Cyanocobalamin, the most common form used, is available as oral and sublingual tablets as well as oral lozenges from numerous sources under various names. These products contain anywhere from approximately 50 to 1,000 ¡¿g of cyanocobalamin. Cyanocobalamin is also available as a nasal spray for daily use (CaloMist 25 ^g/actuation) or weekly use (Nascobal 500 ^g/actuation) and as an injectable for intramascular (IM) or deep subcutaneous (SQ) administration. Hydroxocobalamin is available as two, 2.5-g vials (Cyanokit) for the treatment of cyanide poisoning. Hydroxocobalamin is also available in oral and injectable dosage forms from numerous sources under various names. The only advantage for hydroxocobalamin in the treatment of pernicious anemia would be in patients unable to convert cyanocobalamin to hydroxocobalamin as the result of a rare genetic disorder as discussed previously. Cyanocobalamin and hydroxocobalamin are also available in a host of multivitamin preparations.
Scurvy (from the French word scorbutus) has been recognized as a disease afflicting mankind for thousands of years.231 However, it was not until the early 1500s that natives of North America used teas brewed from pine needles to treat or prevent the symptoms of scurvy without understanding the basis for their curative properties. Citrus fruits such as oranges, lemons, and limes were later identified as equally effective treatments. Only within the last 100 years has a deficiency in vitamin C been definitively identified as the cause of scurvy. In 1932, Waugh and King232,233 isolated crystalline vitamin C from lemon juice and showed it to be the antiscorbutic factor present in each of these treatments. Interestingly, in a series of papers published at approximately the same time,234,235 Svirbely and Szent-Gyorgyi236 showed that the substance the latter had crystallized from peppers and reported 4 years earlier was the same as vitamin C and not a hexuronic acid as originally proposed. The structure and chemical formula of vitamin C was identified in 1933 by Hirst et al.237 as one of a series of possible
Was this article helpful?