Effects of injectable HPβCD-diclofenac on the human delayed rectifier potassium channel current in vitro and on proarrhythmic QTc in vivo.

Novel formulations and administration routes of established drugs may result in higher maximum concentrations or total exposures and potentially cause previously unrecognized adverse events.This study evaluated the proarrhythmic potential of hydroxypropyl-β-cyclodextrin (HPβCD)-diclofenac, a novel injectable diclofenac formulation solubilized with hydroxypropyl-β-cyclodextrin (HPβCD), on ventricular electrical conduction in preclinical and clinical models.We assessed the effects of diclofenac, HPβCD, and HPβCD-diclofenac on the human delayed rectifier potassium channel (IKr) using human embryonic kidney (HEK) 293 cells transfected with a human ether-à-go-go-related gene (hERG) using whole-cell patch-clamp. In a single-dose, active- and placebo-controlled, 4-period crossover, thorough QT in vivo study, 70 healthy volunteers (mean age, 23.3 years; range, 18-49 years; 55.75% male) received HPβCD-diclofenac at 37.5- and 75-mg doses, inactive vehicle (placebo), and an active control (moxifloxacin).In vitro, diclofenac produced no statistically significant effect on IKr. Significant, non-dose-dependent effects were observed in the presence of HPβCD or HPβCD-diclofenac of similar magnitude across the 300-fold dose range of concentrations tested, suggesting an artifact due to the detergent effect of HPβCD in this in vitro model. In vivo, neither HPβCD-diclofenac dose resulted in QTc prolongation ≥2 ms (≥5 ms is the threshold of clinical concern). No correlation was evident between changes in QTc and plasma concentrations of diclofenac or HPβCD. Confirming study sensitivity, moxifloxacin produced a mean QTc prolongation >10 ms.The findings from the present study suggest that HPβCD-diclofenac does not have a dose-dependent effect in the in vitro hERG assay system and does not produce proarrhythmic QTc prolongation in vivo. ClinicalTrials.gov identifier: NCT01812538.