The model was proposed to relate the apparent volume of distribution (Vd') of a drug to the apparent partition coefficient (P') and the volume of blood plasma. It was found that Vd'values for basic drugs were almost constant in the region of low P'and that Vd'increases in the region of high P'. The average Vd'value (1.47 l/kg) for basic drugs with low P'was about thirty times larger than the value of the blood plasma volume (0.05 l/kg).
