Chronic caffeine and the anticonvulsant potency of antiepileptic drugs against maximal electroshock

Caffeine impairs anticonvulsant effects of levetiracetam in the maximal electroshock seizure threshold test in mice

OBJECTIVES

Caffeine is the most widely used psychoactive substance in the world. Animal studies indicate that acute caffeine exposure at high doses may induce seizures and diminish the anticonvulsant activity of antiepileptic drugs (AEDs) at much lower doses. The aim of the current study was to assess the effect of caffeine on the anticonvulsant action of levetiracetam (LEV) and vigabatrin (VGB).

METHODS

The anticonvulsant activity of LEV and VGB was examined in the maximal electroshock seizure threshold test in mice (MEST test). All drugs were administered intraperitoneally by single injections, and caffeine was applied at doses capable of interfering with AEDs. Effects of caffeine exposure on AEDs were also investigated in tests of memory and motor performance.

RESULTS

Caffeine reduced the protective effect of LEV against electroconvulsions. Total brain concentration of LEV was unaffected by caffeine as well as inversely; LEV had no significant impact on the brain caffeine concentration, suggesting a pharmacodynamic nature of the interaction between LEV and caffeine in the MEST test. VGB at applied doses did not affect the convulsive threshold. Administration of VGB, but not LEV, alone or in combination with caffeine, impaired memory retention. In the chimney test, the combined treatment with AEDs and caffeine did not cause motor coordination impairment.

CONCLUSIONS

It is suggested that caffeine may negatively affect the anticonvulsant action of LEV in patients with epilepsy.

Effect of caffeine on the anticonvulsant action of pregabalin against electroconvulsions in mice

BACKGROUND

Experimental data indicate that caffeine (CAF) can reduce the anticonvulsant activity of antiepileptic drugs (AEDs) in animal models of seizures. The purpose of the current study was to examine the effect of CAF on the protective action of pregabalin (PGB) against electroconvulsions in mice.

METHODS

Maximal electroshock seizure (MES) test was used in the current study. In addition, the combined treatment with CAF and PGB was assessed in the passive avoidance task (long-term memory) and the chimney test (motor coordination). Drugs were injected intraperitoneally (ip) as single injections. CAF was administered at doses reported to compromise the anticonvulsant action of AEDs in mice.

RESULTS

CAF at a dose of 23.1 mg/kg reduced the anticonvulsant action of PGB in the MES test. The brain concentration of PGB was not significantly changed by CAF and vice versa. In the chimney test, CAF (23.1 mg/kg) protected mice against PGB-induced motor coordination impairment.

CONCLUSIONS

Regarding seizure control, it might be suggested that patients with epilepsy treated with PGB should avoid taking CAF. The estimated total brain concentration of PGB and CAF does not suggest a pharmacokinetic interaction as an explanation for these results.

Disease awareness and dietary habits of patients with epilepsy in western China: a cross-sectional study

Background

The optimal management of epilepsy includes engaging patients through education on knowledge of the disease, its treatment and diet control.

Methods

This was a cross-sectional survey-based cohort study, aimed to investigate the awareness of epilepsy in Chinese patients and to understand their dietary habits. Participants were consecutively enrolled from epileptic patients treated in a single epilepsy center from October 1, 2019 to February 29, 2020. A self-reported questionnaire (Cronbach’s α = 0.758) consisting of 3 parts was sent to 407 patients with epilepsy. The questionnaire included items on demographic information, epilepsy features, awareness of epilepsy treatment and dietary habits.

Results

About half of the patients (53.8%, 219/407) thought epilepsy was curable and only 80% knew that the first choice of treatment is medication. While 58.6% of the patients with low educational level preferred the use of antiepileptic drugs (p = 0.014), 52.7% believed that the medication should not be stopped immediately after seizure control (p = 0.026), especially after surgery (40.5%, p = 0.011). Patients with lower household monthly incomes had less awareness of the use of antiepileptic drugs than patients with higher incomes: only 39.2 and 49.8% of patients with lower incomes thought that the drugs could be stopped after epilepsy surgery or seizure control, respectively, compared to 51.6 and 66.1% with higher incomes. Alcohol (86.2%), caffeine (56.8%) and strong tea (49.1%) were top three foods considered by the patients to be avoided to prevent seizures. Approximately 30.2% of patients identified at least one food that made them susceptible to seizures.

Conclusions

Patient education on epilepsy, antiepileptic drugs and diet for management of seizures should be provided especially to patients with less education, lower income or inaccurate beliefs of epilepsy in Western China.

Low-frequency Stimulation Decreases Hyperexcitability Through Adenosine A1 Receptors in the Hippocampus of Kindled Rats

INTRODUCTION

In this study, the role of A1 adenosine receptors in improving the effect of Low-Frequency Electrical Stimulation (LFS) on seizure-induced hyperexcitability of hippocampal CA1 pyramidal neurons was investigated.

METHODS

A semi-rapid hippocampal kindling model was used to induce seizures in male Wistar rats. Examination of the electrophysiological properties of CA1 pyramidal neurons of the hippocampus using whole-cell patch-clamp recording 48 h after the last kindling stimulation revealed that the application of LFS as two packages of stimulations at a time interval of 6 h for two consecutive days could significantly restore the excitability CA1 pyramidal neurons evidenced by a decreased in the of the number of evoked action potentials and enhancement of amplitude, maximum rise slope and decay slope of the first evoked action potential, rheobase, utilization time, adaptation index, first-spike latency, and post-AHP amplitude. Selective locked of A1 receptors by the administration of 8-Cyclopentyl-1,3-dimethylxanthine (1 μM, 1 μl, i.c.v.) before applying each LFS package, significantly reduced LFS effectiveness in recovering these parameters.

RESULTS

On the other hand, selective activation of A1 receptors by an injection of N6-cyclohexyladenosine (10 μM, 1 μl, i.c.v.), instead of LFS application, could imitate LFS function in improving these parameters.

CONCLUSION

It is suggested that LFS exerts its efficacy on reducing the neuronal excitability, partially by activating the adenosine system and activating its A1 receptors.

The Use of Caffeine by People with Epilepsy: the Myths and the Evidence

PURPOSE OF REVIEW

Caffeine is the most widely consumed central nervous stimulant. For people with epilepsy, it is often unclear whether drinking coffee carries a risk of triggering seizures.

RECENT FINDINGS

The relationship between caffeine, seizures, epilepsy, and anti-seizure drugs is not fully understood. Clinical studies are scarce. In animal models, caffeine can increase seizure susceptibility but can also protect from seizures. Effects seem dose-dependent and are influenced by the duration of intake and the developmental stage at which caffeine exposure started. Caffeine reduces the efficacy of several anti-seizure medications, especially topiramate. It is unclear how these findings, mainly from animal studies, can be translated to the clinical condition. At present, there is no evidence to advise people with epilepsy against the use or overuse of caffeine. Until clinical studies suggest otherwise, caffeine intake should be considered as a factor in achieving and maintaining seizure control in epilepsy.

Interindividual Differences in Caffeine Metabolism and Factors Driving Caffeine Consumption

Most individuals adjust their caffeine intake according to the objective and subjective effects induced by the methylxanthine. However, to reach the desired effects, the quantity of caffeine consumed varies largely among individuals. It has been known for decades that the metabolism, clearance, and pharmacokinetics of caffeine is affected by many factors such as age, sex and hormones, liver disease, obesity, smoking, and diet. Caffeine also interacts with many medications. All these factors will be reviewed in the present document and discussed in light of the most recent data concerning the genetic variability affecting caffeine levels and effects at the pharmacokinetic and pharmacodynamic levels that both critically drive the level of caffeine consumption. The pharmacokinetics of caffeine are highly variable among individuals due to a polymorphism at the level of the CYP1A2 isoform of cytochrome P450, which metabolizes 95% of the caffeine ingested. Moreover there is a polymorphism at the level of another critical enzyme, N-acetyltransferase 2. At the pharmacodynamic level, there are several polymorphisms at the main brain target of caffeine, the adenosine A2A receptor or ADORA2. Genetic studies, including genome-wide association studies, identified several loci critically involved in caffeine consumption and its consequences on sleep, anxiety, and potentially in neurodegenerative and psychiatric diseases. We start reaching a better picture on how a multiplicity of biologic mechanisms seems to drive the levels of caffeine consumption, although much more knowledge is still required to understand caffeine consumption and effects on body functions.

Caffeine and seizures: A systematic review and quantitative analysis

PURPOSE

Caffeine is the most commonly used central nervous system (CNS) stimulant. The relationship between caffeine, seizures, epilepsy, and antiepileptic drugs (AEDs) is complex and not fully understood. Case reports suggest that caffeine triggers seizures in susceptible people. Our systematic review reports on the relationship between caffeine, seizures, and drugs in animal and human studies. Quantitative analyses were also done on animal studies regarding the effects of caffeine on AEDs.

METHODS

PubMed was searched for studies assessing the effects of caffeine on seizure susceptibility, epilepsy, and drug interactions in people and in animal models. To quantify the interaction between AEDs and caffeine, the data of six animal studies were pooled and analyzed using a general linear model univariate analysis or One-way Analysis of Variance (ANOVA).

RESULTS

In total, 442 items were identified from which we included 105 studies. Caffeine can increase seizure susceptibility and protect from seizures, depending on the dose, administration type (chronic or acute), and the developmental stage at which caffeine exposure started. In animal studies, caffeine decreased the antiepileptic potency of some drugs; this effect was strongest in topiramate.

CONCLUSION

Preclinical studies suggest that caffeine increases seizure susceptibility. In some cases, chronic use of caffeine may protect against seizures. Caffeine lowers the efficacy of several drugs, especially topiramate. It is unclear how these findings in models can be translated to the clinical condition. Until clinical studies suggest otherwise, caffeine intake should be considered as a factor in achieving and maintaining seizure control in epilepsy.

The effects of cimetidine chronic treatment on conventional antiepileptic drugs in mice

PURPOSE

The aim of this study was to evaluate the effects of 1-day, 7-day and 14-day administrations of cimetidine on the anticonvulsant activity of conventional antiepileptic drugs (AEDs; valproate, carbamazepine, phenytoin and phenobarbital) against maximal electroshock (MES)-induced convulsions in mice.

METHODS

Electroconvulsions were evoked in Albino Swiss mice by a current delivered via ear-clip electrodes. In addition, the effects of cimetidine, AEDs alone and their combinations were studied on performance and long-term memory tests. Pharmacokinetic changes in plasma and brain concentrations of AEDs after cimetidine administration were evaluated with immunofluorescence.

RESULTS

Cimetidine (up to 100mg/kg) after 1-day administration did not affect the electroconvulsive threshold in animals. Moreover, in the 14-day treatment, cimetidine administered at a dose of 40mg/kg did not significantly change the electroconvulsive threshold in the MES-test, cimetidine administered 14-day (at 20mg/kg) significantly increased the anticonvulsant activity of carbamazepine, staying without effects after a 1-day and 7-day studies. In contrast, both the 7-day and 14-day administrations of cimetidine resulted in significant reductions of protective efficacy of the phenobarbital. Only valproate and phenytoin were not affected by cimetidine (20mg/kg) in all experimental period. Cimetidine administered 1-day, did not alter total brain concentrations and free plasma levels of all AEDs tested, whilst the 14-day study elevated carbamazepine plasma and brain concentration and reduced phenobarbital brain concentration. Cimetidine co-applied with AEDs did not impair performance of mice evaluated in the chimney test however, it worsened long-term memory in animals.

CONCLUSIONS

Based on this preclinical study, a special caution is advised when treating epileptic patients with combinations of phenobarbital or carbamazepine with cimetidine.

Interaction of carbamazepine with herbs, dietary supplements, and food: a systematic review

Background. Carbamazepine (CBZ) is a first-line antiepileptic drug which may be prone to drug interactions. Systematic review of herb- and food-drug interactions on CBZ is warranted to provide guidance for medical professionals when prescribing CBZ. Method. A systematic review was conducted on six English databases and four Chinese databases. Results. 196 out of 3179 articles fulfilled inclusion criteria, of which 74 articles were reviewed and 33 herbal products/dietary supplement/food interacting with CBZ were identified. No fatal or severe interactions were documented. The majority of the interactions were pharmacokinetic-based (80%). Traditional Chinese medicine accounted for most of the interactions (n = 17), followed by food (n = 10), dietary supplements (n = 3), and other herbs/botanicals (n = 3). Coadministration of 11 and 12 of the studied herbal products/dietary supplement/food significantly decreased or increased the plasma concentrations of CBZ. Regarding pharmacodynamic interaction, Xiao-yao-san, melatonin, and alcohol increased the side effects of CBZ while caffeine lowered the antiepileptic efficacy of CBZ. Conclusion. This review provides a comprehensive summary of the documented interactions between CBZ and herbal products/food/dietary supplements which assists healthcare professionals to identify potential herb-drug and food-drug interactions, thereby preventing potential adverse events and improving patients' therapeutic outcomes when prescribing CBZ.

Is dietary caffeine involved in seizure precipitation?

Caffeine acts as a central nervous stimulant by blocking A1 and A2A adenosine receptors. Its effect on seizures is complex. Animal studies and case reports indicate that acute caffeine exposure may induce seizures, whereas chronic exposure might have an opposite effect. Patients acutely hospitalized for seizures (n = 174) were asked for their consumption of caffeinated beverages 24 h prior to admission as well as their habitual caffeine intake. Twenty-four-hour caffeine consumption was also recorded in a later telephone interview on a seizure-free day (n = 154). Thus, the patients served as their own controls. Categorized data were analyzed using the Wilcoxon's signed-ranks test. No difference was found between the intake of caffeine 24 h prior to the seizure and the habitual consumption (p = 0.37) or the consumption on a seizure-free day (p = 0.13). Thus, caffeine does not appear to be a common seizure precipitant.

A review of the effects of vitamins and other dietary supplements on seizure activity

The role of pharmacological and surgical management of epilepsy continues to expand, but these treatments are often associated with significant side effects and morbidity. As a result, many patients with epilepsy and their physicians alike have gained interest in the role of vitamins and other dietary supplements for seizure management. In this review, we examine the potential anticonvulsant and proconvulsant effects of commonly used dietary supplements, as well as their potential effects on cognition or behavior. Our review was conducted through a literature search focusing on clinical trials involving patients with epilepsy and their seizure response to dietary supplementation. We summarize findings from previous clinical studies and comment on practical considerations regarding dietary supplementation for patients with epilepsy.

Caffeinated beverages and decreased seizure control

Seizure control is often affected by seizure threshold lowering behaviours. In this case report, the authors address excessive caffeine ingestion from tea with increased seizure frequency. When decaffeinated beverages were substituted for the tea, seizure frequency returned to baseline. Similar findings occurred when the patient was re-challenged. The authors recommend avoidance of excessive caffeine in patients with epilepsy.

Influences of caffeine to nitric oxide production and zonisamide concentration in the brain of seizure-susceptible EL mice

To investigate changes of nitric oxide (NO) productions and zonisamide (ZNS) concentrations in the brain of seizure-susceptible EL mice given caffeine orally, mice were given caffeine (600 microg/mL) solution ad libitum as a drinking fluid for 1-3 weeks. Nitric oxide production in the brain was determined by measuring levels of nitrite plus nitrate (NOx). The brain NOx levels of mice treated with caffeine for 3 weeks were significantly higher than the control. Seizures in mice treated with caffeine for 2 and 3 weeks were not suppressed by ZNS at a dose of 75 mg/kg. Serum ZNS concentrations of mice with caffeine intake for 1-3 weeks were higher than in untreated mice. Conversely, brain ZNS concentrations of mice with caffeine intake for the same periods were significantly lower than in untreated mice. These results suggested that caffeine influenced brain NO production and ZNS concentrations in the seizure susceptibility of EL mice.