Effects of potassium ethylxanthogenate and 2,3-dimercaptopropane sulphonate sodium on the pentobarbital pharmacokinetics and metabolism in male mice.

The effects of potassium ethylxanthogenate (PEX) and 2,3-Dimercaptopropane sulphonate sodium (Unithiol) on the pentobarbital (40 mg/kg, body weight i.v.) (PB) sleeping time, pharmacokinetics, and metabolism, were studied in comparative experiments on male albino mice. It was established that the pretreatment of animals with PEX (80 mg/kg of body weight s.c.) potentiated the PB sleeping time. Unithiol in an equimolar dose (105.2 mg/kg of body weight s.c.) had no effect. The pharmacokinetics of PB could be fitted to be a biexponential equation of the type Cp(t) = A.e-alpha t + B.e-beta t. PEX caused an almost two-fold decrease in the elimination rate constant of plasma PB, which led to a higher half-time and a lower total clearance compared with the controls. The curve for the plasma PB metabolites in the PEX-pretreated mice was significantly lower than of the controls. A higher PB level and decreased rate of elimination in PEX-pretreated animals was observed also in the: liver, lungs, kidney, and brain. A conclusion was drawn that the potentiating effect of PEX on the PB sleeping time is mainly due to inhibition of PB liver metabolism. It was suggested that the differences in the biological effects of the two thiol compounds are due to the differences in their chemical structures: PEX possesses a C = S group but Unithiol lacks this group.