Pregabalin abuse among opiate addicted patients

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.

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.

Fatal pregabalin poisoning in Japan: A case report

Pregabalin is a new drug used for treating neuropathic pain, epilepsy, and anxiety disorders. Since 2010, the number of pregabalin prescriptions has dramatically increased in many countries. Although pregabalin has been considered to have a low potential for abuse and toxicity, fatal cases associated with pregabalin misuse or abuse have been increasing with an increased number of prescriptions. In addition, these fatalities are likely under-reported because pregabalin is commonly not part of postmortem routine drug screens. By contrast, pregabalin-related death has not yet been reported in Japan. We encountered a fatal case of pregabalin overdose. The patient has visited hospitals for benzodiazepine dependence, insomnia and anxiety disorder and has been prescribed pregabalin, flunitrazepam, and zolpidem. One day, his home caregivers, who were his constant companions to the hospitals, found him dead. Comprehensive drug screening performed in the police crime laboratory detected 7-aminoflunitrazepam and zolpidem, but not pregabalin in the cardiac blood. By contrast, we could find all drugs, including pregabalin, in our autopsy because pregabalin was a part of our routine drug screening. The pregabalin concentration was fatal at 18.5 μg/mL in the femoral blood, whereas 7-aminoflunitrazepam (0.1 μg/mL) and zolpidem (0.2 μg/mL) were lower than the fatal levels. We concluded that pregabalin played a primary role in the cause of death but not independently. This report addresses Japanese clinicians and forensic toxicologists to the risk of pregabalin poisoning, and pregabalin should be added in postmortem routine drug screening.

Methamphetamine as the most common concomitant substance used with pregabalin misuse

BACKGROUND AND AIM

Non-medical use of Pregabalin (PGB) is a growing concern in many countries because of the serious consequences associated with their abuse. Judicial cases within the probation system, multiple drug users, and patients in treatment programs administered PGB at higher doses than suggested, commonly without prescription. For this reason, it is important to analyze PGB by adding it to the routine analysis scale in determining whether PGB is used for medical purposes or abuse. In this study, PGB analyzed (single or multiple substance use, concomitant substances) in urine samples of forensic and clinical cases by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition to the sociodemographic and clinical characteristics of pregabalin-positive cases, the results were evaluated separately from a clinical and forensic perspective.

METHODS

All urine samples which was admitted to Addiction Toxicology Laboratory from 'drug abuse probation system' (forensic cases, n = 640) and from various departments of our hospital (clinical cases, n = 371) between December 2022 and April 2023. Screening analysis were carried out by immunoassay in total 1011 cases. LC-MS/MS method simultaneously analyzed amphetamine, benzoilecgonine, cocaine, codeine, metamphetamine, morphine, 3,4-metilenedioksi-N-metilamfetamin (MDMA), 11-nor-9-karboksi-Δ9-tetrahidrokannabinol and pregabalin in urine samples. PGB was added to the our routine substance screening analysis scale in December 2022 to detect pregabalin use.

RESULTS

PGB was detected in 12.3% of probabition cases and 13.2% of clinical cases. The mean age of PGB positive cases was 26.55 ± 7,52 years old, predominantly males (%85,9). Single PGB was detected in 53.2% of forensic cases (n = 42), and 38.7% of clinical cases (n = 19). The most common substance detected concomitantly with PGB was amphetamine type stimulants (ATSs:amphetamine, methamphetamine, ecstasy/MDMA etc.) (22.8% of forensic cases and 46.9% of clinical cases), followed by concomitant cannabis use (24.1% of forensic cases and 26.5% of clinical cases). Concomitant opioid use was rare (1.3% of forensic cases and 4.1% of clinical cases). Detection of PGB was significantly different across months on which the samples were collected (x2 = 82.8, df=4, p < 0.001).

CONCLUSION

Inconsistently with previous studies suggesting opioids as the most prevalant substances concominant with PGB, our results showed that stimulants (especially ATSs) were the most prevelant substances concominant with PGB, followed by cannabis. High proportion of PGB detection in probabition cases, frequently as a single substance abuse takes attention. These results suggest that PGB, may be used to avoid legal consequences. It is important for laboratories to be aware that they need to make changes as addition of newly abused substances in their analysis panels, when necessary, as differences between regions and cultures affect substance use patterns.

Cohort study of new off-label gabapentin prescribing in chronic opioid users

INTRODUCTION

Gabapentin is commonly prescribed as an off-label adjunct to opioids because of its safer risk profile. Recent evidence has shown an increased risk of mortality when coprescribed with opioids. Therefore, we aimed to evaluate whether the addition of off-label gabapentin in patients with chronic opioid use is associated with a reduction in opioid dosage.

METHODS

We performed a retrospective cohort study of patients with chronic opioid use with a new off-label gabapentin prescription (2010-2019). Our primary outcome of interest was a reduction in opioid dosage measured via oral morphine equivalents (OME) per day after the addition of a new off-label gabapentin prescription.

RESULTS

In our cohort of 172,607 patients, a new off-label gabapentin prescription was associated with a decrease in opioid dosage in 67,016 patients (38.8%) (median OME/day reduction:13.8), with no change in opioid dosage in 24,468 patients (14.2%), and an increase in opioid dosage in 81,123 patients (47.0%) (median OME/day increase: 14.3). A history of substance/alcohol use disorders was associated with a decrease in opioid dosage after the addition of a new off-label gabapentin (aOR 1.20, 95% CI 1.16 to 1.23). A history of pain disorders was associated with a decrease in opioid dosage after the initiation of a new gabapentin prescription including arthritis (aOR 1.12, 95% CI 1.09 to 1.15), back pain (aOR 1.10, 95% CI 1.07 to 1.12), and other pain conditions (aOR 1.08, 95% CI 1.06 to 1.10).

CONCLUSIONS

In this study of patients with chronic opioid use, an off-label gabapentin prescription did not reduce opioid dosage in the majority of patients. The coprescribing of these medications should be critically evaluated to ensure optimal patient safety.

Pregabalin use in forensic hospitals and prisons in German speaking countries-a survey study of physicians

Background

Pregabalin is a gamma-aminobutyric acid (GABA) analog that was approved in the EU in 2004 for the treatment of neuropathic pain, generalized anxiety disorder and epilepsy. Since its introduction, pregabalin abuse and misuse has increased significantly. In Switzerland, clinical reports suggest that pregabalin misuse is common among patients in forensic hospitals and prisons. However, data on pregabalin use is scarce, especially in these settings. Therefore, we conducted a study to explore patterns of pregabalin use among prison and forensic patients.

Methods

We used a questionnaire to survey physicians working in prison and forensic medicine in German-speaking countries. A total of 131 responses were received.

Results

According to the physicians' subjective assessment, 82.5% of them had observed a recent increase in pregabalin use by their patients and 89.1% of them reported that their patients requested pregabalin without a clear medical indication. Patients misusing pregabalin in combination with other illicit substances were observed by 93.3% of the physicians surveyed. According to 73.5% of the physicians surveyed, they had already encountered patients on pregabalin doses of more than 600 mg/day (the maximum recommended daily dose); the highest dose reported was 4,200 mg/day. According to 85.0% of physicians surveyed, they have observed patients experiencing withdrawal symptoms from pregabalin, with the most commonly reported symptoms being displeasure and high aggression. Regarding the nationality of pregabalin-misusing patients, 58.3% of the interviewed physicians reported to be rather in contact with foreign patients, mainly from Northwest Africa (Maghreb). Only 45.0% of the surveyed physicians prescribe pregabalin. Among patients who developed behavioral problems while taking pregabalin, none of the physicians (0.0%) showed a tendency to continue pregabalin at the same dose; all respondents chose to reduce/substitute/discontinue.

Conclusion

Our study has provided confirmatory evidence that the use of pregabalin presents a significant issue in forensic and prison medicine across German-speaking countries. Prescribing pregabalin in this field can compound use disorder problems and exacerbate challenges in daily life for those in forensic institutions or prisons. It is necessary that all physicians who prescribe pregabalin are clearly informed about the management (including the risks) of this drug.

Content and sentiment analysis of gabapentinoid-related tweets: An infodemiology study

INTRODUCTION

The increasing number of gabapentinoid (pregabalin and gabapentin) harms, including deaths observed across countries is concerning to health-care professionals and policy makers. However, it is unclear if the public shares these concerns. This study aimed to describe posts related to gabapentinoids, conduct a content analysis to identify common themes and describe adverse events or symptoms.

METHODS

Keywords of 'pregabalin' or 'Lyrica' or 'gabapentin' or 'Neurontin' were used to search for related tweets posted by people in the community between 8 March and 7 May 2021. Eligible tweets included a keyword in the post. We extracted de-identified data which included descriptive data of the total number of posts over time; and data on individual tweets including date, number of re-tweets and post content. Data were exported separately for pregabalin- and gabapentin-related tweets. A 20% random sample was used for the thematic analysis.

RESULTS

There were 2931 pregabalin-related tweets and 2736 gabapentin-related tweets. Thematic analysis revealed three themes (sharing positive experiences and benefits of taking gabapentinoids, people voicing their negative experiences, and people seeking opinions and sharing information). Positive experiences of gabapentinoids were related to sharing stories and giving advice. This was contrasted to negative experiences including ineffectiveness, withdrawals, side effects and frustration related to cost and insurance coverage. Brain fog was the most common adverse symptom reported. Gabapentinoid-related deaths were only mentioned in three tweets.

DISCUSSION

The increasing public health concern of gabapentinoid-related deaths was not translated to Twitter discussions.

The safety and efficacy of gabapentinoids in the management of neuropathic pain: a systematic review with meta-analysis of randomised controlled trials

BACKGROUND

There are increasing concerns regarding the abusive potential of gabapentinoids putting at risk patients with neuropathic pain requiring long-term pain management. The evidence to support this is rather inconcusive.

AIM

This systematic review aimed to evaluate the safety and efficacy of gabapentinoids in the management of neuropathic pain with a focus on randomised controlled trials (RCTs) and categorising the side effects according to the body systems they were affecting.

METHOD

Searches were conducted in MEDLINE (PubMed), EMBASE, Web of Science, PsycoINFO, and CINAHL (EBSCO), and included RCTs to identify and critically appraise studies investigating safety and therapeutic effects of gabapentionoids in adults with neuropathic pain. Data extraction was conducted using an established Cochrane form and the risk-of-bias tool was used in the assessment of quality.

RESULTS

50 studies (12,398 participants) were included. The majority of adverse events pertained to the nervous system (7 effects) or psychiatric (3 effects) disorders. There were more adverse effects reported with pregabalin (36 effects) than with gabapentin (22 effects). Six pregabalin studies reported euphoria as a side effect, while no studies reported euphoria with gabapentin. This was the only side effect that may correlate with addictive potential. Gabapentioids were reported to significantly reduce pain compared to placebo.

CONCLUSION

Despite RCTs documenting the adverse events of gabapentionoids on the nervous system, there was no evidence of gabapentinoid use leading to addiction, suggesting an urgent need to design studies investigating their abusive potential.

Patterns of pregabalin prescribing in four German federal states: analysis of routine data to investigate potential misuse of pregabalin

OBJECTIVES

The objectives of this study were to investigate the utilisation patterns of pregabalin, to identify users potentially misusing pregabalin and to compare this group of patients to patients prescribed recommended doses of pregabalin concerning their personal characteristics and the coordination among their prescribers. Unintended coprescription of drugs with addictive potential might occur when care is insufficiently coordinated.

DESIGN

Secondary data analysis of linked data from three regional sickness funds in Germany (AOK) for the years 2014-2016.

SETTING

Ambulatory and hospital care sector in four German federal states.

METHODS

On the basis of routine data, patients who received at least three prescriptions of pregabalin were identified and classified into patients prescribed pregabalin as recommended and those dispensed with a higher than recommended dose (>600 mg/day). Social network analysis was applied to identify prescription networks and to analyse cooperation among the prescribers. With descriptive statistics and univariate statistical tests, typical characteristics of the group of patients potentially misusing pregabalin were compared with the others.

RESULTS

Among the 53 049 patients prescribed pregabalin, about 2% (877) were classified as potentially misusing pregabalin. The majority of this group was male and aged between 30 and 60 years. Of the patients misusing pregabalin, 365 (42%) had a diagnosed history of substance use disorders and 359 (41%) had been prescribed another drug with addictive potential (opioids) before. The prescribers of those patients potentially misusing pregabalin were more loosely connected within networks compared with prescribers of patients prescribed pregabalin as recommended.

CONCLUSION

This study found that patients could exceed recommended doses of pregabalin by getting prescriptions from multiple physicians. Specific patients were at increased risk of potentially misusing pregabalin, and these patients sought to obtain their prescriptions from physicians who were as loosely connected as possible. Coordination and sharing a relevant number of patients seem to be levers to avoid these problems of unintended coprescribing.

Managing the misuse potential and risk of psychological harm from gabapentinoids in primary care in New Zealand

Gabapentinoid prescribing is increasing in New Zealand. International evidence suggests that this prescribing trend is followed by increasing harms, including misuse, dependence, overdose, and psychological harms including suicidal thoughts or behaviours. However, there is limited guidance for prescribers on how to manage these potential harms. Here, we summarise the current international literature and identify three main risk factors that can be used for screening purposes when considering prescribing a gabapentinoid, to identify patients that may be at greater risk of harm. Based on current knowledge of harms, we provide guidance to prescribers on monitoring patients taking gabapentinoids. Finally, we summarise the evidence regarding tapering, and highlight key knowledge gaps including other interventions, referral, and data from primary care populations.

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.

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.

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.

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.

[Pregabalin abuse and dependence in various European countries: Association with substitution policies]

INTRODUCTION

Pregabalin was first approved in 2004 for the treatment of peripheral neuropathic pain and focal epileptic seizures, with or without secondary generalization. Prescription frequency has increased significantly since approval. In the early days, little attention was paid to the problem of misuse and dependence on pregabalin; in recent years, there has been a significant increase in the number of publications focusing on this problem. This review deals with these risk factors and risk groups of pregabalin abuse and dependence in different European countries and their drug policies.

RESULTS

Pregabalin abuse and dependence has increased significantly since its introduction to the market. It was shown that solo abuse of pregabalin is rare. In most cases, pregabalin was combined with other substances, which is also a predictor of pregabalin abuse. There were different reasons for the non-prescription use of pregabalin; it was used to increase the psychotropic effect, on the one hand, and to alleviate withdrawal symptoms, on the other hand. Furthermore, in Sweden, pregabalin was found in 28% of fatal intoxications among drug addicts. Young people were particularly affected. Abuse of pregabalin was detected in countries with restrictive substitution programmes, while in countries with liberal drug policies, no abuse was detected. However, the data situation in Switzerland with a liberal substitution programme is based on only one study, which is why pregabalin use in liberal substitution programmes cannot be conclusively clarified.

CONCLUSIONS

There seems to be a connection between a country's drug policy and the illegal use of pregabalin among persons in a substitution programme in that country. There are also risk factors and risk groups for pregabalin dependence and abuse.

Gabapentinoid Abuse in France: Evidence on Health Consequences and New Points of Vigilance

Introduction: Gabapentinoid drugs (gabapentin and pregabalin) are widely used worldwide for epileptic and pain disorders. First signals of gabapentinoid abuse occurred in the last decade. This study aims to describe clinical characteristics of gabapentinoid use related disorders and health consequences in France. Materials and Methods: We designed a multisource investigation reviewing data reported to the French Addictovigilance Network (FAN) with pregabalin and gabapentin from 2010 to 2019. Information was obtained through the analysis of Spontaneous Reports (SRs) notified by health professionals and the pharmacoepidemiological surveys OSIAP (suspicious prescriptions forms indicators of potential abuse), OPPIDUM (observation of illicit drugs and misuse of psychotropic medications), DRAMES (death related to prescription drugs and other substances), and DTA (toxic deaths due to analgesics). Results: Over 2010-2019 period, were collected: (i) 265 SRs (258 pregabalin; 7 gabapentin); (ii) 816 forged prescription forms (805 pregabalin, 10 gabapentin, 1 involving both drugs); (iii) 145 cases of gabapentinoid use in people who use drugs (121 pregabalin; 24 gabapentin) and (iv) 31 cases of gabapentinoid-related deaths (25 pregabalin; 6 gabapentin). Risk factors of gabapentinoid abuse were opioid use disorders or psychiatric history, but cases of primary abuse in subjects without any substance abuse history were observed. Adverse outcomes concern almost exclusively pregabalin, with coma, dyspnea, convulsion, and conduction disorders. Treatment demands increased from 10.6% in 2018 to 23.1% in 2019, with pregabalin cited as the first substance leading to addictological care in the 2019 OPPIDUM survey. Gabapentinoid-related deaths increased over time. Pregabalin has become the first drug mentioned in forged prescriptions in 2019 (23.8% of OSIAP), while it ranked at the 15th position in 2017 (2.6%). Discussion: This study shows the importance of addictovigilance monitoring for gabapentinoids. Addictovigilance data helped to make visible the gabapentinoid-abuse related health harms (hospitalization for serious neurologic, psychiatric or cardiac effects, requests for addictological support and deaths) and to confirm the intrinsic abuse potential of pregabalin. These data highlight new points of vigilance considering observed primary abuse. At this point in France, the risk of abuse and related complications is very apparent with pregabalin. Still, it is identical to that observed elsewhere with gabapentin.

Current Evidence on Abuse and Misuse of Gabapentinoids

This review summarizes current evidence on the abuse and misuse of the gabapentinoids pregabalin and gabapentin. Pharmacovigilance studies, register-based studies, surveys, clinical toxicology studies, and forensic toxicology studies were identified and scrutinized with the goal to define the problem, identify risk factors, and discuss possible methods to reduce the potential for abuse and misuse. Studies found that gabapentinoids are abused and misused and that individuals with a history of psychiatric disorders or substance use disorder seem to be at high risk. Moreover, some evidence supports the notion that patients with opioid use disorders may be at an increased risk of abusing gabapentinoids. Available evidence also suggests that abuse and misuse are more frequent in users of pregabalin compared with users of gabapentin. Health professionals and prescribers should be aware of the risk for misuse of pregabalin and gabapentin, which eventually could lead to abuse, substance dependence, and intoxications. Prescribing to patients belonging to risk populations such as those with psychiatric disorders or substance use disorder should be avoided if possible and, if prescribed, signs of misuse and abuse should be monitored.

Non-medical use of benzodiazepines and GABA analogues in Europe

AIMS

We investigated the prevalence of non-medical use (NMU) of benzodiazepines and GABA analogues in Europe.

METHODS

Data were collected using the online Non-Medical Use of Prescription Drugs (NMURx) survey from France, Germany, Italy, Spain and the UK.

RESULTS

The study included 55 223 eligible surveys which, after post-stratification weights were applied, represented approximately 260 million European adults. Lifetime NMU of benzodiazepines was highest in Spain (6.5%, 95% CI: 6.0-7.0) and lowest in Germany (1.7%, 1.5-2.0). Lifetime NMU of GABA analogues was highest in Germany (5.4%, 5.0-5.7) and lowest in France (2.2%, 1.9-2.5) and the UK (2.2%, 1.9-2.6) While no notable difference was observed for France or the UK, there was a higher prevalence of last 12-month NMU of benzodiazepines compared to GABA analogues in Italy (2.4 times higher) and Spain (3.0 times higher) and a higher prevalence of NMU of GABA analogues compared to benzodiazepines in Germany (2.6 times higher).

CONCLUSION

This study shows that there is variation in NMU of benzodiazepines and GABA analogues among countries. Of particular interest is the high incidence of GABA analogue NMU in Germany and benzodiazepine NMU in Spain. Further research to identify factors and motivations responsible for the higher prevalence observed are essential to inform public health policies in those countries.

Patterns and correlates of prescribed and non-prescribed pregabalin use among a sample of people who inject drugs in Australia

INTRODUCTION AND AIMS

Pregabalin is a gamma-aminobutyric acid analogue registered and subsidised for the treatment of neuropathic pain in Australia. Despite pre-clinical evidence of low abuse potential, there are increasing reports of extramedical use and overdose deaths involving pregabalin. This study aimed to describe patterns of pregabalin use among an Australian sample of people who inject drugs (PWID) and identify sociodemographic, substance use and mental/physical health correlates of prescribed and non-prescribed use.

DESIGN AND METHODS

Data were obtained from the 2018 Illicit Drug Reporting System, comprising a cross-sectional sample of 905 PWID recruited from Australian capital cities. Multinomial logistic regression was used to identify correlates of past 6-month prescribed and non-prescribed pregabalin use.

RESULTS

One-quarter (25%) of participants reported any past 6-month pregabalin use, with 10% reporting prescribed use and 15% non-prescribed use. Past 6-month use of prescribed benzodiazepines and non-prescribed pharmaceutical opioids were associated with both prescribed and non-prescribed pregabalin use compared to no recent pregabalin use. Pain/discomfort on the day of interview was significantly associated with prescribed pregabalin use. Recent use of non-prescribed benzodiazepines and illicit stimulants and past year non-fatal overdose were significantly associated with non-prescribed pregabalin use (compared to no recent pregabalin use).

DISCUSSION AND CONCLUSIONS

Pregabalin use was relatively common among an Australian sample of PWID. Benzodiazepine and pharmaceutical opioid use were positively correlated with both prescribed and non-prescribed pregabalin use, suggesting that education campaigns regarding the risks of harm associated with concomitant use of these substances are warranted (targeting both health professionals and consumers).

Trends in gabapentinoid prescribing, co-prescribing of opioids and benzodiazepines, and associated deaths in Scotland

BACKGROUND

Gabapentinoid drugs (gabapentin and pregabalin) are effective in neuropathic pain, which has a prevalence of ∼7%. Concerns about increased prescribing have implications for patient safety, misuse, and diversion. Drug-related deaths (DRDs) have increased and toxicology often implicates gabapentinoids. We studied national and regional prescribing rates (2006-2016) and identified associated sociodemographic factors, co-prescriptions and mortality, including DRDs.

METHODS

National data from the Information Service Division, NHS Scotland were analysed for prescribing, sociodemographic, and mortality data from the Health Informatics Centre, University of Dundee. DRDs in which gabapentinoids were implicated were identified from National Records of Scotland and Tayside Drug Death Databases.

RESULTS

From 2006 to 2016, the number of gabapentin prescriptions in Scotland increased 4-fold (164 630 to 694 293), and pregabalin 16-fold (27 094 to 435 490). In 2016 'recurrent users' (three or more prescriptions) had mean age 58.1 yr, were mostly females (62.5%), and were more likely to live in deprived areas. Of these, 60% were co-prescribed an opioid, benzodiazepine, or both (opioid 49.9%, benzodiazepine 26.8%, both 17.1%). The age-standardised death rate in those prescribed gabapentinoids was double that in the Scottish population (relative risk 2.16, 95% confidence interval 2.08-2.25). Increases in gabapentinoids contributing to cause of DRDs were reported regionally and nationally (gabapentin 23% vs 15%; pregabalin 21% vs 7%). In Tayside, gabapentinoids were implicated in 22 (39%) of DRDs, 17 (77%) of whom had not received a prescription.

CONCLUSIONS

Gabapentinoid prescribing has increased dramatically since 2006, as have dangerous co-prescribing and death (including DRDs). Older people, women, and those living in deprived areas were particularly likely to receive prescriptions. Their contribution to DRDs may be more related to illegal use with diversion of prescribed medication.

[Pregabalin and risk of addiction: A new care issue?]

PURPOSE

Pregabalin (PRG) is a gamma-aminobutyric acid (GABA) analogue used for treatment of epilepsy, neuropathic pain, generalised anxiety disorder and currently being studied for other indications. Supported by the results of case studies and a limited number of studies, there is an ongoing debate about the addictive potential of PRG. However, evidence is scarce and no definitive assessment on the potential for abuse and dependence to PRG is available. The objective of our study was to identify the number of cases of abuse or dependence to PRG published and to study potential risk factors of addiction to PRG.

METHODS

We have identified on PubMed and ScienceDirect published case studies of PRG abuse or dependence and analysed these cases on the basis of several clinical parameters.

RESULTS

A total of 118 cases of PRG abuse or dependence were identified, including 21 isolated cases (mean age 33 years, 67 % men). The mean daily dose of PRG was 2,9 g. Current or past polydrug abuse was present in the majority of cases. Psychiatric diagnoses, other than substance-related disorders, were reported in as many patients, and almost all patients experienced withdrawal symptoms when PRG was discontinued.

CONCLUSION

Current literature suggests an important and growing concern for the abuse of PRG. Male sex, psychiatric and/or addiction history, including opioid addiction, may be potential risk factors for the development of addictive behaviours associated with PRG.

Pregabalin and Its Involvement in Coronial Cases

Pregabalin is an anticonvulsant and analgesic designed to treat neuropathic pain and partial seizure disorders and has been available in Australia as a prescription medication since 2005. Studies have found high rates of polydrug use associated with pregabalin and it is reportedly used recreationally for its euphoric and relaxing effects as well as to self-manage opioid withdrawal symptoms. A robust analytical method for the analysis of pregabalin using protein precipitation and LC/MS/MS was developed, validated and employed in routine case work. In recent years a substantial increase in pregabalin detections in coronial case submissions had been noted. This study examines the case characteristics and outcomes of 332 coronial cases submitted to the laboratory and analyzed for pregabalin between 2015 and 2017. Pregabalin was identified in approximately 5% of all coronial cases submitted during this time. A high rate of concurrent drug use with pregabalin was evident with the predominant classes being opioids, benzodiazepines and anti-depressants. Post-mortem blood pregabalin concentrations ranged from <0.05 to 140 mg/kg (median 5.5 mg/kg); however, limited interpretation of levels could be achieved as the drug was rarely identified in the absence of other drugs. Cause of death (COD) was found to be drug related in 58% of all cases, with mixed drug toxicity specifically mentioned as related to COD in 40% of cases.

Pregabalin Abuse in Combination With Other Drugs: Monitoring Among Methadone Patients

INTRODUCTION

In recent years, there has been an increase in the non-medical use of psychoactive prescription drugs including pregabalin (PGB). Studies have shown that multiple drug users and patients in methadone treatment programs administered PGB at high dosages in order to achieve euphoria, reduce withdrawal symptoms, or potentiate the effects of methadone. For these reasons, accurate toxicological monitoring is required for these high-risk individuals.

MATERIALS AND METHODS

The present study investigated whether PGB could be detected in the hair samples of 250 patients with a history of opiate dependency, and under toxicological surveillance assess their compliance with methadone maintenance therapy.

RESULTS

Opiates were found in 54/250 of all hair samples, while cannabis was present in 74/250 patients, cocaine was detected in 21/250 patients, and benzodiazepines without prescription were identified in 49/250 patients. As expected, methadone was present in all 250 patients (100%). PGB without prescription was found in the hair samples of 35/250 patients (14%). Of these, 91.43% were male, 48.57% were <30 y old, and 45.71% were between ages 30 and 50 y. There were no apparent associations among PGB use, daily methadone dosage, and duration of methadone maintenance therapy. Psychiatric comorbidities were present in 25.71% of the patients abusing PGB. Anxiety (55.56%) and depression (33.33%) were the most prevalent psychiatric disorders.

DISCUSSION

Most of the patients taking PGB (57.14%) used other drugs (especially opiates) concurrently. The utility of hair analysis is explained by easy and rapid sample collection and the ability of the hair to reflect long-term drug use and incorporate drug metabolites. The findings of this study suggested that PGB has significant potential for abuse by high-risk populations such as opioid users and patients with dual diagnosis. These risks are particularly high in cases of poly-drug use and drug intake that are not in compliance with prescription guidelines.

A repeated cross-sectional study of factors associated with pregabalin-positive poisoning deaths in Ireland

BACKGROUND

The increasing use of pregabalin and the presence of pregabalin in poisoning deaths, particularly with opioids, highlight it as a potential drug of abuse. In this study we examined factors associated with pregabalin-positive poisoning deaths (PPPD) between 2013 and 2016 in Ireland.

METHODS

Data were extracted from the National Drug-Related Deaths Index (NDRDI). Analysis included univariate and multivariate logistic regression to estimate unadjusted and adjusted odds ratios (OR) and 95 % confidence intervals (CI) for factors associated with PPPD (primary outcome) by logistic regression models for the total sample and stratified by gender.

RESULTS

Pregabalin was present on 240 (16 %) toxicology reports of 1489 poisoning deaths; significantly rising from 15 (4.5 %) in 2013 to 94 (26 %) in 2016. Women (AOR 2.69, 95 % CI: 1.95-3.70), opioid misuse (AOR 1.74, 95 % CI: 1.17-2.59), in receipt of treatment for problem drug use (AOR 1.95, 95 % CI: 1.33-2.86) and year of death (2016 vs 2013) (AOR 7.95, 95 % CI: 4.58-13.79) were associated with increased odds of PPPD. Alcohol dependence was associated with reduced odds of PPPD (AOR 0.59, 95 % CI: 0.41-0.85). For men, opioid misuse, in receipt of treatment for problem drug use, and year of death were associated with increased odds of PPPD, while alcohol dependence was associated with reduced odds of PPPD. For women, in receipt of treatment for problem drug use and year of death were associated with increased odds of PPPD.

CONCLUSIONS

Enhanced training to prescribers and treatment providers on the potential risks associated with pregabalin, particularly among people who use drugs, is required.

Prevalence of Novel Psychoactive Substance (NPS) Use in Patients Admitted to Drug Detoxification Treatment

BACKGROUND

About 15 years ago, a diverse group of new recreational psychotropic substances began to emerge, which were marketed for example as "legal highs," "research chemicals," or "designer drugs." These substances were later subsumed under the label "Novel Psychoactive Substances" (NPS). Important NPS classes are cathinones, synthetic cannabimimetics, phenethylamines, and herbal drugs. The health care system for psychotropic substance use disorders (SUDs) traditionally focused on a few substances, such as alcohol, heroin, cocaine, amphetamines, or cannabis. Users of illicit substances often engage in polydrug use. However little is known about the prevalence of NPS use within the group of "classical" illicit substance users.

OBJECTIVE

We investigated lifetime and recent use of NPS and other drugs in patients who underwent in-patient detoxification treatment from illicit drugs in Germany.

METHODS

In a multicenter study with eight participating facilities, patients admitted to treatment underwent a standardized interview at admission, concerning their past and current substance use. The interview comprised classical substances of abuse, NPS, and rarely used substances such as LSD. In addition, participating sites had the opportunity to analyze their patients' routine drug screenings by means of gas chromatography/mass spectrometry (GC/MS), which permitted detection of NPS.

RESULTS

Interviews from 295 patients could be analyzed. Most patients were opiate dependent and multiple substance users. About 32% reported use of synthetic cannabimimetics during lifetime, but usually only a few times. An important reason for their use was that NPS were not detected by drug testing in prisons or drug treatment facilities. Cathinones, herbal drugs or other NPS had rarely been used during lifetime. NPS use during the last 30 days before admission was nearly zero. This was confirmed by urine analysis results. In contrast, lifetime and current use of opiates, alcohol, cocaine, benzodiazepines, and cannabis was high. In addition, 18% reported of regular unprescribed pregabalin use during lifetime, and 20% had recently used pregabalin.

CONCLUSION

Patients admitted to drug detoxification treatment showed multiple substance use, but this did not include NPS use. The diversion of legal medications such as pregabalin in this group is a serious concern.

Immediate and controlled-release pregabalin for the treatment of epilepsy

Introduction: Epilepsy is a common neurological disease requiring complex therapies, which are unable to achieve seizure control in 30% of patients. Poor adherence has been recognized as a possible determinant of drug-resistance. Prolonged-release formulations of antiepileptic drugs might help increase adherence and minimize side effects.Areas covered: Pregabalin (PGB) has peculiar pharmacodynamics and almost ideal pharmacokinetics, except for a short half-life and therefore requiring multiple daily dosing. PGB immediate-release (IR) is effective in focal-onset epilepsy (FOE), neuropathic pain, generalized anxiety disorder, and fibromyalgia, despite some tolerability issues, especially at higher doses. The controlled-release formulation (CR) shares PGB IR advantages and requires slight dose adjustments to guarantee bioavailability. In 2014, PGB CR (165 and 330 mg/day) failed to prove superior to placebo in a randomized placebo-controlled trial on 323 subjects with drug-resistant FOE, although it was just as tolerable. Therefore, PGB CR is not currently licensed for epilepsy.Expert opinion: Considering the disappointing results of the only controlled trial, PGB CR is unlikely to become an established epilepsy treatment anytime soon. Nevertheless, given its peculiar properties and potential advantages, PGB (in either formulation) should be further evaluated in specific populations of patients, especially fragile subjects with several comorbidities and complex polytherapies.

Prescriptions et usages de prégabaline : analyse d’une cohorte de 419 patients en centre d’étude et de traitement de la douleur et revue de la littérature

Du fait de l’augmentation du nombre de prescription de prégabaline dans le domaine de la douleur chronique et de cas relevés de mésusage récréatif ou toxicomaniaque avec ce médicament dans le monde, dans le contexte de la crise sanitaire en cours avec l’usage des opioïdes aux États-Unis, la crainte d’un risque addictif directement lié à l’usage de cette molécule a incité les autorités de divers pays à une surveillance accrue. Les recueils effectués par les centres de pharmacovigilance concernant la prégabaline relevant avant tout les situations considérées comme anormales, la description de l’usage de cette molécule au quotidien par un ensemble de prescripteurs et d’utilisateurs durant une période prolongée reflète mieux les conditions naturelles d’emploi de cette molécule et permet d’identifier les divers types de comportements des professionnels et usagers de santé à son égard. Une analyse rétrospective des dossiers de patients utilisateurs de prégabaline reçus et suivis dans une structure d’évaluation et prise en charge de la douleur pendant six ans a été réalisée, comprenant des données précises concernant les conditions d’usage et les effets du médicament. Les données issues de la littérature internationale et celles issues de l’étude montrent que le risque de mésusage et addictif est faible dans un contexte de prescription antalgique et de suivi médical adéquat, alors qu’il est élevé et directement lié à un mésusage de type récréatif ou toxicomaniaque en association avec les opioïdes ou l’alcool, en particulier dans la population jeune et en dehors du milieu des soins. Des recommandations d’usage de la prégabaline sont proposées aux professionnels afin de rappeler ces facteurs de risque.

Lack of correlation between the activity of the mesolimbic dopaminergic system and the rewarding properties of pregabalin in mouse

RATIONALE

Pregabalin is a psychoactive drug indicated in the treatment of epilepsy, neuropathic pain, and generalized anxiety disorders. Pregabalin acts on different neurotransmission systems by inactivating the alpha2-delta subunit of voltage-gated calcium channels. In light of this pharmacological property, the hypothesis has been raised that pregabalin may regulate the mesolimbic dopamine pathway and thereby display a potential for misuse or abuse as recently observed in humans. Although some preclinical data support this possibility, the rewarding properties of gabapentinoid are still a matter for debate.

OBJECTIVE

The aim of this work was to evaluate the rewarding properties of pregabalin and to determine its putative mechanism of action in healthy mice.

RESULTS

Pregabalin alone (60 mg/kg; s.c.) produced a rewarding effect in the conditioned place preference (CPP) test albeit to a lower extent than cocaine (30 mg/kg; s.c.). Interestingly, when assessing locomotor activity in the CPP, the PGB60 group, similarly to the cocaine group, showed an increased locomotor activity. In vivo single unit extracellular recording showed that pregabalin had mixed effects on dopamine (DA) neuronal activity in the ventral tegmental area since it decreased the activity of 50% of neurons and increased 28.5% of them. In contrast, cocaine decreased 75% of VTA DA neuronal activity whereas none of the neurons were activated. Intracerebal microdialysis was then conducted in awake freely mice to determine to what extent such electrophysiological parameters influence the extracellular DA concentrations ([DA]ext) in the nucleus accumbens. Although pregabalin failed to modify this parameter, cocaine produced a robust increase (800%) in [DA]ext.

CONCLUSIONS

Collectively, these electrophysiological and neurochemical experiments suggest that the rewarding properties of pregabalin result from a different mode of action than that observed with cocaine. Further experiments are warranted to determine whether such undesirable effects can be potentiated under pathological conditions such as neuropathic pain, mood disorders, or addiction and to identify the key neurotransmitter system involved.

Rising pregabalin use and misuse in Australia: trends in utilization and intentional poisonings

BACKGROUND AND AIMS

Pregabalin is a gamma-aminobutyric acid (GABA) analogue, used to treat neuropathic pain and epilepsy. Pregabalin was registered in Australia in 2005, and subsidized publically in 2013. We aimed to describe Australian patterns of pregabalin use and intentional poisoning, and identify people potentially at high risk of misuse.

DESIGN AND SETTING

Population-based retrospective cohort study of dispensings in the 10% sample of Australian Pharmaceutical Benefits Scheme (July 2012-February 2017); intentional poisoning calls to New South Wales Poisons Information Centre (NSWPIC) (2004-2016); intentional poisonings in two Australian toxicology service databases; and poisoning fatalities in NSW coronial records (2005-2016).

PARTICIPANTS

A total of 122 572 people dispensed pregabalin, people with intentional pregabalin overdoses managed by NSWPIC and the toxicology services and pregabalin-associated deaths referred to the NSW coroner.

MEASUREMENTS

Trends in dispensing, poisoning, death; demographics and patient characteristics, proportion of users at high risk of misuse (latent class analysis, LCA) and characteristics of high-risk users.

FINDINGS

Pregabalin dispensing increased by 73 424 per year [95% confidence interval (CI) = 61726-85 121 P < 0.001] between 2013 and 2016. NSWPIC received 1158 reports of intentional pregabalin poisonings, with a 53.8% increase per year, 2005-2016 (95% CI = 44.0-64.2%, P < 0.001). We identified 88 pregabalin-associated deaths, 57.8% yearly increase (95% CI = 30.0-91.6%, P < 0.001). Patients overdosing on pregabalin commonly co-ingested opioids, benzodiazepines and illicit drugs, and had high rates of psychiatric and substance use comorbidities; 14.7% of pregabalin users were classed by the LCA as at high risk of misuse, and were more likely to be younger, male, co-prescribed benzodiazepines or opioids, have more individual prescribers and higher pregabalin strengths dispensed.

CONCLUSIONS

There has been a dramatic increase in pregabalin use, poisonings and deaths in Australia since it became subsidized publicly in 2013. One in seven Australians dispensed pregabalin appears to be at high risk of misuse.

Misuse and Mortality Related to Gabapentin and Pregabalin are Being Under-Estimated: A Two-Year Post-Mortem Population Study

Due to the rise in their misuse and associated mortality, the UK government is reclassifying gabapentin (GBP) and pregabalin (PGL) to Class C controlled drugs from April 2019. However, it is impossible to gauge the extent of their use with current post-mortem toxicological screening, where GBP and PGL are only screened for if they are mentioned in the case documents. This study determines the prevalence of GBP and PGL, the potential extent of their under-reporting and poly-drug use in a post-mortem population. Between 1 January 2016 and 31 December 2017, 3,750 deceased from Coroners’ cases in London and South East England underwent a routine drugs screen and a specific screen for GBP and PGL. The prevalence of both drugs was determined in the cohort and the subcategories of heroin users and non-heroin-users. The prevalence of both drugs was compared to tramadol (Class C drug). Case documents were reviewed to investigate the under-reporting of GBP and PGL and poly-drug use. Of 3,750 samples analyzed, 118 (3.1%) were positive for GBP, 229 (6.1%) for PGL and 120 (3.2%) were positive for tramadol. If routine analysis without additional screening of GBP and PGL had been performed in this cohort, GBP would have been under-reported by 57.6% (P < 0.0001) and PGL by 53.7% (P < 0.0001) in deaths. The most common drug group observed with GBP and PGL was non-heroin-related opioids at 60.2% and 64.6%, respectively. In total 354 deceased (9.4%) were heroin users. GBP was positive in 23 (6.5%) of these cases and PGL was positive in 69 (19.5%). The prevalence of PGL in heroin users (19.5%) was 4.1 times greater than in non-heroin users (4.7%) (P < 0.0001). GBP and PGL are being significantly under reported in fatalities. Both drugs are extensively used with opioids. The prevalence of PGL in heroin users is highly significant.

Non-cancer pain clinic in three English prisons: understanding prisoner needs and prescribing practice in relation to chronic non-cancer pain (CNCP)

PURPOSE

Prisoner access to opiate-based analgesics and gabapentinoids is a concern to prisons through illicit trading. The purpose of this paper is to describe patient needs following introduction of nine pilot chronic non-cancer pain (CNCP) clinics for chronic pain in three prisons (two male and one female) in the South of England. The study evaluated the effectiveness of this model and assessed the wider practical implementation issues.

DESIGN/METHODOLOGY/APPROACH

Clinical notes were reviewed for 63 consultations, anonymised and recorded for secondary analysis.

FINDINGS

Alongside CNCP, high levels of substance misuse, physical and mental health histories were noted, especially for female patients. Amitriptyline, pregabalin, gabapentin were the main frontline analgesics prescribed prior to assessment. A total of 41 per cent of patients did not change their medication following the consultation; 25 per cent had their medication increased or reintroduced (greater for women prisoners); with one-third (33 per cent) of patients reducing the prescription of strong opioids and gabapentinoids. Significant differences were noted between male and female patients. Prisoners were amenable to changes in medication to facilitate access to work and other therapeutic interventions.

SOCIAL IMPLICATIONS

The prescribing of analgesics has largely been couched in terms of disruption to the prison regime through illicit trading. This study highlights the need to place CNCP within wider contexts of substance misuse, physical and emotional health. There is an opportunity to develop a rehabilitative rather than palliative approach to pain management. Gender specific approaches for female patients should be considered.

ORIGINALITY/VALUE

Few studies of CNCP have been conducted within a prison environment.

Patterns of gabapentin and pregabalin use and misuse: Results of a population-based cohort study in France

AIMS

The aim of this study was to assess the use and factors associated with the misuse of gabapentin and pregabalin in the general French population, through a cohort study in the EGB (General Sample of Beneficiaries), a national representative sample of the French general population.

METHODS

New users of gabapentin and pregabalin were identified from June 2006 to December 2014, and new users of duloxetine served as control group. Misuse was defined as a use of higher daily doses than recommended. Cox proportional hazard regression models were performed to identify associated factors of misuse.

RESULTS

Misuse was more frequent in the 8692 new users of pregabalin (12.8%) than in the 1963 gabapentin (6.6%) or the 3214 duloxetine new users (9.7%) (P < 0.001). Factors associated with misuse were pregabalin (hazard ratio [HR] 1.48; 95% confidence interval [CI] [1.29-1.69]), age (HR_{[18-45] versus > 70 years} 1.98 [1.70-2.31] and HR_{[58-70] versus > 70 years} 1.25 [1.06-1.47]), multiple prescribers (HR_{2 or 3 versus 1 prescriber} 1.29 [1.15-1.45]; HR_{4 or more versus 1 prescriber} 1.54 [1.30-1.83]), cancer (1.28 [1.11-1.47]), multiple sclerosis (1.53 [1.07-2.18]), neuropathy (1.85 [1.19-2.89]), depression (1.26 [1.07-1.49]) and methadone (2.61 [1.16-5.84]). After this first episode of drug misuse, 11.6% of gabapentin and 10.7% of pregabalin misusers developed a primary addiction.

CONCLUSION

In a cohort of new users, misuse is more likely to occur in new users of pregabalin, with different associated factors of misuse compared to gabapentin and duloxetine. Health professionals and prescribers must be aware of this misuse potential, which could lead to abuse and dependence.

Development of a Micellar Electrokinetic Chromatographic Method with Indirect UV Detection for Pregabalin Determination in Serum Samples

Background: A micellar electrokinetic chromatographic (MEKC)/ indirect UV detection method with hydrodynamic and electrokinetic injection has been developed for the determination of pregabalin in the serum samples. Methods: Separation of the drug was achieved on Agilent capillary electrophorese in less than 5 min using a 50 cm × 75 μm i.d. uncoated fused-silica capillary and a background electrolyte (BGE) consisting of 5-aminosalicylic acid (5-ASA, 10 mmol L-1), cetyl trimethylammonium bromide (CTAB, 1 mmol L-1) and tri-sodium citrate (4% w/v). The influence of various parameters on the separation such as separation voltage, injection time, cassette temperature, pH of BGE and organic modifier was investigated. Results: Method validation shown good linearity (R2> 0.999) in the range of 1.5-100 µg mL-1 of pregabalin. A limit of detection (LOD) of 0.8 μg mL-1 and a limit of quantitation (LOQ) of 2.6 μg mL-1 were reported for pregabalin. Conclusion: The proposed method was found to be suitable and accurate for the determination of pregabalin in serum samples.

Intentional Drug Overdose Involving Pregabalin and Gabapentin: Findings from the National Self-Harm Registry Ireland, 2007-2015

INTRODUCTION

Intentional drug overdose (IDO) is a significant public health problem. Concerns about the misuse of gabapentinoids, i.e. pregabalin and gabapentin, including their consumption in IDO have grown in recent years. This paper examines the trends in the prevalence of gabapentinoids taken in IDO, the profile of individuals taking them, and associated overdose characteristics.

METHODS

Presentations to emergency departments involving IDO, recorded by the National Self-Harm Registry Ireland between 1 January 2007 and 31 December 2015 were examined. Data items included patient demographics, drug names, total tablet quantity consumed and alcohol involvement.

RESULTS

Gabapentinoids were involved in 2115 (2.9%) of the 72,391 IDOs recorded. Presentations involving a gabapentinoid increased proportionally from 0.5% in 2007 to 5.5% in 2015. The majority of IDOs involving a gabapentinoid were made by females (59.9%), with over one-third (37.2%) involving alcohol. Compared with IDOs involving other drugs, presentations with a gabapentinoid were made by persons who were older (median 37 vs. 32 years) and involved a significantly greater median quantity of tablets (30 vs. 21, p ≤ 0.001), with over one-quarter (27.4%) of these involving the ingestion of 50 tablets or more. Admission to hospital was significantly more common following IDOs with a gabapentinoid compared with those without (49.4% vs. 41.4%, p ≤ 0.001).

CONCLUSIONS

This study identified the increasing use of gabapentinoids in IDO, describing the profile and overdose characteristics of presentations. It is important for clinicians to exercise vigilance while prescribing gabapentinoids, including being aware of other medications that their patients may have access to. Our findings support the need for routine monitoring for signs of misuse among those prescribed gabapentinoids.

Pregabalin misuse in methadone maintenance treatment patients in Israel: Prevalence and risk factors

BACKGROUND

Drug users reportedly abuse pregabalin, and its combination with opiates was related to fatalities. We aimed to estimate the prevalence of pregabalin misuse and risk factors among patients in methadone maintenance treatment (MMT).

METHODS

A cross-sectional study included all current MMT patients (n = 300) after excluding 9 with prescriptions, from a large tertiary medical center university-affiliated MMT clinic in Israel. Pregabalin was tested in one of the routine urine tests for other substances in December 2017. Data on urine results and patients' characteristics were retrieved from the patients' records.

RESULTS

Pregabalin was detected among 53 (17.7%) patients. The group had higher depressive symptoms severity score (21-HAM-D) (11.1 ± 8.4 vs. 8.3 ± 7.8, p = 0.03), a higher prevalence of sero-positive HIV (13.7% vs. 4.2%, p = 0.02), sero-positive hepatitis C (66.7% vs. 50.4%, p = 0.04), DSM-IV-TR Axis I psychiatric diagnosis (54.0% vs. 41.7%, p = 0.03), and positive urine for opiates (22.6% vs. 8.9%, p = 0.008), cannabis (39.6% vs. 4.0 p < 0.0005) benzodiazepine (BDZ) (77.4% vs. 18.2%, p < 0.0005) and oxycodone (11.3% vs. 0.4%, p < 0.0005). Logistic regression found pregabalin group as more likely to be urine positive to BDZ (OR = 12.8 95%CI 5.0-32.5) cannabis (OR = 22.7, 95%CI 6.3-81.6) and oxycodone (OR = 43.9, 95%CI 3.6-541.4), with higher 21-HAM-D scores (OR = 1.1, 95%CI 1.04-1.2) and hepatitis C sera-positive (OR = 4.1, 95% CI 1.5-11.4). Unexpectedly, 13.2% of the pregabalin group had take-home dose privileges, which are rewards to non-drug abusers.

CONCLUSIONS

High prevalence of pregabalin misuse among both BDZ abusers and non-abusers and patients with depressive symptoms supports both the inclusion of routine monitoring for pregabalin and intervention in MMT population.

Reports of gabapentin and pregabalin abuse, misuse, dependence, or overdose: An analysis of the Food And Drug Administration Adverse Events Reporting System (FAERS)

BACKGROUND

Reports of gabapentinoid (gabapentin and pregabalin) misuse have increased in recent years. Pharmacovigilance data from the Food and Drug Administration Adverse Event Reporting System (FAERS) provides a useful examination of adverse drug event (ADE) reporting for safety signal detection.

OBJECTIVE

This study was conducted to analyze epidemiological information on the nature and extent of gabapentin/pregabalin abuse utilizing the FAERS database.

METHODS

A query was designed utilizing SafeRx, an indexed, searchable database of FAERS data from October 2012-December 2016. All-cause and abuse-related (including abuse/misuse/dependence/overdose events) ADE reports for gabapentin and pregabalin were isolated, as well as limited demographic data. The proportional reporting ratio (PRR) was calculated to compare signal detection.

RESULTS

A total of 10,038 all-cause ADEs were reported to FAERS for gabapentin, including 576 (5.7%) abuse-related events. For pregabalin, 571 all-cause ADEs were identified, including 58 (10.2%) related to abuse. Compared to all-cause ADEs, those involved in abuse-related events were younger and more likely to be male. The PRR of pregabalin versus gabapentin abuse-related events was 1.77.

CONCLUSION

Though not traditionally thought of as drugs of abuse, over 600 cases of gabapentinoid abuse were reported in the time frame analyzed, prompting the need for further study and regulatory investigation.

Oxycodone-induced tolerance to respiratory depression: reversal by ethanol, pregabalin and protein kinase C inhibition

BACKGROUND AND PURPOSE

Oxycodone, a prescription opioid, is a major drug of abuse, especially in the USA, and contributes significantly to opioid overdose deaths each year. Overdose deaths result primarily from respiratory depression. We have studied respiratory depression by oxycodone and have characterized how tolerance develops on prolonged exposure to the drug. We have investigated the role of PKC in maintaining tolerance and have examined whether ethanol or pregabalin reverses oxycodone-induced tolerance.

EXPERIMENTAL APPROACH

Respiration was measured in male CD-1 mice by whole-body plethysmography. Mice were preinjected with oxycodone then implanted with mini-pumps (s.c.) delivering 20, 45 or 120 mg·kg-1 ·day-1 oxycodone for 6 days and subsequently challenged with oxycodone (3 mg·kg-1 , i.p.) or morphine (10 mg·kg-1 , i.p.) to assess the level of tolerance.

KEY RESULTS

Oxycodone-treated mice developed tolerance to oxycodone and cross tolerance to morphine-induced respiratory depression. Tolerance was less with 20 mg·kg-1 ·day-1 than with 45 or 120 mg·kg-1 ·day-1 oxycodone treatment. At doses that do not depress respiration, ethanol (0.3 g·kg-1 ), pregabalin (20 mg·kg-1 ) and calphostin C (45 μg·kg-1 ) all reversed oxycodone-induced tolerance resulting in significant respiratory depression. Reversal of tolerance was less in mice treated with oxycodone (120 mg·kg-1 ·day-1 ). In mice receiving ethanol and calphostin C or ethanol and pregabalin, there was no greater reversal of tolerance than seen with either drug alone.

CONCLUSION AND IMPLICATIONS

These data suggest that oxycodone-induced tolerance is mediated by PKC and that reversal of tolerance by ethanol or pregabalin may be a contributory factor in oxycodone overdose deaths.

Addiction-related interactions of pregabalin with morphine in mice and humans: reinforcing and inhibiting effects

The gabapentinoid pregabalin is a rapid-acting anxiolytic and analgesic, possibly suitable in supervised opioid detoxification. However, clinicians have been cautious in using it because of its unknown addictive risk and rising number of mortalities after pregabalin self-medication in opioid abusers. Here, we studied interactions of pregabalin and morphine on reward functions of the dopamine system in mice and the efficacy of pregabalin on withdrawal in opioid addicts. After the treatment of mice with pregabalin and morphine, we used electrophysiology to study neuroplasticity in midbrain slices, self-administration and conditioned place preference tests to investigate the rewarding potential of pregabalin and naloxone-precipitated morphine withdrawal to evaluate opioid withdrawal symptoms. Further, we ran a pilot single-blind, randomized, controlled trial (34 heroin addicts) to evaluate the efficacy and safety of pregabalin in the treatment of opioid withdrawal syndrome. Pregabalin alone did not induce glutamate receptor neuroplasticity of dopamine neurons in the ventral tegmental area, but pre-treatment with pregabalin suppressed morphine-induced neuroplasticity, hyperlocomotion and morphine self-administration. Pregabalin administration after chronic morphine exposure failed to induce any rewarding effects. Instead, pregabalin suppressed withdrawal symptoms in both morphine-treated mice and opioid addicts and was well tolerated. Intriguingly, pregabalin administration after a low dose of morphine strongly facilitated ventral tegmental area neuroplasticity and led to increased conditioned place preference. Pregabalin appears to have the efficacy to counteract both reinforcing and withdrawal effects of opioids, but it also has a potentiating effect when given to mice with existing opioid levels.

Substance misuse-related poisoning deaths, England and Wales, 1993–2016

Context

In recent years there has been an increase in the availability of ‘novel psychoactive substances (NPS)’ or ‘legal highs’. In turn, there is concern as to the risks these compounds pose as compared to those posed by traditionally misused substances such as illicit diamorphine (heroin), methadone, cocaine, and amfetamines.

Methods

We reviewed deaths where opiates/opioids, stimulants, hypnosedatives, hallucinogens, or volatile substances were mentioned on the death certificate in England and Wales, 1993–2016 as recorded on the Office for National Statistics drug poisoning deaths database. Deaths were analysed by year of registration of death, age, sex, intent, drug(s) involved, and the presence of alcohol (ethanol).

Results

There were 68,347 drug-related deaths in England and Wales (includes both licit and illicit substances), of which 15,457 were either coded as, or had mention of, drug dependent/non-dependent substance abuse on the death certificate. Opioids, particularly diamorphine/morphine and methadone, featured in most deaths. Diamorphine/morphine-related deaths (17,402) increased from 155 in 1993 to 981 in 2001, and then remained relatively stable until 2010 (791). Thereafter, annual numbers of deaths fell to 579 in 2012, but have since increased to 1,209 (2016). Deaths in the age group 20–29 years declined from 46% (1993), to 13% (2016), whereas in those aged 40–49 years the percentage of deaths increased from 13% (1993) to 33% (2016). Methadone was mentioned in 7,894 deaths (1993–2016). Annual numbers of such deaths increased from 206 to 437, 1993–7, then declined, but have since increased, reaching 413 in 2016. As to age, a similar pattern as to diamorphine/morphine-related deaths is apparent. Annual numbers of deaths involving cocaine (1993–2016: 3,342), reached 235 in 2008, declined, but have since increased (2011: 112, 2016: 371). Annual numbers of deaths involving methylenedioxyamfetamine/ methylenedioxyethamfetamine/ methylenedioxymetamfetamine (‘ecstasy’) (1993–2016: 853), have also increased steadily in recent years (2010; 8, 2016: 65). There were relatively few mentions of ‘novel stimulants’ (1993–2016: 386) on death certificates and such deaths have declined in recent years (2015: 88, 2016: 57). Mephedrone was most frequently mentioned (122), as was para-methoxyamfetamine/ para-methoxymetamfetamine (88). Conversely, although synthetic cannabinoids were mentioned infrequently (1993–2016: 37), such deaths have increased recently (2015: 8, 2016: 26).

Conclusions

Illicit diamorphine (heroin) and methadone continue to be the principal drugs of abuse involved in fatal poisonings in England and Wales. The increase in such deaths in recent years has been largely due to an increase in deaths amongst older users, although the role of potent synthetic opioids such as carfentanil is a cause for concern. Overall, stimulants and related compounds have been implicated in an increasing number of deaths annually. The impact of the plethora of NPS that have appeared in recent years on fatal poisonings may have been mitigated by legislation.

Utilization of gabapentin by people in treatment for substance use disorders in Belgium (2011-2014): a cross-sectional study

Background

Although gabapentin has been licensed in the European Union only for neuropathic pain and epilepsy for patients who have partial seizures, it has also been prescribed in treatment for substance use disorders. Many studies report the potential risk of abuse of gabapentin by people with substance use disorders. The objective of this paper is to determine if people who have been in treatment for substance use disorders bought gabapentin in a time span that could indicate consumption at a dose that exceeded the maximum approved dose of 3600 mg/day.

Methods

This analysis is the result of an observational cross-sectional descriptive study with matching. Two datasets were used and linked at individual level. Subjects were selected based on their first registration in the database of the Treatment Demand Indicator (TDI) between 2011 and 2014, without any exclusion criteria concerning nationality or age. Through linkage with the database of the InterMutualistic Agency (IMA) information on health service use and medication use was determined. In addition, each subject was matched on age, sex and place of residence to four comparators from the general population who were not in specialized treatment. The prevalence of gabapentin purchases in the period between 2008 and 2014 for both populations were compared. Quantification of the amount of gabapentin between two consecutive purchases was used as a proxy for potential abuse.

Results

Out of 30,905 patients in treatment for substance use disorders 2.7% had bought at least once gabapentin in a public pharmacy or received it from a hospital pharmacy, compared to 0.7% in the comparison group (n = 122,142). In both populations, more than half of the patients bought only once or twice gabapentin and about 10.0% bought at least once gabapentin in a time span that could indicate potential abuse. A limitation of the study is that it is only based on reimbursed medication without clinical information.

Conclusion

Through the linkage of the TDI-database and the database of the Belgian health insurance companies, no evidence was found for regular abuse of prescribed gabapentin in Belgium by people in treatment for substance use disorders.

Pregabalin Misuse and Abuse: A Scoping Review of Extant Literature

Prescribing of pregabalin is increasing worldwide with public health concerns centering on misuse and abuse of prescribed and diverted pregabalin. To describe and map what is known about misuse and abuse of pregabalin, a scoping review of available published literature was undertaken. A scoping review methodology was used to identify and map available literature on misuse and abuse of prescribed and diverted pregabalin. Four themes emerged on the misuse and abuse of pregabalin: (a) abuse potential, (b) prevalence of abuse, (c) risk and predisposition, and (d) consequences of abuse. Fifty-four records were reviewed and charted. Of note was the dearth of research on the topic prior to 2005, with increased interest in pregabalin abuse potential from 2010 onward. Available literature supports concern around abuse potential of pregabalin, especially among patients with a history of substance abuse. Prescribers should adopt more rational prescribing.

GC-MS/MS detects potential pregabalin abuse in susceptible subjects' hair

Pregabalin, a GABA analogue, binds to the alpha 2 delta subunit of voltage-dependent calcium channels. It is recognised as efficacious in pathologies such as epilepsy, neuropathic pain, and anxiety disorders. Since pregabalin prescriptions have increased worldwide, reports of its abuse have been accumulating, mainly in patients with opioid abuse disorders. The present study investigated potential pregabalin abuse by means of hair analysis, a matrix that provides valuable retrospective information. Half of the pool of 280 susceptible patients had been occasional drug users and were being monitored for driving licence renewals. The other 140 patients had a history of opiate dependency and were monitored to assess compliance with methadone therapy. In view of determining pregabalin in hair samples, it was extracted in methanol, successfully derivatised to give the ethyl chloroformate derivative, and finally pregabalin was analysed by gas chromatography-tandem mass spectrometry. Selectivity, linearity, limit of detection, limit of quantification, recovery, intra- and inter-day precision, and accuracy of the quantification procedure were appraised. Pregabalin limits of detection and quantification were 30 pg/mg and 50 pg/mg, respectively. We found 10.7% of hair samples from methadone patients and 4.29% from occasional drug users were positive to pregabalin without medical prescription. The mean pregabalin concentration in hair was higher than in consumers with medical indications (1.45 ng/mg vs 0.74 ng/mg). These results suggest that pregabalin possesses a significant abuse potential particularly among individuals attending opiate dependence services and that pregabalin abuse is a serious emerging issue, which should be carefully monitored.