Ten new 7-(-furoyl)-2-morpholino[1,3]thiazolo[4,5-d]pyridazine-4(5H)-on derivatives were screened on rat isolated aortic rings and strips of urinary bladder. Test compounds were less potent than drotaverine on the isolated urinary bladder. The compounds IFT 114, IFT 115 and IFT 120 showed significant vasodilatation activity on the phenylephrine precontracted isolated vessels and are promising for further investigations.
