Anti-epileptic drugs

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Anti-epileptic drugs :

Anti-epileptic drugs Prepared & Presented by Dr. Siva Reddy Challa, Professor & HOD, Dept. of Pharmacology KVSR Siddhartha College of Pharmaceutical Sciences, Siddhartha Nagar, Vijayawada-520010 Andhra Pradesh, INDIA Email: sivareddypharma@gmail.com

EPILEPSY:

EPILEPSY Seizures - Transient alteration of behavior due to disordered, abnormal firing of brain neurons Discharge and its spread determines the symptoms of epilepsy

EPILEPSY:

EPILEPSY

ANTI EPILEPTICS:

ANTI EPILEPTICS Classification of epilepsy GENERALIZED EPILEPSY : 40% of all epilepsy Involve both the hemisphere from the outset Loss of consciousness

ANTI EPILEPTICS:

ANTI EPILEPTICS GENERALIZED EPILEPSY : Generalized tonic clonic seizures Absence seizures Myoclonic seizures Infantile spasms

ANTI EPILEPTICS:

ANTI EPILEPTICS PARTIAL : 60% of all the epilepsy Simple : No loss of consciousness Eg : Jacksonian epilepsy Complex : Impairment of consciousness Eg : Psychomotor epilepsy – focus in temporal lobe

ANTI EPILEPTICS:

ANTI EPILEPTICS Seizures : Defective synaptic function Inhibition of inhibitory synapse Excitation of excitatory synapse

ANTI EPILEPTICS:

ANTI EPILEPTICS Goal of the epilepsy management is restoration of normal synaptic activity Activation of inhibitory synapse Inhibition of excitatory synapse

ANTI EPILEPTICS:

ANTI EPILEPTICS Mechanism of action Block ‘Na’ channels Enhance GABA - A synaptic function Inhibit Glutamate synaptic function Block Calcium ‘T’ channels

ANTI EPILEPTICS:

ANTI EPILEPTICS Drugs acting by prolonging the inactivation of Na channels Carbamazepine, Phenytoin, Topiramate Lamotrigine, Valproate, Zonisamide

ANTI EPILEPTICS:

ANTI EPILEPTICS Drugs enhancing GABA induced inhibition : Benzodiazepines, Valproate, Gabapentin, Vagabatrin, Barbiturates

ANTI EPILEPTICS:

ANTI EPILEPTICS Drugs affecting the ‘ T ’ Ca Current Ethosuccimide Valproate Trimethadione

ANTI EPILEPTICS:

ANTI EPILEPTICS

ANTI EPILEPTICS:

ANTI EPILEPTICS PHENYTOIN : Not a Global CNS depressant Prolong the inactivated state of Na channel - Stabilizing effect Also used as Anti-arrhythmic

ANTI EPILEPTICS:

ANTI EPILEPTICS PHENYTOIN : Pharmacokinetics : Oral absorption is variable Zero order kinetics Plasma monitoring Enzyme inducer Should not be used in Absence seizures

ANTI EPILEPTICS:

ANTI EPILEPTICS PHENYTOIN TOXICITY Ataxia, Vertigo and Nystagmus Gum hypertrophy Megaloblastic anemia / Osteomalacia Hirsutism In pregnancy – fetal hydantoin syndrome – Cleft lip and palate

ANTI EPILEPTICS:

ANTI EPILEPTICS Phenytoin Interactions : Phenytoin induces the metabolism of steroids and Vit - D

ANTI EPILEPTICS:

ANTI EPILEPTICS USES OF PHENYTOIN Generalized seizures Partial seizures Status epilepticus Cardiac arrhythmia

Anti-epileptics:

Anti-epileptics Fosphenytoin is a Phenytoin precursor Intravenous fosphenytoin can be used as a substitute for Phenytoin It can be used to control seizures during neurosurgery and status epilepticus.

ANTI EPILEPTICS:

ANTI EPILEPTICS BARBITURATES : Phenobarbital has specific anticonvulsant action at low dose GABA – A mimetic action Anti-glutamate action Ca entry reduction

ANTI EPILEPTICS:

ANTI EPILEPTICS KINETICS OF PHENOBARBITAL : Long half life It is an enzyme inducer It increases heme synthesis – contraindicated in porphyria Tolerance and dependence

ANTI EPILEPTICS:

ANTI EPILEPTICS TOXICITY OF BARBITURATES : Megaloblastic anemia Osteomalacia Long term administration – behavioral abnormalities, diminution of intelligence, impaired learning and memory

ANTI EPILEPTICS:

ANTI EPILEPTICS Primidone This drug is metabolized to Phenobarbital and the main action is through it.

ANTI EPILEPTICS:

ANTI EPILEPTICS CARBAMAZEPINE Prolong the inactivated Na channel Antidiuretic effect by enhancing ADH action Should not be used in absence seizures

ANTI EPILEPTICS:

ANTI EPILEPTICS KINETICS OF CARBAMAZEPINE : Oral absorption is slow Metabolized in liver by oxidation – epoxide derivative Enzyme inducer and Auto induction

ANTI EPILEPTICS:

ANTI EPILEPTICS Adverse effects of Carbamazepine : Sedation, ataxia, vertigo and diplopia Agranulocytosis Liver toxicity, water retention Fetal malformations – craniofacial abnormality and spina bifida

ANTI EPILEPTICS:

ANTI EPILEPTICS USES OF CARBAMAZEPINE : Partial / Generalized epilepsy Trigeminal neuralgia Maniac Depressive Psychosis

Anti-epileptics:

Anti-epileptics Oxcarbazepine (OXC) is an analog of CBZ. OXC does not produce the epoxide metabolite, which is largely responsible for the adverse effects of CBZ.

ANTI EPILEPTICS:

ANTI EPILEPTICS VALPROATE (SODIUM VALPROATE) Broad spectrum anticonvulsant Effective in MDP and acute mania

ANTI EPILEPTICS:

ANTI EPILEPTICS Mechanism of action of Valproate : Prolong inactivation of Na channel Attenuation of calcium T Current Inhibition of degradation of GABA by transaminase

ANTI EPILEPTICS:

ANTI EPILEPTICS KINETICS OF VALPROATE : Oral absorption is good Metabolized by liver It is enzyme inhibitor

ANTI EPILEPTICS:

ANTI EPILEPTICS ADVERSE EFFECTS OF VALPROATE : Anorexia Alopecia Acute fulminant hepatic failure - children Ammonia levels increased Neural tube defects – spina bifida

ANTI EPILEPTICS:

ANTI EPILEPTICS Uses of Valproate : Generalized and Partial seizures Absence seizures Myoclonic seizures MDP and acute mania Migraine

ANTI EPILEPTICS:

ANTI EPILEPTICS BENZODIAZEPINES : Lorazepam, Diazepam, Clonazepam Clonazepam – Absence and Myoclonic seizures Lorazepam, Diazepam – Status epilepticus Sedation and tolerance are the disadvantages – long term.

ANTI EPILEPTICS:

ANTI EPILEPTICS ETHOSUXIMIDE : Primary action is on thalamocortical system which is involved in absence seizures Acts by suppression of the ‘T’ Ca current Used in absence seizures Agranulocytosis is rarely seen.

ANTI EPILEPTICS:

ANTI EPILEPTICS GABAPENTIN GABA agonist Promotes the release of GABA Orally effective Used for Neuropathic pain, Partial and Refractory seizures Sedation and ataxia are the side effects

ANTI EPILEPTICS:

ANTI EPILEPTICS VAGABATRIN : A gamma vinyl analogue of GABA Inhibitor of GABA transaminase Used in Partial epilepsy Adverse effects includes – Visual field defects, depression and psychosis

ANTI EPILEPTICS:

ANTI EPILEPTICS TIAGABINE : Inhibits GABA uptake into the neuron – by blocking the GABA transporter Well absorbed orally It is used for Partial epilepsy Somnolence is a side effect

ANTI EPILEPTICS:

ANTI EPILEPTICS TOPIRAMATE : Delays the recovery of the Na inactivated channels Enhance GABA currents Blocks the activation of AMPA receptors Carbonic anhydrase inhibitors Used as add on therapy for Partial seizures Weight loss and renal stones

ANTI EPILEPTICS:

ANTI EPILEPTICS LAMOTRIGINE : Delays the recovery of inactivation of the Na channels Block of Glutamate receptors Used in Absence seizures, Partial epilepsy and Lennox Gastaut Syndrome Ataxia and SJS are adverse effects

Anti-epileptics:

Anti-epileptics Felbamate : It blocks the NMDA receptors, calcium channels and also sodium-channel Use of Felbamate is restricted to patients with Lennox-Gastaut syndrome Adverse effects - Aplastic anemia and hepatic failure

ANTI EPILEPTICS:

ANTI EPILEPTICS Levetiracetam : It acts by reducing calcium currents Useful in partial epilepsy Somnolence, asthenia and ataxia are the adverse effects

ANTI EPILEPTICS:

ANTI EPILEPTICS ZONISAMIDE Prolong the inactivated state of Na channel Inhibits Ca ‘T’ currents Add on therapy for Partial seizures and absence seizures Ataxia and anorexia are the adverse effects

ANTI EPILEPTICS:

ANTI EPILEPTICS ACETAZOLAMIDE Carbonic anhydrase inhibitor Used for seizures during menses and absence seizures Tolerance is the drawback

PowerPoint Presentation:

Drug Mech action Indications Toxicity Topiramate Blocks AMPA and Na ch, ^GABA Partial seizures Sedation Renal stones Lamotrigine Block glutamate and Na channel Partial and Absence seizures Sedation, SJS Felbamate Block NMDA and Na and Ca Partial, Lennox Gastaut syndrome Aplastic anemia, liver Vigabatrin GABA transaminase Partial seizures Depression, Visual dysf Tiagabine Block GABA transporter Partial seizures Sedation Gabapentin ^ GABA agonist Neuropathic Pain, Migraine, Partial, BPD Sedation

PowerPoint Presentation:

Epilepsy Preferred choice Others Partial Carbamazepine Phenytoin GTC Carbamazepine Phenytoin Absence Ethosuximide Valproate Myoclonic Valproate Clonazepam Infantile spasm ACTH Vigabatrin Febrile Phenobarbital Diazepam Status epilepticus Lorezepam Diazepam Phenytoin

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