Potential effects of the selective β(3)-adrenoceptor agonist mirabegron on cardiac repolarization were studied in healthy subjects. The four-arm, parallel, two-way crossover study was double-blind and placebo- and active (moxifloxacin)-controlled. After 2 baseline ECG days, subjects were randomized to one of eight treatment sequences (22 females and 22 males per sequence) of placebo crossed over with once-daily (10 days) 50, 100, or 200 mg mirabegron or a single 400-mg moxifloxacin dose on day 10. In each period, continuous ECGs were recorded at two baselines and on the last drug administration day. The lower one-sided 95% confidence interval for moxifloxacin effect on QTcI was >5 ms, demonstrating assay sensitivity. According to ICH E14 criteria, mirabegron did not cause QTcI prolongation at the 50-mg therapeutic and 100-mg supratherapeutic doses in either sex. Mirabegron prolonged QTcI interval at the 200-mg supratherapeutic dose (upper one-sided 95% CI >10 ms) in females, but not in males.

1. Nineteen healthy male volunteers participated in a double-blind, six-way, crossover study. With a separation of 1 week between sessions, volunteers received randomly one oral dose of each of the following compounds: 3 or 10 mg of the dopamine (DA2) receptor antagonist and serotonin (5HT1A) agonist DU 29894, 1 mg flesinoxan, 400 mg sulpiride, 3 mg haloperidol or placebo. 2. To assess the dopamine (DA2) antagonistic activity of the different compounds, plasma levels of prolactin were assessed at pre-dose, 0.5, 1, 2, 3, 4, 6 and 24 h post-dose. To assess the serotonin (5HT1A) agonistic activity, plasma levels of ACTH, cortisol and growth hormone were assessed at the same time-points as well as body temperature; the latter was also assessed 8 h post-dose. Plasma levels of DU 29894 were assessed at pre-dose and 2, 3, 4 and 24 h post-dose. 3. Sulpiride, haloperidol and both doses of 3 mg and 10 mg DU 29894 produced statistically significant increases in prolactin levels. The increase produced by 3 mg was roughly equivalent to that produced by 3 mg haloperidol whereas the increase produced by 10 mg DU 29894 was significantly larger. 4. Only 10 mg DU 29894 and 1 mg flesinoxan produced statistically significant increases in ACTH, cortisol and growth hormone. All compounds either showed a significant attenuation of the normal day time increase of body temperature (3 mg DU 29894, haloperidol and sulpiride) or a true significant decrease in body temperature (10 mg DU 29894 and flesinoxan).(ABSTRACT TRUNCATED AT 250 WORDS)

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