[Drug-induced avitaminoses and their prevention (author's transl)].

The concept of "drug induced avitaminoses" originates from the observation that drugs may cause vitamin deficiencies. These avitaminoses belong to the "iatrogenic disvitaminoses" and can be subdivided into two groups since they may either represent unwanted side effects of a drug or may be utilized for therapeutical purpose. In the latter case they can be considered as "planned avitaminoses". All drugs are generally able to produce a deficiency of one or more vitamins and therefore have a "devitaminizing power". It would be desirable to quantify this property of drugs in terms of a "devitaminization index". Knowledge of this index, which should be acquired for new drugs during clinical research, is of primary importance since it allows to adapt the dosage and use of the drug to the vitaminic status of the patient and enables to foresee and prevent damages due to vitamin deficiency. Drug induced avitaminioses are produced more easily and are more severe if the devitaminizing power of the drug and its dosage are high, the therapy is long and the vitaminic status of the patient is optimal. Many subjects (old people, children, etc.) have an elevated risk of avitaminoses. Drug induced avitaminoses are produced by mechanisms acting both at the intestinal level (absorption, endogenous production, etc.) and at the tissue level (metabolism, utilization, etc.). Some of the mechanisms have not been completely clarified. These avitaminoses are numerous and frequent, but their prevention is relatively easy and always achievable. They constitute a new disease and cause an additional damage with respect to the primary illness. The social and economic aspects of this damage are evident considering that many pharmacological profilactic and therapeutic treatments of social illnesses, such as diabetes, tuberculosis, epilepsy, rheumatic diseases, etc. have a devitaminizing power. It is clear therefore that this pathology is particularly important in preventive medicine and that it must be known not only by practitioners and biologists but also outside the medical field.