Risk to heroin users of polydrug use of pregabalin or gabapentin

Gabapentinoids Increase the Potency of Fentanyl and Heroin and Decrease the Potency of Naloxone to Antagonize Fentanyl and Heroin in Rats Discriminating Fentanyl

Despite a significant decrease in the number of prescriptions for opioids, the opioid crisis continues, fueled in large part by the availability of the phenylpiperidine mu opioid receptor (MOR) agonist fentanyl. In contrast, the number of prescriptions for and the off-label use of gabapentinoids (gabapentin and pregabalin) has increased dramatically, with gabapentinoids commonly detected in opioid overdose victims. Although gabapentinoids can decrease the potency of the opioid receptor antagonist naloxone to reverse heroin-induced hypoventilation in male rats, the specificity and nature of interaction between gabapentinoids and MOR agonists and any potential sex difference in those interactions are not well characterized. Gabapentinoids were studied in female and male rats discriminating fentanyl (0.0032 mg/kg, i.p.) or cocaine (3.2 mg/kg, i.p.). Alone, neither gabapentin nor pregabalin significantly increased fentanyl- or cocaine-appropriate responding. In rats discriminating fentanyl, each gabapentinoid dose-dependently shifted the fentanyl and heroin discrimination dose-effect functions to the left, whereas naloxone dose-dependently shifted the fentanyl and heroin discrimination dose-effect functions to the right. Each gabapentinoid (100 mg/kg) significantly decreased the potency of naloxone to antagonize the discriminative stimulus effect of fentanyl or heroin. In contrast, each gabapentinoid dose-dependently shifted the cocaine and d-methamphetamine discrimination dose-effect functions to the right. There were no significant sex differences in this study. These results suggest that gabapentinoids impact the misuse of opioids, the co-use of opioids and stimulant drugs, and the increasing number of overdose deaths in individuals using opioids, stimulant drugs, and gabapentinoids in mixtures. SIGNIFICANCE STATEMENT: The number of prescriptions for and the off-label use of gabapentinoids (gabapentin and pregabalin) has increased dramatically, with gabapentinoids commonly detected in opioid overdose victims. This study reports that in rats gabapentinoids increase the potency of fentanyl and heroin to produce discriminative stimulus effects while decreasing the potency of naloxone to antagonize those effects of fentanyl and heroin. These results can help guide policies for regulating gabapentinoids and treating opioid misuse and overdose.

Experiences of misuse and symptoms of dependence among people who use gabapentinoids: A qualitative systematic review

BACKGROUND

Gabapentinoids are among the most widely prescribed pain medications worldwide. However, there is growing evidence of harms associated with their use. The aim of this study was to systematically review and synthesise qualitative research exploring lived experiences of gabapentinoid (pregabalin and/or gabapentin) misuse and symptoms of dependence.

METHODS

Six databases (MEDLINE, Scopus, Web of Science, CINAHL, EMBASE, PsycINFO) and grey literature sources were searched from inception to September 2023. The methodological quality of included studies was appraised using a modified 11-item version of the Critical Appraisal Skills Programme qualitative checklist, and higher quality studies were prioritised in the thematic synthesis. Confidence in the overall findings of the review was assessed using the GRADE-CERQual approach. The review was prospectively registered on PROSPERO (CRD42023401832).

RESULTS

Twenty-six articles representing 21 original studies were included. The majority used interview methods and were of high methodological quality. Motives for gabapentinoid misuse included getting high, potentiating or offsetting the effects of other drugs, self-medicating for pain, distress, insomnia, or withdrawal symptoms, and substituting for another drug. Symptoms of dependence included the rapid development of tolerance and a severe withdrawal syndrome often involving psychiatric symptoms. Harms including dissociation, loss of consciousness, and overdose were generally reported as a consequence of polysubstance use. Confidence in most of the review findings was moderate with low confidence in one finding.

CONCLUSION

This review provides rich qualitative insights into the potential motives for gabapentinoid misuse as well as the diverse lived experiences of dependence symptomatology. Considering the increasing prescribing of these medications globally, and the potential for public health challenges resulting from misuse, the findings of this review can be used to develop more effective harm reduction strategies.

Systematic review: The relationship between gabapentinoids, etizolam, and drug related deaths in Scotland

In recent years Scotland has been experiencing a disproportionally high number of drug related deaths compared to other European countries, causing significant individual, societal and economic burden. A possible cause of this is the increase in average number of substances involved in Scottish drug related deaths, as well as the changing pattern of substances involved. Opioids, cocaine, and alcohol have been consistently involved in the culture of drug use in Scotland, however recently National Records Scotland have identified that designer benzodiazepines such as etizolam, and prescription drugs such as gabapentinoids are increasingly being detected in Scottish toxicology reports. A systematic literature review following PRISMA guidelines was conducted through searching PubMed and Google Scholar to identify peer-reviewed articles published in English between 2013 and 2023 that investigated Scottish population data on gabapentinoids and etizolam to establish their contribution to the rise in Scottish drug related deaths. 18 studies were included in the review. A high use prevalence of etizolam and gabapentinoids in Scotland has been identified, with both substance-related deaths showing recent increase, marked since 2015. This pattern is replicated in the Scottish prison system. There has also been a significant increase of gabapentinoids prescriptions in Scotland. Polydrug use was identified as the most common determinant of both etizolam and gabapentinoids related adverse effects and fatality in Scotland, especially concurrent opioid use. The results indicate the literature on individual characteristics of Scottish at-risk users of gabapentinoids and etizolam is limited, however the data shows both substances are being used by older cohort, with adverse effects seen more in older women.

Risk of adverse outcomes during gabapentinoid therapy and factors associated with increased risk in UK primary care using the clinical practice research datalink: a cohort study

ABSTRACT

Growing evidence from pharmacovigilance data and postmortem toxicology reports highlights the misuse potential of gabapentinoids. This study aimed to investigate the risk of serious adverse outcomes (drug misuse, overdose, major trauma), and their risk factors, in primary care patients who are prescribed gabapentinoids. Using the UK Clinical Practice Research Datalink, a matched cohort study calculated adverse event rates separately for gabapentinoid-exposed and unexposed cohorts. In the exposed cohort, event rates for exposure to a range of potential risk factors were calculated. Event rates were compared using Cox proportional hazards models, adjusted for age, sex, deprivation, previous mental health diagnosis, and coprescribing with potentially interacting medicines. Substance misuse (gabapentin adjusted hazard ratio [95% CI]: 2.40 [2.25-2.55]), overdose (2.99 [2.56-3.49]), and major trauma (0-2.5 years: 1.35 [1.28-1.42]; 2.5 to 10 years: 1.73 [1.56-1.95]) were more common among patients prescribed gabapentinoids than matched individuals who were not. The association with overdose was stronger for pregabalin than gabapentin. All adverse outcomes were significantly associated with smoking, history of substance misuse, overdose, or a mental health condition and prescription of opioids, benzodiazepines, antidepressants, and Z-drug hypnotics (eg, gabapentin hazard ratios for association of concurrent opioid use: misuse 1.49 [1.47-1.51]; overdose 1.87 [1.78-1.96]; major trauma 1.28 [1.26-1.30]). Our findings highlight the importance of careful patient selection when prescribing gabapentinoids and the need to educate prescribers about the risks of these drugs, particularly in combination with other central nervous system depressants.

Risk of drug-related death associated with co-prescribing of gabapentinoids and Z-drugs among people receiving opioid-agonist treatment: A national retrospective cohort study

BACKGROUND

Prescribing of gabapentinoids and Z-drug-hypnotics has increased in the population and among people receiving opioid-agonist treatment (OAT) for opioid dependence. Evidence is mixed on whether co-prescribing of sedatives such as gabapentinoids and Z-drugs during OAT increases risk of drug-related death (DRD).

METHODS

We conducted a retrospective cohort study of individuals prescribed OAT between 2011 and 2020 in Scotland. Prescribing records were linked to mortality data and other healthcare datasets (sociodemographic, comorbidity). We identified episodes of treatment with gabapentinoids/Z-drugs and used multivariable quasi-Poisson regression to model associations between co-prescription and DRD risk.

RESULTS

Among 46,602 individuals with 304,783 person-years of follow-up, we found that co-prescription was common, with 25 % and 34 % ever being co-prescribed gabapentinoids and Z-drugs, respectively. Gabapentinoid exposure was strongly associated (adjusted hazard ratio (aHR)=2·18, 95 % CI=1·92, 2·46) and Z-drug exposure moderately associated (aHR=1·39, 95 % CI=1·15, 1·66) with elevated risk of DRD. Gabapentinoid exposure was associated with DRD risk on and off OAT; Z-drug exposure was less strongly associated with DRD risk when on OAT.

CONCLUSIONS

Co-prescription of gabapentinoids and Z-drugs is common among OAT patients. However, co-prescription is associated with increased risk of DRD. Alternatives to prescribing sedative medications to OAT patients and/or greater monitoring - if prescribed - are needed.

Gabapentinoid detection in coronial casework in Gold Coast, Australia: a 5-year retrospective study

Gabapentinoids is a class of drug with analgesic, anxiolytic, and anticonvulsant properties and has a reported increase in prescription, use, and adverse outcomes. Regional studies are scant, and postmortem toxicological data may characterise patterns of regional use and inform local interventions. Characterising drug and non-drug-related deaths with gabapentinoid detection may also aid in toxicology interpretation. A 5-year retrospective study on all deaths admitted to the Gold Coast University Hospital under where toxicological analysis was performed. Of the gabapentinoids, only pregabalin was detected over the study period, and annual rates of detection did not differ significantly over the period (7.4-12.4%). In cases where pregabalin was detected, it was 15 times more likely to be a drug-related death. Drug-related deaths where pregabalin was detected have higher levels of pregabalin, are younger, and had a greater proportion of concurrent opioid detection. Postmortem detection of pregabalin was associated with drug-related deaths. Higher levels, younger decedents, and concurrent use of opioids were found in drug-related deaths. Public health interventions and regulated prescribing to target concurrent pregabalin and opioid use may address the burden of pregabalin drug-related deaths.

Gabapentinoids and Risk for Severe Exacerbation in Chronic Obstructive Pulmonary Disease : A Population-Based Cohort Study

BACKGROUND

North American and European health agencies recently warned of severe breathing problems associated with gabapentinoids, including in patients with chronic obstructive pulmonary disease (COPD), although supporting evidence is limited.

OBJECTIVE

To assess whether gabapentinoid use is associated with severe exacerbation in patients with COPD.

DESIGN

Time-conditional propensity score-matched, new-user cohort study.

SETTING

Health insurance databases from the Régie de l'assurance maladie du Québec in Canada.

PATIENTS

Within a base cohort of patients with COPD between 1994 and 2015, patients initiating gabapentinoid therapy with an indication (epilepsy, neuropathic pain, or other chronic pain) were matched 1:1 with nonusers on COPD duration, indication for gabapentinoids, age, sex, calendar year, and time-conditional propensity score.

MEASUREMENTS

The primary outcome was severe COPD exacerbation requiring hospitalization. Hazard ratios (HRs) associated with gabapentinoid use were estimated in subcohorts according to gabapentinoid indication and in the overall cohort.

RESULTS

The cohort included 356 gabapentinoid users with epilepsy, 9411 with neuropathic pain, and 3737 with other chronic pain, matched 1:1 to nonusers. Compared with nonuse, gabapentinoid use was associated with increased risk for severe COPD exacerbation across the indications of epilepsy (HR, 1.58 [95% CI, 1.08 to 2.30]), neuropathic pain (HR, 1.35 [CI, 1.24 to 1.48]), and other chronic pain (HR, 1.49 [CI, 1.27 to 1.73]) and overall (HR, 1.39 [CI, 1.29 to 1.50]).

LIMITATION

Residual confounding, including from lack of smoking information.

CONCLUSION

In patients with COPD, gabapentinoid use was associated with increased risk for severe exacerbation. This study supports the warnings from regulatory agencies and highlights the importance of considering this potential risk when prescribing gabapentin and pregabalin to patients with COPD.

PRIMARY FUNDING SOURCE

Canadian Institutes of Health Research and Canadian Lung Association.

Gabapentinoids in Ireland 2010 to 2020: An observational study of trends in gabapentinoid prescribing, law enforcement drug seizures and postmortem toxicology

AIMS

We explored trends in gabapentinoid prescribing, drug seizures and postmortem toxicology using a national pharmacy claims database, law enforcement drug seizures data and a population-based postmortem toxicology database.

METHODS

Gabapentinoid prescribing rates per 100 000 eligible population (2010-2020), annual number of drug seizures involving gabapentinoids (2012-2020) and gabapentinoid detection (positive) rates per 100 postmortem toxicology case (2013-2020) were calculated. Negative binomial regression models were used to evaluate longitudinal trends for gabapentin and pregabalin separately.

RESULTS

Gabapentin (adjusted rate ratio [RR] 1.06, 95% confidence interval [CI] 1.05-1.06, P < .001) and pregabalin (adjusted RR 1.08, 95% CI 1.08-1.09, P < .001) prescribing increased annually, with higher rates of pregabalin (vs. gabapentin) observed every year. Drug seizures involving pregabalin also increased over time (RR 1.54 95% CI 1.25-1.90, P < .0001). Of the 26 317 postmortem toxicology cases, 0.92% tested positive for gabapentin, and 6.37% for pregabalin. Detection rates increased for both gabapentin (RR 1.28, 95% CI 1.11-1.48, P < .001) and pregabalin (RR 1.13, 95% CI 1.11-1.48, P < .001) between 2013 and 2020. A total of 1901 cases (7.2%) tested positive for heroin/methadone; this sub-group had a higher detection rate for pregabalin (n = 528, 27.8%) and gabapentin (n = 41, 2.2%) over the study period, with a high burden of codetections for pregabalin with benzodiazepines (peaking at 37.3% in 2018), and pregabalin with prescription opioids (peaking at 28.9% in 2020).

CONCLUSION

This study raises concerns regarding the wide availability of pregabalin in Ireland, including a growing illicit supply, and the potential for serious harm arising from poly drug use involving pregabalin among people who use heroin or methadone.

Prescription drugs with potential for misuse in Irish prisons: analysis of national prison prescribing trends, by gender and history of opioid use disorder, 2012 to 2020

BACKGROUND

Pharmacotherapy is essential for the delivery of an equivalent standard of care in prison. Prescribing can be challenging due to the complex health needs of prisoners and the risk of misuse of prescription drugs. This study examines prescribing trends for drugs with potential for misuse (opioids, benzodiazepines, Z-drugs, and gabapentinoids) in Irish prisons and whether trends vary by gender and history of opioid use disorder (OUD).

METHODS

A repeated cross-sectional study between 2012 and 2020 using electronic prescribing records from the Irish Prison Services, covering all prisons in the Republic of Ireland was carried out. Prescribing rates per 1,000 prison population were calculated. Negative binomial (presenting adjusted rate ratios (ARR) per year and 95% confidence intervals) and joinpoint regressions were used to estimate time trends adjusting for gender, and for gender specific analyses of prescribing trends over time by history of OUD.

RESULTS

A total of 10,371 individuals were prescribed opioid agonist treatment (OAT), opioids, benzodiazepines, Z-drugs or gabapentinoids during study period. History of OUD was higher in women, with a median rate of 597 per 1,000 female prisoners, compared to 161 per 1,000 male prisoners. Prescribing time trends, adjusted for gender, showed prescribing rates decreased over time for prescription opioids (ARR 0.82, 95% CI 0.80-0.85), benzodiazepines (ARR 0.99, 95% CI 0.98-0.999), Z-drugs (ARR 0.90, 95% CI 0.88-0.92), but increased for gabapentinoids (ARR 1.07, 95% CI 1.05-1.08). However, prescribing rates declined for each drug class between 2019 and 2020. Women were significantly more likely to be prescribed benzodiazepines, Z-drugs and gabapentinoids relative to men. Gender-specific analyses found that men with OUD, relative to men without, were more likely to be prescribed benzodiazepines (ARR 1.49, 95% CI 1.41-1.58), Z-drugs (ARR 10.09, 95% CI 9.0-11.31), gabapentinoids (ARR 2.81, 95% CI 2.66-2.97). For women, history of OUD was associated with reduced gabapentinoid prescribing (ARR 0.33, 95% CI 0.28-0.39).

CONCLUSIONS

While the observed reductions in prescription opioid, benzodiazepine and Z-drug prescribing is consistent with guidance for safe prescribing in prisons, the increase in gabapentinoid (primarily pregabalin) prescribing and the high level of prescribing to women is concerning. Our findings suggest targeted interventions may be needed to address prescribing in women, and men with a history of OUD.

Gabapentin and Opioids Utilization in Patients With Diabetic Neuropathy Enrolled in Medicare (2012-2016): A Cohort Study

This retrospective cohort study describes the utilization of opioids and gabapentin among patients with diabetic neuropathy who were gabapentin and opioid naïve, and assesses predictors of concomitant use of opioids and gabapentin. Using Medicare claims data (2012-2016), 22 037 patients were identified, of whom 23.42% (N = 5161) initiated opioids without concomitant gabapentin, 4.56% (N = 1004) initiated gabapentin without concomitant opioids, and 3.87% (N = 852) had concomitant use of gabapentin and opioids 12 months following their index date (date of earliest diagnosis). Concomitant gabapentin and opioid use were more common for lower doses of both drugs and for 15 days or more cumulatively. Compared to individuals aged 65-74, those aged 75-84 (OR: .759; 95% CI: 0.653-.882) or ≥ 85 years (OR: .586, 95% CI: 0.462-.743) had lower odds of concomitant use. People residing in the Northeast had lower odds of concomitant use, compared to those residing in the South (OR: .646 95% CI: 0.535-.779). Females compared to males (OR: 1.185, 95% CI: 1.027-1.367), people with higher Charlson's Comorbidity Index (CCI) scores (OR: 1.085, 95% CI: 1.037-1.135) or those having anxiety (OR: 1.462, 95% CI: 1.131-1.889) had higher odds of concomitant use. Concomitant prescriptions of opioids and gabapentin were more common for longer durations, indicating the need for interventions aimed at minimizing this prescribing practice.

Gabapentinoid consumption in 65 countries and regions from 2008 to 2018: a longitudinal trend study

Recent studies raised concerns about the increasing use of gabapentinoids in different countries. With their potential for misuse and addiction, understanding the global consumption of gabapentinoids will offer us a platform to examine the need for any interventional policies. This longitudinal trend study utilised pharmaceutical sales data from 65 countries and regions across the world to evaluate the global trends in gabapentinoid consumption between 2008-2018. The multinational average annual percentage change of gabapentinoid consumption was +17.20%, increased from 4.17 defined daily dose per ten thousand inhabitants per day (DDD/TID) in 2008 to 18.26 DDD/TID in 2018. High-income countries had the highest pooled gabapentinoid consumption rate (39.92 DDD/TID) in 2018, which was more than six times higher than the lower-middle income countries (6.11 DDD/TID). The study shows that despite differences in healthcare system and culture, a consistent increase in gabapentinoid consumption is observed worldwide, with high-income countries remaining the largest consumers.

Trends in overdose deaths involving gabapentinoids and Z-drugs in the United States

INTRODUCTION

As policies have been implemented to limit access to prescription opioids, other drugs have been prescribed off-label, sometimes concurrently with opioids, to manage pain. There are concerns about the use of gabapentinoids and "Z-drugs" with opioids. As the opioid crisis transitions to illicit opioids and polysubstance use, little work quantifies the concurrent involvement of non-opioid prescription drugs and illicit opioids in overdose deaths.

METHODS

Data from the census of deaths in the United States for 1999-2020 were used to understand trends in deaths involving gabapentinoids/Z-drugs and opioid co-involvement. These trends were studied overall and by sex, race, age, and education.

RESULTS

Per capita overdose deaths involving gabapentinoids/Z-drugs increased almost continuously since 1999, averaging 15.8% annual growth. This rate increased to 32% in 2020, primarily due to overdoses involving synthetic opioids. Women typically had higher rates of overdose deaths involving both opioids and gabapentinoids/Z-drugs, though this disparity disappeared in 2020. White Americans and American Indians/Alaskan Natives historically had higher rates than other racial groups; however, Black Americans experienced over 60% annual growth in recent years. Low education groups have been disproportionately impacted. The age incidence tends to be older than overdoses involving opioids more generally.

CONCLUSION

Overdose deaths involving opioids and gabapentinoids/Z-drugs have tended to disproportionately affect women and older age groups compared to all opioid-involved overdoses. As deaths involving synthetic opioids likely reflect use of illicitly-obtained opioids, there may be less of a role for policies targeting the concurrent prescribing of gabapentinoids/Z-drugs with opioids to reduce these deaths.

Theophylline reverses oxycodone's but not fentanyl's respiratory depression in mice while caffeine is ineffective against both opioids

RATIONALE

The opioid epidemic remains a pressing public health crisis in the United States. Most of these overdose deaths are a result of lethal respiratory depression. In recent years the increasing incidence of opioid-involved overdose deaths has been driven by fentanyl, which is more resistant to adequate reversal by naloxone (NARCAN ®) than semi-synthetic or classical morphinan predecessors like oxycodone and heroin. For this and other reasons (e.g., precipitating withdrawal) non-opioidergic pharmacotherapies to reverse opioid-depressed respiration are needed. Methylxanthines are a class of stimulant drugs including caffeine and theophylline which exert their effects primarily via adenosine receptor antagonism. Evidence suggests methylxanthines can stimulate respiration by enhancing neural activity in respiratory nuclei in the pons and medulla independent of opioid receptors. This study aimed to determine whether caffeine and theophylline can stimulate respiration in mice when depressed by fentanyl and oxycodone.

METHODS

Whole-body plethysmography was used to characterize fentanyl and oxycodone's effects on respiration and their reversal by naloxone in male Swiss Webster mice. Next, caffeine and theophylline were tested for their effects on basal respiration. Finally, each methylxanthine was evaluated for its ability to reverse similar levels of respiratory depression induced by fentanyl or oxycodone.

RESULTS AND CONCLUSIONS

Oxycodone and fentanyl dose-dependently reduced respiratory minute volume (ml/min; MVb) that was reversible by naloxone. Caffeine and theophylline each significantly increased basal MVb. Theophylline, but not caffeine, completely reversed oxycodone-depressed respiration. In contrast, neither methylxanthine elevated fentanyl-depressed respiration at the doses tested. Despite their limited efficacy for reversing opioid-depressed respiration when administered alone, the methylxanthines safety, duration, and mechanism of action supports further evaluation in combination with naloxone to augment its reversal of opioid-depressed respiration.

Misuse of Pregabalin: a qualitative study from a patient's perspective

INTRODUCTION

The misuse of Pregabalin has been the subject of growing concern for several years. The effects sought are multiple and it is rarely taken as a single drug. It is most frequently used together with opioids, which may increase the risk of fatal overdose. In response to this emerging phenomenon, we seek to better understand the situation of misuse in Belgium and identify the people involved in it.

METHODOLOGY

A qualitative study using semi-structured interviews with 20 participants who misuse Pregabalin was conducted throughout the French-speaking region of Belgium between August 2021 and January 2022. Recruitment mostly took place in addictions centers, shelters for migrants and homeless persons and primary care centers. We then conducted a thematic analysis with the help of Nvivo software.

RESULTS

A profile emerged, of young male users, immigrants, mainly first generation immigrants coming from North Africa. They had in common a challenging or even traumatic migration pathway and precarious living conditions in Belgian territory. Most of them had no stable income. They saw Pregabalin as enabling them to cope with their daily situation. All had psychiatric and/or somatic comorbidities for which they had apparently not recieved adequate medical care. This seemed to lead many of them to use Pregabalin as self-medication, for anxiety-depressive disorders and chronic pain, and it was sometimes initiated in their home country. Pregabalin was never used alone.

CONCLUSION

This study has highlighted a rare and insufficient documented profile of Pregabalin misuse: self-medication among a group of first generation immigrants, most of whom have no previous history of opioid-related disorders. Measures should be taken to improve access to health and social care for this population, considering all their biopsychosocial vulnerabilities.

Effects of Gabapentinoids on Heroin-Induced Ventilatory Depression and Reversal by Naloxone

Despite an increasing prevalence of gabapentinoids (gabapentin and pregabalin) in opioid overdose deaths, little research has evaluated potentially harmful interactions between gabapentinoids and opioids. This study sought to determine the effects of gabapentinoids on the ventilatory depressive effects of heroin and their reversal by naloxone. Rats were given gabapentin, pregabalin, or saline prior to receiving increasing doses of heroin while ventilation was monitored using whole-body plethysmography. In some sessions naloxone was administered following the largest dose of heroin. The primary outcomes of this study were minute volume and Pause. Heroin dose-dependently reduced minute volume and increased Pause. Administration of naloxone dose-dependently reversed the effects of heroin on ventilation. Gabapentinoids did not alter the ventilatory depressive effects of heroin alone but reduced the potency of naloxone to reverse heroin-induced ventilatory depression. These preliminary findings emphasize the need for further research evaluating interactions between gabapentinoids and opioids related to substance misuse and overdose.

The Role of Gabapentinoids in the Substance Use Pattern of Adult Germans Seeking Inpatient Detoxification Treatment - A Pilot Study

To shed more light on the addictive power of the gabapentinoids (GPTs) gabapentin and pregabalin, we performed a structured face-to-face interview with GPT-users about DSM-IV-dependence-criteria (sedatives), consume-motives and cessation-needs. Among 100 patients consecutively admitted to a detoxification-ward, fifteen (15%) reported lifetime GPT-use (18-50 years old, 2 females): seven (7%) used gabapentin, twelve (12%) pregabalin and four had lifetime experiences with both GPTs. Of the seven gabapentin-users, three patients were dependent including one person with a spontaneous remission. Of the 12 pregabalin-users, five were dependent, including two persons with a spontaneous remission. Fourteen of fifteen cases reported GPT-use side-by-side with an opioid-use, mostly for sparing opioids. Twelve GPT-users additionally co-used benzodiazepines. In no case, a GPT was the reason for detoxification treatment or reported to be involved in an emergency event. Altogether, every 7^th patient (n = 15) of our inpatient detoxification-seeking sample reported GPT-use including 50% (n = 8) who were dependent. Among them, 35% (3/8) had been already spontaneously remitted. As GPT-users reported no cession-need and the vast majority were primarily affected by co-occurring opioid- and benzodiazepine-addiction, we assume that GPTs more likely played a bystander-role than mediating the addictive behavior of this population with multiple recreational drug use experience.

Functional Impairment and Cognitive Symptoms Among People with HIV Infection on Chronic Opioid Therapy for Pain: The Impact of Gabapentin and Other Sedating Medications

Gabapentin is associated with dizziness, falls, and somnolence yet commonly prescribed to people with HIV (PWH) treated with chronic opioid therapy (COT). Physical function and cognition are understudied when prescribed together. Among PWH on COT, we evaluated whether co-prescribed gabapentin is associated with (a) functional impairment; (b) trouble thinking clearly; and (c) difficulty controlling drowsiness using logistic regression models adjusted for prescribed opioid dose, other (non-gabapentin) sedating medication, substance use disorder, and mental/physical health indicators in a cross-sectional study. Among 166 participants, 40% were prescribed gabapentin, 41% reported functional impairment, 41% trouble thinking clearly, and 38% difficulty controlling drowsiness. Gabapentin co-prescribed with COT was significantly associated with trouble thinking clearly but not with functional impairment or difficulty controlling drowsiness. Clinicians should be cognizant of potential problems with thinking clearly when co-prescribing gabapentin and opioid medication.

Association of State-Imposed Restrictions on Gabapentin with Changes in Prescribing in Medicare

BACKGROUND

Between August 2016 and July 2018, three states classified gabapentin as a Schedule V drug and nine states implemented prescription drug monitoring program (PDMP) regulation for gabapentin. It is highly unusual for states to take drug regulation into their own hands. The impact of these changes on gabapentin prescribing is unclear.

OBJECTIVE

To determine the effect of state-imposed regulation on gabapentin prescribing for Medicare Part D enrollees from 2013 to 2018.

DESIGN

Population-based difference-in-difference(DID) analysis study utilizing the Medicare Part D Prescriber Public Use File.

PARTICIPANTS

All eligible Medicare Part D prescribers excluding those outside of the fifty states and the District of Columbia were included in our analysis. Prescriber data and key sociodemographic variables were organized by state and year. States with a gabapentin schedule change or PDMP regulation enacted before 2019 were included in the intervention group. For the Schedule V DID analysis, a control group of the ten highest opioid-prescribing states was used.

INTERVENTIONS

States with gabapentin schedule changes or PDMP regulation before January 1, 2019, were included and compared to control states that did not implement these policies.

MAIN MEASURES

Total days' supply of gabapentin per enrollee per year was the primary outcome variable.

KEY RESULTS

The mean total days' supply of gabapentin per enrollee increased 41% from 19.71 to 27.81 total days' supply per enrollee per year between 2013 and 2018. After adjustment, Schedule V gabapentin regulation resulted in a reduction of 8.37 total days of gabapentin prescribed per enrollee (95% confidence interval of - 10.34 to - 6.39). In contrast, PDMP regulation resulted in a reduction of 1.01 total days of gabapentin prescribed per enrollee (95% confidence interval of - 1.74 to - 0.29).

CONCLUSIONS

Classifying gabapentin as a Schedule V drug results in substantial reduction in total days prescribed whereas PDMP regulation results in modest reduction.

Analysis of the UK Government's 10-Year Drugs Strategy-a resource for practitioners and policymakers

In 2021, during a drug-related death crisis in the UK, the Government published its ten-year drugs strategy. This article, written in collaboration with the Faculty of Public Health and the Association of Directors of Public Health, assesses whether this Strategy is evidence-based and consistent with international calls to promote public health approaches to drugs, which put 'people, health and human rights at the centre'. Elements of the Strategy are welcome, including the promise of significant funding for drug treatment services, the effects of which will depend on how it is utilized by services and local commissioners and whether it is sustained. However, unevidenced and harmful measures to deter drug use by means of punishment continue to be promoted, which will have deleterious impacts on people who use drugs. An effective public health approach to drugs should tackle population-level risk factors, which may predispose to harmful patterns of drug use, including adverse childhood experiences and socioeconomic deprivation, and institute evidence-based measures to mitigate drug-related harm. This would likely be more effective, and just, than the continuation of policies rooted in enforcement. A more dramatic re-orientation of UK drug policy than that offered by the Strategy is overdue.

Risk of major adverse events associated with gabapentinoid and opioid combination therapy: A systematic review and meta-analysis

Background: The use of opioid-gabapentinoid combinations has increased, raising several safety concerns. However, meta-analysis studies focusing on this issue are limited. Objective: To evaluate the risk of central nervous system (CNS) depression, gastrointestinal (GI) adverse events, and mortality of combination therapy compared with those of opioid therapy and to explore the differences in the results according to study design and indications. Methods: Relevant studies were selected (published before 30 January 2022) by searching the MEDLINE, Embase, and CENTRAL databases. The pooled odds ratios (OR) with 95% confidence intervals (CI) of the outcomes were estimated using the Mantel-Haenszel method. Subgroup and meta-regression analyses were performed according to study characteristics. Quality assessment was conducted using the Risk of Bias 2 tool for randomized controlled trials (RCTs) and Cochrane Collaboration's Risk of Bias in non-RCTs tool for non-randomized trials. Results: Adverse events were reported in 26 RCTs and 7 non-RCTs, and mortality was reported in 10 non-RCTs. Compared to opioid therapy, dizziness, cognitive dysfunction, and respiratory depression in combination therapy significantly increased in non-RCTs (OR 3.26, 95% CI 1.82-5.85; OR 3.13, 95% CI 1.51-6.50; OR 1.71, 95% CI 1.31-2.24, respectively), and a similar trend for dizziness and cognitive dysfunction was also identified in the RCT analysis, although the difference was not significant. Combination therapy for cancer pain was associated with the highest risk of sedation in subgroup analysis. Combination therapy significantly decreased the risk of GI adverse events, including nausea, vomiting, and constipation. The mortality risk associated with combination therapy was higher than that associated with opioid therapy (OR 2.76, 95% CI 1.26-6.05). Conclusion: Opioid-gabapentinoid combination therapy could be associated with an increased risk of CNS depression and mortality, despite tolerable GI adverse events. These data suggest that combination therapy requires close monitoring of CNS depression, especially in cancer patients. Caution is needed in interpreting the clinical meanings owing to the lack of risk difference in respiratory depression in the RCT-only analysis and the absence of RCT or prospective studies investigating mortality.

Misuse of Over the Counter and Prescription Only Medication by Adults Accessing Specialist Treatment Services in the UK: A Narrative Synthesis

Background

Concerns about the misuse of over the counter (OTC) and prescription only medication (POM) are due to their impact upon physical/mental wellbeing, drug interactions and drug-related deaths. Improving an understanding of the pattern of use by people accessing specialist substance misuse services (SMSs) should enable improvements to treatment provision.

Aim

To review the literature on the misuse of OTC/POM among adults accessing SMS, including the pattern of use, types of medication and associated characteristics.

Methods

This review is reported in line with PRISMA. The protocol has been registered on PROSPERO (CRD42020135216) and separately published. A search of Cochrane, OVID Medline, Pubmed, Scopus and Web of Science databases and grey literature was undertaken. Only English language publications outlining OTC/POM misuse by adults in receipt of psychological/pharmacological interventions for substance misuse were included. Two reviewers conducted the title, abstract and full-text reviews using predetermined selection criteria and a piloted data extraction form to ensure a consistent approach. A third reviewer resolved disagreements and the Mixed Methods Appraisal Tool assessed for bias. Ethical approval was not required.

Results

Thirteen studies with notable heterogeneity were included in the narrative synthesis after non-UK-based and ineligible publications were excluded, from the 143 potentially relevant papers. To reduce bias all studies were included in the analysis and GRADE-CERQual was applied. 'High confidence' was identified for all review findings, despite moderate methodological limitations. Antihistamine, benzodiazepine and opioid misuse was mentioned most frequently. Usage patterns and supply sources varied. Adverse consequences and polypharmacy are concerning. Withdrawal symptoms perpetuated misuse, often alongside illicit substance use, comorbid psychiatric/pain disorders and street drug shortages.

Conclusion

OTC/POM misuse is common amongst adults accessing SMS. A renewed approach to withdrawal management is required. The limited number of studies may impact on generalisability but allowed for a more detailed review. Restricting to UK studies improved relevance due to drug market variations and availability of medicines in different countries. Further UK-based research on OTC/POM misuse in SMS is needed to build upon the current paucity in the published literature.

An ecological study of temporal trends in 'deaths of despair' in England and Wales

PURPOSE

There is growing interest in the concept of 'deaths of despair' (DoD)-defined as deaths from three causes: suicide, drug poisoning, and alcohol-related conditions-as a more comprehensive indicator of the impact of psychological distress on mortality. The purpose of this study is to investigate the degree of commonality in trends and geographic patterning of deaths from these causes in England and Wales.

METHODS

WHO mortality data were used to calculate age-standardised, sex-specific temporal trends in DoD mortality and in mortality from suicide, drug poisonings, and alcohol-related conditions in England and Wales, 2001-2016. Three-year average crude rates were calculated for English local authorities for 2016-2018 and associations between rates were assessed using Spearman's rank correlation.

RESULTS

Between 2001 and 2016, the DoD mortality rate increased by 21·6% (males) and 16·9% (females). The increase was largely due to a rise in drug poisoning deaths, with limited tracking between trends in mortality by each cause. DoD mortality risk was highest in middle-aged people; there were rises in all age groups except 15-24 year old males and 65 + females. There were strong positive correlations (r = 0.66(males) and 0.60(females)) between local authority-area drug poisoning and alcohol-specific mortality rates in 2016-2018. Correlations of these outcomes with suicide were weaker (r = 0.29-0.54).

CONCLUSIONS

DoD mortality is increasing in England and Wales but there is limited evidence of commonality in the epidemiology of cause-specific mortality from the component causes of DoD (suicide, drug poisoning and alcohol-related conditions), indicating the need for tailored prevention for each outcome.

Fatalities associated with gabapentinoids in England (2004-2020)

The gabapentinoids were reclassified as Schedule II medications and Class C drugs in the UK in 2019 due to their potential misuse. In this study we examined deaths following gabapentinoid use in England reported to the National Programme on Substance Abuse Deaths.

A total of 3051 deaths were reported (gabapentin: 913 cases; pregabalin: 2322 cases [both detected in 184 cases]). Prescribed and illicitly obtained gabapentinoids accounted for similar proportions of deaths (gabapentin illicit 38.0%, prescribed 37.1%; pregabalin illicit 41.0%, prescribed 34.6%). Opioids were co‐detected in most cases (92.0%), and co‐prescribed in a quarter (25.3%). Postmortem blood gabapentinoid concentrations were commonly (sub)therapeutic (65.0% of gabapentin cases; 50.8% of pregabalin cases). In only two cases was gabapentinoid toxicity alone attributed in causing death.

Gabapentinoids alone rarely cause death. Clinically relevant doses can, however, prove fatal, possibly by reducing tolerance to opioids. Doctors and patients should be aware of this interaction.

Gabapentinoid–opioid co‐prescribing needs urgent revision.

Concurrent Use of Prescription Opioids and Gabapentinoids in Older Adults

INTRODUCTION

Concurrent use of prescription opioids with gabapentinoids may pose risks of serious drug interactions. Yet, little is known about the trends in and patient characteristics associated with concurrent opioid-gabapentinoid use among older Medicare opioid users with chronic noncancer pain.

METHODS

A cross-sectional study was conducted among Medicare older beneficiaries (aged ≥65 years) with chronic noncancer pain who filled ≥1 opioid prescription within 3 months after a randomly selected chronic noncancer pain diagnosis (index date) in a calendar year between 2011 and 2018. Patient characteristics were measured in the 6-month baseline before the index date, and concurrent opioid-gabapentinoid use for ≥1 day was measured in the 3-month follow-up after the index date. Multivariable modified Poisson regression hwas used to assess the trends and characteristics of concurrent opioid-gabapentinoid use. Analyses were conducted from January to June 2021.

RESULTS

Among 464,721 eligible older beneficiaries with chronic noncancer pain and prescription opioids, the prevalence of concurrent opioid-gabapentinoid use increased from 17.0% in 2011 to 23.5% in 2018 (adjusted prevalence ratio=1.48, 95% CI=1.45, 1.53). Concurrent users versus opioid-only users tended to be non-Black, low-income subsidy recipients, and Southern residents. The clinical factors associated with concurrent opioid-gabapentinoid use included having a diagnosis of neuropathic pain, polypharmacy, and risk factors for opioid-related adverse events.

CONCLUSIONS

Concurrent opioid-gabapentinoid use among older Medicare beneficiaries with chronic noncancer pain and prescription opioids has increased significantly between 2011 and 2018. Future studies are warranted to investigate the impact of concurrent use on outcomes in older patients. Interventions that reduce inappropriate concurrent use may target older patients with identified characteristics.

Concurrent use of prescription gabapentinoids with opioids and risk for fall-related injury among older US Medicare beneficiaries with chronic noncancer pain: A population-based cohort study

BACKGROUND

Gabapentinoids are increasingly prescribed to manage chronic noncancer pain (CNCP) in older adults. When used concurrently with opioids, gabapentinoids may potentiate central nervous system (CNS) depression and increase the risks for fall. We aimed to investigate whether concurrent use of gabapentinoids with opioids compared with use of opioids alone is associated with an increased risk of fall-related injury among older adults with CNCP.

METHODS AND FINDINGS

We conducted a population-based cohort study using a 5% national sample of Medicare beneficiaries in the United States between 2011 and 2018. Study sample consisted of fee-for-service (FFS) beneficiaries aged ≥65 years with CNCP diagnosis who initiated opioids. We identified concurrent users with gabapentinoids and opioids days' supply overlapping for ≥1 day and designated first day of concurrency as the index date. We created 2 cohorts based on whether concurrent users initiated gabapentinoids on the day of opioid initiation (Cohort 1) or after opioid initiation (Cohort 2). Each concurrent user was matched to up to 4 opioid-only users on opioid initiation date and index date using risk set sampling. We followed patients from index date to first fall-related injury event ascertained using a validated claims-based algorithm, treatment discontinuation or switching, death, Medicare disenrollment, hospitalization or nursing home admission, or end of study, whichever occurred first. In each cohort, we used propensity score (PS) weighted Cox models to estimate the adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) of fall-related injury, adjusting for year of the index date, sociodemographics, types of chronic pain, comorbidities, frailty, polypharmacy, healthcare utilization, use of nonopioid medications, and opioid use on and before the index date. We identified 6,733 concurrent users and 27,092 matched opioid-only users in Cohort 1 and 5,709 concurrent users and 22,388 matched opioid-only users in Cohort 2. The incidence rate of fall-related injury was 24.5 per 100 person-years during follow-up (median, 9 days; interquartile range [IQR], 5 to 18 days) in Cohort 1 and was 18.0 per 100 person-years during follow-up (median, 9 days; IQR, 4 to 22 days) in Cohort 2. Concurrent users had similar risk of fall-related injury as opioid-only users in Cohort 1(aHR = 0.97, 95% CI 0.71 to 1.34, p = 0.874), but had higher risk for fall-related injury than opioid-only users in Cohort 2 (aHR = 1.69, 95% CI 1.17 to 2.44, p = 0.005). Limitations of this study included confounding due to unmeasured factors, unavailable information on gabapentinoids' indication, potential misclassification, and limited generalizability beyond older adults insured by Medicare FFS program.

CONCLUSIONS

In this sample of older Medicare beneficiaries with CNCP, initiating gabapentinoids and opioids simultaneously compared with initiating opioids only was not significantly associated with risk for fall-related injury. However, addition of gabapentinoids to an existing opioid regimen was associated with increased risks for fall. Mechanisms for the observed excess risk, whether pharmacological or because of channeling of combination therapy to high-risk patients, require further investigation. Clinicians should consider the risk-benefit of combination therapy when prescribing gabapentinoids concurrently with opioids.

Opioid use disorder in anaesthesia and intensive care: Prevention, diagnosis and management

Opioid misuse is common, as is opioid agonist treatment of opioid dependence. Almost 3% of Australians and over 3.5% of those living in New Zealand report misuse of analgesics. Over 50,000 Australians receive opioid agonist treatment with methadone or buprenorphine for management of severe opioid use disorder.The perioperative period is an opportunity to identify pre-existing opioid misuse, and to introduce interventions to reduce the risk of development of opioid use disorder. Challenges of acute perioperative pain management or intensive care management of patients receiving opioid agonist treatment include opioid tolerance and ongoing prescribing of methadone or buprenorphine. There has been some ambiguity about the optimal perioperative management of buprenorphine, a partial agonist at the mu receptor.In this article, a framework to identify emerging opioid misuse problems, identify risk of overdose and to manage the opioid-dependent patient on opioid agonist treatment perioperatively or in the intensive care unit is provided. Diagnostic criteria and risk stratification criteria are presented. Management strategies include trauma-informed care, care planning and care coordination with community practitioners and opioid agonist treatment providers. Continuing methadone or buprenorphine perioperatively with additional opioid and non-opioid analgesia is generally recommended. Increased opioid agonist treatment doses may be required on discharge. An algorithm for decisions about opioid agonist treatment management in the intensive care unit based on the risks of opioid withdrawal and toxicity is considered. Strategies for managing the opioid-dependent patient who is not in treatment are also discussed.

Role of Acetaldehyde in Ethanol Reversal of Tolerance to Morphine-Induced Respiratory Depression in Mice

Background: Opioid users regularly consume other drugs such as alcohol (ethanol). Acute administration of ethanol rapidly reverses tolerance to morphine-induced respiratory depression. However, recent research has suggested that the primary metabolite of ethanol, acetaldehyde, may play a key role in mediating the CNS effects seen after ethanol consumption. This research investigated the role of acetaldehyde in ethanol reversal of tolerance to morphine-induced respiratory depression.

Methods: Tolerance was induced in mice by 6-days implantation of a 75 mg morphine pellet with control mice implanted with a placebo pellet. Tolerance was assessed by acute morphine administration on day 6 and respiration measured by plethysmography. Levels of acetaldehyde were inhibited or enhanced by pre-treatments with the acetaldehyde chelator D-penicillamine and the inhibitor of acetaldehyde dehydrogenase disulfiram respectively.

Results: Morphine pellet implanted mice displayed tolerance to an acute dose of morphine compared to placebo pellet implanted controls. Acute acetaldehyde administration dose-dependently reversed tolerance to morphine respiratory depression. As previously demonstrated, ethanol reversed morphine tolerance, and this was inhibited by D-penicillamine pre-treatment. An acute, low dose of ethanol that did not significantly reverse morphine tolerance was able to do so following disulfiram pre-treatment.

Conclusion: These data suggest that acetaldehyde, the primary metabolite of ethanol, is responsible for the reversal of morphine tolerance observed following ethanol administration.

Patterns of opioid and benzodiazepine use with gabapentin among disabled Medicare beneficiaries - A retrospective cohort study

BACKGROUND

Our goal was to describe specific patterns associated with co-prescriptions of gabapentin, opioids, and benzodiazepines among disabled Medicare beneficiaries.

METHODS

Using 2013-2015 Medicare data, we conducted a retrospective cohort study among fee-for-service disabled beneficiaries continuously enrolled in Medicare Parts A, B, and D. The index date was defined as the earliest fill date for a gabapentin, opioid, or benzodiazepine prescription. Monotherapy, dual therapy, and tri-therapy were defined as utilization of one, two, and three medication classes, respectively. Augmentation was defined as a prescription for a different medication class in addition to prescription for initial medication; switching referred to a change in prescription for a different medication class with no subsequent fills of initial medication. We used descriptive statistics, Kaplan Meier analyses and Cox proportional hazards to examine the association between initial therapy and monotherapy, dual therapy, tri-therapy, switching and augmentation.

RESULTS

Among 151,552 disabled beneficiaries, gabapentin initiators were more likely to augment therapy (50.1%) when compared to opioid (28.7%) and benzodiazepine (38.7%) users. When compared to opioid initiators, the risk of augmentation (HR[95%CI]: 1.85[1.82-1.89]) and switching (1.62 [1.51-1.73]) was significantly higher among gabapentin initiators. Risk of augmentation was also significantly higher among beneficiaries with co-morbid pain and mental health conditions (p < 0.01). Overall, the majority of beneficiaries augmented and switched within 2-months and 4-months after initiating therapy, respectively.

CONCLUSIONS

Given safety concerns associated with gabapentin, opioids, and benzodiazepines, it is imperative that the benefits and risks of co-prescribing these medications be examined comprehensively, especially for those in vulnerable sub-groups.

Surveying Over the Counter and Prescription Only Medication Misuse in Treatment Services During COVID-19

Background:

A greater understanding of Over the Counter (OTC) and Prescription Only Medication (POM) misuse amongst adults accessing substance misuse services (SMS) during COVID-19 is required to identify how SMS can better meet the needs of the people who require treatment.

Aim:

To use a questionnaire to explore OTC/POM misuse during COVID-19 in adults accessing community SMS in England.

Methods:

In 2020 to 2021 anonymous self-administered online/paper questionnaires which collated quantitative and qualitative data were completed. They were piloted for suitability and ethical approval was obtained. Thematic analysis was conducted for qualitative data and chi-square tests used to assess the relationship between quantitative variables.

Results:

Participants were Caucasian (94.6% British), majority male (58.9%), aged 18 to 61 years. Most were prescribed medication for problematic substance use, with a 92.5% self-reported adherence rate. The misuse of benzodiazepines (22.2%) codeine products (30.8%) and pregabalin (14.5%) predominated and 37.5% misused 2 or more medicines. Administration was usually oral and concomitant use of other substances was common: alcohol 44.6% (52% daily), tobacco/vaping 73.2% and illicit substances 58.9%. There were statistically significant associations identified, including between changes during COVID-19 to OTC/POM misuse and illicit use. Only 56 questionnaires were included in the analysis: we believe this low number was because of infection control measures, limited footfall in services, pressures on staff limiting their capacity to distribute the paper questionnaires and reliance upon telephone consultations limiting online distribution. Increasing OTC/POM misuse and obtaining illicit supplies were reported when access to usual supplies were restricted; however, changes to doses/dispensing arrangement liberalisation in response to COVID-19 were positively viewed.

Conclusion:

OTC/POM misuse, including polypharmacy and concomitant use of other substances occurred during COVID-19: SMS need to be vigilant for these issues and mitigate the associated risks for example with harm reduction interventions. Further qualitative research is required to explore the issues identified.

Management of Pregabalin Use Disorder: A Case Series

Pregabalin is indicated for the treatment of partial epilepsy, generalized anxiety disorder, and neuropathic pain. The first reports on pregabalin use disorder have been published in Europe in 2010 and notified to the French Addictovigilance Network (FAN) in 2011. The management of pregabalin use disorder is challenging due to the risks associated with the abrupt withdrawal and lack of guidelines. In this retrospective observational study, the management of pregabalin use disorder was analyzed in eight cases reported to the addictovigilance center of Montpellier, France, between 2019 and 2020. Most of these patients had a history of illicit psychoactive substance use. During the withdrawal period, patients experienced mainly psychiatric problems, nervous system symptoms, general disorders, and gastrointestinal symptoms. Multiple strategies were proposed for these patients to manage pregabalin withdrawal, such as hospitalization and pregabalin gradual dose reduction with or without adjuvant medications. Two patients relapsed and the others were lost to follow up. Although other reports of pregabalin use disorder have been published, recommendations or guidelines for its management are not yet available. The current case series and the previous reports suggest that the use of adjunctive therapy may be useful to limit the risk of convulsions and anxiety.

Gabapentin prevalence: clinical and forensic experience in St. Louis, Missouri, USA

Gabapentin (Neurontin) is an anti-epileptic drug that has had wide off-label prescription use since market release due to presumed negligible abuse potential. However, trends in drug misuse have demonstrated that gabapentin misuse is occurring, particularly in those with a history of opioid misuse. This is concerning, because although gabapentin has no direct ligand activity at opioid receptors, it does potentiate the analgesic effect of opioids, and concurrent use of gabapentin and opioids may increase the risk of respiratory depressive effects of opioids. This study investigates the incidence of gabapentin detected in urine samples collected for clinical drug screening purposes in a local hospital emergency department and in postmortem samples submitted by medical examiners in the St. Louis metropolitan area. The prevalence of gabapentin and co-detected drugs in both populations is contrasted, compared, and discussed. This study found that 30% of urine samples collected from patients with suspected drug intoxication presenting to SSM Health Saint Louis University Hospital, a quaternary care medical center, were positive for gabapentin, and nearly two thirds of those were also positive for oxycodone. Over a 6-month period, the incidence of gabapentin positive postmortem cases increased from 18% to 20%. Nearly all gabapentin positive postmortem cases were also positive for an opioid, the most significant being fentanyl, suggesting that gabapentin misuse may be due to its potentiating effect of opioid drug action. This study also highlights the limited utility of immunoassay-based urine drug screens.

Gabapentinoids: The rise of a new misuse epidemics?

Gabapentinoids and opioids have in common that they are used in medicine in the treatment of pain, and by addicts in recreational use. In recent years, in the context of the "opioid epidemics", gabapentinoids, which had a reputation for low risk of abuse, have been increasingly prescribed. This was accompanied by increasingly frequent abuses, the patients most at risk being those suffering from opiate addiction. However, gabapentinoids increase the risks associated with opioids or other sedatives, due to a synergy of central depressant effects. This leads to reconsider the framework of their prescription and the management of chronic pain.

Characteristics of fatal gabapentinoid-related poisoning in Australia, 2000-2020

INTRODUCTION

Gabapentinoids are centrally active GABA agonists whose use has increased substantially in the past decade. The current study aimed to provide a comprehensive clinical profile of a national case series of fatal poisonings related to gabapentinoids.

METHODS

Retrospective study of all deaths due to drug toxicity in Australia in which gabapentinoids were a contributory mechanism, retrieved from the National Coronial Information System (2000-2020). Information was collected on case characteristics, toxicology and major organ pathology.

RESULTS

A total of 887 cases were identified, with a mean age of 45.7 years and 55.2% being male. Death was due to accidental toxicity in 81.3% of cases and intentional in 18.7%. Pre-existing disease was co-contributory to drug toxicity in 19.5%. Pregabalin was present in 92.9% of cases, with a median blood concentration of 7.6 mg/L (range 0.1-850.0 mg/L). Gabapentin was present in 7.2%, with a median blood concentration of 9.5 mg/L (range 0.5-1940.0 mg/L). Both pregabalin and gabapentin were present in five cases. No other gabapentinoids were detected. Drugs other than gabapentinoids were present in 99.8%, most frequently opioids (90.1%), hypnosedatives (76.9%) and antidepressants (60.5%). A body mass index in the obese range was seen in 45.4%. Clinically significant pre-existing disease was common, notably cardiomegaly (24.9%), emphysema (20.2%), nephrosclerosis (18.7%) and severe hepatic steatosis (11.7%).

CONCLUSIONS

The concomitant use of other drugs was close to universal, with CNS depressants predominating. Mental health problems, chronic pain and substance misuse were prominent.

Gabapentinoid Pharmacology in the Context of Emerging Misuse Liability

This article will review the epidemiology and pharmacology of gabapentinoids (gabapentin and pregabalin) relevant to their emerging misuse potential and provide guidance for clinical and regulatory management. Gabapentinoids are γ-aminobutyric acid analogues that produce their therapeutic effects by inhibiting voltage-gated calcium channels and decreasing neurotransmitter release. Recently gabapentinoid prescribing and use have increased tremendously. Although traditionally thought to possess a favorable safety profile, gabapentinoid misuse has also risen significantly. Gabapentinoid misuse generally occurs in combination with other substances, most notably opioids, and may be for purposes of eliciting euphoric effects, enhancing the effects of other substances, or self-treating conditions such as withdrawal, pain, anxiety, or insomnia. Given its faster onset, increased bioavailability and potency, and nonsaturable absorption, pregabalin's pharmacokinetics theoretically enhance its misuse liability versus gabapentin. However, gabapentin can produce similar euphoric effects, and epidemiologic studies have identified higher rates of gabapentin misuse in the United States, likely because of greater availability and less regulated prescribing. Although adverse events of gabapentinoid-only ingestion are relatively benign, a growing body of evidence indicates that gabapentinoids significantly increase opioid-related morbidity and mortality when used concomitantly. In addition, significant withdrawal effects may occur on abrupt discontinuation. As a result of these trends, several US states have begun to further regulate gabapentinoid prescribing, reclassifying it as a controlled substance or mandating reporting to local prescription drug-monitoring programs. Although increased regulation of gabapentin prescribing may be warranted, harm reduction efforts and increased patient and provider education are necessary to mitigate this concerning gabapentinoid misuse trend.

Should gabapentinoids be prescribed long-term for anxiety and other mental health conditions?

Prescription rates for gabapentinoids are rising in England. Pregabalin is currently recommended by NICE for the treatment of anxiety. Gabapentinoids have some overlap with the action of benzodiazepines, and have similar issues with tolerance, dependence, addiction and withdrawal. They were scheduled as class C controlled drugs in 2019 because of these risks. There were 244 deaths due to poisoning recorded by the ONS in 2019 involving pregabalin. Poisonings due to pregabalin usually involve concomitant use of opioids or other drugs. The rate of deaths involving pregabalin has been rising steeply for the last 10 years, and now exceeds those attributed to diazepam, fentanyl, the tricyclics as a group or SSRIs as a group. Evidence for the use of pregabalin in anxiety is derived from short-term trials, with marginal differences from placebo, which do not take into account the longer term effects of tolerance, dependence and withdrawal. We call on NICE to re-evaluate their support for use of pregabalin in anxiety in light of its known harms. The use of gabapentinoids off-label for other psychiatric conditions should also be re-considered. In general, psychotropic medications require longer term efficacy and safety studies before allowing widespread use.

The gabapentinoid drugs and their abuse potential

The gabapentinoid drugs, gabapentin and pregabalin, are first-line treatments for neuropathic pain. The epidemics of chronic pain and opioid misuse have given rise to the widespread use of non-opioid drugs such as the gabapentinoids for treatment. Unfortunately, the widespread use of gabapentinoid drugs has resulted in reports of misuse and abuse. Here we summarize the clinical reports of gabapentinoid abuse in different patient populations to help inform clinical practice of chronic pain management.

Misuse of medication in adult substance misuse services: a systematic review protocol

INTRODUCTION

There is a growing concern about the misuse of over the counter (OTC) and prescription only medication (POM) because of the impact on physical and mental health, drug interactions, overdoses and drug-related deaths. These medicines include opioid analgesics, anxiolytics such as pregabalin and diazepam and antidepressants. This protocol outlines how a systematic review will be undertaken (during June 2021), which aims to examine the literature on the pattern of OTC and POM misuse among adults who are accessing substance misuse treatment services. It will include the types of medication being taken, prevalence and demographic characteristics of people who access treatment services.

METHODS AND ANALYSIS

An electronic search will be conducted on the Cochrane, OVID Medline, Pubmed, Scopus and Web of Science databases as well as grey literature. Two independent reviewers will conduct the initial title and abstract screenings, using predetermined criteria for inclusion and exclusion. If selected for inclusion, full-text data extraction will be conducted using a pilot-tested data extraction form. A third reviewer will resolve disagreements if consensus cannot be reached. Quality and risk of bias assessment will be conducted for all included studies. A qualitative synthesis and summary of the data will be provided. If possible, a meta-analysis with heterogeneity calculation will be conducted; otherwise, Synthesis Without Meta-analysis will be undertaken for quantitative data. The reporting of this protocol follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

ETHICS AND DISSEMINATION

Ethical approval is not required. Findings will be peer reviewed, published and shared verbally, electronically and in print, with interested clinicians and policymakers.

PROSPERO REGISTRATION NUMBER

CRD42020135216.

Toxicological Relevance of Pregabalin in Heroin Users: A Two-Year Post-Mortem Population Study

Pregabalin (PGL) is a gabapentinoid used to treat epilepsy, neuropathic pain and generalized anxiety disorder. PGL is also misused by heroin users as it enhances the effects of heroin. While it is thought those who misuse PGL take it in amounts greater than the recommended therapeutic dose, it is unknown whether there is a significant difference between the amounts of PGL used by heroin users compared to non-heroin users. This study hypothesised that the PGL concentrations in post-mortem samples taken from heroin users positive for PGL would be higher than those in non-heroin users. Between 01.01.2016 and 31.12.2017, a routine drugs screen and a specific screen for PGL was carried out on femoral-vein bloods from 3,750 post-mortem Coroners' cases. Of the cases screened, 354 were heroin users, of which 264 cases were negative for gabapentinoids and therefore used as the control-heroin users group. PGL was positive in 229 cases, of which 69 were heroin users and 160 were non-heroin users. On comparing the PGL concentrations, statistically higher concentrations were observed in the heroin users compared to non-heroin users (P = 0.002). There was no correlation between the concentrations of PGL and morphine (from heroin) in the heroin users (P = 0.95), and the amount of heroin (morphine) consumed was not dependant on whether PGL was consumed or not (P = 0.98). The prevalence of anti-depressants, benzodiazepines, methadone and non-heroin related opioids were seen to be significantly higher in heroin users that were positive for PGL than the control-heroin users (P = < 0.001 for all drugs). This study suggests that heroin users are using greater amounts of PGL compared to non-heroin users; however, the magnitude of the difference in use may not be sufficient to conclude that heroin users are at substantially greater risk of pregabalin toxicity compared to non-heroin users. Results indicate that heroin users who take PGL are more likely to use multiple depressant drugs, hence increasing the risk of multi-drug toxicity and death in this population.

Pharmacologically Induced Ventilatory Depression in the Postoperative Patient: A Sleep-Wake State-Dependent Perspective

Pharmacologically induced ventilatory depression (PIVD) is a common postoperative complication with a spectrum of severity ranging from mild hypoventilation to severe ventilatory depression, potentially leading to anoxic brain injury and death. Recent studies, using continuous monitoring technologies, have revealed alarming rates of previously undetected severe episodes of postoperative ventilatory depression, rendering the recognition of such episodes by the standard intermittent assessment practice, quite problematic. This imprecise description of the epidemiologic landscape of PIVD has thus stymied efforts to understand better its pathophysiology and quantify relevant risk factors for this postoperative complication. The residual effects of various perianesthetic agents on ventilatory control, as well as the multiple interactions of these drugs with patient-related factors and phenotypes, make postoperative recovery of ventilation after surgery and anesthesia a highly complex physiological event. The sleep-wake, state-dependent variation in the control of ventilation seems to play a central role in the mechanisms potentially enhancing the risk for PIVD. Herein, we discuss emerging evidence regarding the epidemiology, risk factors, and potential mechanisms of PIVD.

Explaining the Differences in Opioid Overdose Deaths between Scotland and England/Wales: Implications for European Opioid Policies

BACKGROUNDS

Between 2009 and 2018, the number of opioid-related deaths (ORDs) in Scotland showed a dramatic increase, whereas in England and Wales, a much lower increase in ORD was seen. This regional difference is remarkable, and the situation in Scotland is worrisome. Therefore, it is important to identify the drivers of ORD in Scotland.

METHODS

A systematic literature review according to PRISMA guidelines was conducted to identify peer-reviewed studies about key drivers for the observed differences in ORDs between Scotland and England/Wales. In addition, non-peer-reviewed reports on nationwide statistical data were retrieved via Google and Google Scholar and analysed to quantify differences in ORD drivers between Scotland and England/Wales.

RESULTS

The systematic review identified some important drivers of ORD, but none of these studies provided direct or indirect comparisons of ORD drivers in Scotland and England/Wales. However, the reports with nationwide statistical data showed important differences in ORD drivers between Scotland and England/Wales, including a higher prevalence of people using opioids in a problematic way (PUOP), more polydrug use in people using drugs in a problematic way (PUDP), a higher age of PUDP, and lower treatment coverage and efficacy of PUDP in Scotland compared to England/Wales, but no regional differences in injecting drug use, incarceration/prison release without treatment, and social deprivation in PUDP.

CONCLUSION

It is concluded that the opioid crisis in Scotland is best explained by a combination of drivers, consisting of a higher population involvement in (problematic) opioid use (notably methadone), relatively more polydrug use (notably benzodiazepines and gabapentinoids), a steeper ageing of the PUOP population in the past 2 decades, and lower treatment coverage and efficacy in Scotland compared to England/Wales. The findings have important consequences for strategies to handle the opioid crisis in Scotland.