drugs in epilepsy
DESCRIPTION
TRANSCRIPT
ANTI-EPILEPTIC DRUG
EPILEPSY…????SEIZURE…????
SAWAN….???
FIT…???
Objectives
• To know types of drugs used in treating seizure/epilepsy
• To know the pharmacological actions of the drugs
• To know the effects of drugs on the specific functions of the system
Seizure
• 2nd neurologic disorder after stroke in US• brief episodes of brain dysfunction resulting from
abnormal electrical activity of cerebral neurons causing involuntary movement, sensations or thoughts
• Causes: diseases, infection, head injury, heredity etc• Epilepsy- chronic seizure (abnormal & excessive
electrical discharges of nerve cells)
Seizure
• A seizure occurs when the brain's nerve cells misfire and generate a sudden, uncontrolled surge of electrical activity in the brain
• During a seizure, each cell may fire as many as 500 times a second, much faster than the normal rate of about 80 times a second in the brain and spinal cord.
CLASSIFICATION OF SEIZURES
Generalized seizures Partial seizures
Begin in one area of the brain & rapidly spread throughout both hemispheres of the brain
Begin in a specific area of the brain & often indicate a localized brain lesion such as birth injury, trauma, stroke or tumor
PARTIAL SEIZURES
- Simple partial seizures (consciousness is not
affected)- Complex partial
seizures (level of consciousness is
decreased)
- Tonic-clonic / major motor seizure (common)
• Tonic – involves contraction of skeletal muscles
• Clonic – rapid rhythmic & symmetric jerking movements of the body
- Absence seizure (abrupt alterations in consciousness, lasts few seconds; etc
blank, staring expression with/without blinks of the eyelids)
- Myoclonic type ( contraction of a muscle or group of muscles)
- Akinetic type (absence of movement )- Mixed seizures
GENERALIZED SEIZURES
CAUSES OF SEIZURES
ELDERLYMIDDLE YEARSCHILDREN
• Birth traumas• Infections• Congenital
abnormalities• High fevers
• Head injuries• Infections• Alcohol
stimulant drugs• Medication side
effects
• Brain tumors• Strokes
Antiepileptic / Antiseizure Drugs
Tonic-clonic & partial seizures
Absence seizuresMyoclonic seizures Others
Carbamazepine (Tegrefol)Phenytoin (Dilantin)
Ethosuximide (Zarontin)
Valproic acid (Depakene)
Clonazepam (Klonopin)
Levetiracetam (Keppra)
Gabapentin (Neurontin)
Pharmacokinetic
• Slightly soluble; good absorption; 80-100% dose reaching circulation
• Not highly bound to protein plasma• Cleared by hepatic mechanism; active
metabolites cleared by liver• Medium-to long acting
Carbamazepine (Tegrefol)
• Strong inducing agent; therefore many drug interactions
• It is given orally• It is metabolized in the liver• Contraindicated in patients with previous bone
marrow depression
Phenytoin (Dilantin)
• Use for patients with tonic-clonic seizures and some partial seizures
• Acts to promote intracellular removal of sodium during the refractory period
• Antagonism (blocking) of Na+ channels to reduce excitability
• Antagonism of Ca++ channels• Adverse effects: CNS (ataxia, drowsiness) & GIT
(nausea, vomiting)
Ethosuximide (Zarontin)
• The main drug used to treat absence seizures, may be uses with other AEDs for treatment of mixed seizures
• Adverse effects: nausea and anorexia. (mental disturbances)
Clonazepam (Klonopin)
• Act by potentiating the actions of GABA causing neurotransmission inhibition (primarily in the CNS)
• Can be used to induce sleep (high dose), anticonvulsant therapy and reduction in muscle tone.
• Adverse effects: drowsiness, fatigue, dizziness, muscle hypotonia, co-ordination disturbances; also poor concentration, restlessness, confusion, amnesia
Valproic acid (Depakene)
• Thought to enhance the effects of GABA in the brain
• Used to treat manic reactions in bipolar disorder & to prevent migraine headaches
• Extensively metabolised in the liver• Rapidly transported across the blood brain
barrier• Adverse effects: Nausea, vomiting, anorexia,
abdominal pain, diarrhoea & weight gain
Gabapentin (Neurontin)
• Incompletely absorbed in the gut• Acts via:– Increased synthesis and release of GABA– Decrease degradation of GABA– Inhibition of Ca++ channels
• Adverse effects:– CNS effects (dizzy, drowsy, fatigue, headache, double visions)– Nausea and vomiting
• Contraindication: be careful with sudden withdrawal in the elderly due to kidney effects and alterations in acid-base balance.
Side Effects
• Antiepileptic drugs frequently produce CNS and gastrointestinal side effects
• Some antiepileptic drugs infrequently cause severe hematologic or hepatic toxicity
• Valproate and phenytoin cause birth defects