Winkle R A, Peters F, Kates R E, Harrison D C
Am J Cardiol. 1983 Apr;51(7):1182-8. doi: 10.1016/0002-9149(83)90366-1.
To establish long-term efficacy and the relation between drug plasma concentration and antiarrhythmic response, 12 patients with encainide-responsive frequent complex ventricular ectopic activity underwent 1 year of therapy with encainide. Twenty-four hour ambulatory electrocardiograms were obtained at baseline and every 2 months. Drug withdrawal with concomitant plasma sampling and electrocardiographic monitoring was performed at 6 and 12 months. Average group premature ventricular contraction (PVC) suppression during the year was 97 to 99%, with nearly total suppression of pairs and salvos. The most common adverse effects were transient visual disturbances and dizziness or lightheadedness. During a dose interval (6 to 12 hours) the concentration of encainide metabolites exceeded that of encainide by several-fold. The median time of arrhythmia return after drug withdrawal was 12 to 14 hours. At the time of arrhythmia return encainide was generally no longer detectable but the average concentration of O-demethylencainide and 3 methoxy-O-demethylencainide was 72 +/- 49 and 172 +/- 74 ng/ml, respectively. It is concluded that encainide therapy is extremely effective for continuous long-term suppression of complex ventricular arrhythmias and its metabolites contribute significantly to its antiarrhythmic action during chronic oral therapy.
为确定恩卡胺的长期疗效以及药物血浆浓度与抗心律失常反应之间的关系，12例对恩卡胺有反应的频发复杂性室性异位活动患者接受了为期1年的恩卡胺治疗。在基线时以及每2个月获取24小时动态心电图。在6个月和12个月时进行撤药，并同时采集血浆样本和进行心电图监测。该组患者在这一年中室性早搏（PVC）的平均抑制率为97%至99%，成对和连发早搏几乎完全被抑制。最常见的不良反应是短暂性视觉障碍和头晕或眩晕。在一个给药间隔（6至12小时）内，恩卡胺代谢物的浓度超过恩卡胺数倍。撤药后心律失常复发的中位时间为12至14小时。在心律失常复发时，通常已检测不到恩卡胺，但O - 去甲基恩卡胺和3 - 甲氧基 - O - 去甲基恩卡胺的平均浓度分别为72±49和172±74 ng/ml。结论是，恩卡胺治疗对于持续长期抑制复杂性室性心律失常极为有效，并且其代谢物在慢性口服治疗期间对其抗心律失常作用有显著贡献。
