[Strict additivity of the antispasmodic effects of papaverine and tiemonium: an example of sequential blockage]

The interaction of papaverine and tiemonium alone or combined, with BaCL2 and histamine on guinea pig ileum and with acetylcholine on rat jejunum have been studied with the help of molecular pharmacology techniques. The competitive antagonist effects of tiemonium and the non competitive antagonist effects of papaverine are evidenced and shown to be strictly additive when the two drugs are combined. This reflects a sequential blockage of the effects of acetylcholine, histamine and barium ions at the smooth muscle level. No such antagonism has been previously described in the case of the interaction with barium chloride with any other combination of two spasmolytic drugs.