Pulmonary pharmacology of DT-TX 30 SE, a potent selective combined thromboxane synthetase inhibitor and receptor antagonist, in guinea pigs.

A novel chemical compound, DT-TX 30 SE (E-6-(4-2-(4-chlorobenzenesulphonylamino)-ethyl)phenyl)-6-(3-pyrid yl)- hex-5-enoic acid), was studied in various models of guinea pig pulmonary function. The compound was a potent inhibitor (ED50 0.019 mg/kg, i.v.) of bronchospasm induced by the thromboxane receptor agonist U-46619, indicating thromboxane receptor antagonism. At even lower doses (ED50 0.0036 mg/kg, i.v.), it blocked arachidonic acid-induced bronchospasm. Interpretation of the latter results as evidence for additional thromboxane synthetase inhibitory activity was supported by the inhibition of arachidonic acid- or bradykinin-induced thromboxane B2 production in an isolated lung preparation, although prostaglandin E2 and prostaglandin 6-oxo-F(1 alpha) production measured at the same time were not inhibited. The potency of DT-TX 30 SE was compared with thromboxane receptor antagonists and synthetase inhibitors described in the literature. As a receptor antagonist, DT-TX 30 SE was significantly more potent than BM 13505 and BM 13177 (assessed by antagonism of U-46619-induced bronchospasm), but less potent than SQ 29548, while as a thromboxane synthetase inhibitor, it was significantly more potent than OKY 046 and UK 37248 as assessed by antagonism of arachidonic acid-induced bronchospasm or (OKY 046) inhibition of thromboxane production in isolated lung. The compound was active by the oral route as shown by its ability, at 10 mg/kg, p.o., to significantly reduce the immediate allergic response of sensitized guinea pigs to an ovalbumin aerosol.