Theophylline Pediatric Dose — Asthma & Respiratory
Theophylline is a methylxanthine bronchodilator that acts primarily through phosphodiesterase inhibition, increasing intracellular cAMP to promote smooth muscle relaxation in the airways. It is used as an adjunct in the management of acute and chronic bronchospasm, including severe or refractory asthma in pediatric patients. Due to its narrow therapeutic index, careful dosing and serum level monitoring are essential in clinical practice.
Pediatric Dosing
Initiate therapy with an intravenous loading dose of 5 mg/kg IV administered over 30 minutes. Following the loading dose, begin a continuous IV infusion at a rate determined by the patient’s age:
- Less than 1 year: 0.6 mg/kg/hr
- 1–9 years: 1–1.2 mg/kg/hr
- 9–12 years: 0.9 mg/kg/hr
- Greater than 12 years: 0.7 mg/kg/hr
Worked example: For a 20 kg child aged 5 years — Loading dose: 20 × 5 mg/kg = 100 mg IV over 30 minutes. Maintenance infusion: 20 × 1–1.2 mg/kg/hr = 20–24 mg/hr as a continuous infusion. Consult institutional protocol for maximum dose limits and dose adjustments in the setting of hepatic impairment, cardiac failure, or concurrent medications that alter theophylline clearance.
Indications and Clinical Context
Theophylline is indicated as an adjunctive bronchodilator in pediatric patients with acute severe or refractory asthma, particularly when first-line therapies such as inhaled beta-agonists and systemic corticosteroids have provided insufficient response. It may also be used in the management of chronic obstructive pulmonary conditions and apnea of prematurity in select patients. While no longer a first-line agent per PALS or GINA guidelines, theophylline retains a role in resource-limited settings or in cases of refractory bronchospasm in the PICU.
Age-stratified maintenance dosing reflects the significant variation in theophylline clearance across pediatric age groups, with younger children (1–9 years) demonstrating higher metabolic rates and therefore requiring higher mg/kg/hr infusion rates compared to adolescents and infants.
Administration and Monitoring
The loading dose must be administered by slow IV infusion over a minimum of 30 minutes; rapid administration may precipitate arrhythmias, hypotension, or seizures. Theophylline should be delivered via a controlled infusion pump for both loading and maintenance phases. Target serum theophylline concentrations are generally 10–20 mcg/mL for bronchodilation; levels should be checked after steady state is achieved and with any dose adjustment.
- Route: Intravenous (IV) only for acute inpatient dosing as described
- Adverse effects to monitor: Tachycardia, nausea/vomiting, headache, tremor, seizures, and cardiac arrhythmias — particularly at supratherapeutic levels
- Key interactions: Clearance is significantly altered by macrolide antibiotics, fluoroquinolones, cimetidine, phenytoin, rifampin, and smoking status
- Contraindications: Known hypersensitivity to theophylline or xanthine derivatives; use with extreme caution in patients with seizure disorders or active cardiac arrhythmias
- Consult institutional protocol for adjustments in hepatic dysfunction, cor pulmonale, or congestive heart failure
Disclaimer: This article is an educational reference summarizing standard pediatric dosing values. It is not a substitute for clinical judgment. Always verify doses against institutional protocols, the current edition of authoritative references (e.g., Lexicomp, Harriet Lane Handbook, PALS guidelines), the patient’s accurate weight, and any patient-specific factors (renal/hepatic function, allergies, comedications) before administration.