Screening pharmacological studies of four dihydroisoquinoline derivatives.

Screening studies are carried out of the pharmacological activity of 3,4-dihydropapaverine (DHP) and three of its newly-synthesized derivatives: 6'-iodo-DHP, 6'-bromo-DHP and 6'-iodu-DHP methiodide. All compounds studied manifest central depressive action which is manifested in general depression, potentiation of hexobarbital anaesthesia, without inducing sleep when independently applied, as well as inhibition of the spontaneous and amphetamine-induced motor activity of mice. 6'-Iodo-DHP and its methiodide manifest analgesic effect. All four compounds studied reduce the blood pressure of urethane-anaesthesized cats, but they do not change the noradrenaline and the acetylcholine effects. The hypotensive effect of the compounds is preserved even after atropinization of the cats. The compounds studied manifest no antitussive effect. DHP-derivatives eliminate the spasms in guinea-pig colon, induced by BaCl2 and nicotine, while DHP has no effect on them. 6'-Iodo-DHP methoiodide inhibits the hypertensive nicotine effect on cats. DHP and 6'-iodo-DHP methoiodide manifest vasoconstricting action upon perfusion of the blood vessels of isolated rat hind legs.