Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 38-52: Quinidine & Related Antiarrhythmics Overdose + Key Features Download Section PDF Listen +++ ++ Class Ia antiarrhythmic agents Quinidine Disopyramide Procainamide Class Ic antiarrhythmic agents Flecainide Propafenone + Clinical Findings Download Section PDF Listen +++ ++ Arrhythmias Syncope Hypotension + Diagnosis Download Section PDF Listen +++ ++ Blood levels of quinidine and procainamide (and active metabolite NAPA) are generally available from hospital laboratory ECG monitoring for QRS and QT interval prolongation Widening of the QRS complex (> 100–120 ms) With type Ia drugs, a lengthened QT interval and atypical or polymorphous ventricular tachycardia (torsades de pointes) may occur + Treatment Download Section PDF Listen +++ ++ Activated charcoal Administer 60–100 g orally or via gastric tube, mixed in aqueous slurry for ingestions within 1 h Do not use for comatose or convulsing patients unless they are endotracheally intubated Consider gastric lavage for recent (1 h) large ingestions Consider whole bowel irrigation for ingestion of sustained-release formulations Perform continuous cardiac monitoring Treat cardiotoxicity (hypotension, QRS interval widening) with intravenous boluses of sodium bicarbonate, 50–100 mEq Torsades de pointes ventricular tachycardia may be treated with intravenous magnesium or overdrive pacing