A patient with elevated lipid levels has a new prescription for niacin. The nurse informs the patient that which adverse effects may occur with this medication?

Choice A reason: Avoiding smoking is appropriate, as it can exacerbate asthma and reduce theophylline efficacy by inducing hepatic CYP450 enzymes, increasing drug clearance. This statement reflects correct understanding, as smoke exposure worsens airway inflammation, and theophylline’s narrow therapeutic index requires stable metabolism.

Choice B reason: Taking an extra dose of theophylline during an asthma attack is dangerous. Theophylline, a methylxanthine, is used for maintenance, not acute relief, due to its slow onset and narrow therapeutic index. Extra doses risk toxicity (e.g., seizures, arrhythmias), requiring immediate nurse intervention to correct this misconception.

Choice C reason: Doubling a missed theophylline dose is unsafe due to its narrow therapeutic index. Theophylline’s metabolism varies, and doubling doses can lead to toxic levels, causing nausea, tachycardia, or seizures. The nurse must intervene to educate the patient on adhering to the prescribed schedule without adjustments.

Choice D reason: Avoiding caffeine is correct, as it is a methylxanthine like theophylline, potentially increasing plasma levels and toxicity by competing for metabolism. Caffeine can exacerbate theophylline’s side effects like nervousness or tachycardia, so this statement reflects appropriate patient understanding and does not require intervention.

Choice E reason: Routine follow-up to monitor theophylline levels is appropriate due to its narrow therapeutic index (10-20 mcg/mL). Regular blood tests ensure therapeutic efficacy and prevent toxicity, as metabolism varies. This statement indicates correct understanding, supporting safe use without needing nurse intervention.

Choice A reason: Theophylline, a methylxanthine, causes palpitations by increasing cyclic AMP through phosphodiesterase inhibition, stimulating cardiac beta-1 receptors. This can lead to tachycardia or arrhythmias, especially at high levels. Monitoring heart rate is critical due to theophylline’s narrow therapeutic index and potential for cardiovascular toxicity.

Choice B reason: Diarrhea is not a primary adverse effect of theophylline. Gastrointestinal upset, like nausea or vomiting, may occur due to gastric irritation, but diarrhea is less common. Theophylline’s main toxicities involve the cardiovascular and nervous systems, making palpitations a more significant concern.

Choice C reason: Drowsiness is not associated with theophylline, which acts as a CNS stimulant, potentially causing nervousness or insomnia. Its phosphodiesterase inhibition increases cyclic AMP, enhancing alertness, not sedation. Drowsiness is more linked to antihistamines, making this incorrect for theophylline monitoring.

Choice D reason: Bradycardia is not a typical theophylline effect. Theophylline stimulates the heart via beta-1 receptor activation, causing tachycardia or palpitations. Bradycardia may occur with other drugs, like beta-blockers, but theophylline’s sympathomimetic effects make palpitations a more relevant adverse effect to monitor.