Studies on the affinity and selectivity of tiquizium bromide (HSR-902), a novel spasmolytic agent, for muscarinic receptors

The affinity and selectivity of a novel spasmolytic agent, tiquizium bromide (HSR-902), for muscarinic receptors were studied by the radioligand binding technique using 3H-quinuclidinyl benzilate. The parameters (Ki, nH) of HSR-902 obtained from competition experiments in cerebral cortex and heart muscarinic receptors showed that HSR-902 was an atropine-type, nonselective muscarinic antagonist. The affinity of HSR-902 toward the stomach and ileal muscarinic receptors was about 3-4 times more potent than atropine.