Effect of terfenadine on pulmonary function, histamine release, and bronchial challenges with nebulized water and cold-air hyperventilation.

To assess the effectiveness of terfenadine on bronchoconstriction in asthmatics, 12 asthmatic patients between the ages of 19 and 43 were challenged with ultrasonically nebulized distilled water (UNDW) and treated with terfenadine, 120 or 240 mg, or placebo in a three-way crossover double-blind study. A similar study of 12 asthmatics (nine from the UNDW trial) was performed using cold-air hyperventilation challenge (CAHC). In vitro analyses were also made of samples from ten mild asthmatics to determine the effect of terfenadine on basophil histamine release. Terfenadine, 240 mg, showed significant (P = .012) benefit over placebo in improving pulmonary function after UNDW challenge. Modest but significant (P less than .05) bronchodilator benefits were also demonstrated by terfenadine, 240 and 120 mg, after CAHC. Finally, the in vitro study showed significant inhibition by terfenadine of anti-IgE-induced histamine release from human basophils.