Combined in vivo metabolic effects of quetiapine and methadone in brain and blood of rats.

Changes in pharmacokinetics and endogenous metabolites may underlie additive biological effects of concomitant use of antipsychotics and opioids. In this study, we employed untargeted metabolomics analysis and targeted analysis to examine the changes in drug metabolites and endogenous metabolites in the prefrontal cortex (PFC), midbrain, and blood of rats following acute co-administration of quetiapine and methadone. Rats were divided into four groups and received cumulative increasing doses of quetiapine (QTP), methadone (MTD), quetiapine + methadone (QTP + MTD), or vehicle (control). All samples were analyzed using liquid chromatography-mass spectrometry (LC-MS). Our findings revealed increased levels of the quetiapine metabolites: Norquetiapine, O-dealkylquetiapine, 7-hydroxyquetiapine, and quetiapine sulfoxide, in the blood and brain when methadone was present. Our study also demonstrated a decrease in methadone and its metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in the rat brain when quetiapine was present. Despite these findings, there were only small differences in the levels of 225-296 measured endogenous metabolites due to co-administration compared to single administrations. For example, N-methylglutamic acid, glutaric acid, p-hydroxyphenyllactic acid, and corticosterone levels were significantly decreased in the brain of rats treated with both compounds. Accumulation of serotonin in the midbrain was additionally observed in the MTD group, but not in the QTP + MTD group. In conclusion, this study in rats suggests a few but important additive metabolic effects when quetiapine and methadone are co-administered.

Distribution of morphine and methadone to the brain in a developmental chicken embryo model.

The use and/or misuse of opioids by pregnant women would expose the fetuses to these drugs during critical stages of development with serious effects for the newborn, like the neonatal abstinence syndrome (NAS). We have revisited an established chicken model for NAS to describe the distribution of morphine and methadone to the brain and explore its validity as a valuable alternative to rodent models. For this purpose, chicken eggs were injected with a single dose of 10 mg/kg or 20 mg/kg morphine or 20 mg/kg methadone onto the chorioallantoic membrane (CAM) on embryonal day 13. Whole brains and lungs were harvested and the concentrations of morphine, methadone and their subsequent metabolites (morphine-3-glucuronide and EDDP, respectively) determined in the brain and lungs at different time points using LC-MS/MS. Morphine and methadone, as well as their metabolites, were detected both in the brain and lungs, with significantly higher concentrations in the lungs. Pharmacokinetic modelling showed that the distribution of morphine to the brain followed a first-order absorption with transit compartments and linear elimination, with concentrations linearly dependent on dose. Moreover, methadone, but not morphine, reduced µ receptor (the main morphine receptor) binding, which can be of relevance for opioid tolerance. The present study is the first to report the brain distribution of morphine, which can be described by standard pharmacokinetic processes, and methadone in the developing chicken embryo. The present findings supplement the already established model and support the use of this chicken model to study NAS.

Chronic exposure to methadone induces activated microglia and astrocyte and cell death in the cerebellum of adult male rats.

Methadone is a centrally-acting synthetic opioid analgesic widely used in the methadone maintenance therapy (MMT) programs throughout the world. Considering its neurotoxic effects particularly on the cerebellum, this study aims to address the behavioral and histological alterations in the cerebellar cortex associated with methadone administration. Twenty-four adult male albino rats were randomized into two groups of control and methadone treatment. Methadone was subcutaneously administered (2.5-10 mg/kg) once a day for two consecutive weeks. The functional and structural changes in the cerebellum were compared to the control group. Our data revealed that treating rats with methadone not only induced cerebellar atrophy, but also prompted the actuation of microgliosis, astrogliosis, and apoptotic biomarkers. We further demonstrated that treating rats with methadone increased complexity of astrocyte processes and decreased complexity of microglia processes. Our result showed that methadone impaired motor coordination and locomotor performance and neuromuscular activity. Additionally, relative gene expression of TNF-α, caspase-3 and RIPK3 increased significantly due to methadone. Our findings suggest that methadone administration has a neurodegenerative effect on the cerebellar cortex via dysregulation of microgliosis, astrogliosis, apoptosis, and neuro-inflammation.

Chronic exposure to methadone impairs memory, induces microgliosis, astrogliosis and neuroinflammation in the hippocampus of adult male rats.

Methadone is a centrally-acting synthetic opioid analgesic widely used in methadone maintenance therapy (MMT) programs throughout the world. Given its neurotoxic effects, particularly on the hippocampus, this study aims to address the behavioral and histological alterations in the hippocampus associated with methadone administration. To do so, twenty-four adult male albino rats were randomized into two groups, methadone treatment and control. Methadone was administered subcutaneously (2.5-10 mg/kg) once a day for two consecutive weeks. A comparison was drawn with behavioral and structural changes recorded in the control group. The results showed that methadone administration interrupted spatial learning and memory function. Accordingly, treating rats with methadone not only induced cell death but also prompted the actuation of microgliosis, astrogliosis, and apoptotic biomarkers. Furthermore, the results demonstrated that treating rats with methadone decreased the complexity of astrocyte processes and the complexity of microglia processes. These findings suggest that methadone altered the special distribution of neurons. Also, a substantial increase was observed in the expression of TNF-α due to methadone. According to the findings, methadone administration exerts a neurodegenerative effect on the hippocampus via dysregulation of microgliosis, astrogliosis, apoptosis, and neuro-inflammation.

In vitro-in silico-based prediction of inter-individual and inter-ethnic variations in the dose-dependent cardiotoxicity of R- and S-methadone in humans.

New approach methodologies predicting human cardiotoxicity are of interest to support or even replace in vivo-based drug safety testing. The present study presents an in vitro-in silico approach to predict the effect of inter-individual and inter-ethnic kinetic variations in the cardiotoxicity of R- and S-methadone in the Caucasian and the Chinese population. In vitro cardiotoxicity data, and metabolic data obtained from two approaches, using either individual human liver microsomes or recombinant cytochrome P450 enzymes (rCYPs), were integrated with physiologically based kinetic (PBK) models and Monte Carlo simulations to predict inter-individual and inter-ethnic variations in methadone-induced cardiotoxicity. Chemical specific adjustment factors were defined and used to derive dose-response curves for the sensitive individuals. Our simulations indicated that Chinese are more sensitive towards methadone-induced cardiotoxicity with Margin of Safety values being generally two-fold lower than those for Caucasians for both methadone enantiomers. Individual PBK models using microsomes and PBK models using rCYPs combined with Monte Carlo simulations predicted similar inter-individual and inter-ethnic variations in methadone-induced cardiotoxicity. The present study illustrates how inter-individual and inter-ethnic variations in cardiotoxicity can be predicted by combining in vitro toxicity and metabolic data, PBK modelling and Monte Carlo simulations. The novel methodology can be used to enhance cardiac safety evaluations and risk assessment of chemicals.

Is high sensitive-troponin I a reliable biomarker for cardiac injury in methadone toxicity? A prospective cross-sectional study.

BACKGROUND: Methadone is a synthetic opioid mostly used for detoxification therapy, as its use increases; the possibility for methadone-induced cardiotoxicity may rise. The aim of this study was to determine the association of high-sensitivity troponin I levels as a predictor of cardiac injury in methadone toxicity. METHODS: Sixty methadone toxicity patients included in this prospective cross-sectional study from October 2018-November 2020. High-sensitivity troponin I level and electrocardiogram were assessed in patients at admission. All patients underwent echocardiography at admission and 30 days later and compared this finding between two groups based on high-sensitivity troponin I results. RESULTS: Mean age of the patients was 34.5 ± 11.1 years (males: 67%). Twenty (20%) patients had positive high sensitive-troponin results. Long QT interval and inverted T in precordial leads were mostly observed in individuals with positive high-sensitivity troponin I (75% vs. 35%, P = 0.013 and 83% vs. 16%, P < 0.001, respectively). Patients with elevated troponin had reduced left ventricular ejection fraction in comparison to normal group during admission (43.1 ± 15.4% vs. 55%, P < 0.001) and this left ventricular ejection fraction remained abnormal after 30 days (43.7 ± 21.6%). Patients in positive high-sensitivity troponin I group had higher regional wall motion abnormality frequency both at admission and 30 days later compared to the other group (0 day: 42% vs. 0, P < 0.001, 30th days: 25% vs. 4%, P = 0.020). CONCLUSION: Patients with simultaneous methadone toxicity and positive high-sensitivity troponin I had worse cardiac outcomes and this biomarker could be probably used for better implementation of therapeutic interventions and prognosis.

Time-Dependent Changes in the Serum Levels of Neurobiochemical Factors After Acute Methadone Overdose in Adolescent Male Rat.

Acute methadone toxicity is a major public health concern which has adverse effects on brain tissue and results in recurrent or delayed respiratory arrest. Our study aimed to investigate the time-dependent changes in several serum biochemical markers of brain damage, spatial working memory, and the brain tissue following acute methadone overdose. Adolescent male rats underwent an intraperitoneal (i.p.) injection of 15 mg/kg methadone. In case of apnea occurrence, resuscitation was performed by a ventilatory pump and administrating naloxone (2 mg/kg; i.p.). The animals were classified into groups of treated rats; methadone and naloxone-Apnea (M/N-Apnea), M/N-Sedate, Methadone, Naloxone, and control (saline) groups. The serum levels of S100B, neuron-specific enolase (NSE), myelin basic protein factors, and (Lactate/Pyruvate) L/P ratio were evaluated at the time-points of 6, 24, and 48 h (h). We found that the alterations of S100B and L/P ratio were considerable in the M/N-Apnea and Methadone groups from the early hours post-methadone overdose, while NSE serum levels elevation was observed only in M/N-Apnea group with a delay at 48 h. Further, we assessed the spatial working memory (Y-maze test), morphological changes, and neuronal loss. The impaired spontaneous alternation behavior was detected in the M/N-Apnea groups on days 5 and 10 post-methadone overdose. The morphological changes of neurons and the neuronal loss were detectable in the CA1, striatum, and cerebellum regions, which were pronounced in both M/N-Apnea and Methadone groups. Together, our findings suggest that alterations in the serum levels of S100B and NSE factors as well as L/P ratio could be induced by methadone overdose with the presence or absence of apnea before the memory impairment and tissue injury in adolescent male rats.

Suppressor capacity of copper nanoparticles biosynthesized using Crocus sativus L. leaf aqueous extract on methadone-induced cell death in adrenal phaeochromocytoma (PC12) cell line.

In this research, we prepared and formulated a neuroprotective supplement (copper nanoparticles in aqueous medium utilizing Crocus sativus L. Leaf aqueous extract) for determining its potential against methadone-induced cell death in PC12. The results of chemical characterization tests i.e., FE-SEM, FT-IR, XRD, EDX, TEM, and UV-Vis spectroscopy revealed that the study showed that copper nanoparticles were synthesized in the perfect way possible. In the TEM and FE-SEM images, the copper nanoparticles were in the mean size of 27.5 nm with the spherical shape. In the biological part of the present research, the Rat inflammatory cytokine assay kit was used to measure the concentrations of inflammatory cytokines. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) test was used to show DNA fragmentation and apoptosis. Caspase-3 activity was assessed by the caspase activity colorimetric assay kit and mitochondrial membrane potential was studied by Rhodamine123 fluorescence dye. Also, the cell viability of PC12 was measured by trypan blue assay. Copper nanoparticles-treated cell cutlers significantly (p ≤ 0.01) decreased the inflammatory cytokines concentrations, caspase-3 activity, and DNA fragmentation and they raised the cell viability and mitochondrial membrane potential in the high concentration of methadone-treated PC12 cells. The best result of neuroprotective properties was seen in the high dose of copper nanoparticles i.e., 4 µg. According to the above results, copper nanoparticles containing C. sativus leaf aqueous extract can be used in peripheral nervous system treatment as a neuroprotective promoter and central nervous system after approving in the clinical trial studies in humans.

Integrating in vitro data and physiologically based kinetic modeling-facilitated reverse dosimetry to predict human cardiotoxicity of methadone.

Development of novel testing strategies to detect adverse human health effects is of interest to replace in vivo-based drug and chemical safety testing. The aim of the present study was to investigate whether physiologically based kinetic (PBK) modeling-facilitated conversion of in vitro toxicity data is an adequate approach to predict in vivo cardiotoxicity in humans. To enable evaluation of predictions made, methadone was selected as the model compound, being a compound for which data on both kinetics and cardiotoxicity in humans are available. A PBK model for methadone in humans was developed and evaluated against available kinetic data presenting an adequate match. Use of the developed PBK model to convert concentration-response curves for the effect of methadone on human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) in the so-called multi electrode array (MEA) assay resulted in predictions for in vivo dose-response curves for methadone-induced cardiotoxicity that matched the available in vivo data. The results also revealed differences in protein plasma binding of methadone to be a potential factor underlying variation between individuals with respect to sensitivity towards the cardiotoxic effects of methadone. The present study provides a proof-of-principle of using PBK modeling-based reverse dosimetry of in vitro data for the prediction of cardiotoxicity in humans, providing a novel testing strategy in cardiac safety studies.

Methadone-induced encephalopathy: a case series and literature review.

BACKGROUND: Accidental ingestion or consumption of supra-therapeutic doses of methadone can result in neurological sequelae in humans. We aimed to determine the neurological deficits of methadone-poisoned patients admitted to a referral poisoning hospital using brain magnetic resonance (MR) and diffusion weighted (DW) imaging. METHODS: In this retrospective study, brain MRIs of the patients admitted to our referral center due to methadone intoxication were reviewed. Methadone intoxication was confirmed based on history, congruent clinical presentation, and confirmatory urine analysis. Each patient had an MRI with Echo planar T1, T2, FLAIR, and DWI and apparent deficient coefficient (ADC) sequences without contrast media. Abnormalities were recorded and categorized based on their anatomic location and sequence. RESULTS: Ten patients with abnormal MRI findings were identified. Eight had acute- and two had delayed-onset encephalopathy. Imaging findings included bilateral confluent or patchy T2 and FLAIR high signal intensity in cerebral white matter, cerebellar involvement, and bilateral occipito-parietal cortex diffusion restriction in DWI. Internal capsule involvement was identified in two patients while abnormality in globus pallidus and head of caudate nuclei were reported in another. Bilateral cerebral symmetrical confluent white matter signal abnormality with sparing of subcortical U-fibers on T2 and FLAIR sequences were observed in both patients with delayed-onset encephalopathy. CONCLUSIONS: Acute- and delayed-onset encephalopathies are two rare adverse events detected in methadone-intoxicated patients. Brain MRI findings can be helpful in detection of methadone-induced encephalopathy.

ABCB1, CYP2B6, and CYP3A4 genetic polymorphisms do not affect methadone maintenance treatment in HCV-positive patients.

The aim of this study was to determine the influence of ABCB1, CYP2B6, and CYP3A4 genetic polymorphisms on methadone metabolism in patients with hepatitis C virus (HCV) undergoing methadone maintenance treatment (MMT). The study included 35 participants undergoing MMT, who were divided in three groups: HCV-positive (N=12), HCV-negative (N=16), and HCV clinical remission (CR) (N=7). The concentrations of methadone and its main metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) were determined with gas chromatography-mass spectrometry. The patients were genotyped for ABCB1 rs1045642, CYP2B6 rs3745274, CYP3A4 rs2242480, and CYP3A4 rs2740574 polymorphisms. Differences between single nucleotide polymorphism (SNP) genotypes and methadone-to-EDDP ratio were analysed with one-way ANOVA, which showed no significant difference between the genes (p=0.3772 for ABCB1 rs1045642, p=0.6909 for CYP2B6 rs3745274, and p=0.6533 for CYP3A4 rs2242480). None of the four analysed SNP genotypes correlated with methadone-to-EDDP concentration ratio. A major influence on it in hepatitis C-positive patients turned out to be the stage of liver damage.

Diverse changes in myelin protein expression in rat brain after perinatal methadone exposure.

The national incidence of neonatal abstinence syndrome has dramatically increased over the last decade due to an increase in antenatal opioid exposure. Recent human and animal studies suggest that antenatal opioid exposure impacts the developing brain. The purpose of this study is to evaluate the effects of perinatal methadone exposure on myelination in multiple regions in the developing rat brain. Pregnant Sprague-Dawley rats were randomly assigned into three experimental groups and subsequently exposed to drinking water alone or drinking water containing methadone from 7 days post coitum through day 7 or through day 19 after delivery. Two male neonatal rats were randomly selected from each litter and terminated at day 19. The cerebral cortex, hippocampus, cerebellum, and brainstem were dissected and analyzed for three myelin specific proteins - CNP, PLP, and MBP - by Western blot analysis. All pups with exposure to methadone demonstrated decreased expression of CNP, PLP, and MBP in the cerebral cortex and hippocampus. In the cerebellum, PLP expression was down­regulated without apparent alteration of CNP and MBP expression. PLP and MBP expression, but not CNP expression, were significantly inhibited in the brainstem. Compared to the pups with postnatal methadone exposure via maternal milk through day 7, partial recovery of CNP and PLP expression only occurred in the cerebral cortices of the pups exposed through day 19. The findings show that antenatal opioid exposure in rat pups is associated with regionally­specific alterations in brain myelination that diversely affects myelin proteins.

Biodegradation study of methadone by adapted activated sludge: Elimination kinetics, transformation products and ecotoxicological evaluation.

The biotransformation study of difficult-to-degrade opioid analgesic methadone (MTHD) was performed by activated sludge culture adapted to high concentration of methadone (10 mg/L). The study included determination of elimination kinetics of the parent compound, taxonomic characterization of microbial culture, identification of biotransformation products (TPs) and assessment of ecotoxicological effects of biotransformation processes. The chemical analyses were performed by ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry, whereas the ecotoxicological assessment was made based on determinations of toxicity to freshwater algae. Changes of the adapted sludge culture during the experiment were followed using the 16S rRNA gene amplicon sequencing. Depending on the experimental conditions, the elimination efficiency of methadone (10 mg/L) varied from 9% to 93% with the corresponding half-lives from 11.4 days to 1.5 days. A significantly faster elimination (t1/2 from 1.5 days to 5.8 days) was achieved at cometabolic conditions, using glucose-containing media, as compared to the experiments with MTHD as a single organic carbon source (t1/2 = 11.4 days). Moreover, increased biotransformation rate following the additional supplementation of ammonia, revealed a possible importance of nitrogen availability for the transformation at cometabolic conditions. The elimination of parent compound was associated with the formation of 3 different TPs, two of which were identical to main human metabolites of MTHD, 2-Ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline (EMDP). EDDP represented over 90% of the total TP concentration at the end of experiment. The biodegradation of MTHD was associated with a pronounced drop in algal toxicity, confirming a rather positive ecotoxicological outcome of the achieved biotransformation processes.

The Protective and Restorative Effects of Growth Hormone and Insulin-Like Growth Factor-1 on Methadone-Induced Toxicity In Vitro.

Evidence to date suggests that opioids such as methadone may be associated with cognitive impairment. Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) are suggested to be neuroprotective and procognitive in the brain and may therefore counteract these effects. This study aims to explore the protective and restorative effects of GH and IGF-1 in methadone-treated cell cultures. Primary cortical cell cultures were harvested from rat fetuses and grown for seven days in vitro. To examine the protective effects, methadone was co-treated with or without GH or IGF-1 for three consecutive days. To examine the restorative effects, methadone was added for the first 24 h, washed, and later treated with GH or IGF-1 for 48 h. At the end of each experiment, mitochondrial function and membrane integrity were evaluated. The results revealed that GH had protective effects in the membrane integrity assay and that both GH and IGF-1 effectively recovered mitochondrial function and membrane integrity in cells pretreated with methadone. The overall conclusion of the present study is that GH, but not IGF-1, protects primary cortical cells against methadone-induced toxicity, and that both GH and IGF-1 have a restorative effect on cells pretreated with methadone.

Utilizing postmortem drug concentrations in mechanistic modeling and simulation of cardiac effects: a proof of concept study with methadone.

Methadone-related poisoning has been found to be the leading and increasing cause of death among intoxication cases in several countries. Aside from respiratory depression, methadone is known to cause QT-prolongation, which may lead to sudden cardiac death. Concentrations in heart tissue should be more accurate for estimating cardiotoxic effects. The aim of this study was to investigate whether the effect of methadone on the QT-interval could be simulated and whether the concentrations in heart tissues allowed for better prediction of the Bazett corrected QT-interval (QTcB). A predictive performance study was conducted using the simulation platform Cardiac Safety Simulator to mimic five literature studies using their described study conditions. Both free and total plasma and heart concentrations were investigated using two different in silico models: the O'Hara-Rudy (ORD) model and the 10 Tusscher (TNNP) model. The results showed that the QTcB of methadone was best predicted either with total plasma using the TNNP model or with free plasma using the ORD model. The ORD model was highly sensitive to the total heart concentrations, resulting in overprediction of the QTcB. The TNNP model also overpredicted the QTcB, but to a lesser degree than the ORD model. Furthermore, due to a low baseline QTcB, the ORD model underpredicted the QTcB for both the free plasma and free heart concentrations. In conclusion, it is possible to simulate the cardiac effects of methadone, yet several elements influence the approach uncertainty including but not limited to biophysically details model of cardiac electrophysiology, exposure data, and input parameters.

Suspected Methadone Toxicity: from Hospital to Autopsy Bed.

High mortality rates have been reported for methadone in both adults and children. We aimed to determine the pattern of toxicity, possible underlying diseases and treatment challenges in patients referred to our centre with early diagnosis of methadone toxicity and who later died. Medical files of all methadone-poisoned patients who had been admitted to a referral centre of toxicology between March 2011 and March 2016, died during the hospital stay and sent for autopsy to Legal Medicine Organization were retrospectively evaluated. In a total of 94 patients, autopsy findings and laboratory evaluations showed that cause of death was pure methadone toxicity in 57 (60.6%). Other causes of death were ischaemic heart disease in ten, co-ingestions (toxicities including methadone) in eight, brain haemorrhage, multi-organ failure and pneumosepsis (each in four), meningitis/encephalitis in three and head trauma and other toxicities (other than methadone but including an opioid, each in two) patients. Time of cardiopulmonary arrest was significantly different between those with pure methadone toxicity and those who died due to other causes (p = 0.01). Patients who had died due to co-ingestions and other toxicities were younger (p = 0.029) and took more bolus doses of naloxone (p = 0.042). In methadone users, especially in older ages and those with trivial response to naloxone administration, loss of consciousness should not be strictly attributed to methadone toxicity. In such patients, thorough evaluation for other possible causes of loss of consciousness is mandatory.

Growth hormone is protective against acute methadone-induced toxicity by modulating the NMDA receptor complex.

Human growth hormone (GH) displays promising protective effects in the central nervous system after damage caused by various insults. Current evidence suggests that these effects may involve N-methyl-d-aspartate (NMDA) receptor function, a receptor that also is believed to play a role in opioid-induced neurotoxicity. The aims of the present study were to examine the acute toxic effects of methadone, an opioid receptor agonist and NMDA receptor antagonist, as well as to evaluate the protective properties of recombinant human GH (rhGH) on methadone-induced toxicity. Primary cortical cell cultures from embryonic day 17 rats were grown for 7days in vitro. Cells were treated with methadone for 24h and the 50% lethal dose was calculated and later used for protection studies with rhGH. Cellular toxicity was determined by measuring mitochondrial activity, lactate dehydrogenase release, and caspase activation. Furthermore, the mRNA expression levels of NMDA receptor subunits were investigated following methadone and rhGH treatment using quantitative PCR (qPCR) analysis. A significant protective effect was observed with rhGH treatment on methadone-induced mitochondrial dysfunction and in methadone-induced LDH release. Furthermore, methadone significantly increased caspase-3 and -7 activation but rhGH was unable to inhibit this effect. The mRNA expression of the NMDA receptor subunit GluN1, GluN2a, and GluN2b increased following methadone treatment, as assessed by qPCR, and rhGH treatment effectively normalized this expression to control levels. We have demonstrated that rhGH can rescue cells from methadone-induced toxicity by maintaining mitochondrial function, cellular integrity, and NMDA receptor complex expression.

The ABCB1, rs9282564, AG and TT Genotypes and the COMT, rs4680, AA Genotype are Less Frequent in Deceased Patients with Opioid Addiction than in Living Patients with Opioid Addiction.

Sudden death due to acute intoxication occurs frequently in patients with opioid addiction (OA). To examine whether certain genotypes were associated with this, we examined the frequencies of 29 SNPs located in candidate genes related to opioid pharmacology: ABCB1, OPRM1, UGT2B7, CYP3A5, CYP2B6, CYP2C19, CYP2D6, COMT, KCNJ6 and SCN9A in 274 deceased patients with OA (DOA), 309 living patients with OA (LOA) and in 394 healthy volunteers (HV). The main hypothesis of the study was that subjects homozygous for the variant 3435T in ABCB1 (rs1045642) occur more frequently in DOA than in LOA and HV because morphine and methadone more readily cross the blood barrier in these subjects due to a lower efflux transporter activity of the ABCB1 (p-glycoprotein) transporter. Our results did not support this hypothesis, because no statistically significant difference (p = 0.506) in the frequency of the TT genotype of rs1045642 was observed between the DOA, LOA and HV cohorts. However, for another ABCB1 variant, rs9282564, we found that the frequencies of the AG and TT genotypes were 13, 21 and 25% in DOA, LOA and HV, respectively, and after correcting for age, sex and multiple testing, the differences between DOA and LOA were statistically significantly different (p = 0.027). The COMT rs4680 AA genotype frequencies were 25%, 35% and 31% in DOA, LOA and HV, respectively, and the difference between DOA and LOA was also statistically significant (p = 0.0028). In conclusion, this study generated two hypotheses suggesting possible associations of a reduced risk of death and carrying, respectively, the ABCB1 rs9282564 AG and TT genotypes and the COMT rs4680 AA genotype among patients with OA. These findings should be confirmed in independent cohorts, and if a causal relationship between these variants and fatal poisoning in OA is confirmed, then it may be possible at least in theory to personalize prevention of sudden death in this patient group.

Risk Factors for Mortality and Endotracheal Intubation after Methadone Intoxication.

This was a retrospective chart review to evaluate various risk factors associated with in-hospital mortality and intubation risk in acute methadone overdose. All patients admitted to an academic hospital in Tehran, Iran, during a 10-year period (2000-2009) constituted the study sample. Exclusion criteria were significant comorbidities and age under 18 years. Outcome variables were in-hospital mortality and being intubated during admission. A total of 802 patients were enrolled in the study. There were 15 (1.8%) deaths due to methadone overdose or its complications. The number of yearly admissions was 15 patients in 2000, 16 in 2001, 16 in 2002, 18 in 2003, 23 in 2004, 38 in 2005, 59 in 2006, 110 in 2007, 206 in 2008 and 301 in 2009. Based on logistic regression analysis, the most important independent variable predicting mortality was length of admission in toxicology ward [OR (95% CI): 1.6 (1.1-2.3)]. For the prediction of intubation, independent variables were Glasgow Coma Scale (GCS) score of 5-9 [OR (95% CI): 356.5 (9.8-12907.4)] in the emergency department (ED), miosis in the ED [356.9 (1.4-87872.5)] and respiratory rate in the ED [1.5 (1.1-2.1)]. Linear regression model for length of hospitalization showed patient age as the most important variable for prediction of this outcome. Despite a relatively low mortality rate, the increasing number of methadone-poisoned patients requires special attention to this common intoxication. Careful disposition of patients from ED to ordinary wards or intensive care units and also from higher to lower levels of care should be considered in methadone overdose.