Comparative Therapeutic Effects of Vitamin D₃and Its Derivatives on Experimental Renal Osteodystrophy

Abstract

The comparative effectiveness of vitamin D3 and its derivatives in curing hyperparathyroidism and osteodystrophic bone lesions was examined in a laboratory model of renal osteodystrophy associated with marked secondary hyperparathyroidism in rats. The experimental model was prepared by a single injection of homologous glycopeptide. Plasma levels of 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] appeared to decrease in the rats receiving glycopeptide. Various doses of vitamin D3 derivatives [2 or 10 microgram/kg D3, 2 microgram/kg 25-hydroxyvitamin D3 (25OHD3), 0.1 microgram/kg 1 alpha,25(OH)2D3, and 0.1 or 0.2 microgram/kg 1 alpha-hydroxyvitamin D3 (1 alpha OHD3)] were daily administered orally to the nephritic rats for 23 days before sacrifice. 1 alpha,25(OH)2D3 and 1 alpha OHD3 were much more potent than 25OHD3 and D3 in reducing the hyperplasia of parathyroir glands. The potency of 1 alpha OHD3 in curing the histological changes of osteodystrophy appeared to be greater than that of 1 alpha,25(OH)2D3. The same dose level of 1 alpha OHD3 was more effective than 1 alpha,25(OH)2D3 in enhancing plasma 1 alpha,25(OH)2D3 levels.