Comparison of the rapidity of action of dry-powder inhaler vs pressurized aerosol terbutaline

The speed of bronchodilatation with terbutaline administered through the Turbuhaler system and the same drug administered through a pressurized liquid aerosol device was compared in 9 patients with reversible air flow obstruction. On 2 consecutive days, terbutaline 0.5 mg in aerosol or dry-powder form (Turbuhaler) was administered after baseline spirometric measurements were taken. Spirometry was repeated at 15, 45 and 90 s and at 3, 5, 10, 15, 30, 60 and 120 min after administration of the drug. Both forms of presentation produced approximately 50% of their maximum effect within the first 45 s; 80% of the patients in the dry-powder group reached the mean of maximum FEV1 increase at 10 min, while 83% in the pressurized-aerosol-device group did so. The maximum increase was reached at 52 (54) min with the Turbuhaler and at 69 (50) min for the aerosol. The difference in speed of effect for the two pharmaceutical forms were not statistically significant. The administration of terbutaline in powder form (Turbuhaler) was as fast and effective in achieving bronchodilatation as was the aerosol form.