Therapeutic monitoring of antiarrhythmic drugs

Antiarrhythmic drugs are potent agents which generally have narrow therapeutic indices. The consequences of administering either too little or too much can be life-threatening. Consequently, monitoring of plasma concentrations of these agents is an important part of rational antiarrhythmic therapy. In using therapeutic plasma concentration range guidelines, one must be conscious of the fact that the relationship between measured plasma concentration and therapeutic response is influenced by several factors. The influence of active metabolites and variability in the degree of plasma protein binding are two important factors. In treating arrhythmias, one must take into account the pharmacokinetics of the particular drug being used and the factors which modulate its plasma concentration-response relationship.