Selective 5-ht5a receptor antagonist (pKi values are 8.3, < 6.0, < 6.0, < 6.0, < 5.5 and < 5.5 for 5-ht5a, 5-HT1B/D, 5-HT2A, 5-HT2C, 5-HT1A and 5-HT7 receptors respectively).