Abstract: Azithromycin is an azalide antibiotic, structurally related to the macrolide antibiotics. Protheo is a sustainted release tablet of theophylline. Two groups were investigated: azithromycin with protheo and protheo group, each consisting of ten cases. By moniting the serum concentration of different time after administration.It was concluded that Azithromycin has no effect on the serum concentration of theophylline.

Key words: Azithromycin, theophylline sustainted release tablet, serum concentration