anti epileptic

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SEMINAR ON ANTI EPILEPTIC DRUGS:

SEMINAR ON ANTI EPILEPTIC DRUGS

INTRODUCTION :

INTRODUCTION Epilepsy is a chronic condition produced by temporary changes in the electrical function of the brain, causing seizures which affect awareness, movement, or sensation. FEATURES OF EPILEPSY : i) Loss or disturbance of consciousness. ii) Characteristic body movements (usually but not always). iii) Autonomic hyperactivity.

CAUSES OF EPILEPSY :

CAUSES OF EPILEPSY 1. GENETIC FACTORS : Some types of epilepsy have been traced to an abnormality in a specific gene.500 genes could play a role in this disorder. 2. OTHER DISORDERS: For example, brain tumors, alcoholism,and Alzheimer's disease, Stroke, heart attack, and oxygen insufficiency in brain. 3. HEAD INJURY. 4. POISONING: Lead, carbon monoxide, and many other poisons. 5. OTHER FACTORS: Lack of sleep, alcohol consumption, stress, or hormonal changes associated with the menstrual cycle.

CLASSIFICATION OF SEIZURE :

CLASSIFICATION OF SEIZURE

BRIEF DESCRIPTION OF VARIOUS TYPES OF SEIZURES :

BRIEF DESCRIPTION OF VARIOUS TYPES OF SEIZURES PARTIAL SEIZURES — Excessive neuronal discharge & the extent to which the abnormal electrical activity spread to other brains of neurons. a) SIMPLE PARTIAL SEIZURES ~~ Abnormal electric activity is confined to a localized area of motor cortex. That seizure is limited to one limb or group of muscle controlled by that particular brain region. b) COMPLEX PARTIAL SEIZURES ~~ There is complex sensory hallucination bizarre behavior & loss of consciousness .

TYPES OF SEIZURES:

TYPES OF SEIZURES GENERALIZED SEIZURES : Abnormal electrical discharge throughout both the hemisphere. Immediate loss of consciousness. a) TONIC CLONIC SEIZURES ~~ There is loss of consciousness followed by tonic then clonic phase. b) ABSENCE SEIZURES~~ Brief, abrupt and self limiting loss of consciousness but no convulsion. c) MYOCLONIC SEIZURES ~~ Short episodic convulsion which may reoccur after few minutes. d) FEBRILE SEIZURES ~~ Young children may exhibit convulsions concominent with hyper pyrexia. There are tonic clonic type are of short duration . STATUS EPILEPTICUS — Rapid reoccurent grandmal seizures.

CHEMICAL CLASSIFICATION OF ANTIEPILEPTIC DRUGS:

CHEMICAL CLASSIFICATION OF ANTIEPILEPTIC DRUGS BARBITURATE : Phenobarbitone . DEOXYBARBITURATE : Primidone. HYDANTOIN : Phenytoin,Fosphenytoin. IMINOSTILBENE : Carbamazepine,Oxcarbazepine. SUCCINIMIDE : Ethosuximide. ALIPHATIC CARBOXYLIC ACID : Valproic acid (sodium valproate),Divalproex. BENZODIAZEPINE : Clonazepam,Diazepam. PHENYLTRIAZINE : Lamotrigine. CYCLIC GABA ANALOGUE : Gabapentin,Vigabatrin. NEWER DRUGS : Topiramate,Tiagabine,Zonisamide.

DRUGS USED IN THE TREATMENT OF EPILEPSY :

DRUGS USED IN THE TREATMENT OF EPILEPSY PHENYTOIN : Antiepileptic drug. Suppress the abnormal brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage-gated sodium channels. MECHANISM OF ACTION: Affects physiological actions at neuronal membrane including concentrations of neurotransmitters like non epinephrine & GABA. Block sodium channels & inhibition of the generation of repetitive action potential.

PHENYTOIN:

PHENYTOIN PHARMACOKINETICS: Bioavailability : 80%-90%, Metabolism : liver. t1/2 : 12-24 hours. Excretion: urine.(5% unchange) ADVERSE EFFECTS: Gingival hyperplasia in children,Hirsutism,acne,Megaloblastic anaemia,Osteomalacia. INTERACTION : a) Phenobarbitone competitively inhibits phenytoin metabolism. b) Carbamazepine & phenytoin increase each other’s metabolism. c)Phenytoin completitively inhibits warferin metabolism. USES: 1) In grandmal type epilepsy,Status epilepticas. 2) In cardiac arrhythmias. DOSES: 150-300 mg/day. In children the dose is 5-8mg/kg daily

VALPROIC ACID (SODIUM VALPROATE):

VALPROIC ACID (SODIUM VALPROATE) Valproic acid (VPA): Branched chain aliphatic carboxylic acid. Used to treat migraine headaches and schizophrenia. Effective in partial seizures & absence seizures. MECHANISM OF ACTION: Inhibition of the transamination of GABA by inhibiting GABA transaminase,increase in GABA concentration. Valproic acid also blocks the voltage-gated sodium channels and T type calcium channels . PHARMACOKINETICS: Rapidly absorb orally. plasma half life is 10-15 hrs. It is 90% bound to plasma proteins. metabolized in liver. It is conjugated & excreted in urine.

VALPROIC ACID (SODIUM VALPROATE):

VALPROIC ACID (SODIUM VALPROATE) INTERACTIONS: Valproic acid may interact with carbamazepine & induce each other’s metabolism. Also decreases the clearance of amitriptyline and nortriptyline .Aspirin may decrease the clearance of valproic acid. Also, combining valproic acid with the benzodiazepine clonazepam can lead to profound sedation and increases the risk of absence seizures. USES: 1)Used in absence seizures. 2)Valproate has some prophylatic efficacy in migraine. DOSES: 200 mg. three times daily maximum upto 3.6 gm in devide dosage. ADVERSE EFFECTS: weight gain, jaundice,Hepatitis,fatigue, peripheral edema, acne, dizziness, drowsiness, hair loss, headaches, nausea, sedation and tremors.

REFERENCE :

REFERENCE Loring, David W (1 September 2005). "Cognitive Side Effects of Antiepileptic Drugs in Children". Psychiatric Times XXII (10). http://www.psychiatrictimes.com/showArticle.jhtml?articleID=171201519. Rogawski MA, Löscher W. The neurobiology of antiepileptic drugs. Nat Rev Neurosci. 2004 Jul;5(7):553-564. PMID 15208697. Rogawski MA, Bazil CW. New molecular targets for antiepileptic drugs: α2δ, SV2A, and K(v)7/KCNQ/M potassium channels. Curr Neurol Neurosci Rep. 2008 Jul;8(4):345-352. PMID 18590620. Meldrum BS, Rogawski MA. Molecular targets for antiepileptic drug development. Neurotherapeutics. 2007 Jan;4(1):18-61. PMID 17199015. http://www.joacp.org/index.php?option=com_content&view=article&id=188&catid=1 "According to the Washington Post who quoted research from IMS Health, AEDs were the fifth best selling class of drugs in the US in 2007, with sales topping 10 billion dollars. "

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