Drug Interaction Report

MONITOR: Arsenic trioxide can cause QT interval prolongation and complete atrioventricular block. Theoretically, use of arsenic trioxide during intensive vitamin B12 therapy for the treatment of megaloblastic anemia may potentiate the risk of cardiac arrhythmias such as ventricular tachycardia and torsade de pointes because of the hypokalemia that may develop during the early phase of vitamin B12 therapy due to increasing potassium requirements as normal erythropoiesis is established. Hypokalemia is a known risk factor for ventricular arrhythmias associated with QT interval prolongation.

MANAGEMENT: Caution is advised when arsenic trioxide is administered to patients requiring vitamin B12 for severe megaloblastic anemia. Serum electrolytes should be evaluated and any abnormalities corrected prior to initiating therapy with arsenic trioxide. During therapy, potassium concentrations should be kept above 4 mEq/dL.

MONITOR: Arsenic trioxide can cause QT interval prolongation and complete atrioventricular block. Theoretically, use of arsenic trioxide during intensive vitamin B12 therapy for the treatment of megaloblastic anemia may potentiate the risk of cardiac arrhythmias such as ventricular tachycardia and torsade de pointes because of the hypokalemia that may develop during the early phase of vitamin B12 therapy due to increasing potassium requirements as normal erythropoiesis is established. Hypokalemia is a known risk factor for ventricular arrhythmias associated with QT interval prolongation.

MANAGEMENT: Caution is advised when arsenic trioxide is administered to patients requiring vitamin B12 for severe megaloblastic anemia. Serum electrolytes should be evaluated and any abnormalities corrected prior to initiating therapy with arsenic trioxide. During therapy, potassium concentrations should be kept above 4 mEq/dL.