Synthesis and pharmacological properties of benzothienothiadiazolopyrimidine derivatives. III

2-Substituted derivatives of 5H-benzothieno [3,2-d] [1,3,4]-thiadiazolo [3,2-a]pyrimidin-5-one and of 10H-benzothieno [2,3-d] [1,3,4]-thiadiazolo [3,2-a]pyrimidin-10-one have been synthesized. The analgesic, antiinflammatory and ulcerogenic activities of these derivatives were evaluated. Some derivatives showed an analgesic activity similar to or a little lower than that of indomethacin, and much higher than that of mefenamic acid, acetylsalicyclic acid and phenylbutazone, with a lower acute toxicity and a better gastric tolerance.