The inhalational bronchodilator with long duration of action is:: (A) Salbutamol, (B) Theophylline, (C) Ipratropium bromide, (D) Tiotropium bromide
Answer is D. Tiotropium bromide :
A newer congener of ipratropium bromide which binds very tightly to bronchial M1 / M3 muscarinic receptors producing long lasting bronchodilatation.
Reference: Essentials of Medical Pharmacology Eighth Edition KD TRIPATHI page no 128