In this non-blinded,auto-control study,patients with Chronic Obstructive Pulmonary Disease（COPD）or asthma will serve as their own controls during the 2-week treatment phase.The subjects will be co-administered oral doses of sustained release theophylline (100mg tablets,twice daily) and azithromycin (2x250mg capsules,once daily )in the first week.Then patients will received theophylline therapy alone with the same dose in the second week.Blood samples for the measurement of theophylline plasma concentrations will be collected on Days 8 and 15 prior to dosing.All adverse events whether elicited by query, spontaneously reported or observed by clinic staff will be evaluated by the investigator and reported in the subject's case report form.