Pharmacokinetic study of sodium selenite in low-selenium rabbits

Sodium selenite has been used for prevention and treatment of Keshan disease and Kaschin-Beck's disease. The efficacious dosage regimens of sodium selenite in low-Se human body have not been clear. A single iv or ig of sodium selenite 2.0 mg/kg was given to rabbits. Selenium in whole blood was determined fluorophotomerically. The concentration-time curve following a single iv of sodium selenite in rabbits was found to be of 3-compartment open model. The pharmacokinetic parameters were: T1/2 x 0.11 +/- 0.03 h, T1/2 alpha 6.8 +/- 2.8 h, T1/2 beta 215 +/- 35 h, Vc 0.50 +/- 0.07 L/kg, Cl 19 +/- 5 ml/(kg.h), AUC 146 +/- 26 mg.h/L. The concentration-time curve following a single ig of sodium selenite showed a pattern of 2-compartment open model. The parameters were: T1/2 kappa a 13 +/- 6 h, T1/2 alpha 3.6 +/- 1.9 h, T1/2 beta 338 +/- 107 h, Vc 2.9 +/- 1.3 L/kg, AUC 78 +/- 29 mg.h/L, Cl 27 +/- 11 ml/(kg.h). In low-Se rabbits the distribution in body was more rapid and more extensive, and the bioavailability was higher than that in normal-Se rabbits. Therefore, attention should be paid to the different levels of selenium during therapy with sodium selenite.