Acute and chronic theophylline therapy in exercise-induced bronchospasm

Area of Science:

• Pediatric Pulmonology
• Pharmacology
• Asthma Research

Background:

• Exercise-induced bronchospasm (EIB) is a common condition in children with asthma.
• Theophylline is a bronchodilator used to manage asthma symptoms.
• The effectiveness and tolerance of theophylline for EIB require further investigation.

Purpose of the Study:

• To assess theophylline's efficacy in mitigating EIB in children.
• To determine if tolerance to theophylline develops with continuous, long-term use.
• To explore the relationship between theophylline's effect on EIB and perennial asthma control.

Main Methods:

• A standardized treadmill exercise test was administered to 21 children (7-16 years) with perennial asthma.
• Pulmonary function tests (FEV1, FEF25-75%, PEFR) were measured before and after exercise.
• Tests were conducted before theophylline, 90 minutes after a single dose, and after three weeks of continuous theophylline treatment.

Main Results:

• Theophylline successfully inhibited EIB in 20 out of 21 subjects.
• Significant inter-individual variability in response to theophylline was observed.
• No tolerance to theophylline's anti-EIB effects was noted after three weeks of treatment.
• Theophylline controlled perennial asthma in all subjects, with therapeutic blood levels achieved.

Conclusions:

• Theophylline is effective in reducing EIB in children, though responses vary.
• Prolonged theophylline use does not lead to tolerance for EIB.
• EIB and perennial asthma may have distinct underlying mechanisms.
• Theophylline's effectiveness in controlling perennial asthma does not predict its efficacy for EIB.