Key result
Propafenone and diprafenone (S)-enantiomers yield ~50-fold higher beta-blockade than (R)-enantiomers with equal antiarrhythmic effect.
Why the study?
The stereoselective beta-adrenoceptor blocking and antiarrhythmic effects of propafenone and diprafenone enantiomers in guinea-pig heart were not fully characterized.
Does the stereoisomerism of propafenone and diprafenone affect their beta-blocking and antiarrhythmic properties in guinea-pig hearts?
Does the stereoisomerism of propafenone and diprafenone affect their beta-blocking and antiarrhythmic properties in guinea-pig hearts?
The (S)-enantiomers of propafenone and diprafenone are responsible for the beta-adrenoceptor blocking effects of the racemic drugs, while both enantiomers exert comparable antiarrhythmic activity.
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Animal data link (S)-enantiomers to beta-blockade; leaves open human translation for stereoselective antiarrhythmics.
Groschner et al. (1991) studied this question. Enantiomers of propafenone and diprafenone vs. Racemic mixtures and corresponding enantiomers was evaluated on beta-adrenoceptor affinity and functional refractory period prolongation. The (S)-enantiomers of propafenone and diprafenone block cardiac beta-adrenoceptors with 40-60 fold higher affinity than (R)-enantiomers, while both exert comparable antiarrhythmic activity.
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