CNS - Antiseizure drugs

Question 1

Phenytoin

1. Mechanism?
2. Use?(2)
3. Adverse effects?

Answer 1

1. Na channel block (IB antiarrythimc)
2. Generalized tonic clonic sizure
   Partial seiizures
3. Gingival hyperplasia, hirsutism, neuropathy

INDUCES P450

Question 2

Phenobarbital

1. Mechanism?
2. Use?
3. Adverse effects?

Answer 2

1. Enhances GABAa receptor response
2. As for phenytoin
3. Sedation, ataxia

INDUCES P450

Question 3

Ethosuximide

1. Mechanism?
2. Use?
3. Adverse effects?

Answer 3

1. Ca2+ channel blocker (T-type)
2. Absence seizures
3. GI distress, dizziness, headaches

Question 4

Carbamazepine

1. Mechanism?
2. Use? (2)
3. Adverse effects?

Answer 4

1. Block voltage Na+ channels
   Decreases glutamate release
2. Generalized tonic clonic seizures
   Partial seizure
3. Ataxia, diplopia, headache, nausea

INDUCES P450

Question 5

Diazepam

1. Mechanism?
2. Use?
3. Adverse effects?

Answer 5

1. Enhances GABAa receptor response (frequency)
2. Status Eplepticus
3. Sedation

Question 6

Clonazepam

1. Mechanism?
2. Uses (3)
3. Adverse effects?

Answer 6

1. Enhances GABAa receptor respone (frequency)
2. Abscence and myoclonic seizures, infantile spasms
3. sedation

Question 7

Gabapentin
Pregabalin

1. Mechanism?
2. Uses(3)?
3. Adverse effects?

Answer 7

1. Blocks Ca2+ channels
2. Generalized tonic clonic seizures (Gabapentin)
   Partial seizures
   Neuropathic pain
3. Ataxia, dissiness, somnolence

Renal elimination

Question 8

Vigabatrin

1. Mechanism?
2. Use?
3. Adverse effects?

Answer 8

1. Inhibits GABA transaminase
2. Partial seizures
3. psychosis, occular effects

Renal elimination

Question 9

Valproate

1. Mechanism?
2. Uses?(3)
3. Adverse effects?

Answer 9

1. Block high frequency firing
2. Generalized tonic clonic,
   Partial seizures
   myoclonic seizures
3. Alopecia, weight gain, teratogenic, nausea

Highly protein bound
Inhibits p450
hepatotoxic

Question 10

Lamotrigine

1. Mechanism?
2. Uses?(3)
3. Adverse effects?

Answer 10

1. Blocks, Na+ and Ca2+ channels
   Decrese glutamate release
2. Generalized tonic clonic
   myoclonic
   absence seizures
3. Dizzines, headaches, diplopia, rash

many drug interactions

Question 11

Levetiracetam

1. Mechanism?
2. Uses?(2)
3. Adverse effects?

Answer 11

1. Binds synaptic protein
   Modifies GABA and glutamate release
2. Generalized tonic clonic
   partial seizures
3. depression, seizures, nervousness, dizziness

Some drug interactions

Question 12

Tiagabine

1. Mechanism?
2. Use?
3. Adverse effects?

Answer 12

1. Blocks GABA reuptake
2. Partial seizures
3. As Levetiracetam

Higly protein bound

Question 13

Topiramate

1. Mechanism?
2. Uses? (4)
3. Adverse effects?

Answer 13

1. May block Na+ and Ca2+
   Also increases GABA effects
2. Generalized tonic clonic
   absence seizure
   partial seizures
   migraines
3. Paresthesias, sleepiness, cognitive slowing, confusion

hepatic + renal clearance

Question 14

Zonisamide

1. Mechanism?
2. Uses (2)
3. Adverse effects?

Answer 14

1. Blocks Na+ channels
2. Generalized tonic clonic
   myoclonic seizures
3. sleepiness, cognitive slowing,
   poor concentration, paresthesias