[Should we care about pregabalin for elderly patients with a history of cardiac dysrhythmia?]

Atrial fibrillation induced by gabapentin: a case report

BACKGROUND

Gabapentin is commonly prescribed for the treatment of neuropathic pain, restless leg syndrome, and partial-onset seizures. Although the most frequent side effects of gabapentin are associated with the central nervous system, gabapentin can also affect the cardiovascular system. Case reports and observational studies have showed that gabapentin can be associated with increased risk of atrial fibrillation. However, all the evidence is concentrated in patients older than 65 years old with comorbidities that predispose them to the development of arrhythmias.

CASE PRESENTATION

We describe a case of an African American male in his 20s that presented to our chronic pain clinic with lumbar radiculitis and developed atrial fibrillation 4 days after being started on gabapentin. Laboratory workup did not show significant abnormalities, including normal complete blood count, comprehensive metabolic panel, toxicology screen, and thyroid-stimulating hormone. Transthoracic and transesophageal echocardiography showed a patent foramen ovale with right-to-left shunt. The patient was initially treated with diltiazem for heart rate control and apixaban. Direct current cardioversion with successful conversion to sinus rhythm was performed 24 hours after admission. The patient was then discharged on apixaban and diltiazem. Apixaban was changed to low-dose aspirin 1 month after discharge.

CONCLUSION

With rapidly increasing usage of gabapentin for approved and off-label indications, it is important to identify unintended adverse effects of this drug as they are considered safe alternatives to opioids. New-onset atrial fibrillation could be induced by gabapentin in young individuals.

Gabapentin and Pregabalin and Risk of Atrial Fibrillation in the Elderly: A Population-Based Cohort Study in an Electronic Prescription Database

Introduction

Gabapentin and pregabalin are widely prescribed to elderly people, but data on their pharmacokinetics, safety, and efficacy in this population are scarce. Neurological adverse effects are common. Atrial fibrillation (AF) associated with their use has been described in several case reports and case series, but the incidence is unknown.

Objective

The aim of this study was to assess the association between exposure to gabapentin or pregabalin and AF in the elderly.

Methods

Patients ≥ 65 years of age starting treatment with either gabapentin or pregabalin between January 1 and March 31, 2015, free of cardiovascular disease, and who did not receive the alternate study medications were studied. They were compared with patients who initiated treatment with an analgesic opiate or with alprazolam or diazepam. The two primary outcome variables were a first claim of an oral anticoagulant plus an antiarrhythmic drug (OAC + AA), or of an oral anticoagulant or an antiplatelet agent plus an antiarrhythmic drug (OAC/APA + AA), in the 3 months after treatment initiation.

Results

Compared with opiate analgesics, both gabapentin and pregabalin were associated with an increased risk of initiating OAC/APA + AA. The incidence was 6 of 668 (9.0 per 1000 patients) with gabapentin, versus 12 of 3889 (3.1 per 1000) with opiates, relative risk (RR) 2.91 (95% confidence interval [CI] 1.10–7.73), and for pregabalin it was 6 of 698 (8.6 per 1000) RR 2.79 (95% CI 1.05–7.40). The comparison with alprazolam/diazepam gave similar results. The risks did not vary by age, sex, or co-treatment with NSAIDs, and they increased with dose.

Conclusion

In elderly patients free of cardiovascular disease, an association between new exposure to gabapentin or pregabalin and initiating treatment for AF was found. These results should be confirmed in other studies.

Electronic supplementary material

The online version of this article (10.1007/s40264-018-0695-6) contains supplementary material, which is available to authorized users.

Pregabalin in neuropathic pain: evidences and possible mechanisms

Pregabalin is an antagonist of voltage gated Ca2+ channels and specifically binds to alpha-2-delta subunit to produce antiepileptic and analgesic actions. It successfully alleviates the symptoms of various types of neuropathic pain and presents itself as a first line therapeutic agent with remarkable safety and efficacy. Preclinical studies in various animal models of neuropathic pain have shown its effectiveness in treating the symptoms like allodynia and hyperalgesia. Clinical studies in different age groups and in different types of neuropathic pain (peripheral diabetic neuropathy, fibromyalgia, post-herpetic neuralgia, cancer chemotherapy-induced neuropathic pain) have projected it as the most effective agent either as monotherapy or in combined regimens in terms of cost effectiveness, tolerability and overall improvement in neuropathic pain states. Preclinical studies employing pregabalin in different neuropathic pain models have explored various molecular targets and the signaling systems including Ca2+ channel-mediated neurotransmitter release, activation of excitatory amino acid transporters (EAATs), potassium channels and inhibition of pathways involving inflammatory mediators. The present review summarizes the important aspects of pregabalin as analgesic in preclinical and clinical studies as well as focuses on the possible mechanisms.

Complete atrioventricular block due to overdose of pregabalin

Pregabalin, a synthetic derivate of the inhibitory neurotransmitter γ-aminobutyric acid, shows antiepileptic, analgesic, anticonvulsant, anxiolytic, and sleep-modulating activities. The major advantage of pregabalin is its relative reliability, easy use, high tolerance, and lack of negative interaction with other drugs. A 65-year-old woman with medical histories of diabetes mellitus, lumbar spondylosis, diabetic nephropathy, chronic renal failure, and anemia of chronic disease was admitted with the complaint of dizziness and syncope. She had been taking pregabalin 300 mg daily for 8 months. Electrocardiogram revealed complete atrioventricular (AV) block and right bundle-brunch block with a heart rate of 39 per minute. Her creatinine was 1.8 mg/dL, and creatinine clearance was 50 mL/min. Pregabalin treatment was discontinued. Four days later, the complete AV block resolved spontaneously to Mobitz type II block and to sinus rhythm with right bundle-brunch block on the seventh day. To our knowledge, this is the first case of complete AV block associated with pregabalin. We believe that AV block occurred as a result of pregabalin's effect on L-type Ca++ channels in the heart. Pregabalin's different effects on electrocardiogram and on the heart in different individuals may have an association with the patterns of distribution of the L-type calcium channels in myocardium.

Atrioventricular block following lacosamide intoxication

Lacosamide (LCM) is a novel anticonvulsant that modulates voltage-dependent sodium channels. Although it is known to cause a slight, dose-dependent prolongation of the PR interval on the ECG, third-degree atrioventricular (AV) block has been described as an adverse event in only a few patients participating in diabetic neuropathic pain studies and in no patient with epilepsy. We describe an 89-year old patient with decreased renal function and taking two other negative dromotropic agents who accidentally received two intravenous boli of 400 mg LCM within 6 hours. She had a normal PQ interval before and after the first dose of LCM and developed a reversible complete AV block approximately 30 minutes after the second bolus. We conclude that particular caution must be exercised when using very high doses of LCM in patients with significant cardial and renal risk factors.

Pharmacotherapy of epilepsy: newly approved and developmental agents

This article discusses seven newly available antiepileptic drugs (AEDs) and agents in phase III development. Lacosamide, licensed as an adjunctive treatment for partial-onset seizures, primarily acts by enhancing sodium channel slow inactivation. At daily doses of 200-600 mg, the drug significantly reduced partial-onset seizures in adults with refractory epilepsy. The most common adverse effects are CNS related. Rufinamide, available as adjunctive treatment for seizures associated with Lennox-Gastaut syndrome, has an unclear mechanism of action, although it does block voltage-dependent sodium channels. Coadministration of valproic acid significantly increases rufinamide circulating concentrations. The drug has been shown to have efficacy for partial-onset, primary generalized tonic-clonic, tonic-atonic, absence and atypical absence seizures. Adverse effects are mainly somnolence, nausea and vomiting. Eslicarbazepine acetate, a carbamazepine analogue, was recently licensed as adjunctive treatment for partial-onset seizures. Eslicarbazepine acetate acts at voltage-gated sodium channels, although the precise mechanism of action is unclear. The drug had efficacy for partial-onset seizures in three randomized, double-blind, placebo-controlled studies, using 400, 800 or 1200 mg/day. Adverse effects include dizziness and somnolence. Retigabine (ezogabine) exerts its anticonvulsant effect through the opening of neuronal voltage-gated potassium channels. Following significant seizure reduction rates at dosages of 600, 900 and 1200 mg/day, license applications have been submitted for its use as adjunctive treatment for patients with partial-onset seizures. Dose-related adverse effects include somnolence, confusion and dizziness. Brivaracetam is the n-propyl analogue of levetiracetam. Mixed results have been obtained in phase III studies in patients with partial-onset seizures, and further trials in children, patients with photosensitive epilepsy and patients with partial-onset seizures are ongoing. Dizziness, headache and somnolence are the most common adverse effects reported. Perampanel was designed as an AMPA-type glutamate receptor antagonist. Following encouraging results from phase II studies in patients with refractory partial-onset seizures, recruitment for phase III trials is almost complete. Ganaxolone is a neurosteroid with potent antiepileptic activity that modulates GABA(A) receptors in the CNS. Ganaxolone has shown promise in a variety of seizure types. Dizziness and somnolence have been reported in some patients. The availability of new AEDs has widened the choices for clinicians treating patients with epilepsy. However, given the minimal improvement in prognosis and disappointing efficacy outcomes in double-blind, placebo-controlled, dose-ranging regulatory trials, it seems unlikely that these novel agents will have a major impact on outcomes for people with epilepsy.

Lacosamide: new adjunctive treatment option for partial-onset seizures

IMPORTANCE OF THE FIELD

Epilepsy is one of the most common neurological disorders, affecting up to 2% of the population worldwide. Studies show that patients with refractory seizures have higher morbidity and mortality rates, as well as a poorer quality of life, than those with controlled seizures. Therefore, treatment that reduces the frequency of seizures may improve patients' quality of life. Lacosamide (LCM) is a recently approved anticonvulsant in Europe and the USA which offers new mechanisms of action and favorable safety profiles. Efficacy data have shown fast onset of anticonvulsant effects and significant reduction of partial-onset seizures as adjunctive therapy at LCM 200 and 400 mg/day, even in a severely refractory population.

AREAS COVERED IN THIS REVIEW

This article reviews three pivotal clinical trials of LCM, including its efficacy and tolerability over 7 years. In addition, LCM's key pharmacodynamics and pharmacokinetics from a search of the literature are reviewed in detail. This article also includes recent publications on the safety and use of intravenous LCM solution for patients with epilepsy.

WHAT THE READER WILL GAIN

This article provides comprehensive review of efficacy and safety information of LCM along with comprehensive pharmacokinetic information, which includes absolute bioavailability, low protein binding, lack of hepatic enzyme induction or inhibition, and low potential for drug-drug interactions.

TAKE HOME MESSAGE

Considering the fact that more than 30% of epilepsy patients remain refractory despite various antiepileptic drugs, LCM may provide added benefit to patients with refractory seizures.

New treatment option for partial-onset seizures: efficacy and safety of lacosamide

More than 30% of epilepsy patients remain refractory despite the advent of new antiepileptic drugs (AEDs) over two decades. Although a small percentage of these refractory patients may become seizure free when a new AED is added, combined administration of AEDs or the application of novel AEDs is the most common therapeutic option when surgical treatment cannot be offered. The most recently approved AED in Europe and the USA is lacosamide (LCM), which offers new mechanisms of action and favorable safety profiles. This article reviews LCM's molecular mechanisms of action, pharmacokinetic profiles as well as efficacy and safety from phase II and III clinical trials. In addition, comparison between LCM and other existing AEDs is discussed.