Antiarrhythmic drugs specific agents

PVC s alone with Class IC drugs was not sufficient to reduce mortality in the specific post-infarction population chosen for the CAST study. The failure of Class IC agents in the CAST study and their low efficacy in preventing induction of SVT during electrophysiological testing has increased the interest in alternative approaches to antiarrhythmic therapy, particularly towards Class III agents, a number of which are in Phase II clinical evaluation. 

As our data show, the activity seems to be of a very broad range and is not specific for one organism, which would be a desirable trait if we think of exploiting natural products as plant-protection substances or therapeutic agents. It should be recalled that QA are useful in medicine as antiarrhythmic and obstetric drugs ( ). These observations also hold true for most other natural products. We would stress that natural products form a preselected reservoir of bioactive compounds, useful for further chemical manipulation. 

Type III antiarrhythmics include agents that specifically prolong refractoriness in atrial and ventricular tissue. This class includes very different drugs bretylium, amiodarone, sotalol, ibutilide, and recently, dofetilide they share the common effect of delaying repolarization by blocking potassium channels. The electrophysiologic actions of bretylium are related to its multifaceted pharmacology. 

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