Methylxanthines (Theophylline)

Respiratory

Mark this drug class

Examples

theophylline

Prefix / Suffix: No consistent suffix

Physiology

Bronchial smooth muscle tone affects airway diameter. Relaxation leads to bronchodilation.

Mechanism of Action

They inhibit phosphodiesterase, increasing cAMP, leading to bronchodilation.

Indications

Chronic asthma
COPD (less commonly used now)

Side Effects / Adverse Effects

Tachycardia (cardiac stimulation)
Insomnia (CNS stimulation)
Nausea and vomiting (early toxicity sign)
Seizures (high levels / toxicity)

Contraindications

Uncontrolled arrhythmias
Seizure disorders

Nursing Considerations

Narrow therapeutic range: 10–20 mcg/mL (levels above increase toxicity risk)
Monitor for early toxicity — nausea, vomiting, restlessness (early exam clue)
Avoid caffeine (increases CNS stimulation and toxicity risk)
Monitor heart rate (risk of tachycardia and arrhythmias)

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Disclaimer: PharmPal Nurse is for education only and is not medical advice. Do not use it to diagnose, treat, prescribe, or make patient-care decisions; always verify with current drug references, your instructor, facility policy, and a licensed provider. In emergencies, call local emergency services.