Abstract
1. The effect of some drugs on nutritional status has been studied in the guinea pig, rat and man. 2. The chronic administration of chlordiazepoxide (Librium) to the guinea pig increases the dietary requirements of ascorbic acid. The possible underlying mechanisms and implications of this observation are discussed. 3. The chronic administration of prednisone to the guinea pig causes only an initial increase in the dietary requirements of ascorbic acid. Evidence is presented pertaining to the induction of de novo synthesis of the vitamin by the drug. 4. Patients suffering from rheumatoid arthritis and treated with antirheumatic drugs have lower plasma tryptophan and excrete increased quantities of kynurenine, 3-hydroxy-anthranilic acid and xanthurenic acid in the urine. The significance of these findings is discussed in relation to the nutritional requirements of these patients. 5. The prolonged administration of anticonvulsants and pheno- thiazines in man may lead to folate deficiency. Evidence is presented to the effect that folate deficiency may be the result of the increased activity of the hepatic microsomal drug-metabolising enzymes brought about by the potent inducing properties of these drugs. 6. When anticonvulsants, singly or in combination, or the tricyclic drug, imipramine, are administered for 12 weeks to rats fed on diets containing different concentrations of folic acid, they exacerbate, induce, or have no effect on folic acid status depending on the dietary intake of the vitamin. Furthermore, a deficiency of folic acid impairs or diminishes the extent of induction of cytochrome enzymes by these drugs. 7. The combined administration of phenobarbitone and dilantin for 12 weeks to female rats fed on diets of different folate content increases the frequency of certain congenital abnormalities in the offspring. The implications are discussed.