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

Effect of amoxicillin/clavulanic acid in attenuating pregabalin-induced condition place preference

Substance abuse is a worldwide problem with serious repercussions for patients and the communities where they live. Pregabalin (Lyrica), is a medication commonly used to treat neuropathic pain. Like other analgesic medications there has been concern about pregabalin abuse and misuse. Although it was initially suggested that pregabalin, like other gabapentinoids, has limited abuse liability, questions still remain concerning this inquiry. Changes in glutamate system homeostasis are a hallmark of adaptations underlying drug dependence, including down-regulation of the glutamate transporter 1 (GLT-1; SLC1A2) and the cystine/glutamate antiporter (xCT; SLC7A11). In this study, it was found that pregabalin (90 mg/kg) produces a conditioned place preference (CPP), indicative of reinforcing effects that suggest a potential for abuse liability. Moreover, like other drugs of abuse, pregabalin also produced alterations in glutamate homeostasis, reducing the mRNA expression of Slc1a2 and Slc7a11 in the nucleus accumbens (NAc) and medial prefrontal cortex (mPFC). Amoxicillin clavulanic acid, a β-lactam antibiotic, blocked the reinforcing effects of pregabalin and normalized glutamate homeostasis. These results suggest that pregabalin has abuse potential that should be examined more critically, and that, moreover, the mechanisms underlying these effects are similar to those of other drugs of abuse, such as heroin and cocaine. Additionally, these results support previous findings showing normalization of glutamate homeostasis by β-lactam drugs that provides a novel potential therapeutic approach for the treatment of drug abuse and dependence.

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.

How prevalent and severe is addiction on GABAmimetic drugs in an elderly German general hospital population? Focus on gabapentinoids, benzodiazepines, and z-hypnotic drugs

OBJECTIVE

Gabapentinoids (GPT) are reported to be increasingly misused by opioid- and polydrug-users, but the addictive potential of GPT outside of these populations remains understudied. Investigations comparing GPT abuse and dependence liability to that of other commonly prescribed Central Nervous System-acting medications are therefore warranted. We provide a comparison of GPT-abuse/dependence to that of other GABAmimetics within an elderly population.

DESIGN

DSM-IV-TR-based data (previously prospectively collected by SKID-I-interview) from a random sample of elderly patients admitted to a metropolitan German general hospital were reviewed. The prevalence and severity of GPT, benzodiazepine (BDZ), and z-hypnotic drug (ZD)-abuse and -dependence were compared, stratified also by mono-substance (no concurrent current or previous substance use) and de novo-substance (first)-abuse and -dependence states.

RESULTS

Among 400 patients (75 ± 6.4 years old; 63% females), neither current nor past abuse of BDZ, ZD or GPT, nor other illicit substances was observed. Dependence upon BDZ, ZD or GPT was observed among 55 (13.75%) individuals. The related lifetime/12-month prevalence-rates were: dependence condition (BDZ: 7%/2.45%; ZD: 4.25%/4.25%; GPT: 2.75/2.5%); mono-dependence condition (BDZ: 2.25%/0.75%; ZD: 1%/1%, GPT: 0%/0%); de novo-dependence condition (BDZ: 2.75%/1.75%; ZD: 1%/1%, GPT: 0.5%/0.5%). Opioid analgesic-dependence (N = 43/400) was significantly more frequently linked with BDZ than with GPT (p < 0.01) [Correction added on 29 December 2021, after first online publication: In the sentence 'Opioid analgesic-dependence…', the term 'and ZD' has been deleted]. For all three GABAmimetic classes, most mono- and de novo-dependence states were mild-to-moderate and lasted 2-6 years (median).

CONCLUSION

GABAmimetic-dependence was usually mixed with other substance-dependences. Every third to fourth instance of BDZ- or ZD-dependence was a mono-dependence condition, while a pure GPT-dependence was absent in this elderly (and illicit substance-naïve) population.

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.

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.

Involvement of the dopaminergic system in the reward-related behavior of pregabalin

There has been an increase in cases of drug addiction and prescription drug abuse worldwide. Recently, pregabalin abuse has been a focus for many healthcare agencies, as highlighted by epidemiological studies. We previously evaluated the possibility of pregabalin abuse using the conditioned place preference (CPP) paradigm. We observed that a 60 mg/kg dose could induce CPP in mice and that pregabalin-rewarding properties were mediated through glutamate neurotransmission. Notably, the dopaminergic reward circuitry is also known to play a crucial role in medication-seeking behavior. Therefore, this study aimed to explore the possible involvement of dopaminergic receptor-1 in pregabalin-induced CPP. Mice were randomly allocated to receive saline or the dopamine-1 receptor antagonist SKF-83566 (0.03 mg/kg, intraperitoneal). After 30 min, the mice received either saline or pregabalin (60 mg/kg) during the conditioning phase. Among the control groups that received saline or SKF-83566, the time spent in the two conditioning chambers was not significantly altered. However, among the pregabalin-treated group, there was a marked increase in the time spent in the drug-paired chamber compared to the time spent in the vehicle-paired chamber. Notably, blocking dopamine-1 receptors with SKF-83566 completely prevented pregabalin-induced place preference, thus demonstrating the engagement of the dopaminergic system in pregabalin-induced reward-related behavior.

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.

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.

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.

Acute Cocaine Reduces Excitatory Synaptic Transmission in Pyramidal Neurons of the Mouse Medial Prefrontal Cortex

The medial prefrontal cortex (mPFC) plays critical roles in the development of cocaine addiction. Numerous studies have reported about the effects of cocaine on neuronal and synaptic activities in the nucleus accumbens and ventral tegmental area, which are brain regions associated with cocaine addiction; however, a limited number of studies have reported the effect of cocaine on mPFC neuronal activity. In this study, using whole-cell patch-clamp recordings in brain slices, we present that under the condition where synaptic transmission is enhanced by increasing extracellular K⁺ concentration, cocaine significantly reduced the frequency but not amplitude of spontaneous excitatory postsynaptic currents. These findings suggest that cocaine exposure could be a trigger to induce hypofrontality, which is related to the compulsive craving for cocaine use.

Comment on: An Insight Into Z-Drug Abuse and Dependence: An Examination of Reports to the European Medicines Agency Database of Suspected Adverse Drug Reactions

After the publication of an article discussing the methodological options to detect the diversion potential of prescription drugs, this letter presents the multidimensional functioning of the French Addictovigilance System. This system aims at monitoring all substances with abuse potential, relying on a network of experts specialized in clinical and fundamental pharmacology. For more than 25 years, we have created collaborations with partners at the interface with field data related to substance use and the potential related disorders. When relevant depending on the context, these data sources are explored and crossed to analyze the abuse potential of one given substance. This organizational approach is useful to detect early Addictovigilance warning signals and to take appropriate measures. Generalizing such a multidimensional approach outside France appears an appealing option to move towards more effective Addictovigilance systems at the international level.