A client taking extended-release theophylline develops new symptoms. Which cluster is most concerning for theophylline toxicity?
1Persistent vomiting, a rapid irregular heartbeat, agitation, and seizure activity✓ Correct answer
2Pinpoint pupils, slow respirations, constipation, and increasing somnolence
3Bradycardia, hypothermia, dry skin, and progressively slowed responses
4Facial swelling, stridor, urticaria, and sudden inspiratory wheezing
Explanation
Theophylline has a narrow therapeutic index. Persistent vomiting, tachycardia or cardiac arrhythmias, agitation, and seizures are concerning for toxicity and can be life-threatening. The nurse should hold further doses as directed, obtain urgent clinical evaluation, and anticipate a serum theophylline concentration and cardiac monitoring. The other clusters fit opioid toxicity, severe hypothyroidism, or anaphylaxis rather than theophylline toxicity.
Clinical reasoning Theophylline toxicity often begins with gastrointestinal and stimulant-like symptoms and can progress to dangerous tachyarrhythmias and intractable seizures.
Decision rule Persistent vomiting, rapid heartbeat, or neurologic excitation during theophylline therapy requires prompt serum-level and cardiac evaluation.
Scenario 65-year-old male on theophylline 300 mg PO BID for COPD × 1 year. Trough level today: 22 mcg/mL (therapeutic 10-20). Reports new nausea and tremor.
Narrow therapeutic index — A small separation between therapeutic and toxic exposure that makes serum levels, interactions, and clinical symptoms important for theophylline safety.
Theophylline toxicity — Excess theophylline exposure that can cause persistent vomiting, tachyarrhythmias, agitation, and potentially lethal seizures.
Methylxanthine — Drug class including theophylline, aminophylline, caffeine; phosphodiesterase inhibitor with bronchodilator effect.