Anticonvulsant Classes and Possible Mechanism of Actions

Epilepsy is considered one of the most common neurological disorders worldwide; it needs long-term or life-long treatment. Despite the presence of several novel antiepileptic drugs, approximately 30% patients still suffer from drug-resistant epilepsy. Subsequently, searching for new anticonvulsants with lower toxicity and better efficacy is still in paramount demand. Using target-based studies in the discovery of novel antiepileptics is uncommon owing to the insufficient information on the molecular pathway of epilepsy and complex mode of action for most of known antiepileptic drugs. In this review, we investigated the properties of anticonvulsants, types of epileptic seizures, and mechanism of action for anticonvulsants.

Voltage gated sodium channel inhibitors as anticonvulsant drugs: A systematic review on recent developments and structure activity relationship studies

Voltage-gated sodium channel blockers are one of the vital targets for the management of several central nervous system diseases, including epilepsy, chronic pain, psychiatric disorders, and spasticity. The voltage-gated sodium channels play a key role in controlling cellular excitability. This reduction in excitotoxicity is also applied to improve the symptoms of epileptic conditions. The effectiveness of antiepileptic drugs as sodium channel depends upon the reversible blocking of the spontaneous discharge without blocking its propagation. There are number of antiepileptic drug(s) which are in pipeline to flour the market to conquer abnormal neuronal excitability. They inhibit the seizures through the inhibition of complex voltage- and frequency-dependent ionic currents through sodium channels. Over the past decade, the sodium channel is one of the most explored targets to control or treat the seizure, but there has not been any game-changing discovery yet. Although there are large numbers of drugs approved for the treatment of epilepsy, however they are associated with several acute to chronic side effects. Many research groups have tirelessly worked for better therapeutic medication on this popular target to treat epileptic seizures. The review quotes briefly the developments of the approved examples of sodium channel blockers as anticonvulsant drugs. Medicinal chemists have tried the design and development of some more potent anticonvulsant drugs to minimize the toxicity that are discussed here, and an emphasis is given for their possible mechanism and the structure-activity relationship (SAR).

The Pharmacology and Toxicology of Third-Generation Anticonvulsant Drugs

Epilepsy is a neurologic disorder affecting approximately 50 million people worldwide, or about 0.7% of the population [1]. Thus, the use of anticonvulsant drugs in the treatment of epilepsy is common and widespread. There are three generations of anticonvulsant drugs, categorized by the year in which they were developed and released. The aim of this review is to discuss the pharmacokinetics, drug-drug interactions, and adverse events of the third generation of anticonvulsant drugs. Where available, overdose data will be included. The pharmacokinetic properties of third-generation anticonvulsant drugs include relatively fewer drug-drug interactions, as well as several unique and life-threatening adverse events. Overdose data are limited, so thorough review of adverse events and knowledge of drug mechanism will guide expectant management of future overdose cases. Reporting of these cases as they occur will be necessary to further clarify toxicity of these drugs.

Sodium Channel Blockers in the Treatment of Epilepsy

Sodium channel blockers have been the mainstay of the pharmacological management of focal and generalised tonic-clonic seizures for more than 70 years. The focus of this paper will be on phenytoin, carbamazepine, lamotrigine, oxcarbazepine, rufinamide, lacosamide and eslicarbazepine acetate. All these antiepileptic drugs have similar efficacy and share similar dose-dependent, adverse effect profiles, although phenytoin, carbamazepine and oxcarbazepine are more likely to cause idiosyncratic reactions than the others. With the exception of lamotrigine, rufinamide and lacosamide, all are enzyme inducers and most are minor teratogens; although data on teratogenicity are sparse with lacosamide and eslicarbazepine acetate. There is increasing evidence that these drugs differ mechanistically, with the newer agents, lacosamide and eslicarbazepine acetate, having their major pharmacological effect on the slow inactivation state of the sodium channel, which may be associated with better tolerability at higher dosage, although hard evidence in support of this observation is currently not available. Rufinamide is licensed only for Lennox-Gastaut syndrome in children aged 4 years and above. There is a move away from using enzyme inducers, particularly phenytoin and carbamazepine, in everyday clinical practice. There seems little doubt, however, that some sodium channel blockers will have an enduring place in the management of epilepsy well into the 21st century.

Current role of rufinamide in the treatment of childhood epilepsy: literature review and treatment guidelines

PURPOSE

The literature on the efficacy and safety of rufinamide in childhood-onset epilepsy syndromes currently includes approximately 600 paediatric patients. This paper summarizes the views of a panel of experienced European epileptologists with regard to the current role of rufinamide in the treatment of childhood epilepsies.

RESULTS

Rufinamide is effective in decreasing the seizure frequency in the Lennox-Gastaut syndrome (LGS), especially tonic and atonic seizures. It might consequently be preferred to other drugs as a second-line treatment for LGS when drop-attacks are frequent. The mean responder rate in the published studies is 38% with seizure freedom achieved in 2.4% of patients. Rufinamide has shown some efficacy in epileptic encephalopathies other than LGS. It can be also effective as adjunctive therapy in children and adolescents with drug-resistant partial seizures. The available data suggest that rufinamide has an acceptable risk/benefit ratio with quite a low risk of aggravating seizures. Common adverse effects (somnolence, nausea and vomiting) are usually mild and self-limiting; they are more frequently observed during titration than in the maintenance phase, suggesting that low escalation rates might be associated with fewer adverse effects. Rufinamide appears to have a favourable cognitive profile compared with other antiepileptic drugs.

CONCLUSION

Rufinamide is only approved for adjunctive treatment of seizures associated with LGS in children 4 years of age and older. There are very few data on rufinamide treatment at the onset of LGS or early in the course of the disorder; whether early treatment will improve outcome has yet to be determined.