Monday, March 14, 2011

Folic Acid

It is also called as folacin, folate or pteroylglutamic acid. It is a member of vitamin-B complex family and is essential in the making and maturation of red blood cells. It is present in liver, green vegetables, fruit and yeast, in peptide linkages.

Daily requirements:
Daily folic acid requirement is about 50 µg in normal adults.

Mechanism of action:
Folic acid is a preceding compound for many of the folate cofactors which are important for the synthesis of DNA by the transfer of a carbon atom such as
1. Formation of purine
2. Formation of thymidylic acid from deoxyuridylate

Pharmacokinetics:
Absorption:
Dietary folate in the form of polyglutamate is converted into monoglutamate 5-CH3-H4 folate and it is well absorbed in the proximal jejunum.
Distribution:

It is distributed widely in the body with the help of blood stream. Usually, 5-20 mg of folic acid is preserved in the liver.

Elimination:
More amount of the folic acid, if ingested, is excreted via urine and feces.

Folic acid deficiency:

Its deficiency can be caused by:
1. Greater demand for folic acid such as that in pregnancy or lactation
2. Poor absorption due to any pathological cause of the small intestine
3. Intake of alcohol
4. Dihydrofolate reductase inhibitors such as methotrexate or trimethoprim can also cause its deficiency

Therapeutic uses:
It is used to treat
1. Folic acid deficiency and
2. Megaloblastic anemia which is primarily caused by the decreased production of purines and pyrimidines leading to decreased ability of erythropoietic tissue for the formation of DNA.

Dosage:
It is given in the dose of 1 mg orally per day.

Adverse effects:
It causes no adverse effects as it is immediately excreted through urine.
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