Bitolterol mesylate (WIN 32784) aerosol. A new long-acting bronchodilator with reduced chronotropic effects.

Bitolterol mesylate (WIN 37284) is alpha-[tert-butylaminomethyl]-3,4-dihydroxybenzyl alcohol 3,4-di(p-toluate) methanesulfonate, a diester sympathomimetic amine bronchodilator. Bitolterol mesylate represents a new concept in sympathomimetic amine therapy. It is "prodrug" which is inactive until altered in the body. The intact 3,4-diester molecule is metabolized by esterase hydrolysis to release the active catecholamine, N-t-butylarterenol. Because the level of esterase is greater in the pulmonary tissue than in the heart, bitolterol mesylate aerosol was shown to be an effective bronchodilator drug, without any significant cardic side effects. The onset of action was rapid and lasted more than six hours. The improvement over baseline values in the forced expiratory volume in the first second and the mean forced expiratory flow during the middle half of the forced vital capacity was greater than 15 percent and 30 percent, respectively.