Autonomic Nervous Systems
Which of the following statements is not true about sotalol: (AIIMS Nov 2010)
|A||It is a non-selective beta-blocker|
|B||It prolongs action potential duration throughout the heart|
|C||It is excreted through bile following hepatic metabolism|
|D||Polymorphic ventricular tachycardia is a common side effect|
a. Sotalol is a non-selective beta-adrenergic receptor antagonist that also prolongs cardiac action potentials by inhibiting delayed rectifier and possibly other potassium ion current.
b. Racemic sotalol is approved for use in patients with both ventricular tachyarrhythmias and atrial fibrillation or flutter.
c. It is as effective as most sodium ion channel blocker in ventricular arrhythmias.
d. Sotalol prolongs action potential duration throughout the heart and QT-interval on the ECG.
e. It decreases automaticity, slows AV nodal conduction, and prolongs AV-refractoriness both by potassium ion channel block and block of beta-adrenergic receptors, but it exerts no effect on conduction velocity in fast-response tissue.
f. Sotalol causes EADs and triggered activity in vitro and can cause torsades de pointes (polymorphic ventricular tachycardia associated with long QT intervals), especially when serum K+ is low.
g. Unlike the situation with quinidine, the incidence of torsade de pointes seems to depend on the dose of sotalol, and in fact torsades de pointes are the major toxicity with sotalol overdose.
h. Sotalol is eliminated by renal excretion of unchanged drug.