[Irritative activity of a new anti-inflammatory agent 4-(p-chorophenyl)-2-phenyl-5-thiazoleacetic acid (CH-800) on the gastrointestinal tract in rats (author's transl)].

A single oral administration of CH-800 induced a dose-dependent irritation of the stomach and intestine. As determined from the UD50 value (the dose inducing ulceration by 50%), the potency of gastric irritation was as follows; indomethacin greater than diclofenac Na greater than ibuprofen greater than aspirin greater than CH-800 greater than phenylbutazone. Repeated administrations of CH-800 for 5 days induced a gastric irritation when given in doses from 3 to 100 mg/kg, however, the response was not dose-related. In contrast, the irritation of intestinal mucosa seen with CH-800 administration was dose-related. The degree of gastric or intestinal irritation seen with dosing of other drugs was as follows; indomethacin greater than diclofenac Na greater than ibuprofen greater than aspirin greater than phenylbutazone or indomethacin greater than CH-800 = diclofenac Na greater than ibuprofen greater than phenylbutazone, respectively. CH-800 given for 5 days significantly delayed the healing of active ulcers and the healed ulcers showed a tendency toward re-ulceration. However, the irritating activity of phenylbutazone, diclofenac Na and ibuprofen was more potent than that of CH-800. Thus, CH-800 appears to have a rather weak irritative activity on the gastrointestinal tract of rats without ulceration, in contrast to other commonly clinically prescribed drugs.