Effect of caffeine on the anticonvulsant effects of oxcarbazepine, lamotrigine and tiagabine in a mouse model of generalized tonic-clonic seizures

Caffeinated drinks, fruit juices, and epilepsy: A systematic review

The aim of this systematic review was to provide the required information regarding different aspects of the relationship between epilepsy/antiseizure medications and non-alcoholic drinks. The recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement were followed. MEDLINE and Scopus from the inception until 7 August 2021 were systematically searched. These key words were used: "epilepsy" OR "seizure" OR "antiepileptic" OR "antiseizure" OR "anticonvulsant" AND "coffee" OR "tea" OR "soda" OR "juice" OR "drink" OR "cola" OR "diet" (35 key word combinations). The primary search yielded 21 458 publications (PubMed, n = 4778; Scopus, n = 16 680). Only 50 studies met all the inclusion criteria and were included in the current systematic review. In total, 17 articles investigated various non-alcoholic drinks in human studies, 11 studies were case reports/series, and 22 articles were animal/in vitro studies. None of the studies provided a class 1 of evidence. There is limited evidence suggesting that certain drinks (eg, caffeinated energy drinks) might trigger seizures. Patients with epilepsy should avoid excessive consumption of certain fruit juices (eg, grapefruit, lime, pomegranate, kinnow, and star fruit) and caffeinated drinks. However, daily coffee and tea intake can be part of a healthy balanced diet, and their consumption does not need to be stopped in patients with epilepsy. Coffee/tea consumption is not harmful if consumed at levels of 200 mg (caffeine) in one sitting (about 2½ cups of coffee) or 400 mg daily (about five cups of coffee).

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.

Anticonvulsant active inhibitor of GABA transporter subtype 1, tiagabine, with activity in mouse models of anxiety, pain and depression

BACKGROUND

Tiagabine, a selective inhibitor of GABA transporter subtype 1 is used as an add-on therapy of partial seizures in humans but its mechanism of action suggests other potential medical indications for this drug. In this research we assess its pharmacological activity in several screening models of seizures, pain, anxiety and depression in mice.

METHODS

For pharmacological tests tiagabine was administered intraperitoneally 60 min before the assay. Behavioral tests were performed using models of chemically and electrically induced seizures, thermal acute pain and formalin-induced tonic pain. Anxiolytic-like properties were evaluated using the four plate test and the elevated plus maze test. Antidepressant-like activity was assessed in the forced swim test. In addition, to exclude false positive results in these assays, the influence of tiagabine on animals' locomotor activity and motor coordination was investigated, too.

RESULTS

Tiagabine demonstrated anticonvulsant properties in chemically induced seizures (pentylenetetrazole and pilocarpine seizures). At the dose of 100mg/kg it also elevated the seizure threshold for electrically induced seizures by 31.6% (p<0.01), but it had no activity in the maximal electroshock seizure test. Tiagabine showed anxiolytic-like and antidepressant-like effects. Although it apparently reduced animals' nociceptive responses in pain tests, these activities rather resulted from its sedative and motor-impairing properties demonstrated in the locomotor activity and the rotarod tests, respectively.

CONCLUSIONS

The results obtained in the present study suggest that tiagabine, apart its anticonvulsant effect, has anxiolytic-like, sedative and antidepressant-like properties. In view of this, it can be potentially used in the treatment of anxiety and mood disorders.

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.

Evaluation of anxiolytic-like, anticonvulsant, antidepressant-like and antinociceptive properties of new 2-substituted 4-hydroxybutanamides with affinity for GABA transporters in mice

PURPOSE

The inhibition of plasma membrane GABA transporters (GATs) is responsible for anxiolytic-like, anticonvulsant, antinociceptive and antidepressant-like effects in mice. It also influences animals' motor coordination and their sensitivity to ethanol. The aim of this study was to assess the pharmacological activity of two novel 2-substituted 4-hydroxybutanamides (BM 130 and BM 131) in some screening models. An attempt has been made to establish the relationship between the inhibition of GAT subtype and the observed in vivo activity.

METHODS

The affinity for GAT subtypes was evaluated by means of [(3)H]GABA uptake assay. It indicated that BM 130 inhibited GAT1 and GAT2, whereas BM 131 inhibited GAT1 and GAT3. In mice anxiolytic-like, antidepressant-like, anticonvulsant and antinociceptive properties of the test compounds were assessed. Their influence on motor coordination, locomotor activity and the ability to potentiate effects of subnarcotic doses of ethanol was also tested.

RESULTS

Both compounds administered intraperitoneally exerted a significant anxiolytic-like effect in the four plate test with ED50 values 3.4 and 7.9 mg/kg, respectively. At 30 mg/kg they reduced duration of immobility in the forced swim test for 33% and 19%, respectively. They had no effect on electroconvulsive threshold or pain reactivity in the hot plate assay but they were antinociceptive in the acetic acid-induced writhing test (ED50 values were 12.7 and 18.6 mg/kg, respectively) and in both phases of the formalin test (ED50 values in the first phase were 10.2 and 2.1 mg/kg for BM 130 and BM 131, respectively). No motor adverse effects were observed in mice pretreated with the test compounds in the rotarod or chimney tests but BM 131 caused a transient but statistically significant decrease of animals' locomotor activity.

CONCLUSIONS

In mice BM 130 and BM 131 have anxiolytic-like, antidepressant-like and antinociceptive properties which can be attributed to their affinity for not only mGAT1 but also mGAT2-4.

Synthesis and pharmacological properties of new GABA uptake inhibitors

BACKGROUND

γ-Aminobutanoic acid (GABA) is the principal inhibitory neurotransmitter in the mammalian central nervous system. The identification and subsequent development of the GABA transport inhibitors which enhance the GABA-ergic transmission has shown the important role that GABA transporters play in the control of numerous functions of the nervous system. Compounds which inhibit GABA uptake are used as antiepileptic drugs (tiagabine - a selective GAT1 inhibitor), they are also being investigated for other indications, including treatment of psychosis, general anxiety, sleep disorders, drug addiction or acute and chronic pain.

METHODS

In this paper, the synthesis of 2-substituted-4-(1,3-dioxoisoindolin-2-ylo)-butanamides and 2-substituted-4-aminobutanoic acids derivatives is described. These compounds were tested in vitro for their ability to inhibit GABA uptake. The inhibitory potency towards murine plasma membrane GABA transporters (mGAT1-4) was performed as [(3)H]GABA uptake assay based on stably transfected HEK cells. Compound 18, which demonstrated the highest affinity for mGAT1-4 (pIC(50) ranged from 4.42 for mGAT1 to 5.07 for mGAT3), was additionally investigated in several behavioral tests in mice.

RESULTS

Compound 18 increased the locomotor activity (14-38%) and had anxiolytic-like properties in the four-plate test (ED(50) = 9.3 mg/kg). It did not show analgesic activity in acute pain model, namely the hot plate test, however, it was antinociceptive in the acetic acid-induced writhing test (ED(50) = 15.3 mg/kg) and in the formalin model of tonic pain. In the latter assay, it diminished nocifensive behavior in both phases and in the first (neurogenic) phase of this test the obtained ED(50) value (5.3 mg/kg) was similar to morphine (3.0 mg/kg).

CONCLUSION

Compound 18 exhibited significant anxiolytic-like properties and was antinociceptive in some models of pain in mice. Moreover, it did not impair animals' motor coordination in the chimney test. Some of the described pharmacological activities of compound 18 can be partly explained based on its affinity for plasma membrane GABA transporters.

Analgesic, anticonvulsant and antioxidant activities of 3-[4-(3-trifluoromethyl-phenyl)-piperazin-1-yl]-dihydrofuran-2-one dihydrochloride in mice

Recently we have shown that 3-[4-(3-trifluoromethyl-phenyl)-piperazin-1-yl]-dihydrofuran-2-one dihydrochloride (LPP1) is an antinociceptive and local anesthetic agent in rodents. Below an extended study of the pharmacological activity of LPP1 is described. In vitro LPP1 has no affinity for GABA(A), opioidergic μ and serotonergic 5-HT(1A) receptors. The total antioxidant capacity of LPP1 (1-10mM) measured as ABTS radical cation-scavenging activity showed that LPP1 has dose-dependent antioxidant properties in vitro. Low plasma concentration of this compound detected by means of HPLC method 30min after its intraperitoneal administration suggests a rapid conversion to metabolite(s) which may be responsible for its analgesic and anticonvulsant activities in vivo. In vivo the compound's influence on the electroconvulsive threshold and its activity in the maximal electroshock seizure test (MES) were evaluated. The results demonstrated that LPP1 had an anticonvulsant activity in the MES model (ED(50)=112mg/kg) and at a dose of 50mg/kg was able to elevate the electroconvulsive threshold for 8mA as compared to the vehicle-treated mice. The analgesic activity of LPP1 was investigated in the acetic acid-induced writhing test in two groups of mice: animals with sensory C-fibers ablated, and mice with C-fibers unimpaired. It proved the potent activity of this compound in both groups (approximately 85% as compared to the vehicle-treated mice). The adverse effects of LPP1 were evaluated as acute toxicity (LD(50)=747.8mg/kg) and motor coordination impairments in the rotarod and chimney tests. The results from these tests show that LPP1 at doses higher than 100mg/kg is likely to impair the motor performance of experimental animals. Concluding, LPP1 is an analgesic and anticonvulsant compound which has antioxidant properties in vitro. Further studies are necessary to assess whether the antioxidant activity and the receptor profiling demonstrated in vitro can be confirmed for its metabolite(s) that are formed in vivo.

Herbs in epilepsy: evidence for efficacy, toxicity, and interactions

Herbs and dietary supplements enjoy widespread use in the treatment of epilepsy although supportive data yielding efficacy and safety are lacking. Ten specific products, American hellebore, betony, blue cohosh, kava, mistletoe, mugwort, pipsissiwa, skullcap, valerian, and melatonin, have either multiple-cited recommendations for use in epilepsy or a rationale for antiepileptic action and are discussed in detail. These items paradoxically often have a proconvulsant effect in addition to potentially serious adverse effects. Herb-drug interactions also occur at the level of the P450 hepatic enzyme system of drug catabolism and the P-glycoprotein transport system regulating the entry of exogenous compounds into the vasculature or blood-brain barrier. Thus, significant pharmacokinetic interactions may occur, in addition to pharmacodynamic interactions and proconvulsant effects of alternative medications themselves. Patients should be inquired as to the nature of any alternative medicine products they are using, with the view that these products may be reasonable if traditional antiepileptic drug therapy is continued, potential adverse effects of the alternative agents are monitored, and the alternative and traditional agents do not conflict.

GABA transporters as targets for new drugs

GABA, the principal inhibitory neurotransmitter in the cerebral cortex, maintains the inhibitory tone that counterbalances neuronal excitation. The identification and subsequent development of GABA-transport inhibitors has shown the important role that GABA transporters play in the control of the CNS. To date, four GABA transporters have been cloned (GAT1-4). Compounds that inhibit GABA uptake are targets for epilepsy treatment. Currently, they are also being investigated for other possible indications such as the treatment of psychosis, general anxiety and sleep disorders, drug addiction, acute and chronic pain. These and other issues are discussed in this article.

Effects of 2-chloroadenosine on cortical epileptic afterdischarges in immature rats

Adenosine may represent an endogenous anticonvulsant in the brain. This study focused on the possible anticonvulsant action of an adenosine agonist, 2-chloroadenosine, against cortical epileptic afterdischarges (ADs) in immature rats. Three age groups of rat pups with implanted electrodes were studied: 12-, 18- and 25-days-old. The compound, 2-chloroadenosine, was injected after the first successful stimulation at doses of 1, 4 or 10 mg/kg intraperitoneally, and stimulation at the same intensity was repeated three more times. Movements directly elicited by stimulation, as well as clonic seizures accompanying electroencephalography (EEG) ADs, were markedly suppressed in only the 18-day-old animals. The effects in the 12- and especially the 25-day-old rats were moderate. The duration of the ADs decreased in all three age groups with 2-chloroadenosine treatment, and the shortest AD duration was seen in the treated, 12-day-old rats. The AD suppression also lasted longer in this age group than it did in the older animals. After a brief suppression of the second AD, the treated, 25-day-old group exhibited a significant AD rebound during the third and fourth stimulations. Taken together, our data show that 2-chloroadenosine exhibits an anticonvulsant effect that is dose- and age-dependent.