Automated patch clamp (APC) instruments enable efficient evaluation of electrophysiologic effects of drugs on human cardiac currents in heterologous expression systems. Differences in experimental protocols, instruments, and dissimilar site procedures affect the variability of IC₅₀ values characterizing drug block potency. This impacts the utility of APC platforms for assessing a drug’s cardiac safety margin. We determined variability of APC data from multiple sites that measured blocking potency of 12 blinded drugs (with different levels of proarrhythmic risk) against four human cardiac currents (hERG [I_Kr], hCav1.2 [L-Type I_Ca], peak hNav1.5, [Peak I_Na], late hNav1.5 [Late I_Na]) with recommended protocols (to minimize variance) using five APC platforms across 17 sites. IC₅₀ variability (25/75 percentiles) differed for drugs and currents (e.g., 10.4-fold for dofetilide block of hERG current and 4-fold for mexiletine block of hNav1.5 current). Within-platform variance predominated for 4 of 12 hERG blocking drugs and 4 of 6 hNav1.5 blocking drugs. hERG and hNav1.5 block. Bland-Altman plots depicted varying agreement across APC platforms. A follow-up survey suggested multiple sources of experimental variability that could be further minimized by stricter adherence to standard protocols. Adoption of best practices would ensure less variable APC datasets and improved safety margins and proarrhythmic risk assessments.

自动膜片钳（APC）仪器可在异源表达系统中有效评估药物对人心脏电流的电生理效应。实验方案，仪器和不同现场程序的差异会影响表征药物阻断效力的IC ₅₀值的差异。这影响了APC平台评估药物心脏安全裕度的实用性。我们确定了来自多个站点的APC数据的变异性，这些站点测量了12种盲药（具有不同程度的心律失常风险）对四种人类心脏电流（hERG [I _Kr ]，hCav1.2 [L-Type I _Ca ]，hNav1峰值）的阻断效力.5，[Peak I _Na ]，晚期hNav1.5 [Late I _Na]），并使用推荐的协议（以最大程度地减少差异）在17个站点使用五个APC平台。药物和电流的IC ₅₀变异性（25/75个百分位数）有所不同（例如，hERG电流的多普利特阻滞为10.4倍，hNav1.5电流的美西律阻滞为4倍）。平台内差异主要是12种hERG阻断药物中的4种和6种hNav1.5阻断药物中的4种。hERG和hNav1.5块。布兰德·奥尔特曼（Bland-Altman）的地块描绘了跨APC平台的不同协议。一项后续调查显示，实验变异性的多种来源可以通过更严格地遵守标准协议而进一步减少。采用最佳实践将确保APC数据集的可变性降低，并提高安全系数和心律失常风险评估。