[The toxicity of different forms of 24,25-dihydroxycholecalciferol preparations in rats].

The purpose of the study was to examine the toxicity of 24,25-DOXK on calcium-phosphorus metabolic parameters. The rats from experimental groups received enteral 50- and 1,000-fold physiological doses of 24,25-DOXK (Vitamins Research Production Association) as a combination of R- and S-epimers and homogeneous R-epimer in sunflower oil solutions or ethanol mixture (1:4 propylene glycol) during 3 and 7 days. Though there was a stable tendency for hyperphosphatemia and altered blood calcium concentrations, the 24,25-DOHK formulations under test, unlike 1-OXK and 1,25-DOXK, displayed no toxic properties on the kidney, heart and aorta and produced a mineralizing effect on bone tissue in the acute period. Comparison of the properties shown by 24R,25-DOXK and 24R,S-DOXK showed that a combination of 24,25-DOXK R- and S-epimers was preferable for practical application.