Identification and biophysical characterization of a novel domain-swapped camelid antibody specific for fentanyl.

Opioid use disorders (OUD) and overdoses are ever-evolving public health threats that continue to grow in incidence and prevalence in the United States and abroad. Current treatments consist of opioid receptor agonists and antagonists, which are safe and effective but still suffer from some limitations. Murine and humanized monoclonal antibodies (mAb) have emerged as an alternative and complementary strategy to reverse and prevent opioid-induced respiratory depression. To explore antibody applications beyond traditional heavy-light chain mAbs, we identified and biophysically characterized a novel single-domain antibody specific for fentanyl from a camelid variable-heavy-heavy (VHH) domain phage display library. Structural data suggested that VHH binding to fentanyl was facilitated by a unique domain-swapped dimerization mechanism, which accompanied a rearrangement of complementarity-determining region loops leading to the formation of a fentanyl-binding pocket. Structure-guided mutagenesis further identified an amino acid substitution that improved the affinity and relaxed the requirement for dimerization of the VHH in fentanyl binding. Our studies demonstrate VHH engagement of an opioid and inform on how to further engineer a VHH for enhanced stability and efficacy, laying the groundwork for exploring the in vivo applications of VHH-based biologics against OUD and overdose.

Low-Dose Morphine Does Not Cause Sleepiness in COPD: A Secondary Analysis of a Randomized Trial.

RATIONALE: Regular, low-dose, sustained-release morphine is frequently prescribed for persistent breathlessness in chronic obstructive pulmonary disease (COPD). However, effects on daytime sleepiness, perceived sleep quality and daytime function have not been rigorously investigated. OBJECTIVES: Determine the effects of regular, low-dose, sustained-release morphine on sleep parameters in COPD. METHODS: Pre-specified secondary analyses of validated sleep questionnaire data from a randomized trial of daily, low-dose, sustained -release morphine versus placebo over four weeks commencing at 8mg or 16mg/day with blinded up-titration over two weeks to a maximum of 32mg/day. Primary outcomes for these analyses were week-1 Epworth Sleepiness Scale (ESS) and Karolinska Sleepiness Scale (KSS) responses on morphine versus placebo. Secondary outcomes included Leeds Sleep Evaluation Questionnaire (LSEQ) scores (end of weeks 1 and 4), KSS and ESS beyond week-1 and associations between breathlessness, morphine, and questionnaire scores. MEASUREMENTS AND MAIN RESULTS: 156 people were randomized. Week-1 sleepiness scores were not different on morphine versus placebo (∆ESS [95%CI] versus placebo: 8mg group: -0.59 [-1.99, 0.81], p=0.41; 16mg group: -0.72 [-2.33, 0.9], p=0.38; ∆KSS versus placebo: 8mg group: 0.11 [-0.7, 0.9], p=0.78; 16mg group: -0.41 [-1.31, 0.49], p=0.37). This neutral effect persisted at later timepoints. In addition, participants who reported reduced breathlessness with morphine at 4 weeks also had improvement in LSEQ domain scores including perceived sleep quality and daytime function. CONCLUSIONS: Regular, low-dose morphine does not worsen sleepiness when used for breathlessness in COPD. Individual improvements in breathlessness with morphine may be related to improvements in sleep.

Expiratory Muscle Activity Counteracts Positive End-Expiratory Pressure and Is Associated with Fentanyl Dose in Patients with Acute Respiratory Distress Syndrome.

Rationale: Hypoxemia during mechanical ventilation might be worsened by expiratory muscle activity, which reduces end-expiratory lung volume through lung collapse. A proposed mechanism of benefit of neuromuscular blockade in acute respiratory distress syndrome (ARDS) is the abolition of expiratory efforts. This may contribute to the restoration of lung volumes. The prevalence of this phenomenon, however, is unknown. Objectives: To investigate the incidence and amount of end-expiratory lung impedance (EELI) increase after the administration of neuromuscular blocking agents (NMBAs), clinical factors associated with this phenomenon, its impact on regional lung ventilation, and any association with changes in pleural pressure. Methods: We included mechanically ventilated patients with ARDS monitored with electrical impedance tomography (EIT) who received NMBAs in one of two centers. We measured changes in EELI, a surrogate for end-expiratory lung volume, before and after NMBA administration. In an additional 10 patients, we investigated the characteristic signatures of expiratory muscle activity depicted by EIT and esophageal catheters simultaneously. Clinical factors associated with EELI changes were assessed. Measurements and Main Results: We included 46 patients, half of whom showed an increase in EELI of >10% of the corresponding Vt (46.2%; IQR, 23.9-60.9%). The degree of EELI increase correlated positively with fentanyl dosage and negatively with changes in end-expiratory pleural pressures. This suggests that expiratory muscle activity might exert strong counter-effects against positive end-expiratory pressure that are possibly aggravated by fentanyl. Conclusions: Administration of NMBAs during EIT monitoring revealed activity of expiratory muscles in half of patients with ARDS. The resultant increase in EELI had a dose-response relationship with fentanyl dosage. This suggests a potential side effect of fentanyl during protective ventilation.

Chronic Morphine Treatment Induces Sex- and Synapse-Specific Cellular Tolerance on Thalamo-Cortical Mu Opioid Receptor Signaling.

How cellular adaptations give rise to opioid analgesic tolerance to opioids like morphine is not well understood. For one, pain is a complex phenomenon comprised of both sensory and affective components, largely mediated through separate circuits. Glutamatergic projections from the medial thalamus (MThal) to the anterior cingulate cortex (ACC) are implicated in processing of affective pain, a relatively understudied component of the pain experience. The goal of this study was to determine the effects of chronic morphine exposure on mu-opioid receptor (MOR) signaling on MThal-ACC synaptic transmission within the excitatory and feedforward inhibitory pathways. Using whole-cell patch clamp electrophysiology and optogenetics to selectively target these projections, we measured morphine-mediated inhibition of optically evoked postsynaptic currents in ACC layer V pyramidal neurons in drug-naïve and chronically morphine treated mice. We found that that morphine perfusion inhibited the excitatory and feedforward inhibitory pathways similarly in females but caused greater inhibition of the inhibitory pathway in males. Chronic morphine treatment robustly attenuated morphine presynaptic inhibition within the inhibitory pathway in males, but not females, and mildly attenuated presynaptic inhibition within the excitatory pathway in both sexes. These effects were not observed in MOR phosphorylation-deficient mice. This study indicates that chronic morphine treatment induces cellular tolerance to morphine within a thalamo-cortical circuit relevant to pain and opioid analgesia. Furthermore, it suggests this tolerance may be driven by MOR phosphorylation. Overall, these findings improve our understanding of how chronic opioid exposure alters cellular signaling in ways that may contribute to opioid analgesic tolerance.

In Vitro Hepatotoxicity of Routinely Used Opioids and Sedative Drugs.

A hepatocyte cell line was used to determine the hepatotoxicity of sedatives and opioids, as the hepatotoxicity of these drugs has not yet been well characterized. This might pose a threat, especially to critically ill patients, as they often receive high cumulative doses for daily analgosedation and often already have impaired liver function due to an underlying disease or complications during treatment. A well-established biosensor based on HepG2/C3A cells was used for the determination of the hepatotoxicity of commonly used sedatives and opioids in the intensive care setting (midazolam, propofol, s-ketamin, thiopental, fentanyl, remifentanil, and sufentanil). The incubation time was 2 × 3 days with clinically relevant (Cmax) and higher concentrations (C5× and C10×) of each drug in cell culture medium or human plasma. Afterward, we measured the cell count, vitality, lactate dehydrogenase (LDH), mitochondrial dehydrogenase activity, cytochrome P 450 1A2 (CYP1A2), and albumin synthesis. All tested substances reduced the viability of hepatocyte cells, but sufentanil and remifentanil showed more pronounced effects. The cell count was diminished by sufentanil in both the medium and plasma and by remifentanil only in plasma. Sufentanil and remifentanil also led to higher values of LDH in the cell culture supernatant. A reduction of mitochondrial dehydrogenase activity was seen with the use of midazolam and s-ketamine. Microalbumin synthesis was reduced in plasma after its incubation with higher concentrations of sufentanil and remifentanil. Remifentanil and s-ketamine reduced CYP1A2 activity, while propofol and thiopental increased it. Our findings suggest that none of the tested sedatives and opioids have pronounced hepatotoxicity. Sufentanil, remifentanil, and s-ketamine showed moderate hepatotoxic effects in vitro. These drugs should be given with caution to patients vulnerable to hepatotoxic drugs, e.g., patients with pre-existing liver disease or liver impairment as part of their underlying disease (e.g., hypoxic hepatitis or cholestatic liver dysfunction in sepsis). Further studies are indicated for this topic, which may use more complex cell culture models and global pharmacovigilance reports, addressing the limitation of the used cell model: HepG2/C3A cells have a lower metabolic capacity due to their low levels of CYP enzymes compared to primary hepatocytes. However, while the test model is suitable for parental substances, it is not for toxicity testing of metabolites.

Estimation of the prevalence of opioid misuse in New York State counties, 2007-2018: a bayesian spatiotemporal abundance model approach.

An important challenge to addressing the opioid overdose crisis is the lack of information on the size of the population of people who misuse opioids (PWMO) in local areas. This estimate is needed for better resource allocation, estimation of treatment and overdose outcome rates using appropriate denominators (ie, the population at risk), and proper evaluation of intervention effects. In this study, we used a bayesian hierarchical spatiotemporal integrated abundance model that integrates multiple types of county-level surveillance outcome data, state-level information on opioid misuse, and covariates to estimate the latent (hidden) numbers of PWMO and latent prevalence of opioid misuse across New York State counties (2007-2018). The model assumes that each opioid-related outcome reflects a partial count of the number of PWMO, and it leverages these multiple sources of data to circumvent limitations of parameter estimation associated with other types of abundance models. Model estimates showed a reduction in the prevalence of PWMO during the study period, with important spatial and temporal variability. The model also provided county-level estimates of rates of treatment and opioid overdose using the numbers of PWMO as denominators. This modeling approach can identify the sizes of hidden populations to guide public health efforts in confronting the opioid overdose crisis across local areas. This article is part of a Special Collection on Mental Health.

Naloxone increases conditioned fear responses during social buffering in male rats.

Social buffering is the phenomenon in which the presence of an affiliative conspecific mitigates stress responses. We previously demonstrated that social buffering completely ameliorates conditioned fear responses in rats. However, the neuromodulators involved in social buffering are poorly understood. Given that opioids, dopamine, oxytocin and vasopressin play an important role in affiliative behaviour, here, we assessed the effects of the most well-known antagonists, naloxone (opioid receptor antagonist), haloperidol (dopamine D2 receptor antagonist), atosiban (oxytocin receptor antagonist) and SR49059 (vasopressin V1a receptor antagonist), on social buffering. In Experiment 1, fear-conditioned male subjects were intraperitoneally administered one of the four antagonists 25 min prior to exposure to a conditioned stimulus with an unfamiliar non-conditioned rat. Naloxone, but not the other three antagonists, increased freezing and decreased walking and investigation as compared with saline administration. In Experiment 2, identical naloxone administration did not affect locomotor activity, anxiety-like behaviour or freezing in an open-field test. In Experiment 3, after confirming that the same naloxone administration again increased conditioned fear responses, as done in Experiment 1, we measured Fos expression in 16 brain regions. Compared with saline, naloxone increased Fos expression in the paraventricular nucleus of the hypothalamus and decreased Fos expression in the nucleus accumbens shell, anterior cingulate cortex and insular cortex and tended to decrease Fos expression in the nucleus accumbens core. Based on these results, we suggest that naloxone blocks social buffering of conditioned fear responses in male rats.

Association of opioid use with survival in patients with cancer treated with immune checkpoint inhibitors: it is time for evidence-based behaviors.

Cancer is a leading cause of morbidity and mortality worldwide, with pain experienced by most patients undergoing cancer treatment. Opioids are the recommended treatment for cancer pain management, but recent studies suggest a negative association between opioid use and survival rates among patients undergoing immunotherapy. However, conclusions cannot be drawn regarding causality from these observational data. Immunotherapy, which boosts the body's immune system to fight cancer cells, has emerged as a promising treatment option for all types of cancer. Immune checkpoint inhibitors (ICIs) can activate the anticancer function of exhausted T cells and have shown remarkable survival benefits in patients with multiple malignancies. However, a recent systematic review and meta-analysis suggested that the use of opioids during ICI treatment has an adverse effect on patient prognosis, while the use of NSAIDs is not significantly associated with the prognosis in patients treated with ICIs. These reviews have major limitations due to the retrospective nature of the studies and the multiple factors that can influence the phenomenon. Therefore, caution is required when interpreting results from retrospective data on drug interactions. The findings of this study are alarming and potentially harmful to patients with cancer suffering from pain or other symptoms requiring opioid drugs.

Effects of dopamine and opioid receptor antagonism on the neural processing of social and nonsocial rewards.

Rewards are a broad category of stimuli inducing approach behavior to aid survival. Extensive evidence from animal research has shown that wanting (the motivation to pursue a reward) and liking (the pleasure associated with its consumption) are mostly regulated by dopaminergic and opioidergic activity in dedicated brain areas. However, less is known about the neuroanatomy of dopaminergic and opioidergic regulation of reward processing in humans, especially when considering different types of rewards (i.e., social and nonsocial). To fill this gap of knowledge, we combined dopaminergic and opioidergic antagonism (via amisulpride and naltrexone administration) with functional neuroimaging to investigate the neurochemical and neuroanatomical bases of wanting and liking of matched nonsocial (food) and social (interpersonal touch) rewards, using a randomized, between-subject, placebo-controlled, double-blind design. While no drug effect was observed at the behavioral level, brain activity was modulated by the administered compounds. In particular, opioid antagonism, compared to placebo, reduced activity in the medial orbitofrontal cortex during consumption of the most valued social and nonsocial rewards. Dopamine antagonism, however, had no clear effects on brain activity in response to reward anticipation. These findings provide insights into the neurobiology of human reward processing and suggest a similar opioidergic regulation of the neural responses to social and nonsocial reward consumption.

Machine Learning Discrimination and Ultrasensitive Detection of Fentanyl Using Gold Nanoparticle-Decorated Carbon Nanotube-Based Field-Effect Transistor Sensors.

The opioid overdose crisis is a global health challenge. Fentanyl, an exceedingly potent synthetic opioid, has emerged as a leading contributor to the surge in opioid-related overdose deaths. The surge in overdose fatalities, particularly due to illicitly manufactured fentanyl and its contamination of street drugs, emphasizes the urgency for drug-testing technologies that can quickly and accurately identify fentanyl from other drugs and quantify trace amounts of fentanyl. In this paper, gold nanoparticle (AuNP)-decorated single-walled carbon nanotube (SWCNT)-based field-effect transistors (FETs) are utilized for machine learning-assisted identification of fentanyl from codeine, hydrocodone, and morphine. The unique sensing performance of fentanyl led to use machine learning approaches for accurate identification of fentanyl. Employing linear discriminant analysis (LDA) with a leave-one-out cross-validation approach, a validation accuracy of 91.2% is achieved. Meanwhile, density functional theory (DFT) calculations reveal the factors that contributed to the enhanced sensitivity of the Au-SWCNT FET sensor toward fentanyl as well as the underlying sensing mechanism. Finally, fentanyl antibodies are introduced to the Au-SWCNT FET sensor as specific receptors, expanding the linear range of the sensor in the lower concentration range, and enabling ultrasensitive detection of fentanyl with a limit of detection at 10.8 fg mL-1.

Comparison of the µ-opioid receptor antagonists methocinnamox (MCAM) and naloxone to reverse and prevent the ventilatory depressant effects of fentanyl, carfentanil, 3-methylfentanyl, and heroin in male rats.

The number of opioid overdose deaths has increased significantly over the past decade. The life-threatening effect of opioids is hypoventilation that can be reversed by the µ-opioid receptor (MOR) antagonist naloxone; however, because of the very short duration of action of naloxone, re-emergence of MOR agonist-induced hypoventilation can occur, requiring additional doses of naloxone. The MOR antagonist methocinnamox (MCAM) antagonizes hypoventilation by the non-morphinan fentanyl and the morphinan heroin in laboratory animals with an unusually long duration of action. Whole-body plethysmography was used to compare the potency and effectiveness of MCAM and naloxone for preventing and reversing hypoventilation by fentanyl, heroin, and the ultra-potent and longer-acting fentanyl analogs carfentanil and 3-methylfentanyl in male rats breathing normal air. Sessions comprised a 45-minute habituation period followed by intravenous (i.v.) administration of saline or an acute dose of MOR agonist. The rank order of potency to decrease ventilation was 3-methylfentanyl > carfentanil > fentanyl > heroin. MCAM (0.0001-0.1 mg/kg) and naloxone (0.0001-0.01 mg/kg) dose-dependently reversed hypoventilation by 3-methylfentanyl (0.01 mg/kg), carfentanil (0.01 mg/kg), fentanyl (0.1 mg/kg), or heroin (3.2 mg/kg). For prevention studies, MCAM, naloxone, or vehicle was administered i.v. 22, 46, or 70 hours prior to a MOR agonist. When administered 22 hours earlier, MCAM (0.1-1.0 mg/kg) but not naloxone (1.0 mg/kg) prevented hypoventilation by each MOR agonist. This study demonstrates the effectiveness of MCAM to reverse and prevent hypoventilation by MOR agonists including ultra-potent fentanyl analogs that have a long duration of action. Significance Statement The number of opioid overdose deaths increased over the past decade despite the availability of antagonists that can prevent and reverse the effects of opioids. This study demonstrates the effectiveness and long duration of action of the µ-opioid receptor (MOR) antagonist methocinnamox (MCAM) for reversing and preventing hypoventilation by MOR agonists including ultra-potent fentanyl analogs. These results provide support for the notion that MCAM has the potential to positively impact the ongoing opioid crisis by reversing and preventing opioid overdose.

NCP, a dual kappa and mu opioid receptor agonist, is a potent analgesic against inflammatory pain without reinforcing or aversive properties.

While agonists of mu (MOR) and kappa (KOR) opioid receptors have analgesic effects, they produce euphoria and dysphoria, respectively. Other side effects include respiratory depression and addiction for MOR agonists and sedation for KOR agonists. We reported that 17-cyclopropylmethyl-3,14ß-dihydroxy-4,5α-epoxy-6ß-{[4'-(2'-cyanopyridyl)]carboxamido}cmorphinan (NCP) displayed potent KOR full agonist and MOR partial agonist activities (58%) with 6.5x KOR-over-MOR selectivity in vitro Herein, we characterized pharmacological effects of NCP in rodents. In mice, NCP exerted analgesic effects against inflammatory pain in both the formalin test and the acetic acid writhing test, with A50 values of 47.6 and 14.4 microg/kg (s.c.), respectively. The analgesic effects in the acetic acid writhing test were mediated by the KOR. NCP at doses much higher than those effective in reducing inflammatory pain did not produce antinociception in the hot plate and tail flick tests, inhibit compound 48/80-induced scratching, cause conditioned place aversion (CPA) or preference, impair rotarod performance, inhibit locomotor activity, cause respiratory depression, or precipitate morphine withdrawal. However, NCP (10~100 microg/kg) inhibited gastrointestinal transit with a maximum of ~40% inhibition. In MOR knockout mice, NCP caused CPA, demonstrating that its lack of CPA is due to combined actions on the MOR and KOR. Following s.c. injection, NCP penetrated into the mouse brain. In rats trained to self-administer heroin, NCP (1~320 microg/kg/infusion) did not function as a reinforcer. Thus, NCP produces potent analgesic effects via KOR without side effects except constipation. Therefore, dual full KOR/partial MOR agonists with moderate KOR-over-MOR selectivity may be promising as non-addictive analgesics for inflammatory pain. Significance Statement Developing non-addictive analgesics is crucial for reducing opioid overdose deaths, minimizing drug misuse, and promoting safer pain management practices. Herein, pharmacology of a potential non-addictive analgesic, NCP, is reported. NCP has full KOR agonist / partial MOR agonist activities with a 6.5 x selectivity for KOR over MOR. Unlike MOR agonists, analgesic doses of NCP do not lead to self-administration or respiratory depression. Furthermore, NCP does not produce aversion, hypolocomotion, or motor incoordination, side effects typically associated with KOR activation.

The effects of eating a traditional high fat/high carbohydrate or a ketogenic diet on sensitivity of female rats to morphine.

Patients diagnosed with obesity are prescribed opioid medications at a higher rate than the general population; however, it is not known if eating a high fat diet might impact individual sensitivity to these medications. To explore the hypothesis that eating a high fat diet increases sensitivity of rats to the effects of morphine, 24 female Sprague-Dawley rats (n=8/diet) ate either a standard laboratory chow (17% kcal from fat), a high fat/low carbohydrate (ketogenic) chow (90.5% kcal from fat), or a traditional high fat/high carbohydrate chow (60% kcal from fat). Morphine-induced antinociception was assessed using a warm water tail withdrawal procedure, during which latency (in seconds) for rats to remove their tail from warm water baths was recorded following saline or morphine (0.32-56 mg/kg, IP) injections. Morphine was administered acutely and chronically, which involved 19 days of twice daily injections (increasing in 1/4 log dose increments every 3 days: 3.2-56 mg/kg, IP) to induce dependence and assess tolerance. The adverse effects of morphine (i.e., tolerance, withdrawal, changes in body temperature) were assessed throughout the study. Morphine induced comparable antinociception in rats eating different diets, and all rats developed tolerance following chronic morphine exposure. Additional adverse effects of morphine were also comparable among rats eating different diets; however, withdrawal-induced weight loss was less severe for rats eating ketogenic chow. These results suggest that dietary manipulation might modulate the severity of withdrawal-related weight loss, in ways that could be relevant for patients. Significance Statement The present study in female rats suggests that eating a high fat/low carbohydrate (ketogenic) or a traditional high fat/high carbohydrate diet does not impact the pain-relieving or adverse effects of opioids (i.e., tolerance or withdrawal). However, eating a ketogenic diet may have beneficial effects on opioid withdrawal-related weight loss. Individuals diagnosed with obesity taking opioids for pain-related conditions might therefore consider adopting a ketogenic diet when opioid administration is discontinued to potentially mitigate withdrawal-related weight loss.

Low-Efficacy Mu Opioid Agonists as Candidate Analgesics: Effects of Novel C-9 Substituted Phenylmorphans on Pain-Depressed Behavior in Mice.

Low efficacy mu opioid receptor (MOR) agonists may serve as novel candidate analgesics with improved safety relative to high-efficacy opioids. This study used a recently validated assay of pain-depressed behavior in mice to evaluate a novel series of MOR-selective C9-substituted phenylmorphan opioids with graded MOR efficacies. Intraperitoneal injection of dilute lactic acid (IP acid) served as a noxious stimulus to depress locomotor activity by mice in an activity chamber composed of two compartments connected by an obstructed door. Behavioral measures included (1) crosses between compartments (vertical activity over the obstruction) and (2) movement counts quantified as photobeam breaks summed across compartments (horizontal activity). Each drug was tested alone and as a pretreatment to IP acid. A charcoal-meal test and whole-body-plethysmography assessment of breathing in 5% CO2 were also used to assess gastrointestinal (GI) inhibition and respiratory depression, respectively. IP acid produced a concentration-dependent depression in crosses and movement that was optimally alleviated by intermediate- to low-efficacy phenylmorphans with sufficient efficacy to produce analgesia with minimal locomotor disruption. Follow-up studies with two low-efficacy phenylmorphans (JL-2-39 and DC-1-76.1) indicated that both drugs produced naltrexone-reversible antinociception with a rapid onset and a duration of ~1hr. Potency of both drugs increased when behavior was depressed by a lower IP-acid concentration, and neither drug alleviated behavioral depression by a non-pain stimulus (IP lithium chloride). Both drugs produced weaker GI inhibition and respiratory depression than fentanyl and attenuated fentanyl-induced GI inhibition and respiratory depression. Results support further consideration of selective, low-efficacy MOR agonists as candidate analgesics. Significance Statement This study used a novel set of mu opioid receptor (MOR)-selective opioids with graded MOR efficacies to examine the lower boundary of MOR efficacy sufficient to relieve pain-related behavioral depression in mice. Two novel low-efficacy opioids (JL-2-39, DC-1-76.1) produced effective antinociception with improved safety relative to higher- or lower-efficacy opioids, and results support further consideration of these and other low-efficacy opioids as candidate analgesics.

Photo-affinity and Metabolic Labeling Probes Based on the Opioid Alkaloids.

The opioids are powerful analgesics yet possess contingencies that can lead to opioid-use disorder. Chemical probes derived from the opioid alkaloids can provide deeper insight into the molecular interactions in a cellular context. Here, we designed and developed photo-click morphine (PCM-2) as a photo-affinity probe based on morphine and dialkynyl-acetyl morphine (DAAM) as a metabolic acetate reporter based on heroin. Application of these probes to SH-SY5Y, HEK293T, and U2OS cells revealed that PCM-2 and DAAM primarily localize to the lysosome amongst other locations inside the cell by confocal microscopy and chemical proteomics. Interaction site identification by mass spectrometry revealed the mitochondrial phosphate carrier protein, solute carrier family 25 member 3, SLC25A3, and histone H2B as acylation targets of DAAM. These data illustrate the utility of chemical probes to measure localization and protein interactions in a cellular context and will inform the design of probes based on the opioids in the future.

Prenatal Opioid Exposure and Risk for Adverse Brain and Motor Outcomes in Infants Born Premature.

OBJECTIVE: To compare brain magnetic resonance imaging (MRI) biomarkers and neurodevelopmental test scores in infants born preterm with and without prenatal opioid exposure (POE). STUDY DESIGN: We examined 395 preterm infants (≤32 weeks gestational age) who had term-equivalent brain MRIs, composite scores from the Bayley Scales of Infant and Toddler Development-III at 2 years corrected age, and POE data. MRI parameters included total/regional brain volumes and severe punctate white matter lesions (PWMLs). We conducted bivariable analysis and multivariable logistic regression analyses. RESULTS: The mean ± SD gestational age was 29.3 ± 2.5 weeks; 35 (8.9%) had POE and 20 (5.1%) had severe PWML. Compared with unexposed infants, those with POE exhibited higher rates of severe PWML (17.1% vs 3.9%, respectively; P = .002); findings remained significant with an OR of 4.16 (95% CI, 1.26-13.68) after adjusting for confounders. On mediation analysis, the significant relationship between POE and severe PWML was not indirectly mediated through preterm birth/gestational age (OR, 0.93; 95% CI, 0.78-1.10), thus suggesting the association was largely driven by a direct adverse effect of POE on white matter. In multivariable analyses, POE was associated with a significantly lower score by -6.2 (95% CI, -11.8 to -0.6) points on the Bayley Scales of Infant and Toddler Development-III Motor subscale compared with unexposed infants. CONCLUSIONS: POE was associated with severe PWML; this outcome may be a direct effect of POE rather than being mediated by premature birth. POE was also associated with worse motor development. Continued follow-up to understand the long-term effects of POE is warranted.

Long-term Health Outcomes of New Persistent Opioid Use After Gastrointestinal Cancer Surgery.

BACKGROUND: New persistent opioid use (NPOU) after surgery has been identified as a common complication. This study sought to assess the long-term health outcomes among patients who experienced NPOU after gastrointestinal (GI) cancer surgery. METHODS: Patients who underwent surgery for hepato-pancreato-biliary and colorectal cancer between 2007 and 2019 were identified using the Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked database. Mixed-effect multivariable logistic regression and Cox proportional hazard models were used to estimate the risk of mortality and hospital visits related to falls, respiratory events, or pain symptoms. RESULTS: Among 15,456 patients who underwent GI cancer surgery, 967(6.6%) experienced NPOU. Notably, the patients at risk for the development of NPOU were those with a history of substance abuse (odds ratio [OR], 1.45; 95% confidence interval [CI], 1.14-1.84), moderate social vulnerability (OR, 1.26; 95% CI, 1.06-1.50), an advanced disease stage (OR, 4.42; 95% CI, 3.51-5.82), or perioperative opioid use (OR, 3.07; 95% CI, 2.59-3.63. After control for competing risk factors, patients who experienced NPOU were more likely to visit a hospital for falls, respiratory events, or pain symptoms (OR, 1.45, 95% CI 1.18-1.78). Moreover, patients who experienced NPOU had a greater risk of death at 1 year (hazard ratio [HR], 2.15; 95% CI, 1.74-2.66). CONCLUSION: Approximately 1 in 15 patients experienced NPOU after GI cancer surgery. NPOU was associated with an increased risk of subsequent hospital visits and higher mortality. Targeted interventions for individuals at higher risk for NPOU after surgery should be used to help mitigate the harmful effects of NPOU.

Hospitalization, Overdose, and Mortality After Opioid Prescriptions Tied to Ophthalmic Surgery.

PURPOSE: Opioid prescriptions continue to carry significant short- and long-term systemic risks, even after ophthalmic surgery. The goal of this study was to identify any association of opioid prescription, after ophthalmic surgery, with postoperative hospitalization, opioid overdose, opioid dependence, and all-cause mortality. DESIGN: Retrospective, cross-sectional analysis. PARTICIPANTS: Patients undergoing an ophthalmic surgery in the OptumLabs Data Warehouse. METHODS: We used deidentified administrative claims data from the OptumLabs Data Warehouse to create 3 cohorts of patients for analysis from January 1, 2016, to June 30, 2022. The first cohort consisted of 1-to-1 propensity score-matched patients who had undergone ophthalmic surgery and had filled a prescription for an opioid and not filled a prescription for an opioid. The second cohort consisted of patients who were considered opioid naïve and had filled a prescription for an opioid matched to patients who had not filled a prescription for an opioid. The last cohort consisted of opioid-naïve patients matched across the following morphine milligram equivalents (MME) groups: ≤ 40, 41-80, and > 80. MAIN OUTCOME MEASURES: Short- and long-term risks of hospitalization, opioid overdose, opioid dependency/abuse, and death were compared between the cohorts. RESULTS: We identified 1 577 692 patients who had undergone an ophthalmic surgery, with 312 580 (20%) filling an opioid prescription. Among all patients, filling an opioid prescription after an ophthalmic surgery was associated with increased mortality (hazard rate [HR], 1.28; 95% confidence interval [CI], 1.25-1.31; P < 0.001), hospitalization (HR, 1.51; 95% CI, 1.49-1.53; P < 0.001), opioid overdose (HR, 7.31; 95% CI, 6.20-8.61, P < 0.001), and opioid dependency (HR, 13.05; 95% CI, 11.48-14.84; P < 0.001) compared with no opioid prescription. Furthermore, we found that higher MME doses of opioids were associated with higher rates of mortality, hospitalization, and abuse/dependence. CONCLUSIONS: Patients who filled an opioid prescription after an ophthalmic surgery experienced higher rates of mortality, hospitalization, episodes of opioid overdose, and opioid dependence compared with patients who did not fill an opioid prescription. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Epidural administration of large dose of opioid µ receptor agonist may impair cardiac functions and myocardial viability via desensitizing transient receptor potential vanilloid 1.

The incidence of postoperative myocardial injury remains high as the underlying pathogenesis is still unknown. The dorsal root ganglion (DRG) neurons express transient receptor potential vanilloid 1 (TRPV1) and its downstream effector, calcitonin gene-related peptide (CGRP) participating in transmitting pain signals and cardiac protection. Opioids remain a mainstay therapeutic option for moderate-to-severe pain relief clinically, as a critical component of multimodal postoperative analgesia via intravenous and epidural delivery. Evidence indicates the interaction of opioids and TRPV1 activities in DRG neurons. Here, we verify the potential impairment of myocardial viability by epidural usage of opioids in postoperative analgesia. We found that large dose of epidural morphine (50 µg) significantly worsened the cardiac performance (+dP/dtmax reduction by 11% and -dP/dtmax elevation by 24%, all P < 0.001), the myocardial infarct size (morphine vs Control, 0.54 ± 0.09 IS/AAR vs. 0.23 ± 0.06 IS/AAR, P < 0.001) and reduced CGRP in the myocardium (morphine vs. Control, 9.34 ± 2.24 pg/mg vs. 21.23 ± 4.32 pg/mg, P < 0.001), while induced definite suppression of nociception in the postoperative animals. It was demonstrated that activation of µ-opioid receptor (µ-OPR) induced desensitization of TRPV1 by attenuating phosphorylation of the channel in the dorsal root ganglion neurons, via inhibiting the accumulation of cAMP. CGRP may attenuated the buildup of ROS and the reduction of mitochondrial membrane potential in cardiomyocytes induced by hypoxia/reoxygenation. The findings of this study indicate that epidurally giving large dose of µ-OPR agonist may aggravate myocardial injury by inhibiting the activity of TRPV1/CGRP pathway.

Assessing Substance Use Disorder Symptoms with a Checklist among Primary Care Patients with Opioid Use Disorder and/or Long-Term Opioid Treatment: An Observational Study.

BACKGROUND: Primary care (PC) offers an opportunity to treat opioid use disorders (OUD). The Substance Use Symptom Checklist ("Checklist") can assess DSM-5 substance use disorder (SUD) symptoms in PC. OBJECTIVE: To test the psychometric properties of the Checklist among PC patients with OUD or long-term opioid therapy (LTOT) in Kaiser Permanente Washington (KPWA). DESIGN: Observational study using item response theory (IRT) and differential item functioning (DIF) analyses of measurement consistency across age, sex, race and ethnicity, and receipt of treatment. PATIENTS: Electronic health records (EHR) data were extracted for all adult PC patients visiting KPWA 3/1/15-8/30/2020 who had ≥ 1 Checklist documented and indication of either (a) clinically-recognized OUD (i.e., documented OUD diagnosis and/or OUD medication treatment) or (b) LTOT in the year prior to the checklist. MAIN MEASURE: The Checklist includes 11 items reflecting DSM-5 criteria for SUD. We described the prevalence of 2 SUD symptoms reported on the Checklist (consistent with mild-severe DSM-5 SUD). Analyses were conducted in the overall sample and in two subsamples (clinically-recognized OUD and LTOT only). KEY RESULTS: Among 2007 eligible patients, 39.9% endorsed ≥ 2 SUD symptoms (74.3% in the clinically-recognized OUD subsample and 13.1% in LTOT subsample). IRT indicated that a unidimensional model for the 11 checklist items had excellent fit (comparative fit index = 0.998) with high item-level discrimination parameters for the overall sample and both subsamples. DIF across age, race and ethnicity, and treatment was observed for one item each, but had minimal impact on expected number of criteria (0-11) patients endorse. CONCLUSIONS: The Substance Use Symptom Checklist measured SUD symptoms consistent with DSM-5 conceptualization (scaled, unidimensional) in patients with clinically-recognized OUD and LTOT and had similar measurement properties across demographic subgroups. The Checklist may support symptom assessment in patients with OUD and diagnosis in patients with LTOT.