- To diminish the toxicity and counteract the effect of impaired Methotrexate elimination
- To treat the Megaloblastic anemia due to folate deficiency, as in sprue, nutritional deficiency
- To treat the Megaloblastic anemia of pregnancy and infancy
Therapeutic Class Supportive Care Therapy Description Calcium Folinate is a Calcium salt of Folinic acid (citrovorum factor), is a mixture of the diastereoisomers of the 5-formyl derivative of Tetrahydrofolic acid. It is a metabolite of Folic acid and an essential coenzyme for nucleic acid synthesis used in cytotoxic therapy. Pharmacology Folinic acid is a 5-formyl derivative of tetrahydrofolic acid. It is readily converted to other reduced folic acid derivatives (e.g., tetrahydrofolate), thus has vitamin activity equivalent to that of folic acid. Since it does not require the action of dihydrofolate reductase for its conversion, its function as a vitamin is unaffected by inhibition of this enzyme by drugs such as methotrexate. This is the classical view of folinic acid rescue therapy. In 1980s, however, folinic acid was found to reactivate the dihydrofolate reductase itself even when methotrexate exists. Although the mechanism is not very clear, the polyglutamylation of methotrexate and dihydrofolate in malignant cells is considered to play an important role in the selective reactivation of dihydrofolate reductase by folinic acid in normal cells.Folinic acid, therefore, allows for some purine/pyrimidine synthesis to occur in the presence of dihydrofolate reductase inhibition, so some normal DNA replication processes can proceed.
Dosage & Administration
- Reduction of harmful effects of folic acid antagonists such as. Methotrexate, Trimethoprime etc.: The dose is usually one 15 mg tablet every 6 hours for 2 to 3 days.
- Megaloblastic anemia: In the treatment of Megaloblastic anemia, the dose is one 15 mg tablet daily.
- Adjunct to fluorouracil in colorectal cancer: 200 mg/m2 BSA by slow IV inj over at least 3 min followed by 370 mg/m2 fluorouracil by IV inj. Treatment is given for 5 consecutive days and repeated at intervals of 28 days for 2 courses. Subsequently, may repeat at 4-5 wkly intervals if the patient has recovered completely from the toxic effects of the prior treatment course.
- Folate-deficient megaloblastic anaemia: Up to 1 mg/day.