Conversion from enzyme-inducing antiepileptic drugs to topiramate: Effects on lipids and c-reactive protein

Increased cardiovascular risk in epilepsy

Epilepsy is associated with increased mortality. Cardiovascular disease confers a significant portion of this increased risk. Recently there is increased interest in the burden of cardiovascular mortality in people with epilepsy. This review discusses the most common cardiovascular risk factors and their association with epilepsy including obesity, diabetes mellitus, and hyperlipidemia. Hyperlipidemia related to the use of enzyme inducing anti-seizure medications is also discussed as a topic that is of particular importance to prescribers that have patients with comorbid cardiovascular risk and epilepsy. Heart rate variability (HRV) and its association with SUDEP is discussed as well as a contributor to vascular risk. Finally, the authors discuss a potential role for neurologists who treat epilepsy to engage closer with their patient's cardiovascular risk factors using available tools such as a the ASCVD score calculator to determine the overall risk of mortality, as well as acting upon this information to guide treatment approaches integrating the information provided in this review.

Topiramate treatment during the peripubertal period does not alter aortic endothelial function in female Wistar rats

AIMS

This study aimed to evaluate the short- and long-term adverse effects of blood pressure (BP), vascular endothelial function, and estrogen receptor (ERα and ERβ) modulation on endothelial function in female Wistar rats treated with topiramate (TPM), an antiepileptic drug, during the peripubertal period.

MATERIALS AND METHODS

Female Wistar rats were treated with TPM (41 mg/kg) or water (CTR group) by gavage from postnatal day (PND) 28 to 50 (peripubertal phase). At the end of the treatment, the TPM and CTR rats were divided into two groups and evaluated after 24 h or from PND 85 (adulthood). The rats were evaluated for: thoracic aorta reactivity to phenylephrine (Phenyl), acetylcholine (ACh), and sodium nitroprusside (SNP); aortic ring reactivity after ERα and ERβ antagonism; and BP.

KEY FINDINGS

It was observed that vascular response to Phenyl, ACh, and SNP was similar between TPM and CTR rats in the short- and long-term evaluations. In addition, the ER antagonism did not interfere with aortic contraction or relaxation in either TPM or CTR.

SIGNIFICANCE

Taken together, the results show that TPM treatment during the peripubertal period does not alter aortic endothelial function and its estrogen modulation via classic ER in female Wistar rats, suggesting that TPM treatment in this period is safe for the vascular system.

Effects of lacosamide and carbamazepine on lipids in a randomized trial

Objective

The effects of anticonvulsants on lipids are the subject of considerable concern and investigation, but there are almost no data on this issue from randomized trials. We evaluated serum lipid profiles in adults with newly diagnosed epilepsy, following randomization to lacosamide (LCM) or carbamazepine (CBZ) monotherapy.

Methods

We analyzed data from a Phase 3, international, randomized, double‐blind trial of LCM vs CBZ for the initial treatment of focal epilepsy. Serum lipid profiles in patients not taking lipid‐lowering agents and providing blood samples under fasting conditions before treatment, and following 3 or 12 months of treatment with LCM or CBZ at various doses were analyzed.

Results

At 12 months, 271 patients satisfied the inclusion criteria for the analysis. No change was observed in LCM‐treated patients for total cholesterol, cholesterol fractions, or triglycerides. CBZ‐treated patients showed an increase of 21.1 mg/dL in total cholesterol, 12.6 mg/dL in low‐density lipoprotein (LDL) cholesterol, 12.5 mg/dL in non–high density lipoprotein (non‐HDL) cholesterol, and 8.5 mg/dL in HDL cholesterol; triglycerides remained unchanged. The proportion of patients with elevated total cholesterol levels (above the upper limit of the reference range) did not change in the LCM treatment group (37.0% at Baseline; 34.8% at 12 months), but increased from 30.8% (at Baseline) to 49.6% (at 12 months) in the CBZ treatment group.

Significance

This study provides Class II evidence that CBZ elevates serum lipids, whereas LCM has no effect on lipids. It supports LCM as an appropriate choice for new‐onset focal epilepsy.

Why are epilepsy mortality rates rising in the United States? A population-based multiple cause-of-death study

INTRODUCTION

Epilepsy mortality rates are rising. It is unknown whether rates are rising due to an increase in epilepsy prevalence, changes in epilepsy causes of death, increase in the lethality or epilepsy or failures of treatment. To address these questions, we compare epilepsy mortality rates in the USA with all-cause and all-neurological mortality for the years 1999 to 2017.

OBJECTIVES

To determine changes in US epilepsy mortality rates versus all-cause mortality, and to evaluate changes in the leading causes of death in people with epilepsy.

DESIGN

Retrospective population-based multiple cause-of-death study.

PRIMARY OUTCOME

Change in age-adjusted epilepsy mortality rates compared with mortality rates for all-cause and all-neurological mortality.

SECONDARY OUTCOME

Changes in the leading causes of death in epilepsy.

RESULTS

From 1999 to 2017, epilepsy mortality rates in the USA increased 98.8%, from 5.83 per million in 1999 to 11.59 per million (95% CI 88.2%-110.0%), while all-cause mortality declined 16.4% from 8756.34 per million to 7319.17 per million (95% CI 16.3% to 16.6%). For the same period, all-neurological mortality increased 80.8% from 309.21 to 558.97 per million (95% CI 79.4%-82.1%). The proportion of people with epilepsy who died due to neoplasms, vascular dementia and Alzheimer's increased by 52.3%, 210.1% and 216.8%, respectively. During the same period, the proportion who died due to epilepsy declined 27.1%, while ischaemic heart disease as a cause of death fell 42.6% (p<0.001).

CONCLUSIONS

Epilepsy mortality rates in the USA increased significantly from 1999 to 2017. Likely causes include increases in all-neurological mortality, increased epilepsy prevalence and changes in the underlying causes of death in epilepsy, led by increases in vascular dementia and Alzheimer's. An important finding is that ischaemic heart disease and epilepsy itself are declining as underlying causes of death in people with epilepsy.

Impact of carbamazepine, lamotrigine, and levetiracetam on vascular risk markers and lipid-lowering agents in the elderly

OBJECTIVE

To examine serologic markers of vascular risk under treatment with commonly used antiepileptic drugs (AEDs) in the elderly in a randomized setting, and to determine whether the reduced exposure to hydroxymethylglutaryl-CoA reductase inhibitors ("statins") caused by carbamazepine reduces the effectiveness of the drugs as lipid-lowering agents.

METHODS

Standard lipid fractions, lipoprotein(a), and C-reactive protein (CRP) were examined in a subset of those participating in the STEP-ONE trial, in which elderly patients with new epilepsy were randomized to treatment with carbamazepine, lamotrigine, or levetiracetam. Separate comparisons were made by individual AED, among those treated with statins, and, for CRP, among those treated with anti-inflammatory drugs.

RESULTS

One hundred ninety-four patients had the aforementioned serologic measurements. In patients not taking statins, those treated with carbamazepine had higher total cholesterol than those treated with levetiracetam (+16.6 mg/dL, P = 0.053), with values from patients on lamotrigine intermediate, whereas cholesterol fractions were subject to drug-gender interactions which did not show a consistent pattern. Lipoprotein(a) was significantly lower in lamotrigine patients than in the carbamazepine and levetiracetam groups. After accounting for the effects of steroids, CRP was higher in carbamazepine patients than in other patients. Patients taking a statin had lower lipid levels than those not taking a statin regardless of AED, but the differences between statin-treated and non-statin-treated patients were much larger (50%-100% or more) in the lamotrigine and levetiracetam groups than in the carbamazepine group (P = 0.035 for interaction effect of statin use and AED on total cholesterol).

SIGNIFICANCE

Here, we demonstrate that carbamazepine significantly interferes with the ability of statins to lower total cholesterol, thus making it a poor choice for hyperlipidemic patients or those with cardiovascular disease. Native AED effects on lipids were inconsistent and subject to drug-gender interaction, in contrast with other studies; further investigation is necessary to determine if these latter findings are genuine or spurious.

Discontinuation of carbamazepine due to concerns of long-term consequences of enzyme induction

Objective

Treatment with carbamazepine (CBZ), a potent enzyme inducer, is known to affect the lipid profile, steroid, and vitamin D metabolism. Consequently, it has been postulated that patients on CBZ should be switched to noninducing antiepileptic drugs (AEDs). However, little is known about the seizure outcome following a CBZ switch in seizure‐free patients. We aimed to address this issue using a controlled observational study design.

Methods

Fifty‐eight patients taking CBZ for focal epilepsy were assessed for discontinuing CBZ treatment due to concerns of long‐term adverse‐effects; 34 discontinued its therapy and 24 continued with CBZ. Six‐month seizure freedom was the primary end point. Furthermore, serum samples (total cholesterol (TC), low‐density lipoprotein (LDL), high‐density lipoprotein (HDL), triglycerides, sex hormone–binding globulin (SHBG), free testosterone, and 25‐hydroxyvitamin D levels from before and at least 3 months after discontinuation or continuation were obtained from all patients.

Results

Seizure‐free patients had a 5‐fold elevated odds of seizure recurrence if CBZ was discontinued (95% confidence interval [CI 0.51–49.3; p = 0.17). A significant decrease in serum levels of TC, LDL, HDL, and SHBG as well as a significant increase in that of free testosterone were found in the discontinuation group compared with those who continued CBZ. Nonsignificant changes in triglycerides and vitamin D levels were detected.

Significance

Discontinuation of CBZ in seizure‐free patients seems to carry a moderate, but legitimate, risk of relapse. Conversely, our results indicate that CBZ might have unfavorable effects on serum levels of TC, LDL, HDL, SHBG, and free testosterone.

Clinical Profile and Changes of Serum Lipid Levels in Epileptic Patients after Cerebral Infarction

BACKGROUND

Antiepileptic drugs (AEDs) may increase development of dyslipidemia and cerebrovascular disease (CVD). We examined the clinical profile and changes of serum lipid levels after AED monotherapy in patients with poststroke epilepsy (PSE) after cerebral infarction (CI).

SUBJECTS AND METHODS

Medical records were reviewed in consecutive 2144 CI patients. Monotherapy of valproate, carbamazepine (CBZ), phenytoin (PHT), zonisamide, levetiracetam, or lamotrigine was performed in PSE patients. Serum lipid levels were measured before and at 3 months after AED treatment.

RESULTS

The prevalence of PSE was 7.0% in CI patients. The TOAST etiology disclosed large-artery atherosclerosis in 68 patients (45%), cardioembolism in 63 patients (42%), and undetermined cause in 19 patients (13%). CVD risk profile showed obesity of 18 patients (12%), current smoker of 30 patients (20%), hypertension of 75 patients (50%), diabetes mellitus of 32 patients (21%), dyslipidemia of 15 patients (10%), and atrial fibrillation of 63 patients (42%). CBZ or PHT administration increased serum total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) levels significantly compared to baseline and AED-untreated controls. Those levels were not increased significantly in other AED and control groups. Serum high-density lipoprotein-cholesterol and triglyceride levels did not differ statistically in all groups.

CONCLUSIONS

The prevalence of post-CI epilepsy was 7.0%. The pathogenesis contributed to atherothrombosis and cardioembolism. CBZ or PHT administration increased serum TC and LDL-C significantly. Thus, we should pay more attention to serum lipid levels in patients receiving cytochrome P450 (CYP)-induced AEDs, and might considerer switching to non-CYP-induced AEDs in patients with unfavorable serum lipid changes.

Changes in hormone and lipid levels in male patients with focal seizures when switched from carbamazepine to lacosamide as adjunctive treatment to levetiracetam: A small phase IIIb, prospective, multicenter, open-label trial

Treatment with enzyme-inducing antiepileptic drugs (AEDs) such as carbamazepine (CBZ) can lead to changes in reproductive, endocrine, and lipid parameters, resulting in clinical symptoms for some patients. Previous studies indicate that these changes can be reversed by switching to a nonenzyme-inducing AED. Lacosamide is a newer-generation AED, not known to induce or strongly inhibit cytochrome P450 (CYP450) enzymes. In this phase IIIb, prospective, multicenter, open-label, single-arm trial (NCT01375374), the serum concentrations of CYP-related reproductive hormones, thyroid hormones, and lipids were assessed in otherwise healthy male patients with focal seizures (N=11), before and after a switch from CBZ (600-1200mg/day at baseline) to lacosamide (target dose: 400mg/day by the end of titration) as adjunctive treatment to the nonenzyme-inducing AED levetiracetam (LEV, stable dosage of >1000mg/day throughout). Cross titration took place over 4weeks, followed by an 8-week maintenance period. Serum measurements were conducted at baseline and at the end of maintenance. The median serum sex-hormone-binding globulin (SHBG) concentration was towards the higher end of the normal range at baseline and decreased following the switch (61.7 to 47.5nmol/L, N=10, p=0.027 by Wilcoxon signed-rank test). Free androgen index (100×testosterone/SHBG) and free thyroxine serum concentration increased (25.4 to 36.4 and 13.0 to 14.9pmol/L, respectively, both N=10 and p=0.002). At baseline, the median progesterone serum concentration was below the normal range (0.7nmol/L), whereas median cholesterol and low-density lipoprotein concentrations were above the normal range (5.5 and 3.6mmol/L, respectively). By the end of maintenance, all measured parameters were within the normal range. The safety and tolerability profile of lacosamide was consistent with that observed in previous studies. Furthermore, antiseizure efficacy appeared to be maintained, suggesting that deinduction of CYP enzymes following a switch from CBZ to lacosamide as adjunctive therapy to LEV is feasible within 8weeks and is associated with normalization of serum parameters.

Long-term effect of antiepileptic drug switch on serum lipids and C-reactive protein

BACKGROUND

Prior studies have shown that switching patients from inducing antiepileptic drugs (AEDs) to lamotrigine, levetiracetam, or topiramate reduces serum lipids and C-reactive protein (CRP). These studies were all of short duration, and some drugs, such as zonisamide, have not been investigated.

METHODS

We recruited 41 patients taking phenytoin or carbamazepine who were being switched to zonisamide, lamotrigine, or levetiracetam. We measured serum lipids and CRP before the switch, >6weeks after, and >6months after. An untreated control group (n=14) underwent similar measurement. We combined these data with those of our previous investigation (n=34 patients and 16 controls) of a very similar design.

RESULTS

There were no differences in outcome measures between the two inducing AEDs nor among the three noninducing AEDs. Total cholesterol (TC), atherogenic lipids, and CRP were higher under inducer treatment than in controls. All measures were elevated under inducer treatment relative to noninducer treatment, including TC (24mg/dL higher, 95% CI: 17.5-29.9, p<0.001) and CRP (72% higher, 95% CI: 41%-111%, p<0.001). The difference between drug treatments was clinically meaningful for atherogenic lipids (16%, 95% CI: 11%-20%, p<0.001) but small for high-density lipoprotein cholesterol (5%, 95% CI: 1%-9%, p<0.05). All measures were stable between 6weeks and 6months after drug switch.

CONCLUSIONS

We demonstrate that switching from inducing to noninducing AEDs produces an enduring reduction in serum lipids and CRP. These results provide further evidence that inducing AEDs may be associated with elevated vascular disease risk. These are the first vascular risk marker data in patients taking zonisamide, which shows a profile similar to that of other noninducing AEDs.

Antiepileptic drugs and the risk of ischaemic stroke and myocardial infarction: a population-based cohort study

OBJECTIVES

Hepatic enzyme-inducing antiepileptic drugs (AEDs) increase serum lipid levels and other atherogenic markers via the induction of cytochrome P450 and may therefore increase the risk of vascular events. We sought to assess the risk of ischaemic stroke and myocardial infarction (MI) according to AED enzymatic properties.

DESIGN

Population-based cohort study with nested case-control analysis.

SETTING

650 general practices in the UK contributing to the Clinical Practice Research Datalink.

PARTICIPANTS

A cohort of 252,407 incident AED users aged 18 or older between January 1990 and April 2013. For each case of ischaemic stroke or MI, up to 10 controls were randomly selected among the cohort members in the risk sets defined by the case and matched on age, sex, indication for AED, calendar time and duration of follow-up.

INTERVENTIONS

Current use of enzyme-inducing and enzyme-inhibiting AEDs compared with non-inducing AEDs.

PRIMARY OUTCOME MEASURES

Incidence rate ratios (RRs) of ischaemic stroke and MI.

RESULTS

5069 strokes and 3636 MIs were identified during follow-up. Inducing AEDs use was associated with a small increased risk of ischaemic stroke (RR=1.16, 95% CI 1.02 to 1.33) relative to non-inducing AEDs, most likely due to residual confounding. However, current use of inducing AEDs for ≥ 24 months was associated with a 46% increased risk of MI (RR=1.46, 95% CI 1.15 to 1.85) compared with the same duration of non-inducing AED, corresponding to a risk difference of 1.39/1000 (95% CI 0.33 to 2.45) persons per year. Current use of inhibiting AED was associated with a decreased risk of MI (RR=0.81, 95% CI 0.66 to 1.00).

CONCLUSIONS

The use of enzyme-inducing AEDs was not associated with an increased risk of ischaemic stroke; a small increase of MI with prolonged use was observed. In contrast, use of inhibiting AEDs was associated with a decreased risk of MI.

Atherosclerotic effects of long-term old and new antiepileptic drugs monotherapy: a cross-sectional comparative study

This work aimed to evaluate the metabolic and atherogenic effects of long-term antiepileptic drugs in a group of Egyptian epileptic patients. Sixty-nine epileptic patients on antiepileptic drug monotherapy for at least 2 years and 34 control subjects were recruited in this study. Patients were divided into 5 subgroups according to antiepileptic drugs used (valproate, carbamazepine, lamotrigine, topiramate, and levetiracetam). Fasting lipid profile (total cholesterol, triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol), lipoprotein(a), homocysteine, free thyroxine, thyroid-stimulating hormone, and common carotid artery intima-media thickness were measured for all subjects. Significant higher mean values of low-density lipoprotein cholesterol, low-density lipoprotein / high-density lipoprotein ratio, lipoprotein(a), homocysteine, significantly lower mean value of high-density lipoprotein cholesterol, and significantly larger diameter of common carotid artery intima-media thickness were observed in each drug-treated group versus control group. Our study supports that long-term monotherapy treatment with valproate, carbamazepine, lamotrigine, and topiramate had altered markers of vascular risk that might enhance atherosclerosis, whereas levetiracetam exerted minimal effect.

Seizure recurrence and remission after switching antiepileptic drugs

PURPOSE

Studies of seizure outcome in patients undergoing serial antiepileptic drug trials have all been uncontrolled, with no account made for the spontaneous changes in disease state that could confound the elucidation of drug effects. In addition, no study has ever looked at outcome following antiepileptic drug switch in seizure-free patients, despite the fact that this is done routinely in clinical practice. We aimed to address both of these issues using a matched case-cohort design.

METHODS

We followed patients taking phenytoin or carbamazepine in monotherapy for focal epilepsy who were being crossed over to a newer agent as part of studies on the metabolic effects of anticonvulsant therapy. Many had been seizure-free but were being switched nonetheless due to side effects or concerns about long-term adverse consequences. Each patient was matched with two controls of the same seizure status who were taking anticonvulsant monotherapy and whose drug was not switched. Seizure freedom over the ensuing 6 months was the primary end point.

KEY FINDINGS

There were 43 cases and 86 matched controls. Twenty-three patients (cases) had been seizure-free on their old drug; 5 (21.7%) had seizure recurrence after drug switch compared to 2 (4.3%) of 46 matched controls. Twenty patients (cases) were having seizures on their old drug; 6 (30%) entered remission after drug switch, compared to 8 of 40 matched controls (20%). The two groups differed at baseline in number of anticonvulsants previously failed, which was the most important factor for prognosis. After statistical adjustment to account for this, seizure-free patients had 6.53 times higher odds of seizure recurrence if switched to a new drug (95% confidence interval [CI] 1.02-61.19; p = 0.06). Non-seizure-free patients had 1.66 times higher odds of remission if they remained on the same drug compared to switching, although this was not significant (95% CI 0.36-8.42; p = 0.532). Neither dose changes, nor drug mechanism, nor duration of seizure freedom had any bearing upon the results.

SIGNIFICANCE

Although the large majority of seizure-free patients remain so when switched to another agent, about one sixth have a recurrence attributable to the change. Conversely, our study design provides the first evidence to suggest that most improvements in drug-resistant patients are likely due to spontaneous remissions, not new drug introductions. These findings have conflicting implications for two competing models of comparative antiepileptic drug efficacy, which will require further study to elaborate.

B-vitamin deficiency in patients treated with antiepileptic drugs

Enzyme-inducing antiepileptic drugs (AEDs) produce many alterations in metabolism, including vitamin levels. Whether they produce clinically relevant deficiency of B vitamins has rarely been assessed. We obtained B-vitamin levels in patients who were being converted from an inducing AED (phenytoin or carbamazepine) to a non-inducing AED (levetiracetam, lamotrigine, or topiramate), with measurements both before and ≥ 6 weeks after the switch. A group of normal subjects underwent the same studies. Neither folate nor B12 deficiency was seen in any patient. Vitamin B6 deficiency was found in 16/33 patients (48%) taking inducers, compared to 1/11 controls (9%; p=0.031). After switch to non-inducers, only 7 patients (21%) were B6 deficient (p=0.027). The incidence of deficiency was similar regardless of which inducing or non-inducing AED was being taken. Our findings demonstrate that treatment with inducing AEDs commonly causes pyridoxine deficiency, often severe. This could conceivably contribute to the polyneuropathy sometimes attributed to older AEDs, as well as other chronic heath difficulties.