Nurses Compass
Drug Guide
Theophylline
Classification
Therapeutic: Bronchodilator, Methylxanthine
Pharmacological: Adenosine receptor antagonist, Phosphodiesterase inhibitor
FDA Approved Indications
- Asthma
- Chronic obstructive pulmonary disease (COPD)
Mechanism of Action
Theophylline relaxes airway smooth muscle by inhibiting phosphodiesterase enzymes, leading to increased cAMP levels, resulting in bronchodilation and anti-inflammatory effects.
Dosage and Administration
Adult: Initial dose: 400-600 mg per day, divided into multiple doses; titrate based on response and serum levels.
Pediatric: Dose based on weight or body surface area, typically 6-12 mg/kg/day in divided doses.
Geriatric: Start at lower doses due to decreased clearance; monitor serum levels closely.
Renal Impairment: Reduce dosage; monitor serum levels.
Hepatic Impairment: Use with caution; reduced metabolism may increase levels.
Pharmacokinetics
Absorption: Well absorbed orally.
Distribution: Widely distributed, including across the placenta.
Metabolism: Hepatic metabolism via demethylation and conjugation.
Excretion: Renally excreted, primarily as metabolites.
Half Life: Typically 8-10 hours in adults; longer in elderly and those with hepatic or renal impairment.
Contraindications
- History of hypersensitivity to theophylline or methylxanthines.
- Peptic ulcer disease.
Precautions
- Cardiac arrhythmias, epilepsy, hepatic or renal impairment, congestive heart failure, pregnancy, lactation.
Adverse Reactions - Common
- Nausea, vomiting (Common)
- Insomnia, nervousness (Common)
- Gastrointestinal upset (Common)
Adverse Reactions - Serious
- Arrhythmias (Rare)
- Seizures (Rare)
Drug-Drug Interactions
- Increased toxic levels with cimetidine, erythromycin, fluoroquinolones.
- Decreased effectiveness with barbiturates, phenytoin.
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor respiratory status, serum theophylline levels, heart rate, and rhythm.
Diagnoses:
- Ineffective airway clearance
- Risk for toxicity.
Implementation: Administer with food if GI upset occurs; monitor serum levels regularly to keep within therapeutic range (10-20 mcg/mL).
Evaluation: Assess for relief of symptoms, monitor for adverse effects.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Avoid caffeine and other methylxanthines.
- Report signs of toxicity: nausea, vomiting, insomnia, palpitations, seizures.
Special Considerations
Black Box Warnings:
- Potential for severe cardiovascular and cerebrovascular events in certain populations.
Genetic Factors: Metabolism influenced by CYP1A2 polymorphisms.
Lab Test Interference: May cause interference with certain lab tests, including those measuring serum drug levels.
Overdose Management
Signs/Symptoms: Seizures, severe nausea, vomiting, tachycardia, hypotension, arrhythmias.
Treatment: Activated charcoal, gastric lavage, anticonvulsants for seizures, supportive care, magnesium sulfate in severe arrhythmias.
Storage and Handling
Storage: Store at room temperature away from light and moisture.
Stability: Stable under recommended conditions.