The mode of action of tiaramide hydrochloride: A new antiasthmatic drug

Tiaramide hydrochloride (THC), a benzothiazolinone derivative, displays a direct bronchodilating activity associated with anti-anaphylactic properties. The smooth muscle relaxing capacity of this compound is not related to increased levels of cyclic AMP. The anti-anaphylactic activity has been investigated using isolated lungs from ovoalbumin sensitized guinea-pigs. THC prevents histamine and TXA 2 release from lungs during antigen exposure. In addition to this THC antagonizes the direct effect of histamine on TXA 2 generation in guinea-pig lungs without affecting the cyclo-oxygenase system. Our results indicate that THC can control the anphylactic reaction through at least two different mechanisms: 1) inhibition of mediator release, 2) direct antagonism of their spasmogenic activity.