Neurological (Anti-Epileptic Drugs - Phenytoin)

Question 1

Examples of drug (Anti-Epileptic Drugs - Phenytoin)

Answer 1

• Phenytoin

Question 2

Mechanism of action (Anti-Epileptic Drugs - Phenytoin)

Answer 2

• Acts as a voltage-gated Na+ channel blocker on the pre-synaptic neuronal membrane
• Limits action potential transmission
• Hence limiting spread of seizure activity

Question 3

Indications (Anti-Epileptic Drugs - Phenytoin)

Answer 3

• Epilepsy (including status epilepticus)

- Trigeminal neuralgia

Question 4

Side effects (Anti-Epileptic Drugs - Phenytoin)

Answer 4

• Insomnia
• Headache
• Rash
• Constipation
• Vomiting
• Gingival hyperplasia
• Liver damage
• Stevens-Johnson Syndrome (rare)
• Leucopenia (rare)
• Thrombocytopenia (rare)

Question 5

Important pharmacokinetics/pharmacodynamics (Anti-Epileptic Drugs - Phenytoin)

Answer 5

• Enzyme inducer of cytochrome P450
• Can cause interactions with other anti-epileptic drugs
• Narrow therapeutic index
• Relationship between dose and plasma concentration is non-linear

Question 6

Patient information (Anti-Epileptic Drugs - Phenytoin)

Answer 6

• Avoid alcohol
• Do not take calcium, aluminum, magnesium or iron supplements within 2 hours of ingestion
• Take with food to reduce irritation