Pregabalin and gabapentin: what impact will reclassification have on doctors and patients?

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.

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

INTRODUCTION

Gabapentinoids are among the most widely prescribed pain medications. However, there is growing evidence to suggest that gabapentinoids may be associated with dependence and misuse. The aim of this systematic review is to synthesise the qualitative literature on gabapentinoid misuse and symptoms of dependence. The findings of this study will inform efforts to mitigate emerging harms.

METHODS AND ANALYSIS

A systematic review of qualitative research will explore lived experiences of misuse and symptoms of dependence among people who use gabapentinoids. Six databases (MEDLINE, Scopus, Web of Science, CINAHL, EMBASE and PsycINFO) and grey literature sources will be searched from inception to May 2023. Qualitative studies that include people with lived experiences of gabapentinoid misuse and symptoms of gabapentinoid dependence will be included. Reference lists of included studies will also be screened for additional studies. The methodological quality of included studies will be appraised using the Critical Appraisal Skills Programme qualitative checklist, and higher quality studies will be prioritised in the thematic synthesis. The GRADE-CERQual approach will be used to assess confidence in the overall findings of the review.

ETHICS AND DISSEMINATION

Ethical approval is not required for this systematic review. The findings of this review will be disseminated in peer-reviewed journals, at conferences and on social media.

PROSPERO REGISTRATION NUMBER

CRD42023401832.

Rescheduling gabapentinoids had negligible effects on prescribing behaviour by general practitioners in England

PURPOSE

To determine whether the rescheduling of gabapentinoids in England as Schedule 3 Controlled Substances in April 2019, changed prescribing behaviour for gabapentinoids by general practitioners.

METHODS

Data on the monthly number of prescription items and the monthly average dose per prescription item were analysed for the period April 2017 to April 2021 under three models: (i) a simple linear regression, (ii) a linear spline with a knot at April 2019, and (iii) a parallel slopes model with time before and after the rescheduling as a covariate. Best fit models were selected based on them having the lowest corrected Akaike's information criterion. Auto-regressive integrated moving average (ARIMA) models were also generated.

RESULTS

For gabapentin, the best fit model for the number of prescription items was the simple linear model, and for the dose per prescription item it was the parallel slopes model. For pregabalin, the best fit model was the linear spline for the number of prescription items and the dose per prescription item. For all models, the interval estimates for the slopes were consistent with no change or no meaningful change in prescribing behaviour after April 2019. Forecasts from ARIMA models for gabapentin and pregabalin were consistent with no change in the number of prescription items per month. However, forecasts for the dose per prescription item for gabapentin or pregabalin did not fully capture the post-April 2019 trajectories.

CONCLUSION

The reclassification of gabapentinoids did not materially change the prescribing behaviour of these drugs by general practitioners in England.

Rise of Pregabalin Poisoning and Abuse Cases in Serbia: A Ten-Year Retrospective Study

Purpose

The aim of this study was to analyze data on gabapentinoid-related attendances to the National Poison Control Center of Serbia (NPCC), particularly abuse cases; to estimate its changes and to compare it with trends in national consumption rates of these drugs. We also aimed to analyze the main characteristics of the study population and to investigate the major clinical effects in poisoned patients.

Patients and Methods

This is a retrospective study of patients admitted to the NPCC for acute poisoning involving gabapentinoids from 1 May 2012 to 1 October 2022.

Results

There were 357 (95.5%) pregabalin-related and 17 (4.5%) gabapentin-related poisoning cases in 302 patients. Abuse of pregabalin was detected in 27.8% (84/302), while gabapentin abuse occurred in 0.7% (2/302) of all patients. A steady increase in rates of pregabalin poisoning and abuse cases strongly correlated with the increase in overall consumption of this drug, while there were no significant changes in rates of gabapentin consumption, poisoning and abuse rate during the study period. Most patients who abused pregabalin pregabalin were males (84.5%) and the median age was 26 years (range: 15-45 years). Almost 60% of patients who abused pregabalin (48/84) belonged to the migrant population. Co-ingestions occurred in 89.4% of pregabalin-related cases (319/357), resulting in more severe poisoning. The most often co-ingested drugs were benzodiazepines and among them clonazepam was detected in the largest number of cases.

Conclusion

The poisoning and abuse cases involving pregabalin are on the rise in Serbia, which coincided with an increase in its overall consumption during the study period. Isolated pregabalin ingestions resulted in mild poisoning, although severe symptoms such as coma and bradycardia were recorded. When prescribing pregabalin to patients at risk of abuse caution is needed. Strengthening the measures for dispensing of pregabalin may reduce the risks associated with its abuse.

A snapshot on the usage pattern of gabapentinoids in Oman

Background

Since their introduction as adjunct anticonvulsants, the use of gabapentinoids (gabapentin and pregabalin) has increased substantially worldwide to include a wide range of clinical conditions. Various reports have demonstrated that they possess addiction liability and can produce effects similar to traditional recreational drugs, such as significant euphoric effects, enhanced sociability, and relaxation. However, there is limited information on the use of these agents in the Middle East.

Objectives

Here, we describe the usage pattern of gabapentinoids at Sultan Qaboos University Hospital, a tertiary care medical institution in Oman.

Methods

Adult patients (≥18 years) who were prescribed gabapentinoids for six months (March-August 2019) were included in this retrospective cross-sectional study. Indications and dosing regimens were reviewed according to the Food and Drug Administration labeling. Controlled and restricted drugs were reviewed using Oman National Formulary. Institutional ethical approval was obtained before conducting the study.

Results

We analyzed 291 prescriptions. The mean (standard deviation, SD) age was 60.5 years (SD = 13.0) with the age group of ≥60 years being the most common (190, 65.3%). Most of patients were females (178, 61.2%). The majority of prescriptions were for outpatients (85.8%). Drugs were prescribed as refill and follow-up in 116 (40.0%) and 97 (33.4%) of prescriptions, respectively. Diabetic peripheral neuropathy (50, 79.4%) was the most labeled indication for both. Off-label use was 128 (51.8%) and 31 (70.5%) for pregabalin and gabapentin, respectively, with lower back pain as being the most common indication for both drugs. A total of 54 (19.0%) patients were using at least one of the psychotropic drugs.

Conclusions

Our findings indicate that gabapentinoids are frequently prescribed for off-label use. Awareness programs and the establishment of policy for the use of these drugs are required to ensure their rational use and prevent misuse and/or abuse.

Current Evidence on Abuse and Misuse of Gabapentinoids

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

Non-medical Use of 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.

Molecular and hormonal changes caused by long-term use of high dose pregabalin on testicular tissue: the role of p38 MAPK, oxidative stress and apoptosis

In 1990, pregabalin was introduced as a novel antiepileptic drug that acts by binding selectively to the alpha-2-delta subunits of voltage-gated calcium channels resulting in increasing neuronal GABA levels and inhibiting the release of exciting neurotransmitters. The aim of our study is to assess the hazardous effects of prolonged high-dose pregabalin (like that abused by addicts) on testes and to clarify the potential causative mechanisms. The current study was conducted on 70 adult male Wistar albino rats which were divided into 7 groups. In our study we evaluated the effect of pregabalin, at concentrations 150 and 300 mg/kg/day for 90 days, on hormones; FSH, LH, testosterone and prolactin secretion. Our study also evaluated the expression of apoptosis-related genes BAX and BCL2 in testicular tissue in addition to the western blotted analysis of p38 Mitogen activated protein kinases (p38 MAPK). The levels of reduced glutathione, malondialdehyde and superoxide dismutase were also measured. Pregabalin decreased testosterone level while FSH, LH and prolactin showed a significant increase. It also produced genotoxicity through reversal of the BAX/BCL2 ratio; increased p38 MAPK level and induction of oxidative stress markers. The concomitant administration of vitamin E significantly reduced all the previously mentioned biochemical and hormonal adverse effects caused by pregabalin. Pregabalin can adversely affect male fertility particularly in addicts and patients who are being treated with it for long periods as those suffering from neuropathies and seizures. Antioxidants like vitamin E could have a role in amelioration.

An Insight into Gabapentin and Pregabalin in Scottish Prisoners

The aim of this study was to evaluate the prevalence and abuse potential of antiepileptic drugs (AEDs) among prison populations in Scotland, UK. Participants consisted of all admitted and released prisoners over a 1 month period who consented to provide samples. Urine samples were collected and analyzed by liquid chromatography coupled with triple quadrupole tandem mass spectrometry using a method validated for the simultaneous quantification of 21 AEDs in urine. A total of 904 samples were collected. The samples were also screened for drugs of abuse by using point-of-care testing kits. A total of 18% of the samples were positive for AEDs. Gabapentin (GBP) was identified in 118 samples (13%) and pregabalin (PRG) in 32 samples (3.5%). Interestingly, 12 samples contained both drugs (1.3%). The concentrations ranged from 0.5 to 1,100 mg/L (median, 15 mg/L) for GBP and from 0.5 to 440 mg/L (median, 7.3 mg/L) for PRG. Four samples were found to have concentrations >400 mg/L, two samples for GBP and two samples for PRG. These concentrations are at least 20 times above the median concentrations. Other AEDs detected were levetiracetam (four samples), vigabatrin (four samples), lamotrigine (three samples), valproic acid (three samples), carbamazepine (two samples) and topiramate (one sample). Illicit or non-prescribed drugs were detected in 81% of urine samples of which 80% were from admitted prisoners and 20% from released prisoners. Benzodiazepines, opiates and cannabis were the most frequently detected drugs. Other drugs found in positive AED samples were methadone (26%), cocaine (18%), buprenorphine (17%), amphetamines (4%), methamphetamines (4%) and barbiturates (4%). This study shows a high prevalence of AEDs within the Scottish prison system, primarily due to GBP and PRG; however, due to the anonymity of the sample collection, it is unknown if these are prescribed or illicit drug ingestions.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Antiepileptic Drugs in Pediatrics

Epilepsy affects approximately 1% of the population. First-line treatment for epilepsy is the administration of anti-seizure medication, also referred to as antiepileptic drugs (AEDs), although this nomenclature is erroneous as these medications typically do not impact underlying epileptogenic processes; the goal of these medications is to control symptoms. Over 30% of patients are classified as having "medically refractory" epilepsy, i.e., lack of adequate seizure control despite trials of two or three AEDs (Kwan and Brodie, N Engl J Med 342:314-9, 2000). Epilepsy is associated with worse quality of life in children, adolescents, and their families (Cianchetti et al., Seizure 24:93-101, 2015). Patients with epilepsy have a two to three times greater risk of death than the general population, by various causes including sudden unexplained death in epilepsy patients (SUDEP) (Abdel-Mannan et al., Epilepsy Behav 90:99-106, 2019). It is these factors, among others, that have motivated the continued development of AEDs. This chapter will review the history and evolution of AED development, features of specific AEDs with a focus on the newest generation, and examples of AEDs in development.