PRECLINICAL ELECTROPHYSIOLOGY ASSAYS OF MITEMCINAL (GM-611), A NOVEL PROKINETIC AGENT DERIVED FROM ERYTHROMYCIN

Motilides: a long and winding road: lessons from mitemcinal (GM-611) on diabetic gastroparesis

Mitemcinal (GM-611) is a macrolide motilin receptor agonist with acid-resistance and without antibiotic activity. Since ABT-229 (a first generation of motilin receptor agonist) had failed to demonstrate symptomatic relief in functional dyspepsia and diabetic gastroparesis, there is a controversy for which of prokinetics or relaxants is clinically beneficial. Currently, oral mitemcinal has been focused on diabetic gastroparesis under clinical development. It showed to accelerate gastric-emptying in diabetic animals and in patients with gastroparesis. The latest double-blind, placebo-controlled study demonstrated to be effective at improving diabetes-related gastroparesis symptoms. A sub-group analysis, which included patients with BMI < 35 kg/m2 and hemoglobin A1c < 10%, there were significantly more symptomatic relieves in the 10 mg mitemcinal group than in the placebo group. The frequency of adverse events did not differ between groups. Mitemcinal shows promise in the subset of patients who should be confirmed in future studies.

Literature-based evaluation of four 'hard endpoint' models for assessing drug-induced torsades de pointes liability

In safety pharmacology, a number of preclinical models for detecting drug-induced proarrhythmia liability have been recently introduced that utilize hard endpoints: early after depolarziations (EADs), torsades de pointes (TdP) or both as the principal biomarker. To explore the validity of four of the most common of these models, (the isolated canine/rabbit left ventricular wedge preparation, the isolated rabbit heart, the methoxamine-pretreated anaesthetized rabbit and the complete, chronic AV-blocked (CAVB) dog (conscious and anaesthetized), the present article reviews published data sets for three drugs with recognized and different human TdP liabilities (cisparide, terfenadine and moxifloxacinin). Finally, this review considers the value of inclusion of analysis of beat-to-beat variability of repolarization (BVR) in TdP liability testing to improve sensitivity and specificity.

HEMODYNAMIC AND ELECTROPHYSIOLOGICAL EFFECTS OF MITEMCINAL (GM-611), A NOVEL PROKINETIC AGENT DERIVED FROM ERYTHROMYCIN IN A HALOTHANE-ANESTHETIZED CANINE MODEL

Mitemcinal (GM-611) is a novel erythromycin-derived prokinetic agent that acts as an agonist at the motilin receptor. We investigated the QT-prolonging effects of mitemcinal using a halothane-anesthetized canine model. Intravenous administration of mitemcinal at doses of more than 8.3 mg/kg per 10 min significantly prolonged the QT interval corrected by Fridericia's corrections. Mitemcinal exhibited a bradycardiac effect and produced significantly greater prolongation in monophasic action potential duration (MAP(90)) at sinus rhythm compared with MAP(90) at pacing and showed reverse use-dependent prolongation of repolarization, suggesting that the negative chronotropic effect of mitemcinal potentiates the prolongation of the repolarization period. A technique using MAP/pacing electrodes allowed measurements of both MAP(90) and effective refractory period (ERP) simultaneously at the same ventricular site. Although mitemcinal slightly prolonged the MAP(90(CL400)) and ERP in comparison with the control group at the dose of 25 mg/kg per 10 min, the terminal repolarization period, the difference between MAP(90(CL400)) and ERP, did not increase suggesting the absence of a proarrhythmic effect even with a 7000-fold for the therapeutic blood concentration as free level. The electrophysiological results from mitemcinal in this study indicate that the risk of serious arrhythmia such as torsades de pointes, a major clinical concern related to QT interval prolongation, might be low.