A nurse is providing teaching to a client who has emphysema and a new prescription for Theophylline. Which of the following instructions should the nurse provide?

A. Avoid caffeine while taking this medication: Theophylline is a methylxanthine, similar in structure and effect to caffeine. Concurrent use can increase CNS stimulation and risk of side effects such as insomnia, tachycardia, and tremors. Avoiding caffeine helps prevent toxicity and unwanted stimulation. B. Crush your extended-release tablet and mix it with apple sauce for easier consumption: Extended-release formulations should never be crushed, as this can lead to rapid absorption and potentially toxic drug levels. Theophylline has a narrow therapeutic index, and proper dosing is critical. C. Take this medication as needed when you are not feeling well: Theophylline is a maintenance medication meant to be taken on a regular schedule. Taking it only as needed undermines its therapeutic effectiveness and can lead to inconsistent symptom control. D. Consume a high-protein diet: While diet can influence drug metabolism, there is no routine recommendation for a high-protein diet with Theophylline. In fact, sudden dietary changes can alter its metabolism, requiring careful monitoring of serum drug levels.