四、一藥物以口服途徑給予,在胃腸道的藥量以 DGI(amount of drug in the GI tract)表示,假設藥物在體內可均勻分布,其擬似分布體積(apparent volume of distribution)為 VD,而在體內藥量為 DB(amount of drug in body),藥物的排除量(amount of drug eliminated)則為 DE,請回答下列問題:
(四)請問當藥物到達 Cmax(peak drug concentration)時,此時的 drug absorption rate 和 drug elimination rate 又為何?(5 分)