Therapeutic equivalence of three metered-dose inhalers containing salbutamol (Albuterol) in protecting against methacholine-induced bronchoconstriction in children with asthma

Many pharmaceutical companies sell salbutamol in metered-dose inhalers (MDI ) for the treatment of asthma. However, the therapeutic equivalence of the more recently released generic products has not been compared with the orig inal patented product in children. Twenty children with mild to moderate as thma, presently asymptomatic and with normal lung function, were randomly a llocated to receive 200 mug of inhaled salbutamol (Albuterol) from three MD Is prepared by different manufacturers: the original Glaxo product and two generic products. The three drug formulations and placebo were given 10 min before a methacholine challenge test to determine the degree of protection provided against methacholine-induced bronchoconstriction (MIB) by each sa lbutamol aerosol. Tests were performed on 4 consecutive days. Doubling conc entrations of methacholine were inhaled until the forced expired volume in 1 sec (FEV1) decreased by 20% from its baseline value. Compared to placebo, all patients increased significantly the provocation c oncentration that decreased FEV1 by 20% (PC20) by more than one doubling co ncentration after inhaling each of the three salbutamol aerosols. The effec tiveness was not significantly different between medications (P=0.8). There was a small but significant difference among MDIs in aerosol particle size and total and fine-particle dose released per actuation. However, no relat ion was found between aerosol particle size or released dose and the protec tive effect. This study shows that the three tested brands of salbutamol MDI protected a sthmatic children equally from MIB. When prescribing these salbutamol MDIs to prevent symptoms triggered by nonspecific stimuli in asthmatic children, the selection may be based on cost-benefit criteria. (C) 2001 Wiley-Liss, Inc.