Theophylline (1,3- dimethylxanthine)

Sample type

• plasma ( Lithium heparin)

• Serum (Red top tube)

Uses

• As a bronchodilator to prevent and treat asthma.

• used to monitor the amount of the drugs in the blood to establish appropriate doses, maintain therapeutic levels, and evaluate toxicity.

Precautions

• Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel.

• Serum tube should be centrifuged within 2 hours of collection.

Interfering factors

◇ Due to cross- reactivity with 1,3 dimethyluric acid (metabolic) ,the assay should not be used to quantitate samples from uremic patients.

◇ if mouse antibodies are utilized, the possibility exists for interference by human antimouse antibodies (HAMA) in the sample, which cause falsely elevated results.

◇ The drug is extensively metabolized with peak serum levels reached four hours after oral dose.

Pre analytical errors

If the sample was hemolysis, lipemic or drawn on gel tube.

The Corrective action

Reject the sample and another one is requested

Post analytical errors

Send wrong results to the patient.

The Corrective action

You must communicate with the patient and apologize for this mistake and sent the right report.

Reference range

0-5 months: 6- 12 µg/ml

Adult : 10-20 µg/ml