What is the mechanism of action of antiepileptic drugs?

What is the mechanism of action of antiepileptic drugs?

Abstract. Established antiepileptic drugs (AEDs) decrease membrane excitability by interacting with neurotransmitter receptors or ion channels. AEDs developed before 1980 appear to act on sodium channels, gamma-aminobutyric acid type A (GABAA) receptors, or calcium channels.

How does phenytoin act as an antiepileptic agent?

Phenytoin reduces inward sodium movement by binding to inactivated voltage-gated channels after depolarization and modifying their sodium permeability. This results in an increase in the inactivation (or refractory) period of frequently firing neurons.

Which models are used to test anti epileptic activity?

PTZ model are use in the primary screen while evaluating antiepileptic drugs as per NIH anticonvulsant drug development programme.

What is unique about the elimination of phenytoin?

Phenytoin has unique pharmacokinetics. At therapeutic levels, elimination follows first-order kinetics. In the upper therapeutic and toxic range, elimination changes from first-order to zero-order kinetics due to saturation of the hepatic hydroxylation system.

How is phenytoin excreted?

Hepatic microsomal enzymes primarily metabolize phenytoin. Much of the drug is excreted in the bile as an inactive metabolite, which is then reabsorbed from the intestinal tract and ultimately excreted in the urine. Less than 5% of phenytoin is excreted unchanged in the urine.

What is the mechanism of action of phenytoin and carbamazepine?

Purpose: A common notion of the mechanism by which the antiepileptic drugs (AEDs) carbamazepine and phenytoin act is that they block sodium channels by binding preferentially to the inactivated state, thereby allowing normal neuronal firing while blocking ictal activity.

How does phenytoin affect action potential?

However, it greatly raised the threshold voltage and current for activation of action potentials by intracellularly injected current. It also reduced the maximum rate of rise of the action potential, the spike overshoot and the spike undershoot, while increasing the spike duration.

What are the adverse effects of phenytoin and why explain?

SIDE EFFECTS: Headache, nausea, vomiting, constipation, dizziness, feeling of spinning, drowsiness, trouble sleeping, or nervousness may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. Phenytoin may cause swelling and bleeding of the gums.

What is maximal electroshock seizure?

Maximal electroshock seizure (MES) is an experimental paradigm that induces synchronous neural discharges in the brain through artificial current input (Kamei et al., 1978), and is used to induce acute epileptic behaviors (Fischer & Muller, 1988).

Which chemical produces epilepsy in animals?

Flurothyl is a volatile, fast-acting central nervous system stimulant that causes seizures with myoclonic jerks followed by forelimb clonus, wild running, loss of posture, and severe tonic posturing. Recovery is very fast, and the animals exhibit normal behavior within 30 minutes.

What are the indications for phenytoin use?

Pharmacology. Phenytoin is indicated to treat grand mal seizures, complex partial seizures, and to prevent and treat seizures during or following neurosurgery.