Comparison of terbutaline and placebo from a pressurised metered dose inhaler and a dry powder inhaler in a subgroup of patients with asthma Mjolbolsta Hospital, SF-10350 Mjolbolsta, Finland

Abstract

Background - Reversibility after administration of an inhaled bronchodilator is not always demonstrable in patients with asthma. Bronchodilator aerosol-induced bronchoconstriction has also been reported to occur in some patients. Methods - Fifteen selected patients showing <10% improvement in forced expiratory volume in one second (FEV,) when tested with four doses of salbutamol (0.1 mg/dose) orterbutaline (0.25 mg/dose) from a pressurised metered dose inhaler (MDI) participated in two randomised, double blind studies. They received 2-0 mg terbutaline (4 x 2 doses of 0 25 mg) or a corresponding placebo from an MDI connected to a 750 ml spacer, and 10 mg (2xO 5mg) terbutaline or placebo from a multidose dry powder inhaler free of additives (Turbohaler). Results - Inhalation of placebo MDI resulted in a mean (SD) decrease in FEV, of 20 5 (14.1)% (range -42-9% to + 2-6%). In 14 patients inhalation of 2-0 mg terbutaline MDI with spacer resulted in <10% improvement (mean increase 3-1 (6.0)%). One mg of terbutaline via a Turbohaler resulted in improvements in FEV, of>15% in eight patients (mean increase 16-0 (9.7)%). The improvement was <10% in four patients. Use of placebo Turbohaler did not affect airway calibre (mean change 0-2 (2-9)%). Conclusions - Additives of MDIs may cause bronchoconstriction in some patients with asthma. In these patients inhalation from a pressurised metered dose inhaler is more likely to decrease the bronchodilator response than inhalation from an additive-free inhaler. The frequency of this phenomenon is unknown.