Effect of hexadecane on the pharmacokinetics of hexachlorobenzene.

Sixty rats were divided into two groups; one group received normal Rat Chow and the other the same feed supplemented with 5% hexadecane. Twenty-four hours later, the rats were injected iv with 1.0 mg/kg [14C]hexachlorobenzene (HCB). For 1 month after dosing, the activity of 14C was determined in various tissues and in serum at predetermined intervals. A biexponential decline of radioactivity was observed in serum and tissues of both groups; the decline of 14C in tissues roughly paralleled the decline of radioactivity in serum; exceptions were fat, skin, and the contents of the large intestine, which showed an initial uptake phase. Hexadecane increased the disposition rate constant beta in serum, leading to a significantly reduced body burden after 4 weeks of treatment. The more rapid loss of tissue radioactivity was accompanied by increased levels of 14C in intestinal contents of the large intestine. Biliary excretion was unaffected. Data are compatible with describing the kinetics of HCB by a two-compartment open model, where elimination occurs from a part of the peripheral compartment.