Which statement about theophylline monitoring is least accurate?

• A. It requires monitoring to avoid toxicity.
• B. Levels are measured to ensure efficacy.
• C. It interacts with caffeine.
• D. It does not require any monitoring.

Answer: (D)

The key idea is that theophylline has a narrow therapeutic window and markedly variable metabolism between individuals, so monitoring is essential to balance efficacy with safety. Therapeutic levels are kept within a range where the drug works without causing toxicity; if levels are too low, the drug may be ineffective, while if they are too high, toxicity can occur (nausea, vomiting, tachycardia, arrhythmias, seizures). Because factors such as age, liver function, smoking, and drug interactions can change how quickly theophylline is cleared, levels are checked after starting therapy, after dose changes, or when interacting drugs are added. Caffeine, another methylxanthine, can amplify stimulant effects and adverse effects, and it shares metabolic pathways, so co-consumption can influence safety and necessitate monitoring. Therefore, saying no monitoring is required is not accurate.