THEOPHYLLINE

LAB35

AMINOPHYLLINE

7 mL Red Top Tube

0.3 mL

Refrigerated

Set Up:Daily Report Available:1 day

Theophylline

Therapeutic: 10 - 20 ug/mL Toxic concentration: >25 ug/mL

Theophylline is a methylxanthine derivative which is widely used in the treatment of asthma, obstructive lung disease and neonatal apnea. The primary therapeutic effect of theophylline is due to relaxation of bronchial smooth muscle; however, theophylline has a variety of other effects. These include stimulation of the central nervous system and medullary respiratory centers, decreased peripheral vascular resistance, cardiac stimulation, and diuresis. The effect of theophylline is closely correlated with concentration of the drug in serum. Toxic effects of theophylline usually occur at concentrations above 20 µg/mL in adults, although mild symptoms can occur above 15 µg/mL. These effects include anorexia, nausea, vomiting, headaches and nervousness. Severe side effects such as increased cardiac rate, arrhythmia, cerebral seizures, and respiratory or cardiac arrest occur at concentrations above 40 µg/mL, but may also occur at lower concentrations. Monitoring of theophylline concentrations in serum is essential, since individuals can vary in their rates of theophylline clearance and severe toxicity has been observed without prior occurrence of minor side-effects. Moreover, several factors can alter theophylline elimination. Theophylline elimination is slowed in obese patients, patients with hepatic disease, and in those on a high carbohydrate, low protein diet. Premature infants have very low rates of theophylline elimination. Conversely, theophylline elimination is more rapid among cigarette smokers. In combination with other clinical data, monitoring serum theophylline levels may provide the physician with useful information to aid in adjusting patient dosage to achieve optimal therapeutic effect while avoiding drug toxicity.