Effects of a cyclo-oxygenase inhibitor, flurbiprofen, and an Hi histamine receptor antagonist, terfenadine, alone and in combination on allergen induced immediate bronchoconstriction in man

Abstract

The effect of flurbiprofen, a potent cyclo-oxygenase inhibitor, on histamine and methacholine reactivity was assessed in seven atopic subjects with asthma. Flurbiprofen 150 mg daily for three days displaced the histamine-FEV1, concentration-response curve to the right by 1.5 doubling doses, whereas no effect was observed on the response to methacholine. Subsequently the effects of flurbiprofen and terfenadine, a specific H, histamine receptor antagonist, on allergen induced bronchoconstriction were studied in seven atopic but non-asthmatic subjects. The subjects inhaled the concentration of grass pollen allergen that had previously been shown to produce a 20% fall in FEV1, on separate occasions after prior treatment with placebo, flurbiprofen 150 mg daily for three days, terfenadine 180 mg three hours before challenge, and the combination of flurbiprofen and terfenadine. After placebo, allergen challenge caused a mean (SEM) maximum fall in FEV 1, of 37-6% (2 6%) after 20 (3 7) minutes, followed by a gradual recovery to within 1 5% of baseline at 60 minutes. Terfenadine reduced the maximum allergen provoked fall in FEV1, to 21-5% (2-2%) and reduced the area under the time-response curve (AUC) by 50% (6%). Flurbiprofen alone reduced the mean maximum fall in FEV1, to 29-6% (3-2%) and reduced the AUC by 26%. The effect of the combination of flurbiprofen and terfenadine did not differ significantly from that of terfenadine alone. We conclude that histamine and prostaglandins contribute to immediate allergen induced bronchoconstriction and that a complex interaction occurs between the two classes of mediators.