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PubMed1999

Differential effects of 1,25-dihydroxy-vitamin D3 and 19-nor-1,25-dihydroxy-vitamin D2 on calcium and phosphorus resorption in bone.

1,25-Dihydroxy-vitamin D3 [1,25-(OH)2D3] suppresses the secretion and synthesis of parathyroid hormone (PTH) and has been used in the treatment of secondary hyperparathyroidism. However, 1,25-(OH)2D3 can induce hypercalcemia, which often precludes its use. Therefore, an analog of 1,25-(OH)2D3 that would retain its therapeutic effects but produce minor effects on calcium and phosphorus metabolism could be an ideal tool for the treatment of secondary hyperparathyroidism. It has been shown that 19-nor-1,25-dihydroxy-vitamin D2 [19-nor-1,25-(OH)2D2], an analog of 1,25-(OH)2D3, can suppress PTH levels in uremic rats at doses that do not affect plasma ionized calcium levels. The experiments presented here, using parathyroidectomized rats fed diets deficient in either calcium (0.02%) or phosphorus (0.02%), were performed to compare the effects of 1,25-(OH)2D3 and 19-nor-1,25-(OH)2D2 on calcium and phosphorus resorption in bone. Parathyroidectomized rats received daily intraperitoneal injections of vehicle, 1,25-(OH)2D3 (100 ng), or 19-nor-1,25-(OH)2D2 (100 or 1000 ng) for 9 d. Plasma calcium and phosphorus levels were monitored during the study, and ionized calcium levels were determined at the end of the study. By 9 d, 1,25-(OH)2D3 (100 ng/d) increased total calcium levels to 12.4+/-0.26 mg/dl, compared with 6.32+/-0.25 mg/dl (P<0.001) in control animals. The same dose of 19-nor-1,25-(OH)2D2 (100 ng/d) was much less potent (9.45+/-0.28 mg/dl, P<0.001). Similar results were seen with ionized calcium levels [19-nor-1,25-(OH)2D2, 3.61+/-0.12 mg/dl; 1,25-(OH)2D3, 5.03+/-0.16 mg/dl; P<0.001]. Ionized calcium levels were also lower in rats receiving the higher dose (1000 ng) of 19-nor-1,25-(OH)2D2 (4.59+/-0.09 mg/dl, P<0.05). Similar results were seen in rats fed the phosphorus-deficient diet. 1,25-(OH)2D3 (100 ng) increased plasma phosphorus levels from 4.30+/-0.39 mg/dl in vehicle-treated rats to 7.43+/-0.26 mg/dl (P<0.001). The same dose of 19-nor-1,25-(OH)2D2 had no effect (5.19+/-0.32 mg/dl), whereas the high dose (1000 ng) increased plasma phosphorus levels (7.31+/-0.24 mg/dl) in a manner similar to that of 1,25-(OH)2D3 (100 ng). Therefore, 19-nor-1,25-(OH)2D2 is approximately 10 times less effective in mobilizing calcium and phosphorus from the skeleton, compared with 1,25-(OH)2D3. With its ability to suppress PTH at noncalcemic doses, 19-nor-1,25-(OH)2D2 is a potential therapeutic tool for the treatment of secondary hyperparathyroidism in chronic renal failure.

Animals↗
PubMedDate not supplied

[Correction of mineral and protein metabolism by anabolic preparations and vitamin D2 in rats with dental caries].

The effect of nerabol, namacyte and vitamin D2 introduction (separately or in combination) on the animal mineral and protein metabolism has been studied in the experiment on 210 white Wistar rats with reproduced caries. Biochemical and radioisotopic investigations have permitted determining the quantitative content of phosphorus, calcium, 14C-glycine in the saliva, blood serum, teeth, jaw bones and femur. The data obtained evidence for the pronounced caries-static effect of the tested preparations connected with their active influence on the mineral and protein metabolism of experimental animals as well as for the expediency to use the above drugs for complex prophylaxis and treatment of dental caries normalizing processes.

Anabolic Agents↗
PubMed1982

Acute vitamin D2 (ergocalciferol) toxicosis in horses: case report and experimental studies.

Acute accidental vitamin D2 (ergocalciferol) toxicosis was diagnosed in a 6-month-old foal with extensive lesions of soft tissue mineralization. In an experimental study, three 18-month-old horses were given ergocalciferol per os at a rate of 9,300, 22,200, or 47,200 IU/kg of body weight/day for 21 days. Clinical signs or lesions were not seen in horses given the low and intermediate doses, whereas the horse receiving the highest dose developed clinical signs and lesions similar to those noted in the foal. Signs included depression, loss of appetite, weakness, limb stiffness with impaired mobility, and cessation of growth or weight loss. Gross and histologic lesions of mineralization of various soft tissues, especially of the endocardium and wall of large blood vessels, were seen in the foal and the horse given the high dose. Marked, persistent, hyperphosphatemia (7.0 to 13.0 mg of P/dl of serum) developed in each horse. The horse given the intermediate dose remained normocalcemic. Horses given the low and high doses became hypercalcemic (13.6 to 14.5 mg of Ca/dl of serum), but serum calcium concentrations varied from day to day and both horses were normocalcemic at necropsy (12.4 to 12.7 mg of Ca/dl of serum). Distal metacarpal bone ash concentrations of calcium, phosphorus, and magnesium of the foal were mg/g of bone ash) 400.5, 180.5, and 5.30, respectively. In the horses, treatment with ergocalciferol also had no significant effect on serum magnesium (1.88 to 2.18 mg/dl of serum) or distal metacarpal bone ash concentrations of calcium (352.5 to 362.5 mg/g of bone ash), phosphorus (182.5 to 184.0 mg/g of bone ash), or magnesium (5.48 to 6.02 mg/g of bone ash).

Animals↗
PubMed1983

[Phosphoric esters of vitamin D2 and D3, new substrates for alkaline phosphatase of the bovine intestine].

Phosphate esters of vitamins D2 and D3 (D2-O-P and D3-O-P) are hydrolyzed by the alkaline phosphatase from calf intestine (CAPase). pH optimum and Km values are in agreement with those reported for other substrates for intestinal alkaline phosphatase. No effect of activation was noted at low concentrations of D2-O-P and D3-O-P (10(-5)-10(-4)M) in contrast with that stated in earlier works. At higher concentrations (1-4 mM) of the phosphorilated vitamins, accordingly with their function as substrates of CAPase, an inhibitory effect on the hydrolysis of p-nitrophenylphosphate was observed.

Alkaline Phosphatase↗
PubMed2002

Preparation of chitosan/ethylcellulose complex microcapsule and its application in controlled release of vitamin D2.

A system which consists of chitosan (CS) microcores entrapped within enteric polymer is investigated. Vitamin D2 (VD2) used as a model drug, was efficiently entrapped in CS microcores using spray drying and was microencapsulated by coating of ethylcellulose. The morphology and release properties of microcapsules were tested. The factors which influenced the preparation, including molecular weight of CS, concentration of CS solution, concentration of acetic acid and loading of VD2, were discussed. The results of release in vitro showed that the microcapsules could realize sustained release in intestine juice.

Acetic Acid↗
PubMed1975

Effects of the ultimobranchial and parathyroid glands and vitamins D2, D3 and dihydrotachysterol2 on blood calcium and intestinal calcium transport in the frog.

Administration of 500 mug vitamin D2 or D3 with ingestion of calcium to ultimobranchialectomized (UBX) or UBX-parathyroidectomized (PTX) frogs (Rana pipiens) induced hyerpcalcemia and hypercalciuria not apparent in control or PTX frogs. Calcium transport in isolated everted gut sacs was significantly elevated in UBX and UBX-PTX frogs but not in controls or PTX animals. Further, with Vitamin D3 in UBX frogs the duodenal segment had a greater capacity to transport calcium than the jejunal-ileal segment when compared to control, PTX or UBX-PTX frogs. Dihydrotachysterol2 and calcium ingestion also induced hypercalcemia, hypercalciuria and increased calcium transport in gut of UBX and UBX-PTX frogs, with no change seen in PTX or controls after 5 days. The inhibitory influence of the ultimobranchial glands on intestinal calcium transport apparently does not require the presence of the parathyroids and exhibits an inhibitory influence against a high calcium gradient across the duodenal segment.

Animals↗
PubMed2004

Effect of oral vitamin D2 yearly bolus on hip fracture risk in elderly women: a community primary prevention study.

BACKGROUND AND AIMS: Vitamin D deficiency is a well-known risk for hip fracture, and vitamin D insufficiency is so frequent in the elderly that population-wide preventive intervention would be useful. The objective of the study was to evaluate the efficacy of vitamin D bolus on hip fracture incidence in elderly women. METHODS: All women aged > 65 years registered at Health District 20 of the Regione Veneto, Italy, were eligible for this quasi-experimental, prospective community intervention study. A vial containing 400,000 IU vitamin D2 (Ostelin 800, Teofarma, Italy) was offered for oral administration to all women in the winters of 2000-2001 and 2001-2002. The only exclusion criteria for treatment were age and gender, and the control group included women who did not participate in the Health District initiative. Analysis of hip fracture incidence was carried out for 4 years, from 1999 to 2002. Patients with incident hip fracture were identified as soon as they were admitted to one of the 3 hospitals of the health district and interviewed regarding their participation in the vitamin D preventive intervention program. In 120 of the women (age range 68-90 years), serum concentrations of 25-OH vitamin D were measured from October to June, both before and 1 and 4 months after vitamin D administration. RESULTS: 23,325 and 24,747 women received the vitamin D bolus during winters 2000-2001 and 2001-2002 respectively, i.e. 45-47% of eligible women. The proportion of women who accepted the bolus declined with advancing age, from 50-55% in women aged 60-70 years to 22-26% in those aged > 90 years. The two-year intervention on the community decreased the incidence of fracture by 10% (p = 0.050) in comparison with the previous two years. The age-adjusted risk reduction (RR) of hip fracture during 2001 and 2002 in women who had received vitamin D, with respect to women who had not, decreased by 17% (p = 0.056) and 25% (p = 0.005) respectively. The RR was considerably greater and statistically significant over both 2001 and 2002 in the cohort aged > 75 years. 25-OH vitamin D concentrations, in the subset of women in whom it was measured, rose significantly (p < 0.0001) by 9 ng/ml over 4 months after administration. CONCLUSION: Despite several obvious limitations due to its nature, this study sufficiently documents that yearly vitamin D bolus supplements, given as primary prevention to elderly Caucasian women, may decrease the incidence of hip fracture. For its probable safety and excellent feasibility and cost-effectiveness, this primary intervention has a great potential for generalisability.

Administration, Oral↗
PubMed1996

1 alpha-Hydroxy-vitamin D2: a new look at an 'old' compound.

Calcitriol is effective in suppressing PTH levels in haemodialysis patients with hyperparathyroidism but has a low therapeutic index. There is a search for other vitamin D sterols that suppress PTH but cause less hypercalcaemia. We review evidence that 1 alpha-hydroxy-vitamin D2 (1 alpha-D2) may be an effective and safer alternative to calcitriol. In vitamin D-deficient rats, 1 alpha-D2 is equipotent to 1 alpha-D3, which is converted to calcitriol before it acts; but, in normal rats, 1 alpha-D2 is much less toxic at high doses. In osteopenia models, either steroid-induced or following ovariectomy, 1 alpha-D2 is equal to or more effective than 1 alpha-D3 in preventing bone loss but causes less hypercalciuria. Studies in osteoporotic women reveal minimal hypercalciuria with 1 alpha-D2 at doses up to 4 micrograms/day, data suggesting greater safety than reported with calcitriol or 1 alpha-D3. Preliminary data in haemodialysis patients with secondary hyperparathyroidism demonstrate the efficacy of 1 alpha-D2 in suppressing PTH levels with minimal untoward effects on serum Ca and no effects on serum P. Taken together, these observations suggest that 1 alpha-D2 deserves strong consideration as a therapeutic agent for secondary hyperparathyroidism associated with end-stage renal disease.

Animals↗
PubMed1977

An improved procedure for the isolation of suprasterol2 I and II from a photochemical reaction mixture of ergocalciferol (vitamin D2).

An improved procedure for the isolateion suprasterol2 I and II from a photochemical reaction mixture of ergocalciferol (vitamin D2) and their spectral data are described in this paper. When a solution of ergocalciferol in ethanol was irradiated by UV light from a high-pressure mercury lamp, the reaction mixture gave six spots, including suprasterol2 I and II, on the thin-layer chromatogram, while the peaks corresponding to pyro-D2, isopyro-D2,5,b-trans-D2, suprasterol 2 I and II were observed in the gas chromatogram obtained from a capillary column GLC (Suprasterol2 I and II were main peaks). After purifying the mixture by column chromatography on silica gel containing 12% alumina as an absorbent, two main fractins were isolated. The data of their spectra, TLC and GLC showed that the former fraction was suprasterol2 II while the latter was suprasterol2 I and that the both fractions contained the respective compound only. Both suprasterol2 were crystallized as the 3,5-dinitro-benzoates.

Cyclosteroids↗
PubMed1997

Effective suppression of parathyroid hormone by 1 alpha-hydroxy-vitamin D2 in hemodialysis patients with moderate to severe secondary hyperparathyroidism.

Calcitriol, as used for treating secondary hyperparathyroidism, has a low therapeutic index. The safety and efficacy of the vitamin D analog, 1 alpha (OH)-vitamin D2, (1 alpha D2), which has less toxicity in animals than 1 alpha (OH)-vitamin D3, was tested in a multicenter study of 24 hemodialysis patients with secondary hyperparathyroidism [serum intact (i) PTH > 400 pg/ml]. Calcium-based phosphate binders alone were used to maintain serum phosphorus < or = 6.9 mg/dl. After eight weeks without calcitriol (washout), oral 1 alpha D2, 4 micrograms/day or 4 micrograms thrice weekly, was started, with the dose adjusted over 12 weeks to maintain serum iPTH between 130 and 250 pg/ml. Pre-treatment serum iPTH fell from 672 +/- 70 pg/ml (SEM) to 289 +/- 36 after treatment (P < 0.05). The maximal decrease in serum iPTH was 48 to 96%, with 87.5% of patients reaching target iPTH levels. The final dose of 1 alpha D2 average 14.2 micrograms/week. Pre-treatment serum calcium rose modestly from 8.8 +/- 0.2 mg/dl to 9.5 +/0 0.2 after treatment (P < 0.001). Only once did modest hypercalcemia (serum Ca > 11.2 mg/dl) necessitate stopping treatment. Neither the average serum P level, the incidence of hyperphosphatemia, nor the dose of phosphate binders changed from washout to treatment. Thus, oral 1 alpha D2 is highly efficacious in suppressing secondary hyperparathyroidism in hemodialysis patients and is safe despite exclusive use of calcium-based phosphate-binders. Future studies should clarify the optimal dosage regimen.

Humans↗
PubMed2000

[Determination of vitamin D2 included with beta-cyclodextrin complex in "longmu zhuanggu chongji" by HPLC].

In order to enhance the stability of vitamin D2(VD2), the inclusion complex of VD2 with beta-cyclodextrin(beta-CD) was added in "Longmu Zhuanggu Chongji", a medicine of children for the prevention and cure of rickets. The VD2 in beta-CD-VD2 inclusion complex was satisfactorily determined by both reversed-phase high performance liquid chromatography(HPLC) and ultraviolet spectrometry(UV). The experimental results from UV were in well consistent with those from HPLC. The accuracy and recovery of HPLC measurement were analyzed, and their relative standard deviation(RSD) were given to be 0.63% and 1.54%, indicating the method is quite correct and reliable, and the linear regression equation is reasonable. The "Longmu Zhuanggu Chongji" containing beta-CD-VD2 inclusion complexes was saponified by a mixture of KOH, vitamin C (VC) and alcohol-water(1:2, V/V) at 70 degrees C, then extracted with petroleum ether. An accurate content of the VD2 product was obtained by HPLC. A simple and rapid HPLC method, which can detect VD2 in the inclusion complex and in "Longmu Zhuanggu Chongji", has been established in this work.

Chromatography, High Pressure Liquid↗
PubMed1998

Simultaneous determination of fat-soluble vitamins A, D and E and pro-vitamin D2 in animal feeds by one-step extraction and high-performance liquid chromatography analysis.

Traditionally, alkaline saponification for the extraction of vitamins and step-wise HPLC analyses have been widely used for analysis of fat-soluble vitamins in animal feeds. The objective of present study was to develop an analytical method using one-step extraction and simultaneous determination of the vitamins A, D and E and pro-vitamin D2 in animals feeds b HPLC. Various analytical conditions were tested which included sample particle size extraction solvents, the ratio of solvent to sample, extraction approach, extraction time, N2 protection, prepurification with Sep-Pak cartridge and detection wavelength. The accuracy of the developed method has been proven by comparison with the AOAC method. The reproducibility of the developed method has been substantiated by repeated recovery experiments. The detection limit for the four vitamins was 10 ng/g of feed sample. One of the important properties of the present method is rapidity and ease of use.

Animal Feed↗
PubMed1988

The measurement of vitamins D2 and D3 and seven major metabolites in a single sample of human plasma using gas chromatography/mass spectrometry.

Selected ion monitoring of vitamin D metabolites has previously been described but there has been only one detailed description of the measurement by gas chromatography/mass spectrometry (GC/MS) of a number of metabolites in a single plasma sample. We describe here a GC/MS method, using stable isotope labelled internal standards, which allows the estimation of vitamins D2 and D3, and their 25-hydroxy, 24,25-dihydroxy and 25,26-dihydroxy metabolites in a single 2 ml sample of plasma, although more is needed for the measurement of 1,25-dihydroxyvitamin D3. Plasma was extracted on Bond Elut C18 cartridges and initial fractionation carried out on Sep-Pak SIL. Straight-phase high-performance liquid chromatography was required for separation of polyhydroxylated metabolites prior to GC/MS using an LKB 2091 mass spectrometer with conventional packed columns. n-Butylboronate esters were formed across vicinal hydroxyls, followed by formation of trimethylsilyl ethers using trimethylsilylimidazole. The [M - 90 - 15]+ ion for each compound was monitored. Deuterated internal standards were not available for all metabolites and it was necessary to use (2H6)D3 and (2H6)25OHD3 as standards for the measurement of D2 and D3, and 25OHD3 and 25OHD2, respectively, and (2H6)24,25(OH)2D3 as a standard for 24,25(OH)2D3 and 25,26(OH)2D2. Although the [M - 90 - 15]+ ion of 24,25(OH)2D and 25,26(OH)2D has the same mass: charge ratio, derivatives of these compounds are completely separated in the GC system used. The intra-assay precision for all these assays is usually less than 5%.

Cholecalciferol↗
PubMed1992

Preparative isolation of vitamin D2 from previtamin D2 by recycle high-performance liquid chromatography.

A preparative high-performance liquid chromatographic method, based on recycle chromatography, to separate vitamin D2 (ergocalciferol) from previtamin D is described. The method provides efficient separation by means of a mixture of methanol, acetonitrile and hexane as eluent on a reversed-phase C18 column. Scale-up to a 2-in. diameter column resulted in the collection of 100% pure fractions based on UV detection at 265 nm. The total throughput and the economics of the purification were also optimized.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

[Effect of vitamin D2 and 1 alpha-hydroxycholecalciferol on bone tissue in rats with femoral fractures].

Formation of the callus at the site of a femoral fracture in rats without vitamin D deficiency is accompanied by an increase in the specific mass and mineralization of the unaffected pair bone, which indicates general intensification of the processes of mineralization occurring in the skeleton during fractures. Vitamin D deficiency leads to hypocalcemia, retardation of callus mineralization, and drastic demineralization of the intact thighbone thus pointing to pathological enhancement of skeleton resorption as the main source of calcium required for covering bodily requirements. Like vitamin D2 in a dose of 0.300 microgram, administration of 1 alpha-hydroxyvitamin D3 (1 alpha-HCD3) in a dose of 0.025 microgram daily to rats with femoral fractures kept on the vitamin D-deficient diet provides for effective calcium homeostasis maintenance and mineralization of the callus and unaffected bones. This demonstrates high biological activity of 1 alpha-HCD3 and its efficacy in promoting the processes of mineralization during fractures. The increase in the phosphorus content in the diet until the calcium/phosphorus ratio reaches 1:2 (instead of the optimal 1:1), aggravates hypocalcemia and sharply enhances demineralization of the intact bone in vitamin d-deficient rats with femoral fractures and reduces mineralization of the callus in rats given 1 alpha-HCD3. The data obtained indicate the necessity of reliable correction of potential vitamin D deficiency and optimization of the calcium-phosphorus ratio in the diet and preparations, as well as a possibility of applying 1 alpha-HCD3 in the combined treatment of fractures.

Animals↗
PubMed1997

Simplified method for the determination of 25-hydroxy and 1alpha,25-dihydroxy metabolites of vitamins D2 and D3 in human plasma. Application to nutritional studies.

A simplified method for the determination of 25-hydroxy and 1alpha,25-dihydroxy metabolites of vitamins D2 and D3 in human plasma was developed. Plasma samples were deproteinizated and applied to a Bond Elut C18OH cartridge to separate 25-hydroxyvitamin D (25-OH-D) and 1alpha,25-dihydroxyvitamin D [1,25(OH)2D] fractions. The 25-OH-D fraction was purified by a Bond Elut C18 cartridge and 25-OH-D2 and 25-OH-D3 were assayed by HPLC using a Zorbax SIL column. The 1,25(OH)2D fraction obtained above was subsequently applied to HPLC using a Zorbax SIL column to separate 1,25(OH)2D2 and 1,25(OH)2D3 fractions which were determined by a radioreceptor assay (RRA) using calf thymus receptor. The method was applied to nutritional studies.

25-Hydroxyvitamin D 2↗