Anti-seizure Drugs Flashcards
List out a few anti-seizure drugs
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
Indication of Phenytoin
Partial and Tonic-clonic seizures + generalized seizures
MoA of Phenytoin
Block Na+ channel - Binds to Na+ channels and increases their refractory period
PK/PD of Phenytoin
- Effective in epilepsy
- ineffective in Absence seizures
- Zero-order kinetics
- Plasma conc. should be monitored
- induced hepatic enzyme–> decreases
effect of other anti-convulsant
drugs.
Adverse effects of Phenytoin
- Gum hyperplasia.
- Hirsutism (facial hair in women)
- Teratogenic.
- Hepatotoxic.
- Contraindicated in heart patients and pregnant women
Indication of Carbamazepine
Partial/ generalized/ complex seizures
MoA of Carbamazepine
Block Na+ channel - Binds to Na+ channels and increases their refractory period
PK/PD of Carbamazepine
- Effective in psychomotor epilepsy.
- Ineffective in Absence seizure.
- Effective in trigeminal neuralgia & bipolar disorder.
- Strong liver inducer
Adverse effects of Carbamazepine
- Increased ADH secretion.
- Mental disturbances.
- teratogenic.
- Hepatotoxic.
Indication of Ethosuximide
Main drug for Absence seisures
MoA of Ethosuximide
Blocks thalamic T-type Ca+2 channels
blocks Na+ channels
PK/PD of Ethosuximide
Monitor if renal or hepatic impairment occurs.
Adverse effects of Ethosuximide
- Nausea
- Anorexia
Indication of Valproic acid (Valproate)
- Partial (focal) seizures.
- Generalized Tonic-Clonic seizures
- Absence seizure
- Myoclonic seizures.
- Bipolar disorders.
- Migraine prophylaxis.
- Epilepsy
MoA of Valproate
- Blocking Na+ channels.
- Blocks thalamic T –type Ca2+ channels.
PK/PD of Valproic acid
- chemically unrelated to other anti-epileptic drugs
- Competes with phenytoin at binding sites on plasma proteins & its an inhibitor of CYPR450s.
Adverse effects of Valproate
- Alopecia (hair loss)
- Teratogenicity
- Hepatotoxicity
Drugs used for Generalized Tonic-Clonic seizures
1) Phenytoin
2) Valporate
3) Carbamazepine
Phenobarbital is also used for tonic clonic seizures but in children
–> it is alternatively used in adults
Barbi used to treat Tonic-Clonic seizures?
Phenobarbital in young children
–> used as an alternative agent in adults
Drugs used for Partial seizures
1) Phenytoin
2) Carbamazepine
3) Gabapentin (newer anti-convulsant drug)
Drugs used for Absence Seizures
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.
Drugs used for Status Epilepticus
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
toxic effects of an overdose of anti-epileptic drugs
CNS depressants–> respiratory derpression
Teratogenicity increases the risk of?
Congenital malformation
what deficiency is a result of valproic acid teratogenicity
Neural tube defecets e.g Spina bifida
what deficiency is a result of Carbamazepine teratogenicity
Craniofacial anomalies and spina bifida
what deficiency is a result of phenytoin and carbamazepine teratogenicity
Foetal hydantoin syndrome
