Anti-seizure Drugs

Question 1

List out a few anti-seizure drugs

Answer 1

1) Carbamazepine (partial + generalized seizures)
2) Phenytoin (Partial+ Tonic-clonic seizures)
3) Valproic acid (Absence seizures)
4) Ethosuximide (Absence seizures)
5) Gabapentin (Partial seizures)

these drugs are all classified as Anti-convulsants

Question 2

Indication of Phenytoin

Answer 2

Partial and Tonic-clonic seizures + generalized seizures

Question 3

MoA of Phenytoin

Answer 3

Block Na+ channel - Binds to Na+ channels and increases their refractory period

Question 4

PK/PD of Phenytoin

Answer 4

1. Effective in epilepsy
2. ineffective in Absence seizures
3. Zero-order kinetics
4. Plasma conc. should be monitored
5. induced hepatic enzyme–> decreases
   effect of other anti-convulsant
   drugs.

Question 5

Adverse effects of Phenytoin

Answer 5

1. Gum hyperplasia.
2. Hirsutism (facial hair in women)
3. Teratogenic.
4. Hepatotoxic.
5. Contraindicated in heart patients and pregnant women

Question 6

Indication of Carbamazepine

Answer 6

Partial/ generalized/ complex seizures

Question 7

MoA of Carbamazepine

Answer 7

Block Na+ channel - Binds to Na+ channels and increases their refractory period

Question 8

PK/PD of Carbamazepine

Answer 8

1. Effective in psychomotor epilepsy.
2. Ineffective in Absence seizure.
3. Effective in trigeminal neuralgia & bipolar disorder.
4. Strong liver inducer

Question 9

Adverse effects of Carbamazepine

Answer 9

1. Increased ADH secretion.
2. Mental disturbances.
3. teratogenic.
4. Hepatotoxic.

Question 10

Indication of Ethosuximide

Answer 10

Main drug for Absence seisures

Question 11

MoA of Ethosuximide

Answer 11

Blocks thalamic T-type Ca+2 channels
blocks Na+ channels

Question 12

PK/PD of Ethosuximide

Answer 12

Monitor if renal or hepatic impairment occurs.

Question 13

Adverse effects of Ethosuximide

Answer 13

1. Nausea
2. Anorexia

Question 14

Indication of Valproic acid (Valproate)

Answer 14

1. Partial (focal) seizures.
2. Generalized Tonic-Clonic seizures
3. Absence seizure
4. Myoclonic seizures.
5. Bipolar disorders.
6. Migraine prophylaxis.
7. Epilepsy

Question 15

MoA of Valproate

Answer 15

1. Blocking Na+ channels.
2. Blocks thalamic T –type Ca2+ channels.

Question 16

PK/PD of Valproic acid

Answer 16

1. chemically unrelated to other anti-epileptic drugs
2. Competes with phenytoin at binding sites on plasma proteins & its an inhibitor of CYPR450s.

Question 17

Adverse effects of Valproate

Answer 17

1. Alopecia (hair loss)
2. Teratogenicity
3. Hepatotoxicity

Question 18

Drugs used for Generalized Tonic-Clonic seizures

Answer 18

1) Phenytoin
2) Valporate
3) Carbamazepine

Phenobarbital is also used for tonic clonic seizures but in children
–> it is alternatively used in adults

Question 19

Barbi used to treat Tonic-Clonic seizures?

Answer 19

Phenobarbital in young children
–> used as an alternative agent in adults

Question 20

Drugs used for Partial seizures

Answer 20

1) Phenytoin
2) Carbamazepine
3) Gabapentin (newer anti-convulsant drug)

Question 21

Drugs used for Absence Seizures

Answer 21

1) Valproic acid
2) Ethosuximide

• Ethosuximide is used in uncomplicated absence seizures if patients can tolerate its GI side effects.
• Valproate is particularly useful in patients who have concomitant generalised tonic-clonic or myoclonic seizures.

Question 22

Drugs used for Status Epilepticus

Answer 22

1) IV diazepam or lorazepma is effective in terminating attacks → short-term control.
2) IV phenytoin → for prolonged therapy → less sedating than benzos or barbis BUT → cardiotoxicity.

• In VERY severe status epilepticus –> general anesthesia

Question 23

toxic effects of an overdose of anti-epileptic drugs

Answer 23

CNS depressants–> respiratory derpression

Question 24

Teratogenicity increases the risk of?

Answer 24

Congenital malformation

Question 25

what deficiency is a result of valproic acid teratogenicity

Answer 25

Neural tube defecets e.g Spina bifida

Question 26

what deficiency is a result of Carbamazepine teratogenicity

Answer 26

Craniofacial anomalies and spina bifida

Question 27

what deficiency is a result of phenytoin and carbamazepine teratogenicity

Answer 27

Foetal hydantoin syndrome