Quisultazine is a phenothiazine derivative patented by MARPHA Societe d'Etude et d'Exploitation de Marques as pentagastrin antagonist. In preclinical studies, Quisultazine weakly inhibited pentagastrin-stimulated gastric secretion but was a powerful inhibitor of nocturnal gastric secretion. Quisultazine possesses a very weak affinity to muscarinic receptors in vitro and in vivo. It has negligible anticholinergic properties in rats and mice at the peripheral level but no effect at the central level.