Why the study?
Does propafenone exhibit beta-blocking and calcium antagonist properties in addition to class 1c antiarrhythmic action in rabbit cardiac tissues?
Does propafenone exhibit beta-blocking and calcium antagonist properties in addition to class 1c antiarrhythmic action in rabbit cardiac tissues?
In rabbit cardiac tissues, propafenone acts primarily as a class 1c antiarrhythmic but also possesses clinically significant beta-blocking activity and prolongs action potential duration.
Hypothesis-generating for propafenone's multi-class effects in rabbits; leaves open human translation before any practice implications.
Previous studies of widely different concentrations of propafenone in various species have reported that in addition to having class 1 antiarrhythmic action, the drug was a beta adrenoceptor blocker and a calcium antagonist. High concentration shortened action potential duration in animal experiments, but Q-T interval was reported as being lengthened in man. It was thought desirable to study the effects of propafenone over a range of concentrations equivalent to those used clinically in various cardiac tissues of a single species, the rabbit. It was concluded that although the primary action of propafenone was on fast inward current, the drug being categorised as of group 1c, its potency as a beta blocker was sufficient for the effect to be of clinical significance. Its potency as a calcium antagonist was relatively weak. Action potential duration and effective refractory period were lengthened in both atrium and ventricle, the effects being long-lasting and persisting on wash-out of the drug when other measurements had returned to control values.
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Dukes et al. (1984) studied this question.
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