Concentration–effect modeling based on change from baseline to assess the prolonging effect of drugs on QTc together with an estimate of the circadian time course


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Abstract

As ICH E14 was adopted by the US FDA and the EU CPMC in 2005, thorough QT studies have routinely been analyzed by looking at the time-matched difference between (baseline corrected) QTcF or QTcI under the supra-therapeutic dose and placebo. A study is considered negative, if the two-sided 90% confidence interval for this difference is below 10 ms for all investigated time points. ICH E14 suggests including a positive control, such as moxifloxacin, for assay sensitivity. Concentration–response analysis has been considered a more powerful alternative, but its application to parallel group studies was hampered as a double difference of QTcF per subject cannot be calculated. Recently, a new model based on change from baseline with fixed time and concentration effects has been proposed. It allows for a placebo-corrected prediction of the drug effect with an unbiased standard error, and the estimate of a time effect can be used for assay sensitivity. We demonstrate this approach, utilizing 2 studies reported elsewhere with a crossover design. We compare the results from a conventional concentration–response analysis based on the difference to placebo with results from the novel analysis based on the change from average baseline that includes a fixed time effect.

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