Theophylline

Theophylline and caffeine are methylxanthines – drugs that ease and stimulate breathing. The measurement of theophylline or caffeine in the blood helps establish an appropriate dose and maintain the right level. Theophylline is one of several medicines that may be taken by children and adults who have asthma and by adults who have chronic obstructive pulmonary disease (COPD). It is a bronchodilator with a narrow therapeutic window – too little theophylline will not work and too much can cause toxicity. Chronic theophylline toxicity is associated with an increased risk of seizures. Both short and long-term toxicity can be life-threatening.
Therapeutic drug monitoring measures specific drugs and/or their breakdown products (metabolites) in the blood to ensure they are within a normal range of concentration of the medication in the blood. These drugs tend to have a narrow “therapeutic index,” the ratio between the toxic and therapeutic (effective) dose of medication.