ± 70.1 µg, P < 0.001), postoperative pain had no significant intergroup difference. CONCLUSIONS: Two different analgesics, continuous ketorolac and intermittent fentanyl bolus, administered via dual-chamber intravenous PCA, showed fewer side effects with adequate analgesia than conventional intravenous fentanyl PCA in gynecologic patients undergoing pelviscopic surgery.

Buprenorphine Versus Diclofenac for Pain Relief in Acute Pancreatitis: A Double-Blinded Randomized Controlled Trial.

BACKGROUND: Although both nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids are used for analgesia in acute pancreatitis (AP), the analgesic of choice is not known. We compared buprenorphine, an opioid, and diclofenac, an NSAID, for analgesia in AP. METHODS: In a double-blind randomized controlled trial, AP patients were randomized to receive intravenous diclofenac or intravenous buprenorphine. Fentanyl was used as rescue analgesia, delivered through a patient-controlled analgesia pump. Primary outcome was the difference in the dose of rescue fentanyl required. Secondary outcomes were the number of effective and ineffective demands of rescue fentanyl, pain-free interval, reduction in visual analogue scale (VAS) score, adverse events, and organ failure development. RESULTS: Twenty-four patients were randomized to diclofenac and 24 to buprenorphine. The 2 groups were matched at baseline. The total amount of rescue fentanyl required was significantly lower in the buprenorphine group:130 µg, interquartile range (IQR), 80-255 vs 520 µg, IQR, 380-1065 (P < .001). The number of total demands was 32 (IQR, 21-69) in the diclofenac arm vs 8 (IQR, 4-15) in the buprenorphine arm (P < .001). The buprenorphine group had more prolonged pain-free interval (20 vs 4 hours; P < .001), with greater reduction in the VAS score at 24, 48, and 72 hours compared with the diclofenac group. These findings were confirmed in the subgroup of moderately severe/severe pancreatitis. Adverse events profile was similar in the 2 groups. CONCLUSIONS: Compared with diclofenac, buprenorphine appears to be more effective and equally safe for pain management in AP patients, even in the subcohort of moderately severe or severe pancreatitis (Trial Registration number: CTRI/2020/07/026914).

Ventilatory Effects of Fentanyl, Heroin, and d-Methamphetamine, Alone and in Mixtures in Male Rats Breathing Normal Air .

The number of drug overdoses and deaths has increased significantly over the past decade and co-use of opioids and stimulants is associated with greater likelihood of overdose and decreased likelihood of accessing treatment, compared with use of opioids alone. Potential adverse effects of opioid/stimulant mixtures, particularly methamphetamine, are not well characterized. Two structurally different drugs with agonist properties at µ-opioid receptors (MOR), fentanyl and heroin, and d-methamphetamine, alone and in mixtures, were assessed for their effects on ventilation in rats breathing normal air. Whole-body phethysmography chambers were equipped with a tower and swivel allowing infusions to indwelling intravenous catheters. After a 45-minute habituation period, saline, fentanyl, heroin, or d-methamphetamine, alone and in mixtures, was administered. Five minutes later, the opioid receptor antagonist naloxone or vehicle was injected. Fentanyl (0.0032-0.1 mg/kg) and heroin (0.32-3.2 mg/kg) decreased ventilation [frequency (f) and tidal volume (VT)] in a dose-related manner whereas d-methamphetamine (0.1-3.2 mg/kg) increased f to >400% of control and decreased VT to <60% of control, overall increasing minute volume (product of f and VT) to >240% of control. When combined, d-methamphetamine (0.1-3.2 mg/kg) attenuated the ventilatory depressant effects of fentanyl (0.1 mg/kg) and heroin (3.2 mg/kg). d-Methamphetamine did not alter the potency of naloxone to reverse the ventilatory depressant effects of fentanyl or heroin. These studies demonstrate that d-methamphetamine can attenuate the ventilatory depressant effects of moderate doses of opioid receptor agonists while not altering the potency of naloxone to reverse opioid hypoventilation. SIGNIFICANCE STATEMENT: Co-use of opioids and stimulants is associated with greater likelihood of overdose and decreased likelihood of accessing treatment, compared with use of opioids alone. Potential adverse effects of opioid/stimulant mixtures are not well characterized. This study reports that 1) d-methamphetamine attenuates the ventilatory depressant effects of moderate doses of two structurally different opioid receptor agonists, fentanyl and heroin, and 2) d-methamphetamine does not alter potency or effectiveness of naloxone to reverse the ventilatory depressant effects of these opioid receptor agonists.

Comparison of different sustained-release opioids and acute respiratory conditions in patients with cancer and chronic kidney disease.

STUDY OBJECTIVE: Few data are available on the association between the use of oxycodone in patients with chronic kidney disease (CKD) and acute respiratory conditions. The aim of this study was to investigate whether oxycodone is associated with an increased risk of acute respiratory conditions in patients with cancer and CKD compared with other opioids. DESIGN AND SETTING: The data were obtained from a claims database in Japan. Patients with cancer and CKD who had received sustained-release opioids, including oral oxycodone, oral morphine, or transdermal fentanyl, between April 2014 and May 2021 were selected. The primary outcome was defined as an acute respiratory condition. Data for age and sex, morphine equivalent daily dose, concomitant use of specified medications, comorbidities defined based on the modified Charlson comorbidity index, substance use disorder, and lung cancer or metastatic lung cancer were investigated as covariates. Distribution of acute respiratory conditions was compared among the three sustained-release opioid groups using the log-rank test. Estimates of the incidence of acute respiratory conditions were compared among the groups using a Cox proportional hazards model with time-varying variables. MAIN RESULTS: A significant difference in the distribution of acute respiratory conditions was found among the three groups (p < 0.01). Cox regression analysis showed a significantly higher risk of acute respiratory conditions with morphine (hazard ratio [HR]: 3.04, 95% confidence interval [CI]: 1.07-8.65, p = 0.04) compared with oxycodone but no significant difference in risk with oxycodone (HR 0.67, 95% CI: 0.32-1.38, p = 0.27) compared with fentanyl. CONCLUSIONS: The findings suggest that the risk of acute respiratory conditions may be lower in patients with CKD who use oxycodone for cancer pain than in those who use morphine. Additionally, no difference in the risk of acute respiratory conditions was found between oxycodone and fentanyl use.

Interactions between lorcaserin and opioids: Ventilation and food-versus-drug choice.

Lorcaserin, a selective serotonin 2C (5-HT2C) receptor agonist, was approved for treating obesity and has been investigated for treating substance use disorders including those involving opioids. Although lorcaserin was withdrawn from the market, interest in the therapeutic potential of drugs acting at 5-HT2C receptors continues, supporting the need to further characterize potential adverse effects especially when combined with drugs of abuse. This study examined acute effects of lorcaserin on opioid-induced ventilatory depression, which is the primary cause of overdose, and opioid self-administration, which models factors contributing to opioid abuse, in male and female rhesus monkeys. In one group (n = 4), effects of morphine (0.178 to 5.6 mg/kg, s.c.), fentanyl (0.0032 to 0.1 mg/kg, s.c.), and lorcaserin (0.1 to 1.78 mg/kg, s.c.) alone as well as effects of lorcaserin with each opioid on ventilation were determined using head plethysmography. Another group (n = 5) responded under a food versus fentanyl (0.1 to 3.2 µg/kg/infusion, i.v.) choice procedure, and lorcaserin (0.32 to 1.78 mg/kg, i.v.) was given as a pretreatment. Lorcaserin dose-dependently decreased minute volume to below 70 % of baseline when administered alone and increased the potency of morphine and fentanyl. Consistent with previous studies, lorcaserin failed to alter choice of fentanyl over food. This study demonstrates the novel finding that lorcaserin alone decreases ventilation and enhances the ventilatory-depressant effects of opioids. Taken together with previous studies, these results suggest that combining a 5-HT2C receptor agonist such as lorcaserin with an opioid could increase the risk of ventilatory depression without the benefit of decreasing abuse.

Characterizing prescription opioid, heroin, and fentanyl initiation trajectories: A qualitative study.

We understand the current crisis of overdose deaths to be driven by widespread opioid use, characterized by distinct 'waves' of drug use. The first wave was driven by prescription opioids, the second by heroin, and the third by illicit, non-pharmaceutical fentanyl and fentanyl analogues (henceforth, fentanyl). The purpose of this study is to describe opioid initiation within each of the three waves from the perspective of people who use illicit opioids, with a focus on emerging pathways into fentanyl use. The authors recruited sixty people reporting past-30-day illicit opioid use in Dayton, Ohio. Participants completed a brief survey and a semi-structured in-depth qualitative interview, conducted from March to November 2020 with a total of 13 in-person and 47 virtual interviews. The qualitative interviews were transcribed in their entirety and analyzed thematically using NVivo 12. We noted supply-side changes as influencing trajectories in all three waves. However, we also noted differences in the experiences of prescription opioid and heroin initiation, with these trajectories influenced by pharmacological effects, pain management, curiosity, intergenerational use, pricing, and peers. In comparison, most participants were unaware that they were initiating fentanyl, and many reported overdosing with their first use of fentanyl. We identified a trajectory into fentanyl with limited to no prior heroin use among a few participants. The increased risk of overdose with initiation into fentanyl use further emphasizes the need for an expansion of naloxone distribution and the implementation of more comprehensive measures, such as overdose prevention centers, drug testing, and a safer supply. Further research on the dynamics of the ongoing overdose death crisis in the era of fentanyl and the 4th wave of the overdose crisis is critical in developing responsive prevention and intervention strategies.