Drugs producing vitamin deficiencies.

Many drugs produce vitamin deficiencies. They belong to the most important and common therapeutical classes: analgesics, antianemics, antibacterial and antiblastic agents, antibiotics, antidiabetics, antimalarials, antiphlogistics, antipyretics, diuretics, laxatives and purgatives, tranquilizers and anticonvulsives, radiomimetics, hormones and vitamins themselves. The vitamin deprivation processes may be produced by a variety of mechanisms and may involve all vitamins. Recent experiments indicate that there is a competition for binding sites on proteins between vitamin C and salicylate and between dicoumarol and vitamin K. Usually a drug exerts a "devitaminizing" action with respect to only one vitamin. However there are examples of multiple vitamin deficiencies induced by a single drug, like salicylate which deprives the organism of vitamins C, K and pantothenate. These deficiencies may develop either all at the same time or successively. A direct and concomitant vitamin depriving action occurs when an antibiotic blocks the production of vitamins by the enteric flora. A different mode of action occurs in the drug induced folic acid deficiency, which in turn induces a deficiency of vitamin B12. It has been reported that a vitamin deficiency may result from intake of high pharmacological doses of other vitamins. These data need confirmation in patients treated with high doses of nicotinic acid. The drug induced vitamin deficiencies are studied with the same methodology employed for avitaminoses in general; hence they can be diagnosed using the same criteria.