When reviewing the allergy history of a patient, the nurse notes that the patient is allergic to penicillin. Based on this finding, the nurse would question an order for which class of antibiotics?

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: The purpose of multiple drugs in tuberculosis treatment is not to hope one works but to ensure comprehensive bacterial eradication. Combination therapy targets different aspects of Mycobacterium tuberculosis, preventing resistance and ensuring efficacy, as single-drug therapy is ineffective and promotes resistant strains.

Choice B reason: Multiple drugs do not primarily reduce side effects; they increase the likelihood of adverse effects due to cumulative toxicity (e.g., hepatotoxicity from isoniazid and rifampin). The rationale for combination therapy is to enhance efficacy and prevent resistance, not to mitigate side effects, making this incorrect.

Choice C reason: Combination therapy (e.g., isoniazid, rifampin, ethambutol, pyrazinamide) enhances efficacy by targeting different bacterial populations and metabolic states of Mycobacterium tuberculosis. This synergistic approach ensures rapid bacterial killing, prevents resistance, and shortens treatment duration, making it the standard for effective tuberculosis management.

Choice D reason: The use of multiple drugs is not because drugs are becoming resistant but to prevent resistance development. Combination therapy overwhelms Mycobacterium tuberculosis with multiple mechanisms, reducing the chance of resistant mutants surviving. Resistance occurs with inadequate or monotherapy, not as a rationale for combination therapy.