The gabapentinoid drugs and their abuse potential

Abuse of gabapentinoids in individuals with substance use disorders

The abuse of gabapentinoids has increased rapidly, and death cases have been reported with increasing rates. This study examines the toxicological analysis data of substance abuse cases conducted after legal regulations were implemented in Türkiye. The focus will be on the medicolegal implications of gabapentinoid positivity in these cases. Urine samples collected between July 2021 and July 2022 from individuals (ages 18-45) presenting at Manisa Mental Health and Diseases Hospital with diagnosed or suspected substance use disorders were analyzed for the presence of pregabalin, gabapentin, and other accompanying substances. High-resolution liquid chromatography-mass spectrometry (Orbitrap) was employed for analysis. The analysis reports and sociodemographic data of 10,300 cases were retrieved from the patient record system and subjected to statistical analysis using SPSS 25.0. Gabapentinoid positivity was detected in 21.6% (n = 2224) of these cases (pregabalin (PGB) 18.9% (n = 1943) and gabapentin (GBP) 5.3% (n = 546)). Of the positive cases, 93.9% (n = 2089) were male, with an average age of 28 ± 6.7. Forensic cases (probation and judicial) represented the majority of admitted and positive cases 2.6% (n = 265) of cases tested positive for both pregabalin and gabapentin. While an overall increase in pregabalin and gabapentin positivity rates was observed over time, a statistically significant difference (p < 0.05) was noted between years. Seven substances were detected with gabapentinoids. Methamphetamine was the most common accompanying substance, representing nearly half of the detected substances (46.8%, n = 1040), followed by THC-COOH (26.8%, n = 595). Despite legal regulations, the use of gabapentinoids is increasing rapidly. The study highlights the urgent need to include gabapentinoids in routine screening tests, enforce stricter prescribing guidelines, and actively prevent their illegal use.

Evaluation of the effects of prenatal exposure to pregabalin and postnatal analysis of dental and mandibular bone tissue development in rat offspring

Pregabalin is a gabapentinoid indicated for the treatment of peripheral neuropathic pain, fibromyalgia, and as an adjuvant therapy for epilepsy. The aim of this study was to evaluate the effects of pregabalin on postnatal development, odontogenesis, and mandibular trabecular tissue using computed microtomography. Pregnant rats (N = 24) were divided into two groups: control group/placebo (C), and treated group (PGB). The PGB group received 200 mg/kg of pregabalin via gavage during the embryonic period and the C group received distilled water under the same design. On the 21st day of pregnancy, delivery occurred naturally. On the first postnatal day, the litters were reduced to four pups (2 males and 2 females) and followed up for 30 days. On postnatal day 30, eight animals from each group were randomly selected for analysis of the lower right first molar and adjacent trabecular bone. In the maternal parameters, the data revealed a significant decrease in body weight gain in addition to a smaller number of live pups. In the postnatal analysis, the exposed pups showed a significant decrease in weight and length and a delay in the eruption of the incisor teeth. Microtomography analysis revealed a significant reduction in enamel volume, a lower volume and percentage of open pores, lower total porosity, and a higher percentage of bone volume. The findings of this study showed that pregabalin altered the eruption chronology of the incisors, decreased enamel volume, affected the microarchitecture of mandibular trabecular bone, and impaired postnatal development. CONCEA-CEUA-UEL n. 11,174.2018.36, State University of Londrina, (UEL), Londrina, Paraná, Brazil; retrospectively registered on August 21, 2018.

Pathophysiology-Directed Engineering of a Combination Nanoanalgesic for Neuropathic Pain

Neuropathic pain, one of the most refractory pain diseases, remains a formidable medical challenge. There is still an unmet demand for effective and safe therapies to address this condition. Herein, a rat model of nerve injury-induced neuropathic pain is first established to explore its pathophysiological characteristics. Recognizing the role of neuroinflammation, an inflammation-resolving amphiphilic conjugate PPT is designed and synthesized by simultaneously conjugating polyethylene glycol, phenylboronic acid pinacol ester, and Tempol onto a cyclic scaffold. PPT can self-assemble into nanomicelles (termed PPTN). Following intravenous injection, PPTN preferentially accumulates in the injured nerve, ameliorates the neuroinflammatory milieu, and promotes nerve regeneration, thereby shortening neuropathic pain duration in rats. Moreover, the Ca2+ channel α2δ1 subunit is identified as a therapeutic target by RNA-sequencing analysis of the injured nerve. Based on this target, a mimicking peptide (AD peptide) is screened as an analgesic. By packaging AD peptide into PPTN, a combination nano-analgesic APTN is developed. Besides potentiated anti-hyperalgesic effects due to site-specific delivery and on-demand release of AD peptide at target sites, APTN simultaneously inhibits neuroinflammation and promotes nerve regeneration by reprogramming macrophages via regulating MAPK/NF-kB signaling pathways and NLRP3 inflammasome activation, thus affording synergistic efficacies in treating nerve injury-induced neuropathic pain.

Gabapentinoids related psychiatric disorders: an analysis based on the FAERS database from 2004 to 2023

BACKGROUND

Gabapentinoids, including gabapentin and pregabalin, are commonly used for neuropathic pain but have safety concerns. This study analyzed U.S. Food and Drug Administration's (FDA) Adverse Event Reporting System (FAERS) data to assess risks of psychiatric disorders as adverse effects.

RESEARCH DESIGN AND METHODS

Data from 2004 to 2023 were extracted for disproportionality analysis using reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian Confidence Propagation Neural Network (BCPNN), and the Multi-Item Gamma Poisson Shrinker (MGPS) to evaluate the association between gabapentinoids and psychiatric AEs. Kaplan-Meier and log-rank tests assessed the incidence and onset profiles, while chi-square examined mortality and hospitalization rates differences.

RESULTS

Of 174,321 AE reports, 22.67% involved psychiatric disorders. Gabapentinoids increased psychiatric disorder incidence at SOC level, with events like anxiety and suicidal ideation. Differences in incidence and health outcomes between gabapentin and pregabalin were significant (p < 0.05).

CONCLUSION

There is a correlation between the use of gabapentinoids and psychiatric disorders. Further research is needed into the mechanisms and prevention strategies for these adverse effects.

Gabapentin and pregabalin exposures reported to United States poison centers, 2012-2022

BACKGROUND

Gabapentin and pregabalin were originally introduced as anticonvulsant medications but are now also prescribed on- and off-label for multiple medical disorders, especially for pain management. The national opioid crisis has led to increased use of non-opioid pain medications, including gabapentinoids, which has been associated with changing patterns of adverse events associated with these medications. This study investigated the characteristics and trends of gabapentin and pregabalin exposures reported to US poison centers from 2012 to 2022.

METHODS

National Poison Data System data involving gabapentin and pregabalin exposures for 2012 to 2022 were analyzed.

RESULTS

There were 124,161 exposures involving gabapentin and pregabalin as the primary substance reported to US poison centers during the study period. Most exposures involved gabapentin (85.9%), females (59.4%), single-substance exposures (62.9%), or occurred at a residence (97.2%). Suspected suicides accounted for 45.2% of exposures. Most exposures were associated with a minor effect (27.4%) or no effect (34.0%), while 22.1% experienced a serious medical outcome, including 96 fatalities. The rate of gabapentin and pregabalin exposures per one million US population increased by 236.1% from 22.7 in 2012 to 76.5 in 2019 (P < 0.001), followed by a non-significant decrease to 68.5 in 2022 (P = 0.068).

CONCLUSIONS

The rate of gabapentin and pregabalin exposures reported to US poison centers increased by more than 230% from 2012 to 2019 before plateauing from 2019 to 2022. The observed rate trend was driven primarily by gabapentin exposures and by cases associated with suspected suicide. Although most exposures were associated with a minor or no effect, 22% of individuals experienced a serious medical outcome, including 96 fatalities. These findings contribute to the discussion of rescheduling gabapentin as a federally controlled substance, which is the current status of pregabalin. Prevention of suicide associated with gabapentin and pregabalin merits special attention.

Gabapentinoids for the treatment of stroke

ABSTRACT

Gabapentinoid drugs (pregabalin and gabapentin) have been successfully used in the treatment of neuropathic pain and in focal seizure prevention. Recent research has demonstrated their potent activities in modulating neurotransmitter release in neuronal tissue, oxidative stress, and inflammation, which matches the mechanism of action via voltage-gated calcium channels. In this review, we briefly elaborate on the medicinal history and ligand-binding sites of gabapentinoids. We systematically summarize the preclinical and clinical research on gabapentinoids in stroke, including ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, seizures after stroke, cortical spreading depolarization after stroke, pain after stroke, and nerve regeneration after stroke. This review also discusses the potential targets of gabapentinoids in stroke; however, the existing results are still uncertain regarding the effect of gabapentinoids on stroke and related diseases. Further preclinical and clinical trials are needed to test the therapeutic potential of gabapentinoids in stroke. Therefore, gabapentinoids have both opportunities and challenges in the treatment of stroke.

Secular trends in gabapentinoid dispensing by compensated workers with low back pain: a retrospective cohort study

OBJECTIVES

The increase in gabapentinoid prescribing is paralleling the increase in serious harms. To describe the low back pain workers compensation population whose management included a gabapentinoid between 2010 and 2017, and determine secular trends in, and factors associated with gabapentinoid use.

METHODS

We analysed claim-level and service-level data from the Victorian workers' compensation programme between 1 January 2010 and 31 December 2017 for workers with an accepted claim for a low back pain injury and who had programme-funded gabapentinoid dispensing. Secular trends were calculated as a proportion of gabapentinoid dispensings per year. Poisson, negative binomial and Cox hazards models were used to examine changes over time in incidence and time to first dispensing.

RESULTS

Of the 17 689 low back pain claimants, one in seven (14.7%) were dispensed at least one gabapentinoid during the first 2 years (n=2608). The proportion of workers who were dispensed a gabapentinoid significantly increased over time (7.9% in 2010 to 18.7% in 2017), despite a reduction in the number of claimants dispensed pain-related medicines. Gabapentinoid dispensing was significantly associated with an opioid analgesic or anti-depressant dispensing claim, but not claimant-level characteristics. The time to first gabapentinoid dispensing significantly decreased over time from 311.9 days (SD 200.7) in 2010 to 148.2 days (SD 183.1) in 2017.

CONCLUSIONS

The proportion of claimants dispensed a gabapentinoid more than doubled in the period 2010-2017; and the time to first dispensing halved during this period.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

Pregabalin alters reproductive performance in male mice and causes congenital anomalies in offspring

CONTEXT

Pregabalin is an anticonvulsant drug with analgesic activity for the treatment of neuropathic pain.

AIMS

To valuate the toxicity of pregabalin in reproductive parameters, spermatogenesis, and teratogenicity in the offspring of mice.

METHODS

Twenty male mice were randomly distributed into two groups: PGB group and group C (n =10 per group). The animals in the PGB group received, via gavage, 200mg/kg of pregabalin diluted in distilled water daily, for a period of 45days. Group C received distilled water under the same experimental design.

KEY RESULTS

In the paternal parameters of the PGB group, there was a significant increase in the size of the testicles, morphological alterations in the spermatozoa, a decrease in the Johnsen score, an increase in the Leydig cells, and a decrease in the serum level of testosterone. In the intrauterine development parameters of females mated with males from the PGB group, a significant decrease in placental weight, weight and length of fetuses, and fetal viability rate was observed. There was a significant increase in the number of resorptions and post-implantation losses. The significant anomalies observed in the offspring were alteration in the size of the kidneys, absent metacarpals and phalanges, alteration in the sternum, and supernumerary thoracic vertebrae.

CONCLUSION

Results suggest that pregabalin had toxic effects on the reproductive function of male mice and teratogenic potential.

IMPLICATIONS

The findings of this study may provide new hypotheses, taking into account the risk-benefit ratio for male reproduction and offspring health.

Novel Drug Targets and Emerging Pharmacotherapies in Neuropathic Pain

Neuropathic pain is a debilitating condition characterized by abnormal signaling within the nervous system, resulting in persistent and often intense sensations of pain. It can arise from various causes, including traumatic nerve injury, neuropathy, and certain diseases. We present an overview of current and emerging pharmacotherapies for neuropathic pain, focusing on novel drug targets and potential therapeutic agents. Current pharmacotherapies, including tricyclic antidepressants, gabapentinoids, and serotonin norepinephrine re-uptake inhibitors, are discussed, as are emerging treatments, such as ambroxol, cannabidiol, and N-acetyl-L-cysteine. Additionally, the article highlights the need for further research in this field to identify new targets and develop more effective and targeted therapies for neuropathic pain management.

Pharmacist, prescriber, and drug policy expert opinions on gabapentinoid misuse

BACKGROUND

Gabapentinoids (gabapentin and pregabalin) are widely used in clinical practice, but recent evidence indicates that they carry an increased risk of misuse. As healthcare professionals (HCPs) and policymakers plan different strategies to promote harm reduction, it is important to understand different interested party viewpoints.

OBJECTIVE

To explore prescriber, pharmacist, and drug policy expert (DPE) awareness, opinions, and experiences regarding gabapentinoid misuse.

METHODS

A qualitative description study using individual semi-structured virtual interviews was conducted between February and April 2021. Participants included prescribers (physicians, physician assistants [PA], or nurse practitioners [NP]) and pharmacists practicing in outpatient, ambulatory, or community-based healthcare settings; individuals with relevant drug policy expertise were also included. Qualtrics (Provo, Utah) and Zoom (San Jose, California) were used to facilitate quantitative (for initial screening and participant characteristics) and qualitative (interview) data collection. Data were coded and organized into themes in NVivo (QSR International; Burlington, Massachusetts) using thematic analysis steps.

RESULTS

A total of 43 individuals participated in this study, including 16 (37.2%) pharmacists, 13 (30.2%) physicians, seven (16.3%) NPs, four (9.3%) DPEs, two (4.7%) pharmacist/DPEs, and one (2.3%) PA. Results were organized along four themes: (1) challenges/opportunities in gabapentinoid use; (2) gabapentinoid misuse awareness; (3) solutions to gabapentinoid misuse and (4) contributing barriers in pain management. Participants invoked different opinions in their consideration of gabapentinoid misuse, including the desire for harm reduction, the limitations of the current healthcare and insurance system, the lack of options for pain and substance use disorder treatment, and the influence of patient expectations.

CONCLUSIONS

Gabapentinoid misuse was commonly framed in comparative fashion to ongoing concerns with opioids, and proposed solutions often focused less on regulatory control and more toward patient and HCP education and an overhaul of the health system approach to substance use and healthcare overall.

Pathophysiological Roles of Auxiliary Calcium Channel α2δ Subunits

α2δ proteins serve as auxiliary subunits of voltage-gated calcium channels, which are essential components of excitable cells such as skeletal and heart muscles, nerve cells of the brain and the peripheral nervous system, as well as endocrine cells. Over the recent years, α2δ proteins have been identified as critical regulators of synaptic functions, including the formation and differentiation of synapses. These functions require signalling mechanisms which are partly independent of calcium channels. Hence, in light of these features it is not surprising that the genes encoding for the four α2δ isoforms have recently been linked to neurological and neurodevelopmental disorders including epilepsy, autism spectrum disorders, schizophrenia, and depressive and bipolar disorders. Despite the increasing number of identified disease-associated mutations, the underlying pathophysiological mechanisms are only beginning to emerge. However, a thorough understanding of the pathophysiological role of α2δ proteins ideally serves two purposes: first, it will contribute to our understanding of general pathological mechanisms in synaptic disorders. Second, it may support the future development of novel and specific treatments for brain disorders. In this context, it is noteworthy that the antiepileptic and anti-allodynic drugs gabapentin and pregabalin both act via binding to α2δ proteins and are among the top sold drugs for treating neuropathic pain. In this book chapter, we will discuss recent developments in our understanding of the functions of α2δ proteins, both as calcium channel subunits and as independent regulatory entities. Furthermore, we present and summarize recently identified and likely pathogenic mutations in the genes encoding α2δ proteins and discuss potential underlying pathophysiological consequences at the molecular and structural level.

Analgesic Efficacy of Gabapentin and Pregabalin in Patients Undergoing Laparoscopic Bariatric Surgeries: a Systematic Review and Meta-analysis

This meta-analysis investigated the effect of oral gabapentinoids (i.e., pregabalin and gabapentin) on analgesic consumption (i.e., primary outcome) and pain relief (i.e., secondary outcome) in patients following bariatric surgery. Analysis of five eligible trials published between 2010 and 2019 including 363 participants receiving gabapentinoids revealed a significantly lower morphine consumption [mean difference (MD) =  - 15.1 mg, p = 0.004; evidence certainty: low] and risk of nausea/vomiting [risk ratio (RR) = 0.49, p = 0.002; evidence certainty: high] at postoperative 6-24 h. There was also a lower pain score at postoperative 0-4 h (MD =  - 1.41, p < 0.00001; evidence certainty: low) and 6-12 h (MD =  - 0.9, p = 0.007; evidence certainty: low) compared with controls, while pain severity at postoperative 24 h was comparable between two groups. In summary, preoperative oral gabapentinoids optimized postoperative pain outcomes and reduced risk of nausea/vomiting following bariatric surgery.

Nonsurgical Treatment of Carpal Tunnel Syndrome: A Survey of Hand Surgeons

Background

The nonsurgical treatment of carpal tunnel syndrome (CTS) consists of multiple modalities: splinting, corticosteroid injections, hand therapy, and oral medications. However, data supporting the effectiveness of these different modalities are varied, thus creating controversy regarding the optimal nonsurgical treatment. It is unknown how current hand surgeons utilize nonsurgical treatments for CTS.

Methods

An anonymous web-based survey was sent to 3289 members of the American Society for Surgery of the Hand to assess nonsurgical treatment patterns for CTS. We pretested the survey using expert survey and content review and cognitively tested the survey for readability and understandability.

Results

We analyzed surveys from 770 hand surgeons. Of the respondents, 41.2% of respondents recommend steroid injections for the treatment of CTS, 81.3% of respondents do not believe that oral steroids are beneficial for the treatment of CTS, and 3.6% of respondents typically prescribe gabapentinoids for the treatment of CTS. In total, 561 (72.9%) respondents always, usually, or sometimes encounter patients with more than two steroid injections for CTS before hand surgeon evaluation.

Conclusions

There is variation in the use of nonsurgical modalities for the treatment of CTS among American Society for Surgery of the Hand members. However, patients do not obtain long-term benefit from multiple steroid injections and gabapentinoids for the treatment of CTS, highlighting the importance of dissemination of evidence-based nonsurgical management of CTS. Collectively, these findings underscore the importance of providing clear guidelines as to which patients benefit most from nonsurgical treatments.