Pharmacology of Epilepsy

Question 1

what is epilepsy ?

Answer 1

a neurological disorder marked by sudden recurrent episodes of sensory disturbance, loss of consciousness, or convulsions, associated with abnormal electrical activity in the brain.

Question 2

what is a focal seizure ?

Answer 2

Focal (or partial) seizures may spread to involve the entire brain
– a process known as secondary generalisation.
- Focal seizures may be subclassified on the basis of key clinical features, in particular the part of the brain that they involve (e.g. temporal versus frontal lobe seizures), and whether consciousness is impaired (simple versus complex)

Question 3

What is a tonic-clonic seizure ?

Answer 3

Generalised tonic-clonic, or “grand mal” seizures are most typical, in which the patient falls to the ground stiff (tonic phase), followed by a series of rhythmic jerks (clonic phase).

Question 4

what are generalised onset seizures ?

Answer 4

they occur on both sides and cause a loss of consciousness , excessive activity in all areas of the brain

Question 5

MOA of normal neuronal cleft ?

Answer 5

1)Na+ ENTERS pre synaptic neurone ,this causes voltage gated ca2+ to open
2) Glutamate is released => binds to AMPA, NMDA receptor
- AMPA=> Na+ influx
- NMDA=>Ca2+ influx
=> Depolisation and hyperexcitalbility of the post synaptic neurone

INHIBITORY PATHWAY:

1) GABA is released
2) binds to GABA-A receptor on the post synaptic neurone
3) CL- ions flood into the neurone = more negative to Inhibit hyper excitability, neurone potential is more negative

Question 6

What is Carbamazepine ?

CARBA-MEAN

Answer 6

blocks Na+ ON Pre synaptic neurone
( prevents over excitability )
REMEMBER ITS an enzyme inducer => decrease the concentration of other drugs

CARBA-MEAN
C-confusion ( hyponatremia)
A-ataxia 
R-rashes
B-Blurring vision 
A-Aplastic anaemia 

M-Messes up other drugs, enzyme inducer / bone Marrow suppression
E-eosinophilia
A-Agranulocytosis ( ADH release)
N-Neutropenia

Question 7

Phenytoin

Answer 7

Na+ channel blocker , also HEPATIC ENZYME INDUCER 
- dizziness, ataxia, rash , sedation
Chronic side effect :
- gum hyperplasia 
-Coarse face
-osteopenia ( more vit D metabolism)
-Low folate
-peripheral neuropathy

INCREASE DOSE SLOWLY! THE ORDER OF KINETICS CAN CHANGE RAPIDLY

Question 8

common anti epileptic drugs side effects

Answer 8

1) Gi disturbance

2) sedation and tiredness

Question 9

Sodium Valproate
MOA/ side effects
(VALPROATE)

Answer 9

1) blocks na+ channel on pre synaptic neurone and Ca2+ channels on pre synaptic , T-type on post synaptic neurone , can also block GABA, glutamate too
- TETROGENICTY
Vomiting
Alopecia
Liver toxicity
Pancreatitis/ Pancytopenia
Retention of fats (weight gain)
Oedema (peripheral)
Anorexia
Tremor
Enzyme inhibitor

Question 10

Levetiracteam

Answer 10

binds to the walls of the vesicles the contain glutamate => decrease glutamate secretion 
side effects :
- irritability 
-anxiety 
- fatigue 
-Dizziness
-Behavioural changes 

ONE of the safer options , no significant interactions

Question 11

Lamotrigine

Answer 11

• Similar to other Na+ channel modulators , ca+ BLCOKER , GABA , glutamate blocker
• both inducer and inhibitor
  SIDE EFFECTS :
  -STEVEN JOHNSON SYNDROME ( AFTER RASH can be Fatal)
  -insomnia
• less cognitive effects
• mood stabilising
  -WEIGHT LOSS
  -Teratogenic