Consider dosage reduction with hepatic impairment) Atrial flutter with 1:1 AV conduction , QT prolongation, torsades de pointes, bradycardia, bronchospasm Sinus or AV conduction disease (in absence of pacemaker) Cardiogenic shock Hypotension Reactive airway disease Avoid in structural heart disease (including ischemic heart disease) Atrial flutter (unless concomitant AV nodal therapy to avoid 1:1 conduction) Brugada syndrome Hepatic dysfunction QT-prolonging drugs Drugs with SA and/or AV nodal blocking properties Amiodarone, ritonavir, saquinavir, tipranavir (Continued) Table 7. Continued Drug Initial Daily Dose(s) Maximum Total Daily Maintenance Dose Potential Adverse Effects Precautions (Exclude or Use With Caution) and Interactions (Continued) Class III antiarrhythmic agents Amiodarone 400 600 mg QD in divided doses for 2 4 wk (loading dose); followed by 100 200 mg QD (maintenance dose) Up to 1200 mg QD may be considered in an inpatient monitoring setting (loading dose); up to 200 mg QD maintenance (to minimize long-term adverse effects) Bradycardia, QT prolongation, torsades de pointes (rare), gastrointestinal upset, constipation, hypothyroidism, hyperthyroidism, pulmonary fibrosis, hepatic toxicity, corneal deposits, optic neuritis, peripheral neuropathy, photosensitivity, adult respiratory distress syndrome after cardiac or noncardiac surgery (rare) Sinus or AV conduction disease (in absence of pacemaker) Inflammatory lung disease Hepatic dysfunction Hypothyroidism, hyperthyroidism Peripheral neuropathy Abnormal gait/ataxia Optic neuritis Drugs with SA and/or AV nodal blocking properties Amiodarone is a substrate of and inhibits P-glycoprotein and CYP2C9 (moderate), CYP2D6 (moderate), and CYP3A4 (weak); amiodarone is a substrate for CYP3A4 (major) and CYP2C8 (major); amiodarone is an inhibitor of OCT2 Reduce warfarin dose by 50%, and reduce digoxin dose by 30% 50% Agalsidase alfa, agalsidase beta, azithromycin, bosutinib, ceritinib, colchicine, dabigatran, edoxaban, flecainide, ivabradine, ledipasvir/sofosbuvir, lopinavir, lopinavir/ ritonavir, lovastatin, nelfinavir, pazopanib, propafenone, simvastatin, ritonavir, rivaroxaban, saquinavir, sofosbuvir, topotecan, vincristine, grapefruit juice Dofetilide 500 mcg every 12 h (if CrCl >60 mL/min) 250 mcg every 12 h (if CrCl 40 60 mL/min) 125 mcg every 12 h (if CrCl 20 to <40 mL/min) Not recommended if CrCl <20 mL/min Adjust dose for renal function, body size, and age Initiate for minimum of 3 d in a facility that can provide continuous ECG monitoring and cardiac resuscitation Contraindicated if the baseline QTc interval or QTc >440 ms or 500 ms in patients with ventricular conduction abnormalities Repeat ECG 2 3 h after administering the first dose to determine QTc; if the QTc increased by >15% compared with baseline or if QTc is >500 ms (550 ms in patients with ventricular conduction abnormalities), subsequent dosing should be down titrated by 50%; at 2 3 h after each subsequent dose, determine QTc (for in-hospital doses 2 5); if at any time after the second dose the QTc is >500 ms (550 ms in patients with ventricular conduction abnormalities), dofetilide should be discontinued QT prolongation, torsades de pointes Severe renal dysfunction (contraindicated if CrCl Prolonged QT History of torsades de pointes Concomitant use of hydrochlorothiazide, cimetidine, dolutegravir, itraconazole, ketoconazole, megestrol, trimethoprim, prochlorperazine trimethoprim/ sulfamethoxazole or verapamil, contraindicated Avoid other QT-prolonging drugs Sotalol 40 80 mg every 12 h (Patients initiated or reinitiated on sotalol should be placed in a facility that can provide cardiac resuscitation and continuous electrocardiographic monitoring for a minimum of 3 d). 