Serotonin (5-HT2) receptor antagonist; also exhibits affinity for 5-HT1-receptors. Prepn: NL 6608618; M. Protiva et al., US 3379729 (1966, 1968 both to SPOFA); and pharmacology: K. Pelz et al., Collect. Czech. Chem. Commun. 33, 1895 (1968); J. O. Jilek et al., ibid. 39, 3338 (1974). Receptor-blocking study: M.-A. Monachon et al., Arch. Pharmacol. 274, 192 (1972). Use in classification of 5-HT receptors: P. B. Bradley et al., Neuropharmacology 25, 563 (1986); E. J. Mylecharane, Clin. Exp. Pharmacol. Physiol. 16, 517 (1989).