Revision Year: 2018 Publisher: BIAL Portela & Cª, S.A., À Av. da Siderurgia Nacional, 4745-457 S.Mamede do Coronado Portugal
ATC classification: B03B B01 – Folic acid
Folic acid is an important coenzyme for cellular metabolism. After its absorption in the digestive tract, folic acid is rapidly reduced, giving way to active forms that participate in a number of metabolic reactions essential to life, such as the synthesis of purines, synthesis of pirimidinic nucleotides, and amino acids interconversion (serine to glycine, histidine to glutamic acid, homocysteine to methionine).
Folic acid is absorbed rapidly from the GI tract following oral administration, mainly from the proximal portion of the small intestine. Naturally occurring folate polyglutamates are enzymatically hydrolized in the GI tract to monoglutamate forms of folic acid prior to absorption. The mucosa of duodenum and upper part of jejunum is rich in dihydrofolate reductase, able to perform methylation of reduced folates which are absorbed. Following oral administration, peak folate activity in blood occurs within 30-60 minutes. Normal serum folate concentrations range from 0.005-0.015 mcg/mL. In general, serum folate concentrations below 0.005 mcg/mL indicate folate deficiency and concentrations below 0.002 mcg/mL usually results in megaloblastic anemia.
Tetrahydrofolic acid and its derivatives are distributed into all body tissues; the liver contains about one-half of the total body folate stores. Folates are actively concentrated in CSF and normal CSF concentrations are reported to be about 0.016-0.021 mcg/mL. Folic acid is a water-soluble B complex vitamin, and its elimination is renal, and accumulation is not observed. Following oral administration of single 0.1 – to 0.2 mg doses of folic acid in healthy adults, only a trace amount of the drug appears in urine.
When the maximum renal tubular reabsorption is exceeded, after oral administration beyond daily needs, the folate is excreted unchanged in urine.
About 0.05 mg per day of normal body folate stores is lost by a combination of urinary and fecal excretion.
Non-clinical data reveal no special hazard for humans based on conventional studies of safety pharmacology, repeated dose toxicity, genotoxicity, carcinogenic potential, toxicity to reproduction.
© All content on this website, including data entry, data processing, decision support tools, "RxReasoner" logo and graphics, is the intellectual property of RxReasoner and is protected by copyright laws. Unauthorized reproduction or distribution of any part of this content without explicit written permission from RxReasoner is strictly prohibited. Any third-party content used on this site is acknowledged and utilized under fair use principles.
