Editing Folate (section)

== Drug interference ==
A number of drugs interfere with the biosynthesis of THF from folic acid. Among them are the [[antifolate]] [[:Category:Dihydrofolate reductase inhibitors|dihydrofolate reductase inhibitors]] such as the antimicrobial, [[trimethoprim]], the antiprotozoal, [[pyrimethamine]] and the chemotherapy drug [[methotrexate]],<ref name=Rajagopalan2002>{{cite journal | vauthors = Rajagopalan PT, Zhang Z, McCourt L, Dwyer M, Benkovic SJ, Hammes GG | title = Interaction of dihydrofolate reductase with methotrexate: Ensemble and single-molecule kinetics | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 99 | issue = 21 | pages = 13481–6 | date = October 2002 | pmid = 12359872 | pmc = 129699 | doi = 10.1073/pnas.172501499 | bibcode = 2002PNAS...9913481R | doi-access = free }}</ref><ref name=McGuire2003>{{cite journal | vauthors = McGuire JJ | title = Anticancer antifolates: current status and future directions | journal = Current Pharmaceutical Design | volume = 9 | issue = 31 | pages = 2593–613 | year = 2003 | pmid = 14529544 | doi = 10.2174/1381612033453712 }}</ref> and the [[Sulfonamide (medicine)|sulfonamides]] (competitive inhibitors of PABA in the reactions of [[dihydropteroate synthetase]]).<ref>{{Cite web | vauthors = Boothe DM | title = Sulfonamides and Sulfonamide Combinations | work = Merck Veterinary Manual | publisher = Merck & Co., Inc. | location = Kenilworth, NJ | access-date = 10 October 2019 | url = http://www.merckvetmanual.com/pharmacology/antibacterial-agents/sulfonamides-and-sulfonamide-combinations | archive-date = 7 August 2020 | archive-url = https://web.archive.org/web/20200807020526/https://www.merckvetmanual.com/pharmacology/antibacterial-agents/sulfonamides-and-sulfonamide-combinations | url-status = live }}</ref>

[[Valproic acid]], one of the most commonly prescribed epilepsy treatment drugs, also used to treat certain psychological conditions such as bipolar disorder, is a known inhibitor of folic acid, and as such, has been shown to cause birth defects, including neural tube defects, plus increased risk for children having cognitive impairment and autism. There is evidence that folate consumption is protective.<ref>{{cite journal |vauthors=Verrotti A, Tana M, Pelliccia P, Chiarelli F, Latini G |title=Recent advances on neural tube defects with special reference to Valproic Acid |journal=Endocr Metab Immune Disord Drug Targets |volume=6 |issue=1 |pages=25–31 |date=March 2006 |pmid=16611162|doi=10.2174/187153006776056657 }}</ref><ref>{{cite journal |vauthors=Tanoshima M, Kobayashi T, Tanoshima R, Beyene J, Koren G, Ito S |title=Risks of congenital malformations in offspring exposed to valproic acid in utero: A systematic review and cumulative meta-analysis |journal=Clin. Pharmacol. Ther. |volume=98 |issue=4 |pages=417–41 |date=October 2015 |pmid=26044279 |doi=10.1002/cpt.158|s2cid=205715968 }}</ref><ref>{{cite journal |vauthors=Veroniki AA, Rios P, Cogo E, Straus SE, Finkelstein Y, Kealey R, Reynen E, Soobiah C, Thavorn K, Hutton B, Hemmelgarn BR, Yazdi F, D'Souza J, MacDonald H, Tricco AC |title=Comparative safety of antiepileptic drugs for neurological development in children exposed during pregnancy and breast feeding: a systematic review and network meta-analysis |journal=BMJ Open |volume=7 |issue=7 |pages=e017248 |date=July 2017 |pmid=28729328 |pmc=5642793 |doi=10.1136/bmjopen-2017-017248}}</ref>

Folate deficiency is common in alcoholics, attributed to both inadequate diet and an inhibition in intestinal processing of the vitamin. Chronic alcohol use inhibits both the digestion process of dietary folate polyglutamates and the uptake phase of liberated folate monoglutamates. The latter is associated with a significant reduction in the level of
expression of RFC.<ref name="Said2011"/>