Cardiac drug overdose

Toxicity from cardiac drugs is a particular management challenge since the manifestations of an acute overdose and the initial indications for the drug are often similar. Plasma drug levels are essential but must be interpreted in light of the clinical picture. Hypotension, due to either vasodilatation or decreased myocardial contractility, and arrhythmias are the principal cardiac manifestations, but noncardiac effects are sometimes more troublesome. An antiarrhythmic agent of the same class should not be used in treating an arrhythmia resulting from an overdose.