The Analgesic Activity of 8-(Trifluoromethyl)-1,2,3,4,5-benzopentathiepine-6-amine and Its Hydrochloride

8-(Trifluoromethyl)-1,2,3,4,5-benzopentathiepine-6-amine 1a and its hydrochloride revealed significant analgesic activity in the acetic acid-induced writhing test, and ED50 of the compound 1a was 0.66 mg/kg. In the hot plate pain test, the reliable analgesic activity was found in hydrochloride 1a*HCl, whereas the free base 1a proved to be inactive. Based on the results of the naloxone test, the analgesic effect of the compound 1a*HCl in both tests is mediated with the opioidergic system. Both the free base 1a and its hydrochloride did not show the anti-inflammatory activity. Replacement of the CF3 group for the fluorine atom resulted in complete loss of analgesic activity in the acetic acidinduced writhing test.