AED'S and Anti- Convulsants:

Question 1

Phenytoin:

Answer 1

-Used to treat Partial Seizures 
Voltage gated Na+ channel blocker
-Undergoes CYP liver metabolism
-Enzyme inducer
-Uses zero order kinetics
AE's: Gum Hypertrophy, cerebellar atrophy imbalance and teratogenicity

Question 2

Carbamazepine:

Answer 2

-Used to treat Partial Seizures
Voltage gated Na+ channel blocker
-Undergoes CYP liver metabolism
-Enzyme inducer of itself/ other medications such as estrogen & oral contraceptives
AE’s: Rash, Hyponatriemia, Bone Marrow Suppression, Osteoporosis and Teratogenicity

Question 3

Oxcarbazepine:

Answer 3

-Used to treat Partial Seizures
-Voltage gated Na+ channel blocker
-Undergoes P450 metabolism by the liver
-Less of an enzyme inducer than Carbamazepine
AE’s: Rash, High chance of hyponatriemia and a reduced chance of bone marrow suppression, osteoporosis and teratogenicity compared to Carbamazepine

Question 4

Lamotrigine:

Answer 4

Voltage Gated Na+ channel blocker
-Used to treat Generalized/ Partial Seizures
-Metabolized by glucuronic acid (glucuronidation)
-If commanded with VPA, VPA induces its metabolism and increases Lamotrigine levels by a 2 fold (can lead to toxicity)
-Lamotrigine levels decrease during pregnancy (estrogen presence) and with the use of oral contraceptives as these induce Lamotrigine metabolism
AE’s: Rash, but safe to use during pregnancy (always add folate)

Question 5

Lacosamide:

Answer 5

• Used to treat Partial Seizures
• Slow potentiation of inactivated Na+ channels
• Prolongation of cardiac contraction (PR interval)
• -Important to do a baseline ECG in patients with unknown cardiac disease or conduction effects

Question 6

Valproic Acid (VPA):

Answer 6

-Used to treat Generalized/ Partial Seizures
-Voltage gated Na+ channel blocker/ GABAergic effects (increases GABA concentrations in the brain) @ high enough concentrations
-Main mechanism is through Ca2+ channel blocker
-Promotes increased K+ channel permeabilty
-Heavy protein binding capacities (can displace other drugs & lead to toxicity)
-Blocks liver metabolism and is decreased by P450 enzyme inducers such as Phenytoin
AE’s: Tremor, platelet dysfunction, hepatotoxicity, pancreatitis, hair loss, weight gain, polycystic ovaries and HIGH teratogenic effects.
-NEVER use with a pregnant women and try to avoid in young fertile women.

Question 7

Phenobarbital:

Answer 7

• GABAergic effect (glutamate antagonist)
• Increases duration of Cl- Channel opening
• Used to treat neonatal seizures/ partial seizures

Question 8

Benzodiazepines:

Answer 8

• Diazepam, Lorapezam, Midazolam, Clobazam and Clonazepam
• Increase frequency of Cl- channel opening
• Benzodiazepine withdrawal can induce seizures

Question 9

Tiagabine:

Answer 9

• Blockade of GBA transporters (GAT-1) in neurons and glial cells
• Can cause depression and psychosis
• Used to treat Partial Seizures

Question 10

Vigabatrin:

Answer 10

• Inhibits GABA transaminase (GABA-T), which inhibits the breakdown of GABA
• Can cause loss of vision/ retinitis
• Used to treat Partial Seizures

Question 11

Lorazepam and Midazolam

Answer 11

• Intravenous drugs

- Used in emergency situations only to treat seizures

Question 12

Diastat:

Answer 12

Rectal Diazepam:

-Can be given to children to treat seizures

Question 13

Clobazam and Clonazepam:

Answer 13

-Used for the long term treatment of seizures

Question 14

Primidone:

Answer 14

Barbiturates

• Occasionally used to treat tremors- not used to treat seizures anymore
• Used to be used to treat partial seizures

Question 15

What is the worst adverse effect of a possible Benzodiazepine or Barbiturate’s overdose?

Answer 15

–>Respiratory failure/ arrest and death!

Question 16

Ethosuximide:

Answer 16

• T- type Ca2+ channel blocker in the Thalamic neuronal relay centre
• Specific for ABSENCE SEIZURES

Question 17

Zonisamide:

Answer 17

Voltage gated Na+ channel blocker

• Not approved for children
• Used to treat Generalized/ Partial Seizures

Question 18

Gabapentin / Pregabalin:

Answer 18

• Pre-synaptic voltage gated Ca2+ channel blockers
• Structure similar to that of GABA
• Binds to alpha2gamma subunit of the presynaptic voltage gated Ca2+ channel, leading to a decrease in glutamate excitatory release
• Used to treat Partial Seizures

Question 19

Felbamate:

Answer 19

NMDA Blocker

-Used to treat Generalized/ Partial Seizures

Question 20

Topiramate:

Answer 20

AMPA Blocker

-Used to treat Generalized/ Partial Seizures

Question 21

Perampanel:

Answer 21

AMPA Blocker

Question 22

Ezogabine:

Answer 22

Increased K+ channel permeability

-Used to treat Partial seizures

Question 23

Levetiracetam:

Answer 23

Exocytotic apparatus inhibitor

• ->Binding of the drug to SV2A subunit of the exocytotic apparatus inhibits the release of neurotransmitter from the synaptic vesicles
• Used to treat Generalized/ Partial Seizures

Question 24

What is VPA’s effect on Lamotrigine?

Answer 24

Increases levels of Lamotrigine by a 2 fold.

Question 25

What is VPA’s effect on Phenytoin?

Answer 25

Increases these levels (induces it- can cause toxicity)

Question 26

What is Carbamazepine’s effect on itself?

Answer 26

• Induces it’s own metabolism

* Lower’s levels of the drug

Question 27

Drugs with common DDI’s?

Answer 27

Carbamazepine, Phenobarbital and Phenytoin

Question 28

True or False: It’s safe to add more than 1 AED to a drug regimen within the same mechanism.

Answer 28

FALSE!

-If you need to add another AED, it must be of another mechanism.