This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Pharmacology
Which of the following drugs CANNOT be administered by inhalation? 
Select and explain. 
A. Theophylline, B. Ipratropium bromide, C. Budesonide, D. Terbutaline
A: Theophylline
Answer: A: Theophylline 
Explanation: (Ref: KDT 6/e p220) b2 agonists like salbutamol and terbutaline can be administered by inhalational route. Ipratropium and tiotropium are inhalational anticholinergic agents. Inhalational steroids include budesonide, fluticasone, beclomethasone and flunisolide. Theophylline is given by oral route and is not used by inhalational route.