Quantitative analysis of T-wave morphology increases confidence in drug-induced cardiac repolarization abnormalities: evidence from the investigational IKr inhibitor Lu 35-138

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Claus Graff, Jørgen Matz, Ellen B Christensen, Mads P Andersen, Jørgen K Kanters, Egon Toft, Steen Pehrson, Thomas B Hardahl, Jimmi Nielsen, Johannes J Struijk

This study investigates repolarization changes induced by a new candidate drug to determine whether a composite electrocardiographic (ECG) measure of T-wave morphology could be used as a reliable marker to support the evidence of abnormal repolarization, which is indicated by QT interval prolongation. Seventy-nine healthy subjects were included in this parallel study. After a baseline day during which no drug was given, 40 subjects received an I(Kr)-blocking antipsychotic compound (Lu 35-138) on 7 consecutive days while 39 subjects received placebo. Resting ECGs were recorded and used to determine a combined measure of repolarization morphology (morphology combination score [MCS]), based on asymmetry, flatness, and notching. Replicate measurements were used to determine reliable change and study power for both measures. Lu 35-138 increased the QTc interval with corresponding changes in T-wave morphology as determined by MCS. For subjects taking Lu 35-138, T-wave morphology was a more reliable indicator of I(Kr) inhibition than QTcF (chi(2) = 20.3, P = .001). At 80% study power for identifying a 5-millisecond placebo-adjusted change from baseline for QTcF, the corresponding study power for MCS was 93%. As a covariate to the assessment of QT interval liability, MCS offered important additive information to the effect of Lu 35-138 on cardiac repolarization.
Original languageEnglish
JournalJournal of Clinical Pharmacology
Volume49
Issue number11
Pages (from-to)1331-42
Number of pages11
ISSN0091-2700
DOIs
Publication statusPublished - 2009

Bibliographical note

Keywords: Adolescent; Adult; Delayed Rectifier Potassium Channels; Dihydropyridines; Drug Evaluation, Preclinical; Electrocardiography; Female; Heart Conduction System; Humans; Indoles; Male; Middle Aged; Models, Cardiovascular

ID: 18763875