The bronchodilatory and cardiovascular effects of inhaled naminterol, etanterol, and salbutamol in stable asthmatics

In this study we compared the effects of two new bronchodilators, naminterol and etanterol, with those of salbutamol at the same dosage (200 μg) delivered by metered aerosols. Ten stable asthmatics, aged 34 to 55, with reversible limitation of airflow entered the study. Vital capacity, forced expiratory volume in one second (FEV1), volume of thoracic gas, specific conductance of airways, cardiac rate, and arterial systolic and diastolic pressures were measured at baseline and 5, 15, 30, 60, 90, 120, 180, 240, and 360 minutes after inhalations of treatments on three study days in random order. All treatments caused sustained bronchodilation without any significant changes in the cardiovascular parameters. The peak percent changes from baseline values of FEV1 and specific airway conductance were recorded, respectively, 180 and 120 minutes after naminterol, 120 and 90 minutes after etanterol, and 90 and 60 minutes after salbutamol. The maximal decrease of respiratory trapped gas was observed 240 minutes after naminterol and 180 minutes after both salbutamol and etanterol. The effects of naminterol and salbutamol were similar but naminterol displayed a more prolonged effect. Etanterol showed an intermediate onset of action with a slighly smaller bronchodilating effect, which may be explained by the use of a less than equipotent dose and by the slightly better average baseline condition of the patients. The efficacy and selectivity of naminterol and etanterol suggest a possible role of these agents in the treatment of reversible airway obstruction.