Intranasal Application of the α 2 -Adrenoceptor Agonist BHT-920 Produces Decongestion in the Cat

Abstract

The effect of α₂-selective adrenoreceptor activation on nasal cavity dimension in an experimental model of congestion has not been defined. Presently, we used acoustic rhinometry to evaluate the decongestant activity of BHT-920, a selective α₂-adrenergic agonist against nasal congestion produced by intranasal compound 48/80. Administration of the mast cell liberator compound 48/80 (1%) into a nasal passageway decreased ipsilateral volume and minimum cross-sectional area by 73 ± 4% and 42 ± 6%, respectively. The congestant effect of compound 48/80 was blocked by topical BHT-920 (0.3 and 1%) in a dose related manner. In addition, the decrease in minimum cross-sectional area produced by compound 48/80 was attenuated after topical BHT-920 treatment. As a comparison we also evaluated the topical decongestant activity effects of the α₁-adrenergic agonist phenylephrine, and the nonselective α-agonist oxymetazoline. Both phenylephrine (0.1–1.0%) and oxymetazoline (0.01–0.3%) produced decongestion. The blood pressure effects of these three drugs also were evaluated. At doses of 0.3 and 1.0%, BHT-920 did not produce hypertension. In contrast, oxymetazoline (0.01–0.1%) produced a transient hypertension that peaked at 15 minutes and fully recovered 45 minutes after administration. The hypertensive effect of phenylephrine at 0.3 and 1.0% lasted over 60 minutes. The present findings indicate that selective α₂-agonists may produce decongestant activity with an improved cardiovascular profile compared with current sympathomimetic drugs such as phenylephrine.