Anti-Arrhythmic Drugs MCQs

The drug is being administered continuously and the steady- state concentration (Cp(ss)) for a continuously administered drug is given by the equation. Thus, Dosage = Plasma level × Clearance 1.92 mg/min = Cp(ss) × CL Rearranging : Cp(ss) = 1.92 mg/min 640 mL/min Cp(ss) = 0.003 mg/mL or 3 mg/L Reference : Basic & Clinical Pharmacology by Bertram G. Katzung, Fourteenth Edition, Pg no. 50

Other choices are correct A 45-year-old with supraventricular arrhythmia = Verapamil A 67-year-old on digoxin with supraventricular arrythmia = Propranolol A 56-year old with ventricular arrhythmia due after MI = lidocaine Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 248

Amiodarone is an iodine-containing anti-arrhythmic drug with complex effects on the thyroid gland and thyroid hormones. One of its actions is to inhibit peripheral conversion of T4 to T3. Note that propranolol also reduces conversion of T4 to T3. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg. no. 692

The most effective therapy for procainamide (and quinidine) toxicity appears to be concentrated sodium lactate due to increase in sodium current by increasing the sodium ion gradient and reduced drug-receptor binding by alkalinizing the tissue . Pressor sympathomimetics are to be used to reverse drug-induced hypotension if indicated. Reference: Basic & Clinical Pharmacology by Bertram G. Katzung, 14th Edition, Page Number-241.

This patient has an accelerated idioventricular rhythm, a common finding in patients with successful reperfusion after thrombolytic therapy. This rhythm is benign and requires no further therapy. It invariably resolves on its own. A & C : Amiodarone or metoprolol would be appropriate therapy if this was ventricular tachycardia or perhaps supraventricular tachycardia. Carotid sinus massage would be appropriate in the setting of supraventricular tachycardia. B : Flecainide (a class I antiarrhythmic) is contraindicated in post-MI patients because it was found to increase mortality. Reference: Basic & Clinical Pharmacology, Fourteenth Edition By Bertram G. Katzung Pg no. 244

Drugs causing QT prolongation include: Antiarrhythmics : Quinidine, procainamide, disopyramide, propafenone, amiodarone Antimalarials : Quinine, mefloquine, artemisinin, halofantrine Antibacterials : Sparfloxacin, moxifloxacin Antihistamines : Terfenadine, astemizole, ebastine Antidepressants : Amitriptyline and other tricyclics Antipsychotics : Thioridazine, pimozide, aripiprazole, ziprasidone Prokinetic : Cisapride