What is the mechanism of action of phenytoin?

Mechanism of action Phenytoin is believed to protect against seizures by causing voltage-dependent block of voltage gated sodium channels. This blocks sustained high frequency repetitive firing of action potentials.

What is the mechanism of phenytoin 1 marks?

Mechanism of Action Phenytoin is a hydantoin derivative, a first-generation anti-convulsant drug that is effective in the treatment of generalized tonic-clonic seizures, complex partial seizures, and status epilepticus without significantly impairing neurological function.

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.

What is the pharmacokinetics of phenytoin?

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 proposed mechanism of interaction between FLUoxetine and phenytoin?

phenytoin FLUoxetine This combination may increase the phenytoin levels in your body. You should notify your doctor if you have symptoms such as drowsiness, visual problems, seizures, changes in behavior, nausea, or poor muscle coordination.

Is phenytoin an inducer or inhibitor?

Phenobarbital, phenytoin, primidone and carbamazepine are potent inducers of cytochrome P450 (CYP), epoxide hydrolase and uridine diphosphate glucuronosyltransferase (UDPGT) enzyme systems; oxcarbazepine is a weak inducer of CYP enzymes, probably acting on a few specific isoforms only.

What is the mechanism of phenytoin Mcq?

Mechanism of Action Phenytoin is a voltage-gated, sodium channel blocker, stabilizing the inactive state of the sodium channel and prolonging the neuronal refractory period. Phenytoin acts on the sodium channels on both neuronal and cardiac tissue.

How does phenytoin work to control seizures?

Phenytoin is an anti-epileptic drug, also called an anticonvulsant. Phenytoin works by slowing down impulses in the brain that cause seizures. Phenytoin is used to control seizures. It does not treat all types of seizures, and your doctor will determine if it is the right medicine for you.

How does phenytoin work to prevent seizures?

Phenytoin is used to control certain type of seizures, and to treat and prevent seizures that may begin during or after surgery to the brain or nervous system. Phenytoin is in a class of medications called anticonvulsants. It works by decreasing abnormal electrical activity in the brain.

What enzyme metabolizes phenytoin?

Phenytoin is metabolized by cytochrome P450 (P450) enzymes primarily to 5-(p-hydroxyphenyl-),5-phenylhydantoin (HPPH), which may be further metabolized to a catechol that spontaneously oxidizes to semiquinone and quinone species that covalently modify proteins.

What drugs interact with phenytoin?

Drugs Affected By Phenytoin

Interacting Agent Examples
Other Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D
Drugs whose level is decreased by phenytoin

What is phenytoin used for?

Phenytoin is used to control seizures (convulsions), including tonic-clonic (grand mal) and psychomotor (temporal lobe) seizures, in the treatment of epilepsy. It is also used to prevent and treat seizures that occur during brain surgery.

Phenytoin prolongs the inactivated gate of the Na channel by preventing the reopening of inactivation gate (B). 19. PHENYTOIN Tonic clonic seizures Blocks Na Channels Class 1A antiarrhythmic Zero-order (P E A) Induces P450

What are the indications for phenytoin?

Current indications for phenytoin are treatment and prevention of generalized tonic-clonic (grand mal) seizures and complex partial seizures and management of status epilepticus. Phenytoin is available generically in oral and parenteral formulations. Since its discovery in 1908, phenytoin has become one of the most well-studied anticonvulsants 1).

What is the role of phenytoin in the treatment of hyperexcitability?

Possibly by promoting sodium efflux from neurons, phenytoin tends to stabilize the threshold against hyperexcitability caused by excessive stimulation or environmental changes capable of reducing membrane sodium gradient. This includes the reduction of posttetanic potentiation at synapses.

What are the causes of phenytoin toxicity?

The experience of phenytoin toxicity is not limited to situations of acute ingestion, but may also occur due to drug interactions or due to physiological circumstances that impact serum albumin (ie. kidney disease) or drug metabolism. 3 Other changes that may result in phenytoin toxicity include pregnancy, malnutrition and malignancy. 3