Epilepsy is caused by excessive and synchronous discharge of cerebral neurons resulting in seizures. Seizures can be detected by EEG and categorized by origin, etiology, clinical presentation, and electrophysiology. They are broadly classified as partial or generalized. Anti-epileptic drugs work by enhancing GABA, inhibiting sodium channels, inhibiting calcium channels, or blocking glutamate receptors. Phenytoin is a first-line treatment for tonic-clonic, simple partial, and complex partial seizures as well as status epilepticus. It has many potential adverse effects and drug interactions that require monitoring.

2. Epilepsy
An assortment of different seizure types & syndromes
originating from several mechanisms that have
common sudden, excessive & synchronous discharge of
cerebral neurons resulting in loss of
consiousness,abnormal movements, odd behaviour
/distorted perceptions.
Neuro-imaging techniques such as:
MRI,PET,SPECT.

3. Abnormal electrcal activity during a seizure can be
detected by EEG.
Seizures have been categorized by site of origin,
etiology, electrophysiologc correlation ,clinical
presentation.
Seizures have been classified in to2 broad groups:
• Partial (Simple & Complex)
• Generalized(Tonic-Clonic & Absence).
• Others (Myoclonic, Febrile, Status epilepticus).

8. • Absence seizures:
These involve brief, abrupt,self-limiting loss of
consiousness.
In 3-5 years of age patients(onset occurs) & lasts
till puberty.
Patient stops speaking in mid-sentence, & stares vacantly for
few seconds(3-5sec).

10. Febrile seizures
Young children may develop with illness accompanied by
high fever.
Intermittent muscle spasm & progressive metal
deterioration.

12. ANTI -EPILEPTICS
These are the drugs used in the treatment of EPILEPSY.
Barbiturates : Phenobarbitone.
Deoxybarbiturate : Primidone.
Hydantoin : Phenytoin,Fosphenytoin.
Immunostilbines : Carbamazepine,Carbazepine.
Succimide : Ethosuximide.
Aliphatic carboxylic acids: Sodium valproate, Divalproate.
Phenylriazine : Lamotrigine.
Cyclic GABA analogue : Gabapentin.
Newer drugs :Vigabatrine, Tiagabine,Topiramate,
Levetiractem.
BZD’s : Diazepam,Lorazepam,Oxazepam,
Clonazepam.

13. Mechanism of Action

14. The 3 mechanisms appear to be
important action of Epilepsy.
I. Enhancement of GABA action.
II. Inhibition of Na+2 channel function.
III. Inhibition of Ca+2 channel function.
IV. Inhibition of Glutamate release & Blockade of
receptors.

16. Enhancement of GABA action:( BZD’s, Barbiturates)
Vigabatrin -- Inhibits enzyme“GABATransaminase”.
Tiagabine --Inhibits GABAuptake & enhance action of
GABA.
Gabapetin – designed as an agonist @ GABAA Receptors.
Inhibition of Na+2 channel function:
(Phenyltriazine,Hydantoins,Immunostibines,
Aliphatic –COOH’s).
These drugs affect membrane excitabilty by an action on voltage-
gated Na+2 channels, which carry the inward membrane current
necessary for generation of Action potential.
Inhibition of Ca+2 channels: (Suucimides,Gabapetin).
Succimides blocks T-type Ca+2 channels .
Gabapentin blocks L-type Ca+2 channels .

17. Pharmacokinetics:
Absorption ----Slow on oral administration.
Bioavailability differs in market preparations.
Distribution is wide & 80-90% bound to plasma proteins.
Metabolism– Liver by Hydroyxlation & Glucoronide
conjugation.
T1/2– 12-24hrs & increases up to 60 hrs.
Only 5%Unchanged Phenytoin is excreted in urine.

18. Adverse Effects:
@ Therapeutic levels— Due to over growth of
Collagen fibres causes Gum Hypertrophy.(Can b minimized by
Oral hygiene).
Girls- Hirsutism,Acne,Coarsening of facial features.
Hypersensitivity Reactions-Rashes,Lymphadenopathy,Neutropenia.
Megaloblastic AnaemiaIt decreases Folate absorption &
increases folate excretion.
Osteomalacia, Hypergycemia, In pregnancy—causes
FOETAL HYDANTOIN SYNDROME.

19. @ Higher levels– Cerebellar & Vestibular
manifestations: Ataxia, Vertigo, Diplopia,
Nystagmus. Drowsiness,Mental confuion,
Hallucinations, Disorientation, Muscle rigidity.
Epigastric pain, Nausea & vomiting
(Can b minimized when taken with meals).
I.V injection causes Local injury, oedema, vein
thrombosis, Discolouration of injected
limb,Hypotension & Cardiac arrhythmias.

20. Carbamazepine + Phenytoin creases each others Metabolism.
Isoniazid, Cimetidine, Dicumerol,Warfarin  Inhibits Phenytoin
metabolsim.
Phenytoin induces Steroid degradation.
Sodium Valproate Decreases metabolism & Increases Phenyton
plasma levels.

21. USES
1st line Anti-Epileptic for Generalized Tonic-Clonic
,Simple &Complex partial seizures.
In Status Epilepticus.
In Trigeminal Neuralgia.