Potent and selective 5-HT2B receptor antagonist (pA2 = 7.95). Displays ≥ 135-fold selectivity over 5-HT2C (pKi = 5.82), 5-HT2A (pKi < 5.2), 5-HT1A, 1D, 1E, 5-HT3 and 5-HT4 receptors.