The TH-Lac-A50 coated tablet was further applied to in vivo animal study, where the lactose was incorporated in the drug core and the composition of coating film was CA50%/PEG50%. Figure 5 shows the plasma drug concentration after intravenous injection of theophylline solution, oral administrations of uncoated (TH-Lac) and coated (TH-Lac-A50) theophylline tablets respectively.