Glycopyrrolate causes prolonged bronchoprotection and bronchodilatation in patients with asthma

Inhaled anticholinergic drugs are effective bronchodilators in the treatment of COPD, and tiotropium bromide has recently been introduced as a once-daily bronchodilator for use as a maintenance treatment. Racemic glycopyrrolate is an anticholinergic drug that has been used orally to control gastric acidity, parenterally as an antisialogogue and to reverse neuromuscular blockade, and has been studied by inhalation for asthma and COPD.

We investigated the duration of protection against the constrictor effects of inhaled methacholine of a single dose of inhaled nebulized racemic glycopyrrolate (0.5, 1.0, and 2.0 mg) compared with ipratropium bromide (0.5 mg) and placebo in 10 atopic asthmatic volunteers in a double-blind, five-way, crossover study.

Protection against methacholine-induced bronchospasm after administering glycopyrrolate was maintained to 30 h, the last time point measured. Both bronchodilatation and bronchoprotection were significantly longer with glycopyrrolate than after ipratropium bromide, and bronchoprotection was significant at all time points from 2 to 30 h compared to placebo. Dryness of the mouth and nose was described in 18% of patients after the highest dose of glycopyrrolate.

The prolonged bronchodilator response and the protection against methacholine-induced bronchospasm demonstrated in asthma suggests that inhaled racemic glycopyrrolate would be superior to ipratropium bromide for treatment of stable COPD.