Loxapine delivered as a thermally generated aerosol does not prolong QTc in a thorough QT/QTc study in healthy subjects

The objective of this study was to establish effects of inhaled loxapine on the QTc interval in this randomized, placebo‐controlled, double‐blind crossover study. Forty‐eight healthy volunteers received a single inhaled placebo or 10 mg loxapine. Plasma concentrations of loxapine increased with a median Tmax of 1 minute and a mean Cmax of 312 ng/mL. After an initial rapid distribution phase, plasma concentrations of loxapine declined with a terminal half‐life of 8 hours. Exposure to the active metabolite 7‐OH‐loxapine was 15% of the parent compound based on mean AUCinf and its terminal half‐life was 12 hours. Inhaled loxapine did not increase QT intervals, as demonstrated by the upper bound of the 1‐sided 95% CIs placed on the point estimate of the placebo‐subtracted change of QTcI (ΔΔQTcI) being less than 10 milliseconds at all 11 post‐dose times. The maximum ΔΔQTcI occurred at 1 hour post‐dose (LSmean 5.42 milliseconds, upper confidence bound 7.75 milliseconds). The study outcome was validated by the demonstrated assay sensitivity using the positive control moxifloxacin maximum ΔΔQTcI occurred at 3 hour post‐dose (LSmean 8.36 milliseconds, lower confidence bound 5.82 milliseconds). The analyses of QTc outliers, and the lack of emergent diagnostic findings for QTcI, QTcB, and QTcF; and simple mean placebo‐subtracted changes of QTcI and QTcF supported the primary QT analysis conclusion that this is a negative finding and there is no apparent QT prolongation associated with the therapeutic dose of inhaled loxapine.