Abstract
The distribution of drugs in blood of rat in relation to age were studied in an in vivo experimentation. The volume of erythrocyte and plasma were reversed at about the age of 60-70 days when the body weights were about 200g and this evidence was supported in the hematocrit value which exceeded 50% at this stage. It was elucidated that this reversion caused by the relative decrease in the volume of plasma fraction while the volume of erythrocyte fraction was kept almost constant at these stages of the animal. Reflecting the fluctuation in the volume of these fraction, the distribution ratio (E/P) increased with increasing in the age. Concerning the effect of dose on the E/P ratio, that the ratio increased with increasing the dose of the administered drug was demonstrated and the mechanism of this phenomena was also discussed.
