The work is dedicated to estimation of 14C-propoxazepam dose-dependence processes of absorption and mass transfer. 14C-labeled substance (2,68 mCu/mol (1,61 105 Bk/mol) was administered intragastrally at doses 10, 25, 25 and 45 mg/kg with radioactivity determination in different parts of intestines, organs and tissues after 2 hours. It was found that 14C-propoxazepam absorption degree after the mentioned time was ~60 %, while small intestine acted as non-specific “absorption window”. Absorption constant was ~ 0.3 hour-1 regardless administered dose, that indicates mass transfer dose-dependency (both absorption and distribution). Mass transfer between blood and lipophilic organs is rapid (absence of hysteresis loop): the highest value of distribution constant is determined for organs of biotransformation (1.69 for liver) and excretion (2.79 for kidneys).
