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Quinidine:  Na channel blockers class 1A



               derivative of cinchona plant


               Mechanism :

               Blocks Na+ channels → ↓ conduction in atria & ventricle




               Block K+ channels  Delays ventricular repolarization → ↑ ERP (prolonged action
               potential)




               Strong atropine-like characters → blocks Vagal (Parasympathetic) → ↑
               sympathetic outflow → ↑SA-node automaticity & ↑ in AV-conduction (pro-
               arrhythmic effect)




               Uses:

               Both Supraventricular & ventricular dysrhythmias  used

               Combined with Digoxin, Verapamil or β-blockers. … why ?


               To prevent atropine like actions of Quinidinde

               Side effects
               dry mouth, urine retention

               Cinchonism → tinnitus, headache, vertigo, blurred vision
               Dysrrhthmias (prolong QT interval


               Nausea, vomiting, diarrhea & other GIT symptoms


               Hypotension, dizziness, fainting (due to reduced heart rate, α blocking
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