Effect of dihydrotachysterol on calcium absorption in uremia

The effect of 1alpha-hydroxyvitamin D3 on calcium and mineral content of bone in renal osteodystrophy

Ten patients with renal osteodystrophy were treated with 1alpha-hydroxyvitamin D3 for 18 months. The effect of treatment was measured by a number of different methods and bone mass assessed by mineral and neutron activation analysis. In the majority of patients, raised serum levels of parathyroid hormone and alkaline phosphatase, histological features and radiological changes returned to normal. These effects were inconsistent in patients with a raised serum calcium level before starting treatment. In general, in patients without evidence of severe hyperparathyroidism there was a reduction in the rate of fall or an increase in the mineral and calcium content of the bone.

The effect of 5,6-trans-25-hydroxycholecalciferol in relative vitamin D resistancy

The relative vitamin D resistance in patients with chronic renal failure and in those with hypoparathyroidism is due to an impairment of 1-hydroxylation of cholecalciferol. 5,6-trans-25OHCC, which has a similar steric configuration as 1,25(OH)2CC was examined at a daily dose of 18,000 IU fro 14 days in both diseases. Intestinal 47calcium absorption as well as serum calcium level could be normalized in most patients with hypoparathyroidism. The improvement was less in patients with chronic renal failure, suggesting an additional depressing influence of uremia on calcium metabolism.

Pharmacokinetics of 5,6-trans-25-hydroxycholecalciferol, a synthetic analogue of vitamin D3, in man

Vitamin D analogues of high biological activity are probably useful in the treatment of renal osteodystrophy. The pharmacokinetics of the synthetic compound 5,6-trans-25-hydroxycholecalciferol have been studied in healthy subjects who were of normal vitamin D status. In comparison to natural 25-hydroxy-cholecalciferol, serum levels of the analogue were lower and its half-life in blood after oral or intravenous administration was considerably shorter. In normal subjects no increase of dihydroxylated metabolites in serum was observed within seven days of an intravenous dose.