Phenytoin is a widely used drug in the medical field, as an antiepileptic and as an anticonvulsant. Phenytoin is one of the most preferred drugs in focal seizures, status epilepticus, and general tonic-clonic seizures. Phenytoin is a popular and potent drug on the market.
DILANTIN and PHENYTEK are the drugs on the market
Uses
- Di Phenyl Hydantoin also known as phenytoin.
- It is a 1st line drug in focal seizures.
- and 2nd line drug in GTCS
- Used as a drug also in status epilepticus
Class of drug
- Phenytoin is an Anti epileptic drug.
- It is a sodium channel blocker to be more precise.
Mode of administration and dosage
- The drug has an oral dosage.
- It is preferred to be given i/v
- Phenytoin as i/v is given at 50 mg/kg.
Mechanism
- Phenytoin is an acidic drug.
- When introduced into the body and absorbed, the drug binds to albumin.
- The albumin-bound drug gets displaced when another drug is introduced.
- The displaced drug enters the blood flow.
Metabolism
- Phenytoin is metabolized by the CYP2C9.
- It follows zero-order kinetics.
- and pseudo zero-order kinetics
Toxicity
- Phenytoin enters the blood flow after getting displaced.
- This drug is a narrow therapeutic index drug, meaning it can exceed a certain amount in the blood.
- When exceeded it leads to toxicity
- 10 to 20 micrograms/ml is the therapeutic index of phenytoin
Adverse Reactions
- The adverse effects are classified into 2 categories.
- reactions due to high doses ( exceeding 20 ug/ml)
- reaction at a low dose ( within 20ug/ml)
- reactions at higher dose
- cerebellar toxicity
- cerebral toxicity
- cardiac toxicity
- Reactions at lower doses are non-preventable like the above adverse effects.
- Hyperplasia gums
- Hirsutism
- Heavyweight
- Hyperglycemia
- Hypersensitivity
- Hamper vitamin absorption of vitamins K, D, and folic acid.
- Hodgkin like lymphoma
- Hydantoin syndrome in children
Contraindications
- Phenytoin is strictly contraindicated in the absence of seizures as it.
- As it does not affect calcium channel metabolism
- Psychosis and maniac patients should be prescribed.
- As it has cerebral toxicity
- Phenytoin is usually avoided in pregnancy.
- As it hampers vitamin absorption
- It is avoided in young adolescent girls.
- As it has PCOD side effects
Some other facts
- A new formulation is discovered known as dos-phenytoin
- This drug is faster and more soluble.
- It’s given in 150mg/kg.
- But it also has a higher risk of heart problems and arrhythmia.