Misuse of the γ-aminobutyric acid analogues baclofen, gabapentin and pregabalin in the UK

Neurological adverse events associated with baclofen: A disproportionality analysis based on FDA Adverse Event Reporting System

Purpose

Baclofen is a muscle relaxant that could carry the risk for neurological adverse events (nAEs). We aim to analyze the nAE profile of frequently used baclofen for its clinical application.

Methods

Our research is a disproportional analysis based on the FDA Adverse Event Reporting System (FAERS) database. We obtained adverse event reports of baclofen from January 2004 to June 2023 from the FAERS database. Reporting odds ratio (ROR) and Bayesian confidence propagation neural network (BCPNN) were performed to find nAE associated with baclofen.

Results

We extracted a total of 9305 nAE cases with baclofen as the primary suspect. The patients were mostly under 18 years old (45.49%), with markedly more males (43.72%) than females (36.52%). In all, 7275 (78.18%) reports were from the United States. There were 2023 of 9305 (21.74%) reports that occurred serious adverse events (SAE). The median onset time of reports with baclofen-related nAE was 10 days (interquartile range (IQR) 1-112). Intrathecal injection (75.78%) was more than oral (23.06%). We detected 119 significant signals, among which the higher frequencies were somnolence (ROR: 4.69, 95% CI (4.37, 5.03); IC: 2.17, IC025 (2.06)), tremor (ROR: 2.76, 95% CI (2.50, 3.04); IC: 1.43, IC025 (1.29)), lethargy (ROR: 6.37, 95% CI (5.71, 7.10); IC: 2.61, IC025 (2.45)), status epilepticus (ROR: 8.71, 95% CI (7.07, 10.73); IC: 2.98, IC025 (2.69)), generalized tonic-clonic seizure (ROR: 3.17, 95% CI (2.54,3.95); IC: 1.62, IC025 (1.30)], and cerebrospinal fluid leakage (ROR: 229.56, 95% CI (197.76, 266.47); IC: 6.61, IC025 (6.43)]. Unexpected significant nAE might also occur, such as intracranial hypotension (ROR: 428.52, 95% CI (355.18, 517.00); IC: 6.75, IC025 (6.56)], cognitive disorder (ROR: 2.65, 95% CI (2.21, 3.19); IC: 1.38, IC025 (1.11)], anterograde amnesia (ROR: 7.35, 95% CI (2.74, 19.72); IC: 1.69, IC025 (0.90)], metabolic encephalopathy (ROR: 14.77, 95% CI (10.40, 21.00); IC: 3.55, IC025 (2.93)], and myoclonus (ROR: 5.98, 95% CI (4.70, 7.59); IC: 2.46, IC025 (2.13)].

Conclusion

Given the wide use of baclofen, clinicians should be well-informed about important potential nAE. Although disproportional analysis is a refinement approach, it is still necessary to be vigilant about the nAE of baclofen. It is extremely crucial to early monitoring, especially in minors and the initial stage following the commencement of use.

Pregabalin concentrations: establishing 'normal' and 'cause for concern' concentration ranges in postmortem blood

Pregabalin (PGL) is prescribed for the treatment of neuropathic pain, epilepsy, and general anxiety disorder; however, studies have shown that PGL is being misused. It is generally accepted that those who misuse PGL use it in amounts significantly greater than the recommended therapeutic dose. In some instances, such high doses may be well tolerated, and in some instances, the same dose may cause death. Individual variation and postmortem (PM) changes make it extremely challenging for toxicologists to determine if a drug concentration found at PM was contributory to death or not. Unfortunately, meaningful PM data, which can help with interpreting PGL concentrations in femoral-vein blood, are rare. Only one recommendation was found where an author suggested that a PGL concentration of >25 µg/mL in PM blood should be considered as significant; however, in this case series PGL was only screened for in specific cases. To aid interpretation of PGL concentrations, reference data from toxicological analysis conducted on femoral-vein blood only from all manners of death are needed to compile meaningful and unbiased concentration ranges. This study looked at PGL femoral-vein blood concentrations in PM cases from all manners of death over a 2-year period. As it is impossible to define a PM concentration that should be considered toxic/fatal, this study aimed to provide a concentration cut-off where the PGL may be considered a 'normal' incidental finding (unlikely to be the cause of death) or a 'cause for concern' where it may have been taken in excess and caused or contributed to death. This study recommends that a PGL concentration of ≥20 µg/mL in femoral-vein blood should be considered as significant and a 'cause for concern'. Concentrations of ≤19 µg/mL may be considered a 'normal' incidental finding in death, but tolerance and other drug findings need to be considered.

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.

Electronic survey investigating UK veterinarians' perceptions of the potential for veterinary prescription medication misuse or abuse

OBJECTIVE

To investigate veterinarians' experience and perception of the risk of veterinary prescription medication (VPM) misuse and abuse by the public and veterinary professionals and to determine the clinical context in which respondent veterinarians prescribed certain VPMs.

STUDY DESIGN

Anonymous online voluntary survey.

POPULATION

A total of 361 of 7126 veterinarians registered as practicing in the UK, who provided e-mail contact details to the Royal College of Veterinary Surgeons Knowledge for participation in research. Respondents included general practitioners, with or without further qualifications, and European specialists, covering charity, private or academic small, large or mixed animal practice.

METHODS

The anonymous online survey, open from September to December 2021, posed 27 questions regarding personal experience and perception of VPM misuse or abuse, including which VPMs were considered most at risk of abuse by clients or veterinary staff. Thematic analysis was performed on free-text sections.

RESULTS

The participation rate was 5% (361/7126), and the completion rate 60% (216/361 respondents). Of these, 88% of respondents somewhat agreed, agreed or strongly agreed that some VPMs were at risk of abuse. A third (29.9%; 107/358) had suspected an owner of taking VPMs, and one fifth (20.1%; 72/358) had suspected veterinary staff. Perceptions regarding the likelihood of public VPM abuse ranged from not suspecting a problem to having first-hand experience. Drugs considered most at risk of owner abuse were opioids, benzodiazepines and gabapentin, and those for veterinary staff were opioids, benzodiazepines and ketamine. Numerous 'red flags' prompting suspicion of VPM abuse were identified alongside ways of mitigating risk.

CONCLUSIONS AND CLINICAL RELEVANCE

Veterinarians in the UK reported varied experiences with, awareness of, and attitudes towards VPM abuse by the public and veterinary staff. Although not quantified, the UK veterinary industry could be a source of abusable drugs.

Systematic Review to Identify Predictors of Treatment Response to Neuromodulation in Patients With Neuropathic Pain-Protocol

OBJECTIVES

Patients who suffer from long-term, neuropathic pain that proves refractory to conventional medical management are high consumers of health care resources and experience poorer physical and mental health than people with other forms of pain. Pharmacologic treatments have adverse effects; nonpharmacologic interventions have limitations. Spinal cord stimulation (SCS) is an effective treatment for neuropathic pain, although 30% to 40% of patients fail to achieve acceptable levels of pain relief. There are currently no objective methods to predict the success of SCS to treat neuropathic pain, and therefore, it is important to understand which patient factors may be predictive of a lack of response to SCS, to inform future patient treatment options. This study proposes a protocol for a systematic review and meta-analysis of published studies to examine these predictive factors.

MATERIALS AND METHODS

Several bibliographic databases will be searched to identify relevant studies published since 2012 that provide data on patient characteristics (eg, age, gender, pain severity) as predictors of SCS outcomes of pain, function, and health-related quality of life. Two independent reviewers will screen citations; data will be extracted after full-text screening. Risk of bias will be assessed using the Quality In Prognosis Studies tool.

RESULTS

A formal quantitative synthesis is planned in which data from studies with the same predictive factors are available; this will be considered for pooling into separate meta-analyses. In cases of high heterogeneity or inconsistency in the data, subgroup analysis will be conducted.

CONCLUSIONS

This study seeks to provide a contemporary review of patient predictors of success of neuromodulation for neuropathic pain. We anticipate that findings may guide the use of neuromodulation in patient subgroups and the design and reporting of future clinical studies in this field.

Non-medical use of baclofen: A case series and review of the literature

BACKGROUND

Baclofen is widely used for spastic disorders and, most recently, for addictive disorders. The first signals of baclofen abuse occurred in the last decade. This study aims to assess the motives, diversion sources, and routes of administration associated with the non-medical use of baclofen and examine health problems related to the non-medical use of baclofen.

METHODS

Spontaneous reports of baclofen abuse reported to the addictovigilance centre of East France were analysed. A literature search was conducted using PubMed®, Web of Sciences®, and Google Scholar® databases. Both investigations were performed in February 2021 without a time limit.

RESULTS

Forty-six cases were analysed (33 from the literature review and 13 from the addictovigilance base). Baclofen's non-medical use mainly affected male subjects with addictive history, but issues of primary abuse in subjects without any substance abuse history were also observed. Euphoria search was the most common reason for misuse. The route of administration included oral, snorting, and sublingual use. Some cases involving illegal sources were also observed. Most patients misusing baclofen presented severe complications, mainly represented by neurological and respiratory disturbances. Physical and psychological dependence on baclofen was observed in three persons.

CONCLUSIONS

Although baclofen abuse remains relatively infrequent or (most likely) underestimated, this study helped confirm baclofen's intrinsic abuse potential and make visible the baclofen-abuse-related health visible harms. Careful consideration and benefit-risk analysis should be employed when prescribing baclofen, and emergency departments should be aware of baclofen dangers in abuse situations.

Effect of Gabapentin-Fluoxetine Derivative GBP1F in a Murine Model of Depression, Anxiety and Cognition

Background and Objective

Gabapentin is a commonly prescribed antiepileptic agent for seizures, which is also used for pain and addiction management. Due to growing evidence of its abuse liability, there has been an incentive to synthesise potentially useful gabapentin derivatives devoid of adverse effects. A gabapentin adduct with a fluoxetine moiety, GBP1F, was assessed for any sedative, cognitive, anxiolytic, or antidepressant-like actions in murine behavioral models.

Materials and Methods

Selected groups of mice were used for each behavioral paradigm, and the effect of GBP1F (5, 10, and 15 mg/kg) was assessed using spontaneous locomotor activity, the tail suspension test, elevated plus maze test, and the Y maze test models. Immediately following behavioral experiments, postmortem striatal and hippocampal tissues were evaluated for the effect of GBP1F on concentrations of dopamine, DOPAC, HVA, serotonin, 5-HIAA, vitamin C, and noradrenaline using high performance liquid chromatography with electrochemical detection.

Results

GBP1F induced a mild suppression of locomotor activity, ameliorated anxiety and depression-like behavior, did not alter cognitive behavior, and raised serotonin and 5-HIAA concentrations in the hippocampus and striatum. GBP1F also positively enhanced dopamine and vitamin C tissue levels in the striatum. Thus, GBP1F represents a compound with anxiolytic- and antidepressant-like effects though further studies are warranted at the molecular level to focus on the precise mechanism(s) of action.

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.

Spinal Cord Stimulation for Neuropathic Pain in England From 2010 to 2020: A Hospital Episode Statistics Analysis

OBJECTIVES

Spinal cord stimulation (SCS) is a recognized intervention for the management of chronic neuropathic pain. The United Kingdom National Institute of Health and Care Excellence has recommended SCS as a management option for chronic neuropathic pain since 2008. The aim of this study is to undertake an assessment of SCS uptake across the National Health Service in England up to 2020.

MATERIALS AND METHODS

Hospital Episode Statistics were obtained for patients with neuropathic pain potentially eligible for SCS and patients receiving an SCS-related procedure. Data were retrieved nationally and per region from the years 2010-2011 to 2019-2020.

RESULTS

There were 50,288 adults in England attending secondary care with neuropathic pain in 2010-2011, increasing to 66,376 in 2019-2020. The number of patients with neuropathic pain with an SCS procedure increased on a year-to-year basis until 2018-2019. However, less than 1% of people with neuropathic pain received an SCS device with no evidence of an increase over time when considering the background increase in neuropathic pain prevalence.

CONCLUSION

Only a small proportion of patients in England with neuropathic pain potentially eligible for SCS receives this intervention. The recommendation for routine use of SCS for management of neuropathic pain has not resulted in an uptake of SCS over the last decade.

Off-label and investigational drugs in the treatment of alcohol use disorder: A critical review

Compounds known to be successful in the treatment of alcohol use disorder include the aversive agent, Disulfiram, the glutamatergic NMDA receptor antagonist, Acamprosate, and the opioid receptor antagonists, Naltrexone and Nalmefene. Although all four are effective in maintaining abstinence or reduction of alcohol consumption, only a small percentage of patients receive pharmacological treatment. In addition, many other medications have been investigated for their therapeutic potential in the treatment of alcohol use disorder. In this review we summarize and compare Baclofen, Gabapentin, Topiramate, Ondansetron, Varenicline, Aripiprazole, Quetiapine, Clozapine, Antidepressants, Lithium, Neuropeptide Y, Neuropeptide S, Corticotropin-releasing factor antagonists, Oxytocin, PF-05190457, Memantine, Ifenprodil, Samidorphan, Ondelopran, ABT-436, SSR149415, Mifepristone, Ibudilast, Citicoline, Rimonabant, Surinabant, AM4113 and Gamma-hydroxybutyrate While some have shown promising results in the treatment of alcohol use disorder, others have disappointed and should be excluded from further investigation. Here we discuss the most promising results and highlight medications that deserve further preclinical or clinical study. Effective, patient-tailored treatment will require greater understanding provided by many more preclinical and clinical studies.

Abuse liability of gabapentin in the Saudi population after the pregabalin restriction: A cross-sectional study

Objective

Following the recently conducted local studies on the growing misuse of pregabalin, Pregabalin misuse has received national attention. These studies have led to the authorities restricting the availability of pregabalin to hospital pharmacies alone. While the recent epidemiological studies and case reports found gabapentin to be misused worldwide, it was previously presumed to be free of any abuse potential. This study assesses the likelihood of there being a diversion to Gabapentin abuse following the Pregabalin restriction in Jeddah, KSA.

Methods

A cross sectional observational study was conducted between November 2017 and December 2017 using a self-constructed online survey via Twitter and WhatsApp. The survey items included participants' demographics, additional history, Gabapentin for non-medical use (frequency, concurrent use with other drugs, and motivators), and how the participants knew about the Gabapentin misuse. The data was subjected to a descriptive analysis via the utilization of frequencies and percentages. The analysis was carried out by using SPSS V21.

Results

Data of the 370 respondents who took the surveys were collected. Most of the respondents were women (n = 289; 78.1%) and below the age of 30 years (n = 300; 81.1%). A total of 72 respondents (19.5%) had a history of psychoactive drug abuse. Ten of the respondents reported Gabapentin misuse (2.7%). Half of the participants reported prior Pregabalin misuse, and were un-employed. Most of the misusers (n = 8; 80%) came to know about the psychotropic effects of Gabapentin from friends. The most common motives for using it were to 'have fun' and 'peer pressure' (n = 6; 60%). Half of the misusers used Gabapentin on a weekly basis.

Conclusion

The findings of our study suggest a potential diversion from Pregabalin to Gabapentin misuse. Regulations and periodic reviews of the psychoactive prescription medications available in the community pharmacies are essential.

Identifying risk factors that increase analgesic requirements at discharge among patients with burn injuries

Patients with burn injuries require large doses of opioids and gabapentinoids to achieve pain control and are often discharged from hospital with similar amounts. This study aimed to identify patient risk factors that increase analgesic requirements among patients with burn injuries and to determine the relationship between opioid and gabapentinoid use. Patient charts from July 1, 2015 - 2018 were reviewed retrospectively to determine analgesic requirements 24 hours before discharge. Linear mixed regression models were performed to determine patient risk factors (age, gender, history of substance misuse, total body surface area of burn, length of stay in hospital, history of psychiatric illness, or surgical treatment) that may increase analgesic requirements. This study found that patients with a history of substance misuse (p = 0.01) or who were managed surgically (p = 0.01) required higher doses of opioids at discharge. Similarly, patients who had undergone surgical debridement required more gabapentinoids (p < 0.001). For every percent increase in TBSA, patients also required 14 mg more gabapentinoids (p = 0.01). In contrast, older patients (p = 0.006) and those with a longer hospital stay (p = 0.009) required fewer amounts of gabapentinoids before discharge. By characterizing factors that increase analgesic requirements at discharge, burn care providers may have a stronger understanding of which patients are at greater risk of developing chronic opioid or gabapentinoid misuse. The quantity and duration of analgesics prescribed at discharge may then be tailored according to these patient specific risk factors.

A Retrospective Analysis of Gabapentinoid and Opioids to Opioid Monotherapy for Pain Relief in Patients with Chronic Neck and Low Back Pain

OBJECTIVE

We compared the reduction in pain and opioid consumption in patients with chronic spinal pain on concomitant gabapentinoids and opioids with patients using opioids only.

DESIGN

This was a retrospective chart review of patients with chronic neck or low back pain who were on opioids with at least a 24-month follow-up.

SETTING

Single-center pain clinic in an urban setting.

SUBJECTS

167 patients with chronic spinal pain lasting at least six months.

METHODS

Patients on gabapentin or pregabalin were included in the gabapentinoid group, while the other patients were included in the non-gabapentinoid group. Primary outcome was assessment of pain scores measured via a numeric rating scale (NRS), and secondary outcomes were response to the treatment (>2 point reduction on NRS) and daily opioid use measured in morphine milliequivalents.

RESULTS

Pain scores were reduced in the first six months and plateaued after that in both groups. At the end of 24 months, the average pain score was 6.71 in the gabapentinoid group, while the average pain score was 7.18 in the non-gabapentinoid group. There was no statistical significance between the groups (p = 0.28). There was no difference in response to treatment in gabapentinoid group (33.3%) when compared with non-gabapentinoid group (32.7%). We also failed to find any significant difference in daily opioid usage between the two groups.

CONCLUSION

Gabapentinoids may not lead to reduction in pain or opioid consumption in patients with chronic spinal pain. A careful approach must be adopted while prescribing gabapentinoids in the chronic spinal pain patient population.

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.

Baclofen: To Screen or Not to Screen in Postmortem Blood?

Baclofen (BLF) has been prescribed in the UK since 1972 for the alleviation of spasticity. However, evidence suggests BLF is also recreationally misused. It has been associated with ethanol, gamma-hydroxybutyric acid (GHB), pregabalin (PGL) and gabapentin (GBP) use/abuse, and deaths have been reported. With current postmortem (PM) toxicological screening approaches, BLF is not routinely included in the general drugs screen and is only screened for if specifically mentioned in the case documents. The extent of BLF misuse is thus unclear. This study was carried out to determine the prevalence and concentrations of BLF in Coroners' toxicology, to investigate whether BLF misuse with ethanol, GHB, PGL and GBP is causing death and to determine the potential extent of the underreporting of BLF-associated deaths. Between 1 January 2016 and 31 December 2017, 3,750 PM femoral vein bloods were screened for BLF; all positive cases were quantified. Only 0.56% of samples screened positive for BLF, with concentration ranging from 0.08 to 102.00 µg/mL (median = 0.28). It was determined that if routine analysis without additional screening of BLF had been performed, 43% of BLF positives cases would have been missed. However, given the low incidence of detection, this only represents 0.25% of the cohort. Likely illicit use of BLF with GHB was seen in one case only. Death from the recreational use of BLF with PGL and GBP was not observed. Only two cases positive for BLF had an ethanol concentration of ≥50 mg%. Two cases of presumed intentional overdose of BLF were observed. This study highlights that although BLF abuse may be occurring, deaths are rare. It is therefore not cost- or time-effective to screen for BLF in all PM cases. With BLF currently being investigated for the treatment of alcoholism and withdrawal symptoms of illicit drug use, BLF-related deaths may rise in the future.

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.

Gabapentinoid misuse, abuse and non-prescribed obtainment in a United States general population sample

Background Reports of gabapentinoid (gabapentin and pregabalin) misuse are on the rise, but few studies have assessed this within the general US population. Objective Describe lifetime misuse/abuse/non-prescribed obtainment of gabapentinoids and descriptive characteristics associated with such actions in a US general population sample. Setting This cross-sectional questionnaire was administered online by Qualtrics^® research panel aggregator via quota-based sampling. Methods Data were collected from a sample of respondents that mirrored the general US population aged 18-59 years with regards to age, geographic region, ethnicity, income, and education level, based on most recent census data. Misuse/abuse/non-prescribed obtainment was collectively defined as use of a gabapentinoid for reasons other than a diagnosed medical condition, using with the intention of altering one's state of consciousness, or obtaining without a prescription. A multivariable logistic regression model was created to predict misuse/abuse/non-prescribed obtainment of gabapentinoids, incorporating relevant covariates. Main outcome measure Proportion of sample indicating lifetime misuse/abuse/non-prescribed obtainment of gabapentinoids. Results Among 1,843 respondents, 121 (6.6%) reported gabapentinoid misuse/abuse/non-prescribed obtainment. Specifically, 2.1% (n = 39) and 1.5% (n = 27) of respondents for gabapentin and pregabalin, respectively, met study criteria for abuse. Opioids were the most common medication co-administered with gabapentinoids (among 50-70% of respondents) for misuse/abuse. Previous treatment for addiction (OR: 2.61, 95% CI: 1.32-5.14, p = 0.005) and the total attitudinal risk score (OR: 1.14, 95% CI: 1.09-1.19, p < 0.001) were associated with gabapentinoid misuse/abuse/non-prescribed obtainment. Conclusion Among those surveyed, 6.6% reported previous gabapentinoid misuse/abuse/non-prescribed obtainment, providing one of the first estimates within a nationally distributed, US general population sample.

Non-medical Use of Prescription Gabapentinoids (Gabapentin and Pregabalin) in Five European Countries

Background: Non-medical use (NMU) of prescription GABA analogs (pregabalin and gabapentin) has been reported especially in opiate dependent persons. However, by now the prevalence of NMU of gabapentinoids in the general population has not been sufficiently evaluated. The aim of this research paper is to determine the prevalence of prescription GABA analog NMU and associated demographics in five European countries with special detail of Spain. Methods: The RADARS Survey of Non-Medical Use of Prescription Drugs Program (NMURx) is a harmonized series of contemporaneous cross-sectional surveys of adults conducted in multiple countries. NMURx collects data from the general population in each participating country about NMU of prescription drugs, illicit drugs, and associated demographics. NMU was defined as "using a medication without a doctor's prescription or for any reason other than what was recommended by their doctor." Responses from Spain (4Q2017, n=10,062) were analyzed in detail. Comparative data were available from France, Germany, Italy, and UK. Responses were collected using non-probability quota sampling and post-stratification population weighting was applied to reflect the national distributions of adults, based on age, gender, and census region. Rates of NMU and associated demographics were reported as rate of past 90-day NMU per 100,000 adult population with 95% confidence intervals. Results: Germany (1,197 per 100,000 adult population [95% CI: 1,004.3-1,379.1]) and United Kingdom (1,067 per 100,000 adult population [95% CI: 851.3-1,283.2]) presented the highest prevalence of gabapentinoids NMU. In Spain the prevalence of past 90 days GABA analog NMU was: 344.4, 95% (CI 204.8-484.0), with male predominance. Those who non-medically use GABA analogs had a higher prevalence of lifetime chronic pain, lifetime illicit drug use, and previous substance abuse treatment. In Spain, 20% of respondents who ever have used gabapentinoids, reported a lifetime NMU; the prevalence was higher for pregabalin 624 (6.2%) than for gabapentin 444 (4.4%). The main reasons for use were to self-treat pain and other medical conditions. Conclusions: The risk of NMU of gabapentinoids should not be neglected. Subjects with a history of chronic pain and lifetime substance use disorders had an increased risk of NMU of gabapentinoids.

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.

Gabapentinoid Benefit and Risk Stratification: Mechanisms Over Myth

INTRODUCTION

Recent years have seen a dramatic escalation of off-label prescribing for gabapentin and pregabalin (gabapentinoids) owing in part to generic versions of each being released over the past two decades, but also in part as a response to increasing calls for multimodal and non-opioid pain management strategies. In this context, several recent articles have been published alleging widespread misuse, with speculations on the unappreciated addictive potential of the gabapentinoid class of drugs. Reports of a 1% population-level abuse prevalence stem from a single internet survey in the UK, and the vanishingly small adverse event outcomes data do not support such frequency. In this targeted narrative review, we aim to disabuse pain physicians and other clinicians, pharmacists, and policymakers of both the positive and negative myths concerning gabapentinoid medications.

RESULTS

Gabapentinoids inhibit the joint action of voltage-gated calcium channel (VGCC) α2δ subunits in conjunction with the n-methyl-D-aspartate (NMDA) receptor, with subsequent downregulation of VGCC expression and excitatory neurotransmitter release, and possibly synaptogenesis as well, through actions on thrombospondins. These activities reduce the likelihood of central sensitization, which explains in part the efficacy of the gabapentinoids in the management of neuropathic pain. Gabapentinoids also facilitate slow-wave sleep, a relatively rare phenomenon among central nerve system-acting agents, which is also thought to explain some of the therapeutic benefit of the class in conditions such as fibromyalgia. The number needed to treat to see benefit overlaps that of the nonsteroidal anti-inflammatory drugs, but with a considerably improved safety profile. Along these lines, in the context of over 50 million prescriptions per year in the USA alone, the gabapentinoids display remarkably low risk, including risks of misuse, abuse, and dependence. Furthermore, the neurobiology of these agents does not lend plausibility to the allegations, as they have never been shown to elicit dopaminergic activity within the nucleus accumbens, and in addition likely confer a "negative-feedback loop" for habituation and dependence by serving as functional NMDA antagonists, possibly through their actions on thrombospondins. Clinical and epidemiological addictionology studies corroborate the lack of any significant addictive potential of the gabapentinoids, and these drugs are increasingly being used in the treatment of addiction to other substances, with excellent results and no evidence of cross-addiction. However, among individuals with other substance use disorders and, in particular opioid use disorder, there are consistent data showing misuse of gabapentinoids in up to 20% of this population. Although there are allegations of using gabapentinoids to amplify the hedonic effects of opioids, the vast majority of misuse events appear to occur in an attempt to ameliorate opioid withdrawal symptoms. Furthermore, rare but potentially serious respiratory depression may occur, again amplified in the context of opioid or other sedative use. Careful risk:benefit assessment and stratification are warranted when prescription of a gabapentinoid is under consideration, in particular among individuals using opioids.

CONCLUSIONS

Gabapentinoids remain a vital tool in the pain physician's multimodal armamentarium, but these drugs may not be effective in every clinical situation. Individuals with central sensitization and pain associated with slow-wave sleep deficits and potentially persons with comorbid addictions may benefit the most. The gabapentinoids appear to possess no addictive potential on their own, based on laboratory and clinical data, but they may be abused by persons with opioid use disorders; consequently, cautious risk stratification must take place.

Prescription medicine misuse in the Asia-Pacific region: An evolving issue?

Prescription medicine misuse, especially misuse of opioids has become a major public healthcare issue in many developed countries such as the USA and Australia where this is associated with significant morbidity (Emergency Department visits due to acute toxicity) and mortality. In this review, we looked at the available data obtained from peer-reviewed articles and population surveys to gain an insight into the current situation in the Asia-Pacific region. There is currently limited information available, but data from subpopulation surveys in a number of countries suggests that prescription medicine misuse is likely to be an issue of concern from a public health perspective in the Asia-Pacific region. The available data suggest that misuse prevalence rates and the medicines that are commonly misused are similar to countries such as the USA and UK. Further studies are required to determine the overall prevalence of misuse, the harms associated with this and the sources of drugs being misused so that appropriate interventions can be implemented to tackle issues related to prescription medicine misuse in this region.

Abuse and Misuse of Pregabalin and Gabapentin: A Systematic Review Update

BACKGROUND

A 2017 systematic review (SR) identified 59 studies examining gabapentinoid (pregabalin and gabapentin) misuse/abuse. Evidence of gabapentinoid misuse/abuse has since grown substantially.

OBJECTIVE

Update previous SR and describe new insights regarding gabapentinoid abuse.

METHODS

A SR of PubMed was conducted to identify studies published from 7/29/2016-8/31/2020. Four searches were performed using the following terms: "gabapentin [MeSH] OR pregabalin [MeSH] OR gabapentinoid" AND one of the following substance misuse/abuse-related terms: "substance-related disorders [MeSH]", "overdose", "abuse", or "misuse". Clinicaltrials.gov and the Cochrane Library database were searched to identify ongoing studies or similar SRs. Reference lists of included studies were reviewed to identify additional literature. All studies with novel data related to pregabalin and/or gabapentin abuse, misuse, or overdose conducted during the study period were included. Articles not written in English, review articles, and animal studies were excluded.

RESULTS

Fifty-five studies were included (29 [52.7%] from North America, 17 [30.9%] Europe, 6 [10.9%] Asia, and 3 [5.5%] Australia). Forty-six observational studies and 10 case reports/series were included (one manuscript included both). Twenty (36.4%) studied gabapentin only, 18 (32.7%) pregabalin only, and 17 (30.9%) both pregabalin/gabapentin. These studies corroborate findings from the previous SR that gabapentinoids are increasingly abused or misused to self-medicate, that gabapentinoids can produce desirable effects alone but are often used concomitantly with other drugs, and that opioid use disorder is the greatest risk factor for gabapentinoid abuse. While the original SR identified the largest studies having been published in Europe, this review identified several more generalisable US studies that have subsequently been conducted. The most concerning finding was increased evidence of associated patient harm, including increased hospital utilisation and opioid-related overdose mortality risk.

CONCLUSION

Evidence suggests that gabapentinoid misuse/abuse represents a growing trend that is causing significant patient harm. Prescribers should exercise appropriate caution with use in high-risk populations and monitor for signs of misuse or abuse.

Regional, national and international datasets: How they improve our understanding of the acute harms associated with prescription medicine misuse

Prescription medicine misuse is a significant problem in many areas of the world. Understanding the acute and chronic harms related to misuse of prescription medicines allows healthcare professionals, drug addiction treatment services and legislative authorities to determine what interventions may be beneficial to reduce these harms and protect individuals and society. However, it is difficult to obtain systematic data on the harms associated with prescription medicine misuse because of how patient visits to clinics and hospitals are recorded and coded in regional or national databases. In this review, we discuss how regional, national and international sources of information can help develop a greater understanding of the prevalence and pattern of acute harms related to prescription medicine misuse using data from ambulance attendances, emergency department presentations and poisons information services.

Baclofen overdose following recreational use in adolescents and young adults: A case report and review of the literature

Over the past twenty years, psychotropic drug abuse by young people, especially by teenagers, has received special attention. Here, we present the case of baclofen overdose in a 16-year-old male who recreationally, and probably recurrently, self-administered baclofen. In addition, a review of other cases was conducted. The 16-year-old boy presented to emergency department with digestive signs followed by agitated confusion. Detection and determination of baclofen concentration were achieved using liquid chromatography tandem mass spectrometry. Baclofen was detected in plasma and urine, at 420 ng/mL and 64 900 ng/mL respectively. Further, an English exhaustive literature search was performed using several different scientific databases without any limiting period in order to identify scientific articles dealing with baclofen overdose following a recreational use among adolescent and young adults. Five publications describing baclofen overdoses following a recreational use among adolescents and young adults have been published reporting19 cases, all involving a non-fatal overdose, with baclofen concentrations ranging from less than 20-1322 ng/mL. Baclofen is a psychotropic drug and its recreational use among adolescents and young adults represent a serious problem and should be considered by healthcare professionals. Among young people, baclofen poisoning remains relatively infrequent or most likely underestimated and these observations highlight the importance of constructive communication and joining efforts of clinicians and analytical toxicologists.

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.

Prevalence and characteristics of self-reported kratom use in a representative US general population sample

BACKGROUND

Reports of kratom (Mitragyna speciosa) use, a medicinal plant widely found in Southeast Asia, are on the rise in the US. However, the prevalence and characteristics of individuals who use kratom in the US is unknown.

OBJECTIVE

To estimate lifetime prevalence of, and descriptive characteristics associated with, kratom use in a sample of the US general population.

METHODS

A cross-sectional survey was administered online by Qualtrics® research panel aggregator. Utilizing quota-based sampling, data was collected from a US sample aged 18-59 years, representative to age, geographic region, ethnicity, income, and education level. Data was collected regarding respondent demographic/clinical characteristics, as well as frequency/patterns of kratom and other drug use.

RESULTS

Among 1,842 respondents, 112 (6.1%) reported use of kratom within their lifetime. Respondents who used kratom were largely between 25-44 years old, male, employed, and at higher educational levels. A total of 24.1% to 47.3% of respondents indicated self-reported diagnoses for addiction, and 42.9% reported having previously received treatment for addiction. A total of 71.4% to 92% of respondents who used kratom also reported use of other drugs, including nicotine, cannabis, cocaine, ecstasy, methamphetamine, and heroin.

CONCLUSIONS

To our knowledge, this analysis provides the first estimate of kratom use in the general US population, providing insight on demographic/clinical characteristics of individuals reporting use.

Safety and Tolerability of the Anxiolytic and Nootropic Drug Phenibut: A Systematic Review of Clinical Trials and Case Reports

Phenibut is a nootropic drug that exerts anxiolytic and antinociceptive effects by acting on the GABA_B receptor and the α₂-δ subunit of voltage-dependent calcium channels. An increased number of reports of dependence to and intoxication by phenibut purchased online on the one hand and the wide prescription of phenibut in Eastern Europe for more than half a century on the other hand have resulted in a number of controversies regarding its use. In this review, we have summarized currently available information from case reports of phenibut dependence and intoxication and safety data from clinical trials. We included 14 dependence and intoxication case reports (16 patients) and reviewed 11 phenibut clinical trials (583 patients). The clinical symptoms in the case reports included cardiovascular effects, insomnia, anxiety and agitation, hallucinations, and depressed level of consciousness. In addition, the doses used (0.5-100 g/day) were much higher than the recommended daily dose (0.25-2 g/day). An analysis of phenibut side effects described in the clinical trials showed adverse events in only 5.66% of patients, and the most reported side effect was somnolence (1.89%). There are discrepancies in the reported side effects of phenibut in clinical trials compared to those reported in cases of online-purchased phenibut dependence and intoxication. The current systematic review provides evidence that, at therapeutic doses, phenibut is safe and well tolerated with minor adverse effects, but questions regarding the quality of phenibut obtained online and the contribution of alcohol and other drug abuse to phenibut dependence and intoxication remain open.

Preliminary Evidence of Pregabalin Misuse among Prescription and/or Illicit Opioid (Mis)users

Pregabalin is approved for the management of neuropathic pain, partial-onset seizures, and fibromyalgia. Although it is considered to have low potential for abuse, reports of misuse of pregabalin are emerging. The present study contributes to this literature by presenting preliminary evidence of pregabalin misuse. Mixed method interviews were conducted with prescription and/or illicit opioid (mis)users who reported a history of pregabalin misuse (N = 5). During semi-structured interviews, respondents provided descriptions of this practice, including motivation, route of administration, source, and drugs used/misused in combination with pregabalin. Motivations for pregabalin misuse included the self-treatment of physical pain (N = 1) and to achieve a desired psychoactive effect and/or combat opioid withdrawal symptoms (N = 4). Respondents described the misuse of pregabalin to potentiate the effects of heroin and cocaine, to feel "tipsy," and to experiment. We believe this report represents the first detailed contextual data about the misuse of pregabalin in the U.S. These misuse practices may represent an early indication of a growing problem. The recent permissibility of lower price generic versions has the potential to increase availability, decrease prices, and exacerbate pregabalin misuse.

Gabapentin drug misuse signals: A pharmacovigilance assessment using the FDA adverse event reporting system

BACKGROUND

Although there have been increasing reports of intentional gabapentin misuse, epidemiological evidence for the phenomenon is limited. The purpose of this study was to determine whether there are pharmacovigilance abuse signals for gabapentin.

METHODS

Using FDA Adverse Events Reporting System reports from January 1, 2005 to December 31, 2015, we calculated pharmacovigilance signal measures (i.e., reporting odds ratio, proportional reporting ratio, information component, and empirical Bayes geometric mean) for abuse-related adverse event (AR-AE)-gabapentin pairs. Loglinear modeling assessed the frequency of concurrent reporting of abuse-related and abuse-specific AEs (AS-AEs) associated with gabapentin. Findings were compared to a positive (pregabalin) and negative (duloxetine) control.

RESULTS

From 2005-2015 there were 5,951,229 unique AE reports submitted to the FDA including 99,977 for gabapentin, 73,977 for duloxetine, and 97,813 for pregabalin. Significant drug-AR-AE pair signals involving gabapentin included: drug abuser, multiple drug overdose, and substance-induced psychotic disorder. Significant drug AR-AE signals involving gabapentin and pregabalin, but not duloxetine, were: ataxia, dependence, drug abuse, increased drug tolerance, and overdose. Compared to duloxetine, gabapentin had significantly greater odds of a co-report for an AS-AE with drug withdrawal syndrome (OR: 6.55), auditory hallucinations (OR: 4.57), delusions (OR: 2.36), euphoric mood (OR: 5.45), ataxia (OR: 2.85), drug abuser (OR: 3.01), aggression (OR: 1.98), psychotic disorder (OR: 1.96), and feeling abnormal (OR: 1.31).

CONCLUSIONS

We identified abuse-related signals for gabapentin and highlighted several CNS effects that may be associated with its abuse. Gabapentin prescribers should be aware of the drug's abuse liability and effects that may accompany its use.

Validation of a High-throughput Screening and Quantification Method for the Determination of Gabapentinoids in Blood Using a Combination of LC-TOF-MS and LC-MS-MS

Gabapentinoids such as gabapentin (GP) and pregabalin (PGL) have been used to treat a wide range of neurological and psychiatric disorders. In recent years, there has been an increasing awareness of GP and PGL misuse among individuals with a history of polysubstance use. Both GP and PGL are understood to potentiate the effects of opioids, with fatalities involving GP and PGL being reported with increasing frequency. An efficient procedure was developed to screen and quantitate GP and PGL in blood samples using a combination of liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) and liquid chromatography tandem mass spectrometry (LC-MS-MS). The developed LC-MS-MS method was linear from 0.5-50 mg/L, with a limit of detection (LOD) of 0.1 mg/L for GP and PGL. An LOD of 0.5 mg/L was determined for both analytes on the LC-TOF-MS screen. A total of 1,091 blood specimens were subjected to a protein crash with methanol, in the presence of deuterated internal standards, PGL-d6 and GP-d10, to minimize the effects of varying matrix conditions. Specimens tested included both post-mortem blood and preserved blood specimens collected for the purposes of investigating drug-impaired driving and suspected drug-facilitated crimes. Of the total of specimens tested, 101 (9.3%) screened positive using the developed LC-TOF-MS method for GP while only 13 (1.2%) blood specimens screened positive for PGL. All (100%) of the cases that screened positive for GP and PGL were confirmed positive by LC-MS-MS. Blood concentrations of GP and PGL ranged from <0.5 to 215 mg/L and from <0.5 to 32 mg/L, respectively. Of the blood specimens that had previously screened negative by LC-TOF-MS, 10% (N = 100) were randomly selected and tested by LC-MS-MS with 100% confirmed negative for GP and PGL. The developed methods provide a fast and reliable high-throughput screening and confirmation testing strategy for the detection of GP and PGL in blood specimens.

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.

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.

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.

Gabapentin use, abuse, and the US opioid epidemic: the case for reclassification as a controlled substance and the need for pharmacovigilance

The abuse potential of gabapentin is well documented; with gabapentin having been noted as an agent highly sought after for use in potentiating opioids. When combined with opioids, the risk of respiratory depression and opioid-related mortality increases significantly. In the US, gabapentin was approved by the Food and Drug Administration as a non-controlled substance. To date, and in spite of empirical evidence suggestive of diversion and abuse with opioids, gabapentin remains a non-controlled substance at the federal level. This has forced individual US states and jurisdictions – often significantly impacted by the opioid epidemic – to forge ahead with legislative initiatives designed to reclassify and/or monitor the use of gabapentin. Since August 1, 2016, 14 of 51 US states and jurisdictions have either implemented legislative mandates requiring pharmacovigilance programs, amended rules and regulations, are in the throes of crafting policy, or are in the midst of gathering additional data for decision making. This fragmented geographic approach yields only a modest benefit in combating the abuse of gabapentin and/or the national opioid epidemic. Herein, we report state-by-state efforts to enhance pharmacovigilance and call for a re-evaluation of the schedule status of gabapentin at the federal level, and design and implementation of a national pharmacovigilance program.

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.

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.

Longitudinal pharmacoepidemiological and health services research for substance users in treatment: protocol of the Belgian TDI-IMA linkage

Background

Not much is known about the health seeking behavior of people with substance use disorders before they enter specialized treatment and afterwards. This paper explains in detail the protocol that has been followed to establish the Belgian TDI-IMA-database, which is linking two separate databases: the Treatment Demand Indicator (TDI) and the database of the Intermutualistic Agency (IMA). The Treatment Demand Indicator is measuring incidence of people with substance use disorders entering drug treatment. The IMA-database covers data, collected in the framework of the compulsory Belgian health care and benefits insurance program, on reimbursed medication and the use of reimbursed health services. The linkage results in pharmacoepidemiological and health service data for people who were in treatment for substance use disorders and for a group of comparators.

Methods

The TDI-database was linked to the IMA-database for the period between 01/01/2008 and 31/12/2017, based on the national identification number of patients who have been in alcohol or drug treatment between 01/01/2011 and 31/12/2014. Through this linkage, pharmacoepidemiological and health service data became available for at least 3 years before the first registered episode in the TDI-database till at least 3 years after the first episode. For each person in TDI four comparators, who were not in specialized treatment, were matched on age, sex and place of residence.

Discussion

The TDI-IMA-database allows for an analysis of health seeking behavior and health care pathways of people before and after they entered specialized alcohol and drug treatment. The presented protocol could be used in other European countries to establish a linkage between existing health databases. This will allow for a better understanding of the health care needs of patients with substance use disorders.

A qualitative analysis of gabapentin misuse and diversion among people who use drugs in Appalachian Kentucky

Gabapentin, an anticonvulsant and analgesic for postherpetic neuralgia, has been thought to have no abuse potential despite numerous published reports to the contrary. Gabapentin has been linked with impaired driving and opioid use, highlighting the need to more fully understand its risk profile. Thirty-three individuals reporting recent nonmedical use of gabapentin were recruited from two ongoing longitudinal studies of drug users in Appalachian Kentucky to participate in focus groups. Four sessions were held (two in the community and two in jail settings), during which participants responded to questions regarding their personal experiences with gabapentin misuse. Focus group participants were similar to other gabapentin users in the larger cohort studies with respect to demographics and drug use behaviors. Overall, the sample reported having initiated gabapentin more than 10 years earlier after having it prescribed for a legitimate, though generally off-label, medical indication (e.g., pain, anxiety, opioid detoxification). Participants reported use of gabapentin in combination with buprenorphine, other opioids, cocaine, and caffeine to produce sought-after central nervous system effects (e.g., muscle relaxation, pain reduction, sleep induction, feeling drunk, and feeling "high"). Focus group responses highlighted the low cost of gabapentin for the purpose of getting high and noted increasing popularity in the community, particularly over the last 2 years. Gabapentin was a prominent drug of abuse in two cohorts of the primarily opioid-using individuals. Providers should be aware of gabapentin's abuse potential, and a reexamination of the need for scheduling is warranted. (PsycINFO Database Record

How addictive are gabapentin and pregabalin? A systematic review

In the last ten years, gabapentin and pregabalin have been becoming dispensed broadly and sold on black markets, thereby, exposing millions to potential side-effects. Meanwhile, several pharmacovigilance-databases have warned for potential abuse liabilities and overdose fatalities in association with both gabapentinoids. To evaluate their addiction risk in more detail, we conducted a systematic review on PubMed/Scopus and included 106 studies. We did not find convincing evidence of a vigorous addictive power of gabapentinoids which is primarily suggested from their limited rewarding properties, marginal notes on relapses, and the very few cases with gabapentinoid-related behavioral dependence symptoms (ICD-10) in patients without a prior abuse history (N=4). In support, there was no publication about people who sought treatment for the use of gabapentinoids. Pregabalin appeared to be somewhat more addictive than gabapentin regarding the magnitude of behavioral dependence symptoms, transitions from prescription to self-administration, and the durability of the self-administrations. The principal population at risk for addiction of gabapentinoids consists of patients with other current or past substance use disorders (SUD), mostly opioid and multi-drug users, who preferred pregabalin. Pure overdoses of gabapentinoids appeared to be relative safe but can become lethal (pregabalin > gabapentin) in mixture with other psychoactive drugs, especially opioids again and sedatives. Based upon these results, we compared the addiction risks of gabapentin and pregabalin with those of traditional psychoactive substances and recommend that in patients with a history of SUD, gabapentinoids should be avoided or if indispensable, administered with caution by using a strict therapeutic and prescription monitoring.