Vitamin D ... is hydroxylated at the 25 position in liver to produce 25-hydroxy-vitamin D3 which is the major metabolite circulating in the plasma. The metabolite is further hydroxylated in the kidney to 1,25-dihydroxy-vitamin D3, the most active metabolite in initiating intestinal transport of calcium & phosphate & mobilization of mineral from bone.
A polar, biologically active metabolite of vitamin D2, 25-hydroxyergocalciferol, which is about 1.5 times more active in curing rickets in rats, has been isolated from pig plasma.
来源:Hazardous Substances Data Bank (HSDB)
代谢
Dihydrotachysterol 是一种维生素 D 类似物，可以被认为是维生素 D2 的还原产物... 在抗佝偻病活性测试中，Dihydrotachysterol 的活性大约是维生素 D 的 1/450，但在高剂量下，它在动员骨矿物质方面比维生素 D 要有效得多。
Dihydrotachysterol is a vitamin D analog that may be regaurded as a reduction product of vitamin D2 ... Dihydrotachysterol is about 1/450 as active as vitamin D in the antirachitic assay, but at high doses it is much more effective than vitamin D in mobilizing bone mineral.
Neither normal nor excessively high intakes of vitamin D are associated with liver injury or liver test abnormalities. Hypervitaminosis D and vitamin D intoxication generally arise with intakes above 50,000 IU daily, but lower doses may induce toxicity in susceptible individuals such as patients with renal osteodystrophy (secondary hyperparathyroidism), and a safer upper limit of recommended intake is 10,000 IU daily. Symptoms of vitamin D intoxication are caused by hypercalcemia and can include dehydration, thirst, polyuria, anorexia, nausea, vomiting, constipation, fatigue, bone pains and muscle cramps. Complications can include renal dysfunction, nephrocalcinosis, decreased consciousness and seizures. Symptoms arise a few weeks to several months after starting excess doses of vitamin D given orally or parenterally. A common cause of hypervitaminosis D is the mislabeling of an over-the-counter or locally prepared nutritional supplement, excessive fortification of milk or foods, and inadvertent prescription or dispensing errors. In clinical descriptions of vitamin D intoxication, typical laboratory findings are hypercalcemia, increase in serum creatinine, and high 25-OH vitamin D levels (usually above 200 ng/mL or 500 nmol/L). Serum aminotransferase and bilirubin levels are typically normal, while alkaline phosphatase levels may actually be lower than normal.
The effect of calcitriol (1,25-dihydroxyvitamin D3) on the conversion of ergocalciferol (vitamin D2) to 25-hydroxyvitamin D in 20 normal subjects receiving 2 separate doses of ergocalciferol, one with and one without concomitant administration of calcitriol is described. The concurrent administration of the 2 drugs made no difference to serum calcitriol concentrations.
The effects of glutethimide therapy, 500 mg/day, on the metabolism of vitamin D in a 77 yr old female patient who had taken an overdose of vitamin D2 are reported. Hypercalcemia in this patient was associated with raised serum concentrations of total 25-hydroxyvitamin D and total 1,25-dihydroxyvitamin D. Eight days after administration of glutethimide, plasma gamma-glutamyltransferase activity rose above the upper limit of normal, peaking at 90 IU/L on days 18-22 of therapy. The plasma calcium concentration fell to within the normal range on day 13. The serum concentration of 1,25-dihydroxyvitamin D began to fall within 4 days, and after 8 days it was near the lower limit of the reference range, at 70 pmol/L. The serum concentration of total 25-hydroxyvitamin D did not change appreciably until hepatic enzymes were induced; thereafter it fell gradually. Although the 25-hydroxyvitamin D concentration remained high, the concentration of 1,25-dihydroxyvitamin D did not rise again but remained within the lower part of the normal range.
The effect of a high cholesterol diet and corticosteroids on the toxicity of vitamin D2 in rats was studied. Vitamin D2 was administered orally at the dosage of 5X10+4 to 60X10+4 IU/kg, once daily for 4 days. Animals fed cholesterol showed a decrease in mortality due to vitamin D2 treatment. Dietary cholesterol inhibited toxic responses such as a diminished growth rate following anorexia, elevated serum calcium level and calcium deposition in tissues, which were produced by a sublethal dose of vitamin D2 (20X10+4 IU/kg, once daily for 4 days). Animals pretreated with the high cholesterol diet from 2 wk before the first vitamin D2 administration showed much more symptomatic relief than those given this diet after the first vitamin D2 administration. On the other hand, dexamethasone as well as corticosterone remarkably increased the mortality due to vitamin D2. The degree of vitamin D2 toxicity, enhanced by dexamethasone, was correlated with the degree of hypercalcemia and tissue calcification. Therefore, the inhibitory effect of cholesterol is not likely to be due to activation of the cholesterol corticosterone system in the adrenal gland.
The effect of short term treatment with pharmacological doses of vitamin D2 or vitamin D3 on the serum concentration of 1,25(OH)2D metabolites was examined in epileptic patients on chronic anticonvulsant drug therapy. Nine patients were studied before and after treatment with vitamin D2 4000 IU daily for 24 wk and 10 before and after treatment with vitamin D3 in the same dose. Before treatment the serum concentrations of 1,25(OH)2D and 25(OH)D were significantly lower in epileptics than in normal subjects (p< 0.01). Vitamin D2 treatment increased the serum concentration of 1,25(OH)2D2, but a corresponding decrease in 1,25(OH)2D3 resulted in an unchanged serum concentration of total 1,25(OH)2D. The serum concentration of 25(OH)D2 and 25(OH)D increase significantly, whereas there was a small decrease in 25(OH)D3. Vitamin D3 treatment did not change the serum concentration of 1,25(OH)2D3 whereas serum 25(OH)D3 increased significantly. The correlation between the serum ratio of 1,25(OH)2D2/1,25(OH)2D3 and 25(OH)D2/25(OH)D3 estimated on vitamin D2 treated epileptic patients and normal subjects was highly significant (p< 0.01). The data indicate that the serum concentration of 1,25(OH)2D2 and 1,25(OH)2D3 are directly proportional to the amount of their precursors 25(OH)D2 and 25(OH)D3 and that the concentration of total 1,25(OH)2D is tightly regulated.
Both vitamin D2 & vitamin D3 are absorbed from the small intestine, although vitamin D3 may be absorbed more efficiently. The exact portion of the gut that is most effective in vitamin D absorption reflects the vehicle in which the vitamin is dissolved. Most of the vitamin appears first within chylomicrons in lymph.
The presence of bile is required for absorption of ergocalciferol and the extent of GI absorption may be decreased in patients with hepatic, biliary, or GI disease (e.g., Crohn's disease, Whipple's disease, sprue).
A longitudinal, randomized, double blind, placebo controlled study was conducted for 6 months to monitor ultraviolet B light exposure in human milk-fed infants both with and without supplemental vitamin D2, and to measure longitudinally the bone mineral content, growth, and serum concentrations of calcium, phosphorus, 25-hydroxyvitamin D3, 25-hydroxyvitamin D2, 1,25-dihydroxyvitamin D, and parathyroid hormone. Sequential sampling was performed of 46 human milk-fed white infants; 24 received 400 IU/day of vitamin D2, and 22 received placebo. An additional 12 patients were followed who received standard infant formula. 83% of patients completed a full 6 months of the study. Ultraviolet B light exposure and measurements of growth did not differ between groups. At 6 months, the human milk groups did not differ significantly in bone mineral content or serum concentrations of parathyroid hormone or 1,25-dihydroxyvitamin D, although total 25-hydroxyvitamin D values were significantly less in the unsupplemented human milk group (23.53 + or - 9.94 vs 36.96 + or - 11.86 ng/ml; p< 0.01). However, 25-hydroxyvitamin D3 serum concentrations were significantly higher in the unsupplemented human milk-fed group compared with the supplemented group (21.77 + or - 9.73 vs 11.74 + or - 10.27 ng/ml, p< 0.01) by 6 months of age. It was concluded that unsupplemented, human milk-fed infants had no evidence of vitamin D deficiency during the first 6 months of life.
来源:Hazardous Substances Data Bank (HSDB)
吸收、分配和排泄
对维生素D和25-羟基维生素D在猫体内提升血浆浓度的能力进行了比较。与ergocalciferol相比，通过口服油剂形式的cholecalciferol能够迅速提升血浆中cholecalciferol的浓度，随后迅速下降。相比之下，血浆中25-羟基维生素D的浓度在给药后第3天达到峰值，并持续升高5天。当向10只猫口服油剂形式的337微克cholecalciferol和ergocalciferol时，血浆中cholecalciferol和ergocalciferol的峰值浓度出现在给药后8或12小时。cholecalciferol的峰值浓度是ergocalciferol的两倍以上（570 +/- 80 vs. 264 +/- 42 nmol/l）。cholecalciferol在0-169小时内的曲线下面积也比ergocalciferol大两倍以上。当以亲脂性油基乳剂形式给予ergocalciferol和cholecalciferol时，血浆中25-羟基维生素D3的浓度高于25-羟基维生素D2。当两种维生素以营养范围内的剂量包含在饮食中时，血浆中25-羟基维生素D2的浓度是25-羟基维生素D3的0.68。猫对ergocalciferol的排斥似乎是由于两种形式维生素D的代谢物与结合蛋白的亲和力不同。这些结果表明，猫对ergocalciferol的利用效率为cholecalciferol的0.7，以维持血浆中25-羟基维生素D的浓度。
A comparison was made of the ability of ergocalciferol and cholecalciferol to elevate plasma concentrations of vitamin D and 25-hydroxyvitamin D in cats. Cholecalciferol, given as an oral bolus in oil, resulted in a rapid elevation of plasma concentration of cholecalciferol followed by a rapid decline. In contrast, 25-hydroxyvitamin D concentration in plasma increased until day 3 after administration and remained elevated for a further 5 days. When 337 microg of both cholecalciferol and ergocalciferol in oil were given as an oral bolus to 10 cats, the peak plasma concentrations of cholecalciferol and ergocalciferol occurred at 8 or 12 h after administration. Peak concentrations of cholecalciferol were over twice those of ergocalciferol (570 +/- 80 vs. 264 +/- 42 nmol/l). The area under the curve 0-169 h for cholecalciferol was also more than twice that for ergocalciferol. When ergocalciferol and cholecalciferol were administered in a parenteral oil-based emulsion, higher concentrations of 25-hydroxyvitamin D3 than 25-hydroxyvitamin D2 were maintained in plasma. When both vitamins were included in the diet in the nutritional range, plasma concentrations of 25-hydroxyvitamin D2 were 0.68 of those of 25-hydroxyvitamin D3. Discrimination against ergocalciferol by cats appears to result from differences in affinity of the binding protein for the metabolites of the two forms of vitamin D. These results indicate that cats discriminate against ergocalciferol, and use it with an efficiency of 0.7 of that of cholecalciferol to maintain plasma 25-hydroxyvitamin D concentration.
Osteoporosis diminishes the quality of life in adults with cystic fibrosis (CF). Vitamin D deficiency resulting from malabsorption may be a factor in the etiology of low bone mineral density (BMD) in patients with CF. OBJECTIVE: Absorption of oral ergocalciferol (vitamin D2) and the consequent response of 25-hydroxyvitamin D in 10 adults with CF and exocrine pancreatic insufficiency was compared with that of 10 healthy control subjects. DESIGN: In this pharmacokinetic study, CF patients and control subjects were pair-matched on age, sex, and race. Each subject consumed 2500 microg oral vitamin D2 with a meal. The CF group also took pancreatic enzymes that provided > or = 80000 U lipase. Blood samples were obtained at baseline and at 5, 10, 24, 30, and 36 h after vitamin D2 consumption to measure serum vitamin D2 and 25-hydroxyvitamin D concentrations. RESULTS: Vitamin D2 concentrations in all subjects were near zero at baseline. CF patients absorbed less than one-half the amount of oral vitamin D2 that was absorbed by control subjects (P < 0.001). Absorption by the CF patients varied greatly; 2 patients absorbed virtually no vitamin D2. The rise in 25-hydroxyvitamin D in response to vitamin D2 absorption was significantly lower over time in the CF group than in the control group (P = 0.0012). CONCLUSIONS: Vitamin D2 absorption was significantly lower in CF patients than in control subjects. These results may help explain the etiology of vitamin D deficiency in CF patients, which may contribute to their low BMD.
A method for preparing analogues of C1,C24-dihydroxy-vitamin D is disclosed. Especially the method for preparing calcipotriol and tacalcitol from a starting material of Vitamin D2 is disclosed here. Calcipotriol (compound 1(a)) and tacalcitol (compound 1(b)) can be synthesized by the method of the present invention. Moreover, only nine steps are needed for the synthesis of calcipotriol using the method. Likewise, only ten steps are needed for the synthesis of tacalcitol by the present method. Hence, the present method, with less process steps and higher yields, represents an improvement over the conventional methods.
(20S)-2-METHYLENE-19-NOR-22-DIMETHYL-1alpha,25-DIHYDROXYVITAMIN D3 AND (20R)-2-METHYLENE-19-NOR-22-DIMETHYL-1alpha,25-HYDROXYVITAMIN D3
申请人：DeLuca Hector F.
公开号：US20110237556A1
公开（公告）日：2011-09-29
Compounds of formula I are provided where X
1
, X
2
and X
3
are independently selected from H or hydroxy protecting groups. Such compounds may be used in preparing pharmaceutical compositions and are useful in treating a variety of biological conditions.
NEW SYNTHONES FOR PREPARATION OF 19-NOR VITAMIN D DERIVATIVES
申请人：Chodynski Michal
公开号：US20130006003A1
公开（公告）日：2013-01-03
The present invention discloses the synthone of Formula (I), wherein R
1
and R
2
are the same or different and represent independently hydrogen atom or hydroxyl protecting group, and its use for preparation of 19-nor vitamin D derivatives of general Formula (IV), wherein
represents single or double bond, p represents an integer 0 to 3, R
1
and R
2
represent independently hydrogen atom or hydroxyl protecting group, R
3
represents hydrogen atom, CH
3
or hydroxyl group, R
4
, R
5
and R
6
represent independently hydrogen atom, C
1
-C
3
-alkyl or hydroxyl group or two of R
4
, R
5
and R
6
substituents altogether form cyclopropyl group, in particular for preparation of paricalcitol.
An improved synthesis of a highly potent vitamin D3 analog, 24, 24-difluoro-1α, 25-dihydroxyvitamin D3 has been accomplished. The total yield was 9.3% from inexpensive vitamin D2 in 11 steps.
