ANTI EPILEPTIC DRUGS.pdf

. mampu sangat sangat maaf , section ubat-ubat ni saya dah tak Phenytoin (PTN) Mecha...

. mampu sangat sangat maaf , section ubat-ubat ni saya dah tak Phenytoin (PTN) Mechanism of Phenytoin Action of Phenytoin on Na+ Channel A. Resting State A. Activation B. Arrival of Action Gate close Potential causes M depolarization and channel opens allowing sodium to flow in Na+ C. Refractory State, B. Activation Inactivation Gate Open Mechanism of Action: Na+ Sustain channel in Membrane stabilization by blocking Na & Ca influx into the neuronal axon. this conformation or inhibits the release of excitatory amino acids via inhibition of Ca influx Carbamazepine Ethosuximide Hydantoin  Mechanism of action, similar to phenytoin Indication – partial seizures; generalized tonic-clonic seizures but worsens absence of seizures Adverse effects – Bone marrow depression (neutropenia, thrombocytopenia, aplastic anaemia) Ca2+ channel blocker Characteristics of Ca++ Channel Carried Current L-type currents require strong depolarization (high Phenobarbital (Luminal) L- activation threshold), are long-lasting (slow  duration of opening of chloride-channel inactivation rate) and are blocked by organic calcium Type antagonists of dihydropyridine, phenylalkylamines and benzothiazepine chemical classes. They are the main The action of barbiturates on the currents recorded in muscle and endocrine cells initiating contraction and secretion. GABA GABAA receptor is to prolong the opening of the channel elicited by T- T-type currents are activated at weak depolarization GABA potentials, are transient (fast inactivation) and resist L- type and N- and P/Q-type blockers. They are involved Cl- Type in the shaping of the action potentials and controlling GABA PB patterns of repetitive firing in a wide variety of cell types. - - -- -- - - - (Luminal) Phenobarbital Mechanism of action: - Long-acting barbiturates, elevates the seizure threshold and prevent the spread of electrical seizure activity by enhancing the inhibitory effect of GABA GABA - Increases the inhibitory neurotransmitters (e.g: GABA ) and decreases the excitatory transmission Gamma-AminoButyric Acid (GABA) Uses: GABA – like the brakes in a car to slow down brain - An effective anticonvulsant activity and help us to relax and maintain a sense of - Primarily used as an alternative when single, non- calmness sedating anti-convulsants are unsuccessful in controlling seizures. - Most useful in treating partial and generalized tonic- clonic seizures Phenobarbital (Luminal) AED which interfere with GABA transmission GABAA receptor agonist F Barbiturates F Benzodiazepines F Topiramate GABA-T inhibitor F Valproic acid F Vigabatrin GABA reuptake inhibitor F Tiagabine  Benzodiazepines (BZD) BZD: NSAIDS: Mechanism COX inhibitor of action BZD: NSAIDS: Mechanism COX inhibitor of action  frequency of opening of calcium-channel BDZ receptor linked to GABA-A receptor complex (Bound to Cl- channels) - BDZ enhance GABA effect - GABA act as an inhibitory neurotransmitter GABA Open Cl channels in response to GABA activation, Cl- hyperpolarization, decrease neuronal firing GABA-A BZD Effects: Sedative, hypnotic, anti-convulsant, muscle- relaxant - - -- -- Tiagabine Vigabatrin ~ EFFECTIVEFUTURE Gabapentin Tiagabine: Mechanism of action AED with dual or more mechanisms of action Gabapentin Lamotrigine Zonisamide Valproic acid Gabapentin Topiramate Felbamate Topiramate (TPM, Topamax ®) Zonisamide Valproic Acid (Sodium Valproate) Topiramate Mechanism of Action