|
Classification
Pharmacy Medicine
Dosage
It is recommended that women considering pregnancy take 0.8mg folic acid daily from four weeks before conception to three months after.
Purpose/Usage
Folic acid is a member of the vitamin B group.
Folic acid is reduced to a number of compounds including tetrahydrofolic acid in the body. In the reduced form it is a coenzyme acting as an acceptor of one-carbon units. It is required for the synthesis of purine and pyrimidine bases, for the metabolism of amino acids such as serine-glycine interconversion, methionine methyl group biosynthesis and the degradation of histidine.
It is involved in the maturation of all rapidly proliferating tissues particularly those of bone marrow and gastrointestinal tract. Folate deficiency leads to megaloblastic anaemia.
A number of recent trials have also shown that administration of folic acid in the early stages of pregnancy can reduce the incidence of spina bifida by up to two thirds.
Precautions
Megaloblastic anaemia due to vitamin B12 deficiency should not be treated with folic acid as the neurological defects of vitamin B12 deficiency will not be alleviated, and may become irreversible.
Caution is advised in patients who may have folate-dependant tumours.
Sensitivity to folic acid is a contraindication.
Folic acid treatment may correct the haematological features of vitamin B12 deficiency without correcting the progressive neurological damage due to vitamin B12 deficiency. Therefore vitamin B12 deficiency needs to be excluded before treatment with folic acid alone.
Patients receiving diphenylhydantoin treatment should be monitored for possible loss of seizure control following large doses of folic acid. Folic acid does not correct folate deficiency due to dihydrofolate reductase inhibitors, such as methotrexate. Folinic acid should be used for this purpose.
Folic acid should not be added to multi-vitamin preparations as it may lower the concentration of vitamin B12 in the blood.
In pregnancy, Folic acid crosses the placenta, however adequate and well-controlled studies in humans have not shown that folic acid causes adverse effects on the foetus.
In lactation, folic acid is excreted in breast milk, however, problems in humans have not been documented with intake of normal daily requirements.
Adverse Effects
Folic acid is generally well tolerated. Gastrointestinal disturbances such as nausea, flatulence and diarrhoea may occur. Allergic reactions such as bronchospasm, erythema, fever, rash or itching may occur rarely.
Interactions
The requirements for folic acid may be increased in patients receiving analgesics, anticonvulsants particularly hydantoin and carbamazepine, oestrogens and oral contraceptives.
Folic acid may also interact with antacids, which contain aluminium or magnesium, antibiotics and cholestyramine, sulphonamides including sulphasalazine and zinc supplements.
Methotrexate, pyrimethamine, triamterene and trimethoprim act as folate antagonists by inhibiting dihydrofolate reductase. This is most significant with high doses or prolonged use. Leucovorin calcium must be used instead of folic acid in these patients.
Medicines have benefits and some may have risks. Always read the label
carefully and use strictly as directed. If symptoms continue or you have
side effects consult your pharmacist or doctor immediately.
|
Only $ 9.06
|
)