Calciferol solution

Dihydroxyprecholecalciferol A solution of ia,25-diacetoxyprecholecalciferol (0.712 g, 1.42 mmols), potassium hydroxide (2.0 g, 35.6 mmols) and methanol (40 ml) was stirred at room temperature under argon for 30 hours. The reaction mixture was concentrated under reduced pressure. Water (50 ml) was added to the residue and the mixture was extracted with methylene chloride (3 x 100 ml). The combined organic extracts were washed with saturated sodium chloride solution (3 x 50 ml), dried over anhydrous sodium sulfate, filtered and evaporated under reduced pressure to give 0.619 g of 10f,25-dihydroxyprechole-calciferol asa thick oil. 

Calandria evaporator, in sodium chloride solution mining, 22 804 Calcicard, molecular formula and structure, 5 97t, 118t Calciferols, 25 791-793 dietary sources of, 25 793 Calcination, 2 353, 403, 407—410 12 726-727... 

An X-ray crystal structure determination of calciferol (vitamin D-2,71) showed that steric crowding in the s-cis diene system resulted in a twisted conformation with a dihedral angle of 53° [59], On irradiation with a mercury lamp, it was partially converted into ergosterol (72) and tachysterol (73) [60, 61]. When a solution of calciferol in light petroleum containing a trace of iodine was exposed to diffuse daylight, the vitamin was photoisomerized to (74) [62],... 

Cholecalciferol (vitamin D-3) differs from calciferol only in the alkyl side-chain, so it was assumed to be in the twisted conformation (75a). In alcoholic solution, vitamin D-3 was irradiated with a mercury arc lamp through a cupric sulphate solution filter to give wavelengths above 250 nm. Six products were isolated. Conformation (75a) could reasonably give rise to the assigned structures (76a), (77a) and (78a) (Scheme 2.3). Photoisomerization could give conformation (75b), which would explain the isolation of (76b), (77b) and (78b). The report is confident on four of the new compounds, but notes that the cyclobutene structures (78a) and (78b) are tentatively assigned [63]. 

Figure 3.19 Variation of retention with composition in LSC according to the simplified linear relationship of eqn.(3.74). Stationary phase Lichrosorb ALOX T (Alumina). Mobile phase n-propanol (

volume fraction) in n-heptane. Solutes lumisterol (1), tachysterol (2), calciferol (3) and ergosterol (4). Figure taken from ref. [357]. Reprinted with permission. 

System Suitability Preparation Dissolve about 250 mg of USP Vitamin D Assay System Suitability Reference Standard in 10 mL of a 1 1 (v/v) mixture of toluen. Mobile Phase. Reflux this solution at 90° for 45 min, and cool. (This solution contains cholecalciferol, pre-cholecalciferol, and fraws-chole-calciferol.)... 

In oral formulations, medium-chain triglycerides are used as the base for the preparation of oral emulsions, microemulsions, self-emulsifying systems, solutions, or suspensions of drugs that are unstable or insoluble in aqueous media, e.g. calciferol. Medium-chain triglycerides have also been investigated as intestinal-absorption enhancers and have additionally been... 

The UV absorption of vitamin D In solution (e 19,500) points to the predominance of the cZt form, which Is Indicated also by the FMR data. Furthermore, this conformer Is the one found In the crystalline state of vitamin D derivatives as demonstrated by the X-ray analyses of Hodgkin Crowfoot, Webster, and Dunltz (71) (calciferol 4-lodo-3-nltrobenzoate) and Knobler al. (72a)... 

Many poorly water soluble substances can, molecularly disperse, adsorb or absorb on or into micelles. These micellar solutions are optically clear. This is called solubilisation. Examples from the Dutch formulary FNA are oral aqueous preparations with vitamin A (retinol palmitate) or D (chole-calciferol (Table 18.15)). Another example is a licensed oral mixture with ciclosporin. 

Prepare individual standards (Sigma) of vitamin A palmitate, vitamin D2 (calciferol), and vitamin E (dl-a-tocopherol) as l-pg/pl solutions in benzene. Prepare each standard by dissolving 10 mg of the vitamin in 10 ml of benzene (benzene is a carcinogen and should be handled with extreme care). Prepare a mixed standard of the three vitamins by weighing 10 mg of each vitamin and dissolving in 10 ml of benzene to achieve a concentration of 1 pg/lil for each. 

Decomposition products of calciferol appear to give practically no colour with antimony trichloride- acetyl chloride reagent, and the colorimetric method applied direct to a chloroformic extract of a decomposed sample of calciferol, or of ground tablet material, gives the same result before and after chromatography. In the case of the comparatively low-potency oily solutions of calciferol where the phytosterols present in the oil give colours which interfere, chromatography is necessary. 

Proceed as described under Solution of Calciferol beginning Mix 1 ml of this solution with 9 ml of antimony trichloride reagent. . . . 

Dissolve the residue in exactly 1 ml of ethanol-free chloroform and add 9 ml antimony trichloride reagent. Determine the units of vitamin D per tablet as described under Solution of Calciferol. 

Solution of Calciferol, B,P. A solution in a suitable vegetable oil to contain 3,000 units of vitamin D per ml. 

Carry out the colorimetric procedure on a 1 -ml aliquot of a standard solution containing 0 003 per cent of calciferol in ethanol-free chloroform. 

Properties.—Vitamin D, or calciferol, CjgHjj.OH, is isomeric with ergosterol, but differs in optical activity, ultra-violet spectrum, and other properties. The vitamin occurs in colourless needles, m.p. 114-5-117° C., [a] ° = + 102-5°, in alcohol. The solutions show an intense absorption band in the region 265 m/x. The vitamin gives none of the carotinoid reactions characteristic of vitamin A. 

Vitamin D Standard and Begnirements.— The international standard adopted by the I eague of Nations (1931) is the biological activity of 1 mg. of a standard solution of calciferol in oil. This quantity given daily to a young rat rendered rachitic by a diet free from vitamin D will produce in eight days a characteristic band of calcium deposits in the metaphyses of the long bones. One gm. of crystalline calciferol is equivalent to more than 40,000 international units. The daily requirements of vitamin D needed to prevent or cure mild rickets in children is about 3,000 units, in the form of calciferol, or 1,000 units in the form of liver oil (vitamin Dj). 

Havinga and Bots (1954) were the first to describe a method for the preparation of C -labeled cholecalciferol. Cholecalciferol-3-C was obtained by irradiation of 7-dehydrocholesterol synthesized from labeled cholesteryl acetate. The photochemical conversion from 7-dehydrocholesterol to cholecalciferol is accompanied by the formation of several other products such as lumisterols, tachysterols, and prechole-calciferol. A solution of NaNOs in water (0.4 ) effectively absorbs ultraviolet rays of wavelengths shorter than 250 mji which are supposed to promote die formation of side products. In order to minimize the formation of overirradiation products the ethereal solution of 7-dehy-drocholesterol-3-C is irradiated till 44.5% has been converted. The Havinga-Bots irradiation vessel, unique in itself, consists of three annular chambers made of quartz enclosing the irradiating lamp. 7-Dehydrocholesterol-3-C has been prepared recently from diolesterol-3-C (Kulkami et al., 1963) by the appKcation of an isocaproate adaptation (Nes et al., 1956) of the allylic bromination of cholesterol with 2V-bromosuccinimide followed by dehydrobromination. 

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