Anticonvulsants

Question 1

Carbamazepine

Answer 1

Inhibit voltage-gated Na+ channels to prolong refractory period
Stimulate phenytoin metabolism
Tx: partial simple, partial complex, tonic-clonic, trigeminal neuralgia, bipolar disorder
Oral
Slow absorption
Rapidly penetrates brain
Chronic administration: induces P450 enzymes to increase its own metabolism
SE: hepatotoxicity, teratogenic

Question 2

Ethosuximide

Answer 2

Blocks T-type Ca channels in thalamus
Oral
Not bound to plasma proteins
Long half life
Most metabolized in liver, rest excreted in urine
Tx: absence seizures

Question 3

Gabapentin

Answer 3

Blocks Ca2+ channels and release of glutamate
Enhances GABAergic synaptic transmission
Short half-life
Eliminated by kidneys
Not metabolized!
Tx: simple and complex partial and tonic-clonic

Question 4

Lamotrigine

Answer 4

Inhibit voltage-gated Na+ channels to prolong refractory period
Inhibits release of glutamate
Half life increased by valproic acid
Tx: simple and complex partial and tonic-clonic

Question 5

Phenobarbital

Answer 5

Barbiturate
Enhances GABAergic neurotransmission
Oral
Tx: febrile seizures, anxiety
SE: teratogenic

Question 6

Phenytoin

Answer 6

Inhibit voltage-gated Na+ channels and Ca2+ channels to prolong refractory period
Drug of choice for initial therapy of epilepsy in adults
Effective for partial simple, partial complex, and tonic-clonic
NOT used for absence
Oral- chronic, IV-emergency
Metabolized by CYP2C9 and CYP2C19
Enhances P450 system for other drugs
SE: gingival hyperplasia, megaloblastic anemia, teratogenic

Question 7

Valproic acid

Answer 7

Inhibit voltage-gated Na+ and Ca2+ channels to prolong refractory period
Enhances GABAergic neurotransmission
Drug of choice for myoclonic seizures
Oral, rapid absorption
SE: hepatotoxicity, thrombocytopenia, teratogenic

Question 8

Pregabalin

Answer 8

Blocks Ca2+ channels and release of glutamate
Tx: simple and complex partial seizures
SE: thrombocytopenia

Question 9

Topiramate

Answer 9

Blocks Na+ channels and increases activity of postsynaptic GABAa receptors
Tx: simple and complex partial and tonic-clonic

Question 10

Levetiracetam

Answer 10

Binds to synaptic SV2A protein and blocks transmission of glutamate and GABA
Adjunct treatment for partial and tonic-clonic

Question 11

Clonazepam

Answer 11

Benzodiazepine

Enhances GABAergic neurotransmission

Question 12

Diazepam

Answer 12

Benzodiazepine
Enhances GABAergic neurotransmission
IV for status epilepticus
Longer-lasting
Tx: anxiety
Tolerance after 1-6 months

Question 13

Lorazepam

Answer 13

Benzodiazepine
Enhances GABAergic neurotransmission
IV for status epilepticus
Shorter-acting
Tx: anxiety
Tolerance after 1-6 months