Answer
Theophylline has a narrow safety margin and its clearance varies considerably, so blood levels help identify inadequate exposure or toxicity risk.
Sources for this answer
- Aminophylline hydrate 25mg/ml Solution for injection — Current selected SmPCemc · Summary of Product Characteristics
- NHS Specialist Pharmacy ServiceNHS Specialist Pharmacy Service · NHS medicine guidance
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.