AJCN North Carolina Research Campus
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text (PDF)
Right arrow Purchase Article
Right arrow View Shopping Cart
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Zimmerman, J.
Right arrow Articles by Rosenberg, I. H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Zimmerman, J.
Right arrow Articles by Rosenberg, I. H.
Agricola
Right arrow Articles by Zimmerman, J.
Right arrow Articles by Rosenberg, I. H.

American Journal of Clinical Nutrition, Vol 46, 518-522, Copyright © 1987 by The American Society for Clinical Nutrition, Inc

ORIGINAL RESEARCH COMMUNICATIONS

Competitive inhibition of folate absorption by dihydrofolate reductase inhibitors, trimethoprim and pyrimethamine

J Zimmerman, J Selhub and IH Rosenberg

Trimethoprim and pyrimethamine, inhibitors of dihydrofolate reductase (DHFR), cause folate deficiency in some patients. We investigated impairment of intestinal folate absorption by these drugs. By use of the in vivo intestinal-loop methods in rats, absorption of [3H] folic acid was significantly decreased in the presence of either drug. Kinetic studies using the influx chamber method demonstrated a pattern of competitive inhibition of folate transport. [3H] folic acid absorption from jejunal loops was determined 3-16 h after IV administration of methotrexate; this treatment abolished DHFR activity in the small intestine. In rats pretreated with methotrexate, luminal disappearance and systemic absorption of folic acid were significantly enhanced with respect to controls. Trimethoprim and pyrimethamine are weak competitive inhibitors of intestinal folate transport and folate absorption inhibition occurs at the site of membrane transport and appears to be unrelated to concurrent inhibition of DHFR activity in enterocytes.




HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1987 by The American Society for Nutrition