I successfully implemented a two-compartment (gut-blood) mathematical model for a single oral dose (20 mg/kg) to simulate the SWCNT distribution in the blood using intestinal absorption constant (Ka = 0.033 min^-1/1.98 hrs^-1), volume of distribution ((Vd = D/C0), experimentally determined), and volume of the gut compartment (V1 = 82.5 ml/kg). The methodology might be further applied to build the two-compartment (peritoneum-blood) PBPK model for a single i.p. drug injection if the peritoneum-blood permeation constant is established.