C. Studenik et al., Biological activities of novel thienothiazine derivatives on heart and smooth muscle preparations of guinea pigs, ARZNEI-FOR, 49(9), 1999, pp. 740-744
New thienothiazine derivatives which differ in their side chains on the nit
rogen atom of the thienothiazine ring were investigated regarding their bio
logical activity and compared with calcium antagonistic drugs. Isometric co
ntraction force was measured in guinea-pig papillary muscles, aortic strips
and terminal ilea. Chronotropic activity was studied in right atria guinea
pigs. MS 69 with a ethylpyridylcarbonyl side chain had the most potent neg
ative inotropic effect on isolated papillary muscles, followed by MS 74, wh
ich has an ethylmethylpiperazinylthiocarbonyl side chain. The negative inot
ropic effect could be antagonized by increasing the extracellular calcium c
oncentration. MS 87 with an ethylpyridylcarboxamide side chain had the most
potent relaxing effect on aortic strips and MS 48 with an ethylbenzylpiper
azinyl-carbonyl side chain was most potent on terminal ilea. Compounds with
a more hydrophilic side chain had less activity. It is concluded that incr
easing the lipophilicity by substitution of an oxygen atom by a sulfur atom
(MS 74) or addition of a pyridine ring (MS 69) results in a higher biologi
cal activity.