Clinical outcomes in newer anticonvulsant overdose: a poison center observational study

Pharmacokinetic and pharmacodynamic data from the NEOLEV1 and NEOLEV2 studies

OBJECTIVES

To confirm that levetiracetam (LEV) demonstrates predictable pharmacokinetics(PK) at higher doses and to study the pharmacodynamics(PD) of LEV.

DESIGN

Pharmacokinetic data from the NEOLEV1 and NEOLEV2 trials were analysed using a non-linear mixed effects modelling approach. A post hoc analysis of the effect of LEV on seizure burden was conducted.

SETTING

Neonatal intensive care unit.

PATIENTS

Term neonates with electrographically confirmed seizures.

INTERVENTIONS

In NEOLEV1, neonates with seizures persisting following phenobarbital (PHB) received LEV 20 or 40 mg/kg bolus followed by 5 or 10 mg/kg maintenance dose(MD) daily. In NEOLEV2, patients received a 40 mg/kg intravenous LEV load, followed by 10 mg/kg doses 8 hourly. If seizures persisted, a further 20 mg/kg intravenous load was given. If seizures persisted, PHB was given. PK data were collected from 16 NEOLEV1 patients and 33 NEOLEV2 patients. cEEG data from 48 NEOLEV2 patients were analysed to investigate onset of action and seizure burden reduction.

MAIN OUTCOME MEASURES

Clearance (CL) and volume of distribution (Vd) were determined. Covariates that significantly affected LEV disposition were identified.

RESULTS

Primary outcome: The median initial LEV level was 57 µg/mL (range 19-107) after the first loading dose and at least 12 µg/mL at 48 hours in all infants. CL and Vd were estimated to be 0.0538 L/hour and 0.832 L, respectively. A direct relationship between postnatal age and CL was observed. The final population pharmacokinetic(PopPK) model described the observed data well without significant biases. CL and Vd were described as CL (L/hour)=0.0538×(weight in kg/3.34)0.75×(postnatal age in days/5.5) 0.402 and Vd (L)=0.832×(weight in kg/3.34).Seizure burden reduced within 30 min of LEV administration. 28% of patients were completely seizure free after LEV. In an additional 25% of patients, seizure burden reduced by 50%.

CONCLUSIONS

LEV pharmacokinetics remained predictable at higher doses. Very high-dose LEV can now be studied in neonates.

TRIAL REGISTRATION NUMBER

NCT01720667.

Concurrent Gabapentin and Opioid Use and Risk of Mortality in Medicare Recipients with Non-Cancer Pain

Gabapentin is prescribed for pain and is perceived as safe generally. However, gabapentin can cause respiratory depression, exacerbated by concomitant central nervous system depressants (e.g., opioids), a concern for vulnerable populations. We compared mortality rates among new users of either gabapentin or duloxetine with or without concurrent opioids in the 20% Medicare sample. We conducted a new-user design retrospective cohort study, in Medicare enrollees ages 65-89 years with noncancer chronic pain and no severe illness who filled prescriptions between 2015 and 2018 for gabapentin (n = 233,060) or duloxetine (n = 34,009). Daily opioid doses, estimated in morphine milligram equivalents (MMEs), were classified into none, low (0 < MME < 50), and high (≥ 50 MME), based on Centers for Disease Control and Prevention (CDC) recommendations. The outcomes were all-cause mortality (primary) and out-of-hospital mortality (secondary). We used inverse probability of treatment weighting to adjust for differences between gabapentin and duloxetine users. During 116,707 person-years of follow-up, 1,379 patients died. All-cause mortality rate in gabapentin users was 12.16 per 1,000 person-years vs. 9.94 per 1,000 in duloxetine users. Risks were similar for users with no concurrent opioids (adjusted hazard ratio (aHR) = 1.03, 95% confidence interval (CI): 0.80-1.31) or low-dose daily opioids (aHR = 1.06, 95% CI: 0.63-1.76). However, gabapentin users receiving concurrent high-dose daily opioids had an increased rate of all-cause mortality compared with duloxetine users on high-dose opioids (aHR = 2.03, 95% CI: 1.19-3.46). Out-of-hospital mortality yielded similar results. In this retrospective cohort study of Medicare beneficiaries, concurrent use of high-dose opioids and gabapentin was associated with a higher all-cause mortality risk than that for concurrent use of high-dose opioids and duloxetine.

Topiramate-Induced Coma in a 39-Year-Old Female Patient: Burst Suppression on EEG

Reported cases of topiramate ingestion resulting in coma and generalized convulsive status epilepticus are very rare. Such a phenomenon of a relatively safe antiepileptic drug (AED) causing serious neurological compromise should be carefully reviewed. A 39-year-old female with a history of uncontrolled epilepsy, migraine headaches, hypothyroidism, obsessive-convulsive disorder, and depression presented with generalized tonic-clonic seizures that progressed to status epilepticus and coma thereafter. She was intubated due to a depressed level of consciousness and transferred afterward to our hospital. Electroencephalography (EEG) demonstrated a burst suppression pattern without receiving any sedating agents. The level of consciousness improved on the fourth day, and she achieved complete neurological recovery by the sixth day of hospitalization. She was offered AEDs and supportive therapy during her admission. Upon further investigation into the cause of her seizures, it was discovered that she had ingested a large dose of topiramate in a suicide attempt.

Topiramate intoxications & hemodialysis - Literature review and the first case report of a massive suicidal intoxication treated with hemodialysis

Background

Topiramate is an anticonvulsant from sulfamate-substituted monosaccharides that is increasingly used to treat migraines. Serious topiramate intoxications have been described. Unfortunately, indications for and the effect of interventions, including hemodialysis, in severe intoxications seem expert-based and lack empirical evidence. We aim to review the literature on topiramate intoxication cases and to describe the first topiramate intoxication with toxicokinetic data following treatment with hemodialysis.

Methods

A literature review was conducted using the PubMed database. Included articles were reviewed for symptoms; management, including acute hemodialysis; toxicokinetic data; and outcomes.

Results

We found 61 hits in the PubMed database and checked 392 references in the snowball search; 22 were included for data extraction, reporting 29 cases. The majority of the patients were female (n = 23/29, 79%), ranging in age from 2 to 44 years (median 21). The ingested topiramate amount ranged from 175 to 40,000 mg (usual maintenance dose of 50 mg BID and a general maximum of 500 mg BID). Topiramate concentrations were reported in eight cases, ranging from 3.7 to 356.6 mg/L (for reference, the therapeutic range is 2-30 mg/L). Serious topiramate intoxications can result in seizures, coma, hemodynamic instability and severe metabolic acidosis. In no single case was hemodialysis used.

Conclusion

Serious symptoms of topiramate intoxications exist, and hemodialysis is used infrequently. If symptoms are refractory to symptomatic treatment, hemodialysis can reduce topiramate concentrations and symptomatology.

Patterns of opioid and benzodiazepine use with gabapentin among disabled Medicare beneficiaries - A retrospective cohort study

BACKGROUND

Our goal was to describe specific patterns associated with co-prescriptions of gabapentin, opioids, and benzodiazepines among disabled Medicare beneficiaries.

METHODS

Using 2013-2015 Medicare data, we conducted a retrospective cohort study among fee-for-service disabled beneficiaries continuously enrolled in Medicare Parts A, B, and D. The index date was defined as the earliest fill date for a gabapentin, opioid, or benzodiazepine prescription. Monotherapy, dual therapy, and tri-therapy were defined as utilization of one, two, and three medication classes, respectively. Augmentation was defined as a prescription for a different medication class in addition to prescription for initial medication; switching referred to a change in prescription for a different medication class with no subsequent fills of initial medication. We used descriptive statistics, Kaplan Meier analyses and Cox proportional hazards to examine the association between initial therapy and monotherapy, dual therapy, tri-therapy, switching and augmentation.

RESULTS

Among 151,552 disabled beneficiaries, gabapentin initiators were more likely to augment therapy (50.1%) when compared to opioid (28.7%) and benzodiazepine (38.7%) users. When compared to opioid initiators, the risk of augmentation (HR[95%CI]: 1.85[1.82-1.89]) and switching (1.62 [1.51-1.73]) was significantly higher among gabapentin initiators. Risk of augmentation was also significantly higher among beneficiaries with co-morbid pain and mental health conditions (p < 0.01). Overall, the majority of beneficiaries augmented and switched within 2-months and 4-months after initiating therapy, respectively.

CONCLUSIONS

Given safety concerns associated with gabapentin, opioids, and benzodiazepines, it is imperative that the benefits and risks of co-prescribing these medications be examined comprehensively, especially for those in vulnerable sub-groups.

Data on the relationship between lamotrigine and levetiracetam serum/plasma levels and toxicity: Experience at an academic medical center

Lamotrigine and levetiracetam are second-generation anti-epileptic drugs used for the management of seizure disorders and some other medical conditions. In the related research article using retrospective data from an academic medical center, we analyzed 5046 samples originating from 1930 unique patients that had lamotrigine drug levels performed on serum/plasma and 4359 samples from 2451 patients that had levetiracetam drug levels performed. The data in this article provides the patient demographic, clinical location at time of drug level, and specific lamotrigine or levetiracetam serum/plasma drug level for all patients. For those instances with lamotrigine drug level greater than 14.0 mg/L or levetiracetam drug level of 80 mg/L or higher, additional data from chart review includes: indication for ordering the drug level, two main presenting signs or symptoms at time of drug level, timing of drug level (random, trough, peak, or unknown), changes in drug dosing following the drug level, concomitant therapy with valproic acid (lamotrigine only), and details related to drug overdose (if applicable). The analyzed data is provided in the supplementary tables included in this article. Volumes of test ordering by year is included in a figure. The dataset reported is related to the research article entitled "Correlation of Elevated Lamotrigine and Levetiracetam Serum/Plasma Levels with Toxicity: A Long-Term Retrospective Review at an Academic Medical Center" [K. E. Wood, K. L. Palmer, M.D. Krasowski, Correlation of elevated lamotrigine and levetiracetam serum/plasma levels with toxicity: A long-term retrospective review at an academic medical center, Toxicol. Rep. (2021) 8:1592-1598].

Extracorporeal Treatment for Gabapentin and Pregabalin Poisoning: Systematic Review and Recommendations From the EXTRIP Workgroup

Toxicity from gabapentin and pregabalin overdose is commonly encountered. Treatment is supportive, and the use of extracorporeal treatments (ECTRs) is controversial. The EXTRIP workgroup conducted systematic reviews of the literature and summarized findings following published methods. Thirty-three articles (30 patient reports and 3 pharmacokinetic studies) met the inclusion criteria. High gabapentinoid extracorporeal clearance (>150mL/min) and short elimination half-life (<5 hours) were reported with hemodialysis. The workgroup assessed gabapentin and pregabalin as "dialyzable" for patients with decreased kidney function (quality of the evidence grade as A and B, respectively). Limited clinical data were available (24 patients with gabapentin toxicity and 7 with pregabalin toxicity received ECTR). Severe toxicity, mortality, and sequelae were rare in cases receiving ECTR and in historical controls receiving standard care alone. No clear clinical benefit from ECTR could be identified although major knowledge gaps were acknowledged, as well as costs and harms of ECTR. The EXTRIP workgroup suggests against performing ECTR in addition to standard care rather than standard care alone (weak recommendation, very low quality of evidence) for gabapentinoid poisoning in patients with normal kidney function. If decreased kidney function and coma requiring mechanical ventilation are present, the workgroup suggests performing ECTR in addition to standard care (weak recommendation, very low quality of evidence).

Pregabalin poisoning: Evaluation of dose-toxicity relationship

Context

Pregabalin poisoning is mostly benign, although coma and convulsions occasionally occur.

Aim

To determine the dose‐toxicity relationship of pregabalin.

Methods

Dose‐toxicity data of isolated pregabalin poisonings were collected from (1) a prospective study performed by the Dutch Poisons Information Centre (4 April 2014 to 4 October 2016) and from (2) case reports and case series reported in literature. Poisonings were graded using the Poisoning Severity Score (PSS) and the relationship between dose (mg kg⁻¹) and PSS was evaluated.

Results

In our study (n = 21 patients), the most commonly observed symptoms were drowsiness (62%), confusion (29%) and apathy (24%). PSS was none in three (14%), minor in 15 (71%), and moderate in three patients (14%). Most case series also reported a PSS of none to minor in the majority of poisonings (69‐100%). For 34 individual patients (21 from our study and 13 from literature), detailed data on dose and clinical course were available to examine the dose‐toxicity relationship.

The median dose was significantly lower in the PSS none‐minor group (“benign”) (8.6 mg kg⁻¹, interquartile range (IQ25‐75) 5.0‐17.6 mg kg⁻¹) than in the PSS moderate‐severe group (“significant toxicity”) (46.7 mg kg⁻¹, IQ25‐75 21.3‐64.3 mg kg⁻¹); estimate of the median difference = 27.3 mg kg⁻¹ (95% confidence interval (CI): 10‐48.6).

Conclusions

In general, higher pregabalin doses result in more severe poisonings. Below 20 mg kg⁻¹ the majority of patients (83%) only suffer from mild poisoning. However, large interindividual differences exist in pregabalin‐induced toxicity. Therefore, pre‐hospital triage should not only include pregabalin dose, but also underlying illnesses, co‐exposures and reported symptoms.

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.

Correlation of elevated lamotrigine and levetiracetam serum/plasma levels with toxicity: A long-term retrospective review at an academic medical center

Lamotrigine and levetiracetam are widely used second-generation anti-epileptic drugs. Existing literature indicates that overdose of either drug is typically benign, but neurologic and cardiac toxicity can occur in some cases. In this retrospective study, we analyzed a large dataset of serum/plasma drug levels for lamotrigine and levetiracetam. The data covered 1,930 unique patients (5,046 levels) for lamotrigine and 2,451 patients (4,359 levels) for levetiracetam. We performed detailed chart review on all patients with one or more lamotrigine levels greater than 14.0 mg/L (293 unique patients) and all patients with one or more levetiracetam levels of 80 mg/L or higher (106 unique patients). No deaths directly attributable to lamotrigine or levetiracetam toxicity were reported. For cases with lamotrigine levels greater than 14.0 mg/L, the majority of patients were asymptomatic (55.3 %, n = 162). The most common presenting symptoms were ataxia (14.3 %, n = 42), seizures (14.0 %, n = 41), dizziness (11.9 %, n = 35), and altered mental status (11.6 %, n = 34). There were 12 overdoses (11 intentional) involving lamotrigine, all of which presented with either altered mental status (n = 8) or seizures (n = 4). The highest estimated dose reportedly ingested was 20 g. Cardiac toxicity was observed in two cases involving intentional overdose of lamotrigine. For patients with levetiracetam serum/plasma levels of 80 mg/L or higher, 48 patients (45.3 %) were asymptomatic. Symptomatic patients most commonly presented with seizures (31.1 %, n = 33) and altered mental status (15.1 %, n = 16), and none showed cardiac symptoms. There were only two cases involving intentional levetiracetam overdose, one of which presented with altered mental status after ingestion of 45 g and the other asymptomatic after ingestion of 6 g. Overall, our data is consistent with previous investigations that lamotrigine and levetiracetam toxicity most typically presents with neurologic symptoms and rarely cardiac arrhythmias. Approximately half of the patients with elevated lamotrigine or levetiracetam drug levels are asymptomatic.

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.

Association of gabapentinoid utilization with postoperative pulmonary complications in gynecologic surgery: a retrospective cohort study

OBJECTIVE

To investigate gabapentinoid utilization and association with postoperative pulmonary complications after gynecologic surgery.

METHODS

After Institutional Review Board approval, we performed this retrospective cohort study using the Premier Healthcare Database. We used ICD-10 and charge codes to identify adults who underwent elective gynecologic surgery from 2015 to 2018 and received either gabapentin or pregabalin on the day of surgery. Our primary outcome was a composite of pulmonary complications: respiratory failure, pneumonia, reintubation, pulmonary edema, and non-invasive or invasive ventilation. Secondary outcomes included mortality, intensive care unit admission, mechanical or non-invasive ventilation, hospital length of stay, re-admission within 30 days, opioid consumption and antiemetic use. Multivariable generalized linear mixed models were utilized to examine the associations between gabapentinoids and our outcome measures, adjusted for all covariates.

RESULTS

Data from 253,013 patients were analyzed, with 19,121 (7.6%) receiving gabapentinoids. Gabapentinoid utilization increased from 3.9% in 2015 to 12.3% in 2018, and was associated with increased pulmonary complications (OR 1.19; 95% CI 1.03-1.38), non-invasive ventilation (odds ratio [OR] 1.53; 95% CI 1.29-1.81), duration of hospital stay (% change 1.75; 95% CI 0.92-2.59), daily antiemetic doses on day of surgery (mean difference [MD] 1.37; 95% CI 1.26-1.49) and subsequently (MD 1.61; 95% CI 1.30-1.99), and higher daily average (MD 4.59 mg; 95% CI 3.55-5.63) and total (MD 8.74 mg; 95% CI 6.83-10.62) parenteral morphine equivalents.

CONCLUSIONS

Gabapentinoid utilization in gynecologic surgery is increasing and is associated with postoperative pulmonary complications.

Use of injectable lipid emulsion and sodium bicarbonate to treat severe cardiovascular collapse secondary to lamotrigine toxicosis in a dog

CASE DESCRIPTION

A 2-year-old 5.1-kg (11.2-lb) sexually intact male Maltese was admitted because of vomiting and seizures after a known ingestion of up to 206 mg/kg (93.6 mg/lb) of lamotrigine (a commonly prescribed human antiepileptic medication) approximately 3 hours earlier.

CLINICAL FINDINGS

On presentation, the dog was having a seizure; however, the seizure stopped before interventional treatment, and the dog was obtunded, tachycardic, and hypertensive. Fluid therapy was initiated, and a bolus of injectable lipid emulsion (ILE) was administered. The dog's cardiovascular and mentation signs improved, and the dog was hospitalized for supportive care and monitoring. Hours later, the dog developed ventricular tachycardia that progressed to ventricular fibrillation, then cardiac arrest.

TREATMENT AND OUTCOME

Cardiopulmonary resuscitation, including defibrillation, was initiated. With no response after several minutes of resuscitation efforts, another bolus of ILE was administered, and the dog's heartbeat returned shortly thereafter, albeit with severe ventricular arrhythmias that were treated medically, including with sodium bicarbonate. The dog was discharged 48 hours later with no neurologic or cardiovascular abnormalities. Six months later, the owner reported that the dog was doing well and had no abnormalities.

CLINICAL RELEVANCE

To our knowledge, there are no previous case reports in veterinary medicine regarding the successful use of ILE to treat cardiac arrest secondary to lipophilic drug toxicoses nor the use of and physiologic response to sodium bicarbonate during treatment of lamotrigine toxicoses in dogs; therefore, findings in the dog of the present report may help other veterinarians treating similarly affected dogs in the future.

Respiratory depression in the post-anesthesia care unit: Mayo Clinic experience

The anesthesia recovery is a complex physiologic process as systems recover from the effects of surgery and anesthesia. Inadequate recovery of respiratory physiology can lead to severe hypoxemia-induced end-organ damage and even death. Emerging evidence suggests that signs of respiratory depression during early anesthesia recovery may portend increased risk for future severe adverse events. This article briefly reviews the Mayo Clinic research experience and advances in clinical practice. From the implementation of a step-down model of discharge criteria in the post-anesthesia care unit (PACU), consisting of PACU nurses monitoring patients in predetermined periods for signs of respiratory depression, and delaying PACU discharge for patients who exhibit signs of respiratory depression, and early intervention in high-risk patients. Subsequent studies found that even a single episode of respiratory depression in the PACU was strongly associated with subsequent respiratory complications. Further, patient baseline characteristics found to be associated with respiratory depression included obstructive sleep apnea and low body weight, and surgical factors associated with increased risk included the use of preoperative sustained-release opioids, perioperative gabapentinoid use, higher intraoperative opioids, isoflurane as the volatile anesthetic, and longer surgical duration. Based in part of Mayo Clinic research, the FDA issued a warning in 2019 on gabapentinoids use and respiratory complications, increasing the recommended level of respiratory vigilance in patients using this medication. Understanding the complex nature of postoperative respiratory events requires a range of translational and clinical research and constant update of practice.

Characterization of gabapentin use in Kentucky after reclassification as a Schedule V controlled substance

BACKGROUND

Owing to increasing concern over the potential for gabapentin misuse, gabapentin was reclassified as a schedule V controlled substance in Kentucky (July 2017).

OBJECTIVE

This study aimed to characterize gabapentin use among Kentucky residents in the first year after its scheduling.

METHODS

This study used Kentucky All Schedule Prescription Electronic Reporting data (2018). Gabapentin use was defined as having at least 1 dispensed gabapentin prescription, and high-dose gabapentin use was defined as an average daily dose of more than 3600 mg at the patient level. The prevalence of gabapentin use, concurrent use of gabapentin with opioid analgesics (OAs) (gabapentin-OA), and gabapentin with OAs and benzodiazepines (BDZs) (gabapentin-OA-BDZ) were assessed. Estimated prevalence rate ratio and its 95% CI were reported to compare gabapentin use rates across different demographic groups.

RESULTS

A total of 16% of all 2018 controlled substance prescriptions were for gabapentin, and approximately 20% of Kentucky residents with controlled substance prescriptions received gabapentin at least once in 2018. The overall prevalence of gabapentin use was 63 per 1000 residents, with the highest rates among residents aged 55-64 years (126.9 per 1000). The prevalence of gabapentin use was higher in females (74.6 per 1000) versus males (50.6 per 1000) and in residents living in the Appalachian region (88.57 per 1000) versus Central (51.78 per 1000) and Delta (66.41 per 1000) regions. Among gabapentin users, 1% were high-dose users; 27.4% and 11.9% received gabapentin-OA or gabapentin-OA-BDZ concurrently, respectively. As the average daily dose increased from less than 900 mg to high-dose, the percentage of concurrent gabapentin-OA use increased from 13.4% to 50.7%.

CONCLUSION

Gabapentin is widely prescribed in Kentucky, with higher rates of use observed in females, those older than 55 years and individuals living in the Appalachian region. Concurrent use of gabapentin and OAs is common, especially in those receiving high-dose gabapentin. Future studies are needed to assess the risks associated with gabapentin use.

Unintentional exposure to pregabalin in ≤6-year-old children: a nationwide French Poison Control Center study

INTRODUCTION

In France, pregabalin is widely prescribed in adults but still not approved for children. We aimed to investigate the incidence of pregabalin exposure in ≤6-year-old children, to describe the characteristics and outcome of ingestions involving pregabalin alone, and to estimate a clinically relevant toxic dose in this population.

METHODS

Retrospective analysis of pregabalin exposures in ≤6-year-old children, collected by the French Poison Control Centers in 2004-2019. The incidence was estimated using pregabalin prescription data from the Health Improvement Network database (the French version of THIN). The poison severity score (PSS) was used to grade severity.

RESULTS

We found 313 unintentional immediate-release pregabalin ingestions in ≤6-year-old children. The number of cases per 100,000 pregabalin-treated adults increased over time (p < 0.001). One hundred twenty-six cases involving pregabalin alone (age, 2 years [1.6-3.0] (median [25th-75th percentiles]); median ingested dose 6.4 mg/kg [3.6-10.9]) were analyzed. No child presented an underlying neurological/cardiac disease and/or took concomitant medications. Most of the children (77%) remained asymptomatic (PSS0) while 21% and 2% developed minor (PSS1) or moderate (PSS2) neurological symptoms, respectively. No severe complications/fatalities were reported. All symptomatic children recovered within 24 h. The ingested pregabalin dose was positively correlated with PSS (p < 0.0001). Using a ROC curve approach (area under the curve, 0.85; p < 0.001), ingestion of ≥19.4 mg/kg pregabalin was appropriate to recommend hospital referral (sensitivity, 39% [95% confidence interval (95% CI), 24-56], specificity, 100% [95% CI, 96-100], predictive positive value, 100% [95% CI, 64-100], and negative predictive value, 85% [95% CI, 82-89]). Symptomatic children who ingested <19.4 mg/kg pregabalin developed minor symptoms.

CONCLUSION

Despite increasing prescriptions in adults in France, unintentional pregabalin ingestions in ≤6-year-old children remain rare and cause minimal toxicity. Children with no underlying neurological/cardiac disease and concomitant medication ingesting <19.4 mg/kg immediate-release pregabalin alone can be safely observed at home.

Multimorbidity and Critical Care Neurosurgery: Minimizing Major Perioperative Cardiopulmonary Complications

With increasing prevalence of chronic diseases, multimorbid patients have become commonplace in the neurosurgical intensive care unit (neuro-ICU), offering unique management challenges. By reducing physiological reserve and interacting with one another, chronic comorbidities pose a greatly enhanced risk of major postoperative medical complications, especially cardiopulmonary complications, which ultimately exert a negative impact on neurosurgical outcomes. These premises underscore the importance of perioperative optimization, in turn requiring a thorough preoperative risk stratification, a basic understanding of a multimorbid patient’s deranged physiology and a proper appreciation of the potential of surgery, anesthesia and neurocritical care interventions to exacerbate comorbid pathophysiologies. This knowledge enables neurosurgeons, neuroanesthesiologists and neurointensivists to function with a heightened level of vigilance in the care of these high-risk patients and can inform the perioperative neuro-ICU management with individualized strategies able to minimize the risk of untoward outcomes. This review highlights potential pitfalls in the intra- and postoperative neuro-ICU period, describes common preoperative risk stratification tools and discusses tailored perioperative ICU management strategies in multimorbid neurosurgical patients, with a special focus on approaches geared toward the minimization of postoperative cardiopulmonary complications and unplanned reintubation.

Pregabalin poisoning and rising recreational use: a retrospective observational series

AIMS

With rising use worldwide, pregabalin is increasingly implicated in poisoning deaths. We aimed to investigate the clinical effects and complications of pregabalin poisoning.

METHODS

This is a retrospective review of patients presenting with pregabalin poisoning to two tertiary toxicology units from 1 July 2014 to 30 June 2019. Patients were identified from prospective databases maintained by both units and data were extracted from these in addition to medical records.

RESULTS

There were 488 presentations in 413 patients (237 [57%] male) over the five-year period. The median age was 41 years (IQR 31-50 years). Deliberate self-poisonings accounted for 342 (70%) presentations, with 121 (25%) recreational exposures. Recreational exposures increased over the period from 2 (4%) in the first year to 54 (39%) presentations in the final year. The median dose of pregabalin was 1200 mg (IQR 600-3000 mg, range 75-16 800 mg). Co-ingestions occurred in 427 (88%) presentations, with sedating agents being co-ingested in 387 (79%)-most commonly opioids and benzodiazepines in 201 (41%) and 174 (36%) presentations respectively. Coma (GCS < 9) occurred in 89 (18%) cases, with 52 (11%) patients being intubated. Only one (0.2%) of these patients had not co-ingested a sedating agent. Hypotension occurred in 26 (5%) cases, all with co-ingestants. Seizures occurred in 11 (2%) cases, 3/59 (5%) in pregabalin-only overdoses. The median length of stay was 16.5 hours (IQR 10-25 hours).

CONCLUSIONS

Pregabalin overdose does not cause severe toxicity, but rather mild sedation and, uncommonly, seizures. Coma is common in the presence of sedating co-ingestants. Recreational use is increasing.

Multimodal Pain Management and Postoperative Outcomes in Lumbar Spine Fusion Surgery: A Population-based Cohort Study

STUDY DESIGN

Retrospective population-based cohort analysis.

OBJECTIVE

Given the lack of large-scale data on the use and efficacy of multimodal analgesia in spine fusion surgery, we conducted a population-based analysis utilizing the nationwide claims-based Premier Healthcare database.

SUMMARY OF BACKGROUND DATA

Multimodal analgesia, combining different pain signaling pathways to achieve additive and synergistic effects, is increasingly emerging as the standard of care.

METHODS

Cases of posterior lumbar fusion surgery were extracted (2006-2016). Opioid-only analgesia was compared to multimodal analgesia, that is, systemic opioid analgesia + either acetaminophen, steroids, gabapentinoids, ketamine, nonsteroidal anti-inflammatory drugs (NSAIDs), cyclooxygenase-2 (COX-2) inhibitors, or neuraxial anesthesia (categorized into 1, 2, or >2 additional analgesic modes). Mixed-effects models measured associations between multimodal analgesia categories and outcomes, including opioid prescription dose, cost/length of hospitalization, and opioid-related complications. Odds ratios (ORs, or % change) and 95% confidence intervals (CIs) are reported.

RESULTS

Among 265,538 patients the incidence of multimodal analgesia was 61.1% (162,156); multimodal pain management-specifically when adding NSAIDs/COX-2 inhibitors to opioids-was associated with reduced opioid prescription (-13.3% CI -16.7 to -9.7%), cost (-2.9% CI -3.9 to -1.8%) and length of hospitalization (-7.3% CI -8.5 to -6.1%). Multimodal analgesia in general was associated with stepwise decreased odds for gastrointestinal complications (OR 0.95, 95% CI 0.88-1.04; OR 0.84, CI 0.75-0.95; OR 0.78, 95% CI 0.64-0.96), whereas odds were increased for postoperative delirium (OR 1.14, 95% CI 1.00-1.32; OR 1.33, 95% CI 1.11-1.59; OR 1.31, 95% CI 0.99-1.74), and counterintuitively- naloxone administration (OR 1.25, 95% CI 1.13-1.38; OR 1.56, 95% CI 1.37-1.77; OR 1.84, 95% CI 1.52-2.23) with increasing analgesic modes used: one, two, or more additional analgesic modes, respectively. Post-hoc analysis revealed that specifically gabapentinoid use increased odds of naloxone requirement by about 50%, regardless of concurrent opioid dose (P < 0.001).

CONCLUSION

Although multimodal analgesia was not consistently implemented in spine fusion surgery, particularly NSAIDs and COX-2 inhibitors demonstrated opioid sparing effects. Moreover, results suggest a synergistic interaction between gabapentinoids and opioids, the former potentiating opioid effects resulting in greater naloxone requirement.

LEVEL OF EVIDENCE

3.

Prescribed and non-prescribed gabapentin use among persons seeking inpatient opioid detoxification

BACKGROUND

Persons with opioid use disorder (OUD) are at increased risk for gabapentin misuse. Rising rates of concomitant gabapentin-opioid use in the U.S. are concerning given heightened risk of fatal overdose.

OBJECTIVE

To examine predictors of ever using gabapentin among persons seeking treatment for opioid use and to assess if reasons for gabapentin use differed by gender and how gabapentin was procured (prescribed, non-prescribed, or both).

METHOD

Persons with OUD were recruited from a managed withdrawal program. t-Tests and Pearson χ2 tests of independence were used to compare reasons for gabapentin use by gender and source of acquisition.

RESULTS

Among participants (n = 401; 69.1% male, 84.5% White, 86.8% sought treatment for heroin use, 90.0% insured), female gender, higher educational attainment, injection drug use (IDU), history of overdose, and chronic pain were associated with gabapentin use. Overall, reasons for use were similar across genders among those reporting a history of gabapentin use (65.8%), although males were more likely to use to get high than females. About half (47.0%) reported only using gabapentin that was not prescribed, 20.5% had only used prescribed gabapentin, and 32.5% reported prescribed and non-prescribed use. Persons prescribed gabapentin were most likely to use it to control pain (81.5%); for those using diverted gabapentin only and those reporting both prescribed and non-prescribed gabapentin use, the most common reasons for intake were to: get high, increase effects of heroin, substitute for opioids, and help with opioid withdrawal.

CONCLUSIONS

In this sample of people with OUD entering inpatient detoxification program, a majority reported a history of gabapentin use, with most using diverted gabapentin. The range of reasons for gabapentin use point to the need to better understand why co-use is common.

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.

Patient Survival After Acute Voluntary Poisoning With a Huge Dose of Oxcarbazepine and Olanzapine

INTRODUCTION

Oxcarbazepine is a carbamazepine pre-drug with less drug interactions. Its adverse effects, including hyponatremia, somnolence and ataxia, are dose dependent. Olanzapine is an atypical antipsychotic drug most commonly used to manage psychoses and symptoms of irritability and aggressive behavior. Main side effects include extrapyramidal and anticholinergic symptoms, weight gain, and hyperglycemia.

CASE REPORT

In this manuscript a case of oxcarbazepine and olanzapine intoxication is discussed. A 45-year-old woman, previously diagnosed with bipolar disorder and chronic alcoholism, was presented two hours after ingestion of 30,000mg of oxcarbazepine and 140 mg of olanzapine, combined with alcohol. She was immediately treated with gastric lavage and administration of activated charcoal. During her hospitalization she was hemodynamically and respiratory stable with no neurological signs and symptoms except for somnolence. Another side effect was hyponatremia. She was discharged from our department in stable clinical condition after being evaluated by a psychiatrist.

CONCLUSION

Early approach is crucial for the management of drug intoxication. Late symptoms can be avoided through close monitoring of vital signs, mental status and laboratory values. Psychiatric consultation is essential for a better long-term outcome.

Antiepileptic drugs: Role in paediatric poisoning

Intoxications, both accidental and intentional, are common in children and adolescents and often require hospitalisation and intensive treatment. Antiepileptic drugs are a possible cause of poisoning and intoxications because this category of medications has shown a rising trend in recent years. They might be responsible for multi-organ dysfunctions of variable severity, ranging from subtle symptoms to life-threatening complications. No guidelines on the management of these intoxications in the paediatric population are currently available, and treatment is mainly supportive. Activated charcoal administration and extracorporeal circulation techniques for drug removal have been proposed. Facing the complexity of this clinical scenario, it is of utmost importance to maintain a high index of suspicion to guarantee a prompt intervention and ensure the best possible management for the patient.

Medications for alcohol use disorders: An overview

Patients who suffer from alcohol use disorders (AUDs) usually go through various socio-behavioral and pathophysiological changes that take place in the brain and other organs. Recently, consumption of unhealthy food and excess alcohol along with a sedentary lifestyle has become a norm in both developed and developing countries. Despite the beneficial effects of moderate alcohol consumption, chronic and/or excessive alcohol intake is reported to negatively affect the brain, liver and other organs, resulting in cell death, organ damage/failure and death. The most effective therapy for alcoholism and alcohol related comorbidities is alcohol abstinence, however, chronic alcoholic patients cannot stop drinking alcohol. Therefore, targeted therapies are urgently needed to treat such populations. Patients who suffer from alcoholism and/or alcohol abuse experience harmful effects and changes that occur in the brain and other organs. Upon stopping alcohol consumption, alcoholic patients experience acute withdrawal symptoms followed by a protracted abstinence syndrome resulting in the risk of relapse to heavy drinking. For the past few decades, several drugs have been available for the treatment of AUDs. These drugs include medications to reduce or stop severe alcohol withdrawal symptoms during alcohol detoxification as well as recovery medications to reduce alcohol craving and support abstinence. However, there is no drug that completely antagonizes the adverse effects of excessive amounts of alcohol. This review summarizes the drugs which are available and approved by the FDA and their mechanisms of action as well as the medications that are under various phases of preclinical and clinical trials. In addition, the repurposing of the FDA approved drugs, such as anticonvulsants, antipsychotics, antidepressants and other medications, to prevent alcoholism and treat AUDs and their potential target mechanisms are summarized.

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.

Treatment of Generalized Anxiety Disorder with Gabapentin

Gabapentin is frequently used in the treatment of anxiety disorders. However, there are no randomized controlled trials on the effectiveness of this medication in generalized anxiety disorder (GAD), and there are only a few case reports. We present a case of a 59-year-old female with a psychiatric history of GAD. The patient discontinued benzodiazepines after more than 7 years of daily treatment which led to rebound anxiety, benzodiazepine withdrawal symptoms, and suicidal ideation. She was psychiatrically hospitalized and started on gabapentin. Over the next 10 months of outpatient follow-up, she attempted to taper off gabapentin due to personal preference to limit medications. During this time, we observed a clear dose-response pattern of gabapentin on GAD symptoms. In the absence of controlled studies, these findings may offer important information about the effectiveness of gabapentin in GAD.

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.

Non-health care facility anticonvulsant medication errors in the United States

INTRODUCTION

This study provides an epidemiological description of non-health care facility medication errors involving anticonvulsant drugs.

METHODS

A retrospective analysis of National Poison Data System data was conducted on non-health care facility medication errors involving anticonvulsant drugs reported to US Poison Control Centers from 2000 through 2012.

RESULTS

During the study period, 108,446 non-health care facility medication errors involving anticonvulsant pharmaceuticals were reported to US Poison Control Centers, averaging 8342 exposures annually. The annual frequency and rate of errors increased significantly over the study period, by 96.6 and 76.7%, respectively. The rate of exposures resulting in health care facility use increased by 83.3% and the rate of exposures resulting in serious medical outcomes increased by 62.3%. In 2012, newer anticonvulsants, including felbamate, gabapentin, lamotrigine, levetiracetam, other anticonvulsants (excluding barbiturates), other types of gamma aminobutyric acid, oxcarbazepine, topiramate, and zonisamide, accounted for 67.1% of all exposures.

CONCLUSIONS

The rate of non-health care facility anticonvulsant medication errors reported to Poison Control Centers increased during 2000-2012, resulting in more frequent health care facility use and serious medical outcomes. Newer anticonvulsants, although often considered safer and more easily tolerated, were responsible for much of this trend and should still be administered with caution.

Levetiracetam and topiramate poisoning: Two overdoses on those drugs with no lasting effects

Levetiracetam and topiramate are newer anticonvulsants, which is why international data on overdoses of these drugs are lacking. Only a few mild adverse reactions have been noted. These anticonvulsants have been the drug of choice for neurologists. Despite their wide usage, there is a dearth of literature on symptoms and signs of their toxicity. Presented here is the case of a 21-year-old female who overdosed twice on levetiracetam and topiramate. The woman was admitted and discharged after the first overdose. Ten days later, she took multiple tablets of both drugs and was seen again. Amazingly, the woman went home after the incident with no complications at all.

Safety profile of lamotrigine in overdose

BACKGROUND

Lamotrigine is an anticonvulsant as well as a mood stabilizer. Apart from its established use in the treatment of epilepsy, there has been an expansion of its use in the treatment of mental disorders. Patients with epilepsy as well as those with mental disorders are at increased risk of deliberate drug overdoses. An evidence base for the safety profile of lamotrigine in overdose is an essential tool for prescribers. The objective of this study was to carry out a narrative synthesis of the existing evidence for the safety profile of lamotrigine in overdose.

METHODS

A systematic search was conducted of EMBASE (1974 to December 2015), MEDLINE (1946 to December 2015), PsycINFO (1806 to December 2015) and CINAHL (1981 to December 2015) databases. Studies were included in which there was a deliberate or accidental single drug overdose of lamotrigine, with its toxic effects described. Studies that did not involve an overdose were excluded. A narrative synthesis of the described toxic effects was carried out.

RESULTS

Out of 562 articles identified, 26 studies were included, mainly in the form of case reports and series. The most commonly described toxic effects of lamotrigine were on the central nervous system, specifically seizures, movement disorders and reduced consciousness. Other toxic effects included QTc interval and QRS complex prolongations, hypersensitivity reactions, serotonin syndrome as well as rhabdomyolysis possibly due to seizures and/or agitation. Deaths were recorded in two studies, with cardiovascular and neurological toxic effects described.

CONCLUSIONS

Even though lamotrigine has been reported to be well tolerated, there is a risk of toxic effects which can be life threatening in overdose. This needs to be borne in mind when prescribing to patients at an increased risk of deliberate drug overdose.

Thirteen years of oxcarbazepine exposures reported to US poison centers

Objectives:

Oxcarbazepine (OXC) is a 10-keto analogue of carbamazepine used in patients with partial and secondary generalized seizures. We evaluated ingestions of OXC reported to US poison centers for adverse effects from supratherapeutic doses and/or overdose.

Method:

Retrospective analysis of data reported to National Poison Data System from single-substance OXC ingestions between January 2000 and December 2012.

Results:

There were 18,867cases with a mean of 1451 exposures/year. The patients were predominantly adults with 5464 exposures in children <6 years (29%). The most commonly reported clinical effects were drowsiness ( n = 4703, 25%), vomiting ( n = 1559, 8%), tachycardia ( n = 590, 3%), agitated ( n = 342, 1.8%), hypotension ( n = 178, 0.9%), electrolyte disturbance ( n = 153, 0.8%), coma (n = 156, 0.8%), and seizures ( n = 121, 0.6%). There were 176 patients with a major effect of which 31 involved were children and 1728 (9%) patients with moderate effects of which 300 involved were children. Five deaths were reported in adults. Intentional exposure (e.g. suicide) was the reason for exposure in 68% of patients with major effects and in all fatalities. Fifty-three percent of adults and 38% of children were managed in a health-care facility (HCF). HCF utilization levels remained consistent.

Discussion:

Severe outcomes appear to be infrequent (<1%). Unlike other anticonvulsants OXC does not appear to be proconvulsant in overdose.

Conclusion:

Serious outcomes for OXC overdoses are unlikely in the pediatric patient. With only mild symptoms likely, observation at home may be appropriate for the majority of cases. In the adult population there appears to be few neurologic and cardiovascular complications even in the intentional exposure.

A Decade of Gabapentinoid Misuse: An Analysis of the European Medicines Agency's 'Suspected Adverse Drug Reactions' Database

INTRODUCTION

The gabapentinoids pregabalin and gabapentin are being increasingly prescribed for a range of clinical conditions. Recently, although gabapentinoids at therapeutic dosages may present with low addictive liability levels, cases of misuse and rising numbers of related fatalities have been reported.

OBJECTIVES

The aim of the study was to identify and assess cases of gabapentinoid misuse or dependence as reported to the European Medicines Agency's EudraVigilance database, to identify the magnitude of this problem and the characteristics of these reactions.

METHODS

All spontaneous reports of both gabapentin- (2004-2015) and pregabalin- (2006-2015) related misuse/abuse/dependence were retrieved. A descriptive analysis by source, sex, age, and type of report was performed.

RESULTS

From the EudraVigilance database 7639 (6.6 % of a total of 115,616) and 4301 (4.8 % of 90,166) adverse drug reaction reports of misuse/abuse/dependence were, respectively, associated with pregabalin and gabapentin, with an overall reporting frequency increasing over time. For both molecules, subjects typically involved were female adults. A total of 27 and 86 fatalities, respectively, associated with pregabalin and gabapentin, and mostly in combination with opioids, were identified. Analysis of proportional reporting ratios for drug abuse/dependence/intentional product misuse values seem to indicate that these adverse drug reactions were more frequently reported for pregabalin (1.25, 1.39, and 1.58, respectively) compared with gabapentin.

CONCLUSIONS

Despite data collection/methodological approach limitations, the present data seem to suggest that gabapentinoid misuse may be a cause for concern, especially in patients with a history of substance misuse. Hence, healthcare professionals should be vigilant when prescribing these molecules.

Gabapentin misuse, abuse and diversion: a systematic review

BACKGROUND AND AIMS

Since its market release, gabapentin has been presumed to have no abuse potential and subsequently has been prescribed widely off-label, despite increasing reports of gabapentin misuse. This review estimates and describes the prevalence and effects of, motivations behind and risk factors for gabapentin misuse, abuse and diversion.

METHODS

Databases were searched for peer-reviewed papers demonstrating gabapentin misuse, characterized by taking a larger dosage than prescribed or taking gabapentin without a prescription, and diversion. All types of studies were considered; grey literature was excluded. Thirty-three papers met inclusion criteria, consisting of 23 case studies and 11 epidemiological reports. Published reports came from the United States, the United Kingdom, Germany, Finland, India, South Africa and France, and two analyzed websites not specific to a particular country.

RESULTS

Prevalence of gabapentin misuse in the general population was reported to be 1%, 40-65% among individuals with prescriptions and between 15 and 22% within populations of people who abuse opioids. An array of subjective experiences reminiscent of opioids, benzodiazepines and psychedelics were reported over a range of doses, including those within clinical recommendations. Gabapentin was misused primarily for recreational purposes, self-medication or intentional self-harm and was misused alone or in combination with other substances, especially opioids, benzodiazepines and/or alcohol. Individuals with histories of drug abuse were most often involved in its misuse.

CONCLUSIONS

Epidemiological and case report evidence suggests that the anti-epileptic and analgesic medication gabapentin is being misused internationally, with substance abuse populations at special risk for misuse/abuse.

Cardiovascular toxicity with levetiracetam overdose

OBJECTIVE

To describe the cardiovascular toxicity and pharmacokinetics of levetiracetam in overdose.

CASE REPORT

A 43-year-old female presented 8 h post ingestion of 60-80 g of levetiracetam with mild central nervous system depression, bradycardia, hypotension and oliguria. Her cardiovascular toxicity transiently responded to atropine and intravenous fluids. A bedside echocardiogram demonstrated normal left and right ventricular contractility. Despite her cardiovascular toxicity and oliguria, she had normal serial venous lactates and renal function; and made a complete recovery over 48 h. Her levetiracetam concentration was 463 mcg/ml 8 h post ingestion (therapeutic range 10-40 mcg/ml) and her concentration-time data best fitted a one-compartment model with first-order input and an elimination half-life of 10.4 h.

DISCUSSION

Levetiracetam in large ingestions appears to cause bradycardia and hypotension that is potentially responsive to atropine and intravenous fluids. Based on a normal echocardiogram, the mechanism for this effect may be levetiracetam acting at muscarinic receptors at high concentration. The pharmacokinetics of levetiracetam in overdose appeared to be similar to therapeutic levetiracetam dosing.

Abuse Potential of Pregabalin: A Systematic Review

BACKGROUND

Several case reports and epidemiological studies have raised concern about the abuse potential of pregabalin, the use of which has increased substantially over the last decade. Pregabalin is, in some cases, used for recreational purposes and it has incurred attention among drug abusers for causing euphoric and dissociative effects when taken in doses exceeding normal therapeutic dosages or used by alternative routes of administration, such as nasal insufflation or venous injection. The magnitude of the abuse potential and the mechanism behind it are not fully known.

OBJECTIVE

The aim of this study was to present a systematic review of the data concerning the abuse potential of pregabalin.

METHODS

We performed a systematic literature search and reviewed the preclinical, clinical and epidemiological data on the abuse potential of pregabalin.

RESULTS

We included preclinical (n = 17), clinical (n = 19) and epidemiological (n = 13) studies addressing the abuse potential of pregabalin. We also reviewed case reports (n = 9) concerning abuse of pregabalin. The preclinical studies indicated that pregabalin possesses modulatory effects on the GABA and glutamate systems, leaving room for an abuse potential. Further, clinical studies reported euphoria as a frequent side effect in patients treated with pregabalin. The majority of case reports concerning abuse of pregabalin involved patients with a history of substance abuse and, similarly, epidemiological studies found evidence of abuse, especially among opiate abusers.

CONCLUSIONS

Overall, the available literature suggests an important clinical abuse potential of pregabalin and prescribers should pay attention to signs of abuse, especially in patients with a history of substance abuse.

The role of gabapentin in the management of alcohol withdrawal and dependence

OBJECTIVE

To review the literature evaluating gabapentin for alcohol withdrawal and dependence.

DATA SOURCES

A literature search of MEDLINE (1966 to end of March 2015) and PubMed was performed using the terms alcohol, gabapentin, withdrawal, and dependence. Additional references were identified from a review of literature citations.

STUDY SELECTION AND DATA EXTRACTION

English-language prospective studies evaluating gabapentin for alcohol withdrawal and dependence were evaluated.

DATA SYNTHESIS

A total of 10 publications utilizing gabapentin in alcohol withdrawal (n = 5) and alcohol dependence (n = 5) were included in this review. Limited data suggest that gabapentin can provide benefit in managing mild alcohol withdrawal syndrome. There were 5 reported or suspected seizures in the withdrawal studies, suggesting that additional safety data are necessary before gabapentin monotherapy can be routinely considered. Sleep and mood/anxiety-related outcomes were positively influenced by gabapentin, which may result in long-term benefits if continued beyond the withdrawal period for the treatment of alcohol dependence. Studies evaluating gabapentin for alcohol dependence demonstrated dose-dependent benefits for complete abstinence, rates of no heavy drinking, and cravings. Gabapentin used to treat alcohol dependence was well tolerated with no severe adverse reactions reported in the extant literature.

CONCLUSION

Gabapentin may have a role in the treatment of mild alcohol withdrawal, but future studies should focus on adequate dosing strategies. Gabapentin should be considered for the treatment of alcohol dependence when barriers prevent the use of traditional agents. Additional studies should be conducted to further validate findings from the research conducted to date, but the current literature is promising for gabapentin in the treatment of alcohol dependence.

An acute gabapentin fatality: a case report with postmortem concentrations

Gabapentin (GBP) (Neurontin®, Horizant®, Gralise®) is a widely prescribed medication used primarily for the treatment of epilepsy and neuropathic pain. GBP has a favorable adverse effect profile in therapeutic dosing with the most common reported effects being dizziness, fatigue, drowsiness, weight gain, and peripheral edema. Even with intentional GBP self-poisonings, serious effects are rare. A 47-year-old female was found dead at work with her daughter's bottle of GBP 600 mg. There were 26 tablets missing and the decedent's only known medication was hydrocodone/acetaminophen. Following initial detection by an alkaline drug screen (GC-MS), analysis utilizing specific liquid chromatography-mass spectrometry revealed an elevated postmortem GBP peripheral blood concentration of 37 mg/L, central blood 32 mg/L, liver 26 mg/kg, vitreous 32 mg/L, and gastric contents 6 mg. Screening for volatiles, drugs of abuse, alkaline compounds, and acid/neutral compounds was negative with the exception of ibuprofen (<2 mg/L) detected in peripheral blood. This report presents a fatality that appears to be associated with an isolated and acute GBP ingestion.

Misuse and abuse of pregabalin and gabapentin: cause for concern?

Gabapentinoids (e.g. pregabalin and gabapentin) are widely used in neurology, psychiatry and primary healthcare but are increasingly being reported as possessing a potential for misuse. In fact, increasing levels of both prescriptions and related fatalities, together with an anecdotally growing black market, have been reported from a range of countries. This article reviews the current evidence base of this potential, in an attempt to answer the question of whether there is cause for concern about these drugs. Potent binding of pregabalin/gabapentin at the calcium channel results in a reduction in the release of excitatory molecules. Furthermore, gabapentinoids are thought to possess GABA-mimetic properties whilst possibly presenting with direct/indirect effects on the dopaminergic 'reward' system. Overall, pregabalin is characterized by higher potency, quicker absorption rates and greater bioavailability levels than gabapentin. Although at therapeutic dosages gabapentinoids may present with low addictive liability levels, misusers' perceptions for these molecules to constitute a valid substitute for most common illicit drugs may be a reason of concern. Gabapentinoid experimenters are profiled here as individuals with a history of recreational polydrug misuse, who self-administer with dosages clearly in excess (e.g. up to 3-20 times) of those that are clinically advisable. Physicians considering prescribing gabapentinoids for neurological/psychiatric disorders should carefully evaluate a possible previous history of drug abuse, whilst being able to promptly identify signs of pregabalin/gabapentin misuse and provide possible assistance in tapering off the medication.