anti convulsant

Question 1

What is a seizure

Answer 1

an abnormal discharge in a group of neurons in the brain

Question 2

what types of generalised seizures are there

Answer 2

• tonic clonic
• absence
• myoclonic
• atonic

Question 3

What are the 2 main things we need to do to treat seizures

Answer 3

1. decrease membrane excitability
2. enhance effects of inhibitory neurotransmitters

Question 4

What are the 4 drugs to treat tonic conic and partial seizure

Answer 4

1. phenytoin
2. carbamazepine
3. phenobarbitone
4. valproate

Question 5

How does phenytoin work at decreasing seizure

Answer 5

deactivate the voltage-sensitive sodium channel, decreasing membrane excitability and blocks the repetitive firing of neurons

Question 6

How is phenytoin metabolised

Answer 6

• hydroxylation and conjugation in the liver. Non linear, saturable enzyme. If plasma concentration too high it goes into saturable state

Question 7

What order of kinetics is the elimination of phenytoin

Answer 7

first order when in normal therapeutic range, zero order kinetics when reaches above therapeutic range

Question 8

What are some adverse effect of phenytoin

Answer 8

gum hypertrophy, skin hirsutism ( hairy skin), teratogenic, liver necrosis,

Question 9

What drug does carbamazepine have the same PD as

Answer 9

phenytoin

Question 10

Which of the drugs are strong enzyme inducers, and what does that result in

Answer 10

carbamazepine and phenobarbitone.

Results in increase breakdown of other drugs.

Question 11

What are therapeutic use of carbamazepine

Answer 11

• seizures
• mood disorder
• trigeminal neurlgia

Question 12

What are some adverse effect of carbamazepine

Answer 12

GI upset, diplopia, nystamus, drowsiness, folate vit D deficiency, antidiuretic effect

overdose can lead to ataxia, confusion

hypersensitivity like SLE, Rashes, stevens johnson

teratogenic

Question 13

how does phenobarbitone work

Answer 13

bind to GABA receptor channel complex and potentiates the effects of GABA

Question 14

What happens at low dose and high dose of phenobarbitone

Answer 14

at low dose, potentiates GABA actions, increases frequency of channel opening induced by GABA

at high dose, independent of GABA, leads to prolonged channel opening that can lead to death

Question 15

Whats the difference between benzodiazepines and phenobarbitone

Answer 15

phenobarbitone leads to prolonged channel opening, but BZD only causes increase in frequency of channel opening

Question 16

What are the adverse effect of phenobarbitone

Answer 16

sedation, drowsiness, ataxia, diplopia, loss of concentration, behaviour disturbances like hyperactivity

Question 17

How does valproate work

Answer 17

Increase GABA by preventing its breakdown (inhibit GABA transaminase).. hyperpolarises membrane potential by increasing potassium conductance, cell become more relaxed

Question 18

which drug is an enzyme inhibitor

Answer 18

valproate, inhibits metabolism of other anti epileptics

Question 19

valproate is highly bound to plasma protein, so what does it do?

Answer 19

displaces other anti-epileptics like diazepam from binding proteins

Question 20

what are some adverse effect of valproate

Answer 20

GI upset, sedation, weight gain

Hepatotoxicity, thrombocytopenia

teratogenic–> spina bifida, digital, orofacial