The effects of formoterol, a long-acting beta 2-adrenoceptor agonist, on mucociliary activity

The effect on mucociliary function of formoterol, a beta 2-adrenoceptor agonist bronchodilator with a prolonged duration of action (as compared with salbutamol or terbutaline), was investigated both in vitro and in vivo with a photoelectric technique. Formoterol, and its (R,R)-enantiomer, increased ciliary beat frequency in vitro in guinea pig trachea preparations (peak increase 17.2 +/- 2.0% at a concentration of 10(-7) M) and in vivo in the rabbit maxillary sinus (peak increase 23.0 +/- 4.0% at a dosage of 1 nmol/kg). Formoterol was approximately 100 times more potent than terbutaline in vitro, as judged from the dose-response curve. The main difference between their effect in vivo was the 2-fold longer duration of the mucociliary acceleration after formoterol at 1 nmol/kg than after terbutaline at the equi-effective dosage of 10 nmol/kg terbutaline (20 vs. 10 min, respectively). The findings indicate formoterol to be a powerful, long-acting ciliostimulant, a property which may be of clinical advantage in the treatment of airway disease.