Microdetermination of ergocalciferol (vitamin D2) in pharmaceutical preparations by differential spectroscopy using trifluoroacetic acid in the absence of vitamin A.
A differential spectroscopy method for the determination of microgram quantities of ergocalciferol, using trifluoroacetic acid and hydrogen peroxide, was applied to commercially available pharmaceutical preparations. Tablets were powdered and extracted with methanol after being made basic with diethylamine. The methanol was concentrated, chloroform was added, and the mixture was chromatographed on neutral alumina using chloroform as the eluent. Ergocalciferol was determined in an aliquot of the eluate by differential spectroscopy and was compared with a reference ergocalciferol standard treated similarly. The method applied to low potency formulations (2.5-6 mug/tablet) is simple and quantitative, needs less than 5 hr for completion, and has a precision of less than +/- 2%. A simple and accurate chromatographic method for the determination of ergocalciferol in stabilized powders and high potency tablets, which precludes the necessity of solvent-solvent extraction, was also developed. The results are comparable with those obtained by the rat bioassay and the USP XVIII chemical assay.
Vitamin D: a reawakening.
Clear descriptions of the clinical picture of rickets were published in the 17th century although mention of various aspects of the syndrome goes back even further. That a chemical factor could reverse the rachitic process was well settled by the mid-1920s. It is now clear that a number of sterols can be rendered antirachitic under the influence of ultraviolet irradiation. The significant sterols, in this regard, are ergosterol (derived from plant sources) and 7-dehydrocholesterol (from animals). When appropriately irradiated, these compounds form ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3), respectively. Historically, "vitamin D1" was really found to be a mixture of substances and not a separate entity. Vitamin D in Man Of course, irradiating many types of plant or animal sterols will produce therapeutic amounts of D2or D3that can prevent or cure rickets when ingested. But it has been known for generations that irradiating
Vitamin D dependency.
A condition still quite unfamiliar to many physicians is discussed in this issue of Pediatrics. The disease, called "Vitamin-D-dependent rickets" in the accompanying article, was first segregated from the array of "Vitamin-D-resistant rickets" by Fraser and Salter2 (Type III, A, ii, in their classification), and by Prader and colleagues3 (hereditary pseudo-vitamin-D-deficiency rickets, in their terminology). The condition is characterized by signs and symptoms which appear in the first year of life, and which are easily mistaken for those of severe (Stage III) vitamin D deficiency4. As revealed in typical case reports of the condition3,5, manifestations include muscular weakness, convulsions, severe rickets, growth failure, hypophosphatemia, low or normal total serum calcium, mild renal tubular acidosis, and hyperaminoaciduria.