Association Study Between CYP1A2 Gene Polymorphisms and Metabolism of Theophylline

Inclusion Criteria: * Aged 18-75 years,Weight 40-80kg COPD patients, male or female; regularly visiting our hospital; taking a sustained-release preparation of theophylline continuously for at least 2 weeks Exclusion Criteria: * Patients with renal or hepatic dysfunction; Patients with congestive heart failure; Patients with hypothyroidism or hyperthyroidism; Patients currently taking drugs likely to effect theophylline metabolism or who had taken such drugs in the preceding week; Patients with extreme obesity Patients with very severe Chronic Obstructive Pulmonary Disease(COPD)