Metabolic effects of A-methopterin in man.

Although folic acid antagonists have been used in clinical medicine for 10 years, the metabolic effects of these agents have not been systematically evaluated in man. Since the patients who receive these drugs are generally poor subjects for metabolic balance studies, the lack of data is understandable. Furthermore, the few balance studies that have been reported with the anti-metabolites have been concerned with the catabolism of tumor tissue and have thus provided little information regarding the response of the host. During the course of treatment with A-methopterin of patients with histologically proved metastatic choriocarcinoma, we have had the opportunity of examining its metabolic effects. Since the subjects of this study had only minimal disease, it was hoped that any metabolic alterations would reflect the action of A-methopterin on the host. A-methopterin in high doses proved to have only a minimal catabolic effect, and the findings suggested that this effect was the result of the action of A-methopterin on normal tissue.