Ipratropium Bromide onset of action is typically:

• A. 15-20 mins
• B. 1-3 mins
• C. 30-60 mins
• D. 2-5 hours

Answer: (B)

Onset of action for inhaled ipratropium bromide reflects its anticholinergic mechanism, which takes time to reduce vagally mediated bronchoconstriction. In practice, inhaled ipratropium typically produces noticeable bronchodilation within about 15 minutes, with peak effect around 1–2 hours and several hours of duration. This slower onset contrasts with fast-acting beta-agonists like albuterol, which act within minutes. Since ipratropium’s effect develops more gradually, a 1–3 minute onset would be unusually rapid for this drug.