Epilepsy is characterized by recurrent seizures and is treated using anticonvulsant drugs like phenytoin, carbamazepine, valproic acid, phenobarbital, and benzodiazepines. Phenytoin works by blocking sodium channels in neurons to inhibit neuronal firing and seizures. Carbamazepine has a similar mechanism of action and indication as phenytoin. Valproic acid enhances GABA levels to reduce seizures. Choice of anticonvulsant depends on seizure type, with carbamazepine, phenytoin, and valproic acid used for partial seizures and valproic acid and diazepam used for absence seizures.

1. ANTIEPILEPTIC
S

2. DEFINITION
 Epilepsy
 Epilepsy is a chronic disorder of brain
function characterized by recurrent
seizures often accompanied by episodes
of unconsciousness or amnesia.
 Seizure
 Seizure is a transient alteration in
behaviour because of disordered firing
of group of neurons.

3. SEIZURE TYPES

4. CLASSIFICATION OF
ANTIEPILEPTICS
 HYDANTOINS-Phenytoin, Mephenytoin
 BARBITURATES- Phenobarbotone,
Mephobarbitone
 DEOXYBARBITURATES - Primidone
 IMINOSTILBENE - Carbamazepine
 SUCCINIMIDE - Ethosuximide
 GABA transaminase inhibitor - Valproic acid
 BENZODIAZEPINES - Diazepam,Clonazepam,
Lorazepam

5. CLASSIFICATION (Cont...)
 NEWER AGENTS
 GABA analogs - Gabapentin ,vigabatrin
 OTHERS - Zonisamate,felbamate

6. PHENYTOIN
 PHARMACOLOGICAL ACTION
 CNS - Phenytoin has good anti seizures
activity and is one of the most effective
drugs against generalized tonic-clonic
seizures and partial seizures.

7. MECHANISM OF ACTION

8. Phenytoin
Blocks Na + Channels in Post
Synaptic Neuron
Inhibits the action Potential of
Neurons

9. ADVERSE EFFECTS
 Nausea, vomitting, epigastric pain
 Hypersensitivity
 Megaloblastic anemia
 Teratogenicity –when taken to the
pregnant lady ,it produce fetal
hydantoin syndrome (Cleft Palate, Cleft
lip & Microcephaly)
 Hyperglycemia

10. USES
 1. Generalized tonic clonic seizures and
partial seizures
 2.Status epileptics –phenytoin is used by
slow IV Injection.
 3.trigeminal neuralgia – as an
alternative to carbamazepine.
 4.cardiac arrhythmias- phenytoin is
useful in digitalis induced arrhythmias.

11. Drug interaction
 Phenytoin is an enzyme inducer.
phenobarbitone competitively inhibit s
phenytoin metabolism.
 Carbamazepine and pheytoin enhances
each others metabolism.
 Valproate displace protein bound and
may result in phenytoin toxicity.
 Antacid ↓ absorption of phenytoin.

12. Fosphenytoin
 It is a prodrug of phenytoin that has
certain advantages over phenytoin for
Parenterally use:
 It is quickly converted to phenytoin in
the body.
 More potent.
 Less cardiotoxic.
 Safer on the intestine.

13. PHENOBARBITONE
 It has specific antiepileptic activity.
Primidone which is rarely used .
Phenobarbitone is effective in tonic-
clonic seizures and ineffective in absence
of seizures.

14. MECHANISM OF ACTION
 Acts on the Synapse
 Enhance the action of Inhibitory neurotransmitters
(Eg. GABA)
 Suppresses the excitatory neurotransmitters (Ach)
 Opens Cl – ion Channels
 Decreases the Seizures

15. Pharmacokinetics
 Oral Absorption
 50 % bounds to plasma
proteins
 Metabolizes in liver
 Excreted via urine

16. ADVERSE EFFECT
 Sedation
 Megaloblastic anemia
 Osteomalacia
 Ataxia
 Skin rashes
 USES
 Generalized tonic –clonic seizures
 Partial seizures

17. CARBAMAZEPINE
 Carbamazepine is a tricyclic compound
 Anti seizure activity
It has good Anti seizure activity .its
mechanism of action and anti epileptic
action are similar to phenytoin.
 Carbamazepine is also used in the
treatment of trigeminal neuralgia

18. ADVERSE EFFECTS
 Drowsiness
 Vertigo
 Nausea & Vomiting
 Ataxia
 USES
 Generalized Tonic – Clonic Seizures
 Simple & Complex, Partial Seizures
 Trigeminal Neurolgia

19. VALPORIC ACID MoA
 Enhances the level of GABA (↓se
Metabolism of GABA)
 Blocks Na + Channels
 Decreases low threshold Ca + current in
thalamus
 Reduce Seizure

20. ADVERSE EFFECTS
 Sedation, Rashes, Ataxia and Tremors
USES
 Partial & Generalized Seizures
 Useful particularly in Absence Seizures (Petit
Mal Seizures)
 Generalized Tonic Clonic Attacks

21. BENZODIAZEPINE
 Diazepam is the drug of choice in status
epilepticus.
 Clonazepam is a potent anti epileptic drug
useful in absence and myoclonic seizures.
 Nitrazepam is used for treatment of
myoclonic seizures.

22. NEWER ANTI
EPILEPTICS
 Gabapentin – It is a highly lipid soluble
drug.
 It crosses the BBB.
 Effective in tonic clonic seizure
 Exact MoA is unknown.

23. CHOICE OF ANTI SEIZURE
DRUGS Simple / Partial Seizure – Carbamazepine,
Phenytoin, Valproic Acid
 Complex / Partial Seizure - Carbamazepine,
Phenytoin, Valproic Acid
 Partial with Secondarily Generalized -
Carbamazepine, Phenytoin, Valproic Acid
 Absence Seizures – Valproic Acid
 Tonic Clonic Seizure - Carbamazepine, Phenytoin,
Valproic Acid
 Tonic Clonic + Absence Seizure – Valproic Acid
 Myoclonic Seizures – Diazepam, Valproic Acid
 Status Epilepticus – Diazepam, Phenytoin, GA
 Febrile Convulsion - Diazepam