Comparison of bronchodilator responses with bitolterol mesylate solution with the use of two different nebulizer systems in asthma.

Bitolterol mesylate is a beta 2-adrenergic bronchodilator that has been studied in a metered-dose inhaler formulation and as an aerosol in a closed, intermittent-flow nebulizer system. The optimum dose was found to be 1.0 mg in the closed system. In this dose-response study, 1.0 mg by closed-system nebulizer was compared with different doses delivered by an open, continuous-flow nebulizer system. Treatment with 2.5 mg of bitolterol mesylate in the open system is comparable to 1.0 mg in a closed system. Onset of bronchodilator activity occurred within 5 minutes for most patients, and median duration of action with different doses was 8 hours or longer. Mean maximum percent increases in FEV1 with 2.5, 3.5, and 4.5 mg of bitolterol mesylate with the open system were approximately 50% and comparable with that obtained with 1.0 mg with the closed system. Treatments with doses up to 3.5 mg in the open system were well tolerated with few side effects. We conclude that bitolterol mesylate is an effective, long-lasting bronchodilator when it is used as a nebulized aerosol by both open and closed delivery systems; a larger dose is optimal for the former system than for the latter. We believe that manufacturers' recommended doses should take into account the different efficiencies of open and closed nebulizer systems.