Are current pediatric dose recommendations for intravenous theophylline appropriate?

Area of Science:

• Pharmacology
• Pediatric Pulmonology
• Infectious Diseases

Background:

• Theophylline is a primary asthma medication with a narrow therapeutic index.
• Theophylline toxicity is a concern, particularly in children with concurrent upper respiratory tract infections (URTI).
• The exact mechanism inhibiting theophylline clearance during URTI (viral effect vs. fever) remains debated.

Purpose of the Study:

• To assess the appropriateness of current theophylline dosing recommendations for pediatric asthma patients with URTI.
• To determine whether viral infection or fever is responsible for reduced theophylline clearance.
• To propose dose adjustments to mitigate toxicity risk.

Main Methods:

• Retrospective review of 2254 medical records of asthmatic children (1987-1990).
• Calculation of theophylline clearance rate based on infused dose and steady-state concentrations.
• Modeling of serum concentrations using standard dosing recommendations for children with URTI.

Main Results:

• Reduced theophylline clearance was significantly associated with URTI (p=0.029), but not fever.
• Age was also a significant factor correlating with theophylline clearance (p=0.027).
• Two-thirds of children with URTI would exceed 15 mg/L, and one-third would exceed 20 mg/L with standard doses.

Conclusions:

• Current theophylline dosing guidelines are inadequate for pediatric asthma patients experiencing URTI.
• A 60% dose reduction is recommended during URTI to prevent supratherapeutic serum concentrations.
• Implementing dose correction factors can significantly lower the risk of theophylline toxicity in this population.