Effects of thiazinamium chloride on human isolated bronchial muscle preparations

In human bronchial muscle preparations contracted with histamine, the rank order potency for the relaxant effect of various antagonists was: thiazinamium chloride less than tripelennamine less than atropine (pD2 values: 7.78, 6.16 and greater than 4 for each antagonist, respectively). These antagonists also relaxed human isolated bronchial muscle preparations contracted with acetylcholine. The rank order potency was: atropine less than thiazinamium chloride less than tripelennamine (pD2 values: 7.76, 6.94 and 4.05, respectively). Tripelennamine and thiazinamium chloride displaced histamine concentration-effect curves and atropine and thiazinamium chloride antagonized acetylcholine curves in human isolated bronchial muscle preparations. These results suggest that thiazinamium chloride may have important therapeutic value in airways disease since this drug not only relaxed human isolated airway muscle preparations but also antagonized contractile responses in these tissues to both histamine and acetylcholine.