Core pharmacology

Class Group

Antiarrhythmic –
Vaughan Williams Class III
K channel blocker

Legacy Cicm Level

Level 3

Introduction

beta blocker but it also has class III effects and is
often categorised in this class

Indications Uses

used for the prevention of SVT and in the
treatment of ventricular tachyarrhythmias

Chemical Pharmaceutics

Racemic mixture of d- and l- sotalol
both isomers: similar Class III effects
l-isomer: all of the Class II effect

Presentation

PO: 80 or 160mg tablets. IV: clear liquid 10mg/ml

Mechanism of action

Non-selective beta adrenergic antagonist
Cause anti-arrhythmic effect by:
--- Decreased pacemaker potential current
--- Decreased slow-inward Ca2+ current
--- Decreased repolarising K+ and Cl- currents
--- Decreased Ca2+ stored in the sarcoplasmic reticulum
--- Increased serum [K+]*

Onset Peak Duration

Onset IV: 5-10mins, PO 1-2hrs
Duration 8-16hrs

Physiological effects

Effect: Prolonged Action potential. Reduced Inotropy
Ventricular rate is slowed
QT interval is prolonged

Adverse Effects Toxicity

class III: QT prolongation predisposes torsades de pointes (with a risk of 2% in pts with sustained VF/VT). This risk is
increased in electrolyte imbalance.
May precipitate heart failure.
Other:bronchospasm, visual disturbances and sexual dysfunction.

Absorption

IV, PO BA 95%

Protein binding

Nil

Volume of distribution

1.2—2.4 L/kg

Metabolism

None

Excretion

urine unchanged

Half-life

12 hrs

Route And Dose

Doses 80-160mg PO or 50-100mg IV over 20mins