Which drug interaction can exacerbate the effects of theophylline?

Which drug interaction can exacerbate the effects of theophylline?

• A. Timolol
• B. Lisinopril
• C. Amlodipine
• D. Atorvastatin

Answer: (A)

Theophylline effects are intensified when another drug raises its levels or adds to its cardiac and CNS stimulatory actions, and it has a narrow therapeutic window. Timolol fits this pattern because, although used as an eye drop, it can be absorbed systemically and acts as a nonselective beta-blocker. When present with theophylline, timolol can magnify adverse cardiovascular and CNS effects, increasing risks such as tachycardia, arrhythmias, and seizures in susceptible individuals. The other drugs listed don’t have a meaningful, commonly recognized interaction with theophylline to worsen its effects, so timolol is the best answer.

Theophylline effects are intensified when another drug raises its levels or adds to its cardiac and CNS stimulatory actions, and it has a narrow therapeutic window. Timolol fits this pattern because, although used as an eye drop, it can be absorbed systemically and acts as a nonselective beta-blocker. When present with theophylline, timolol can magnify adverse cardiovascular and CNS effects, increasing risks such as tachycardia, arrhythmias, and seizures in susceptible individuals. The other drugs listed don’t have a meaningful, commonly recognized interaction with theophylline to worsen its effects, so timolol is the best answer.