Folinic Acid (Calcium folinate)
Indications
Folinic Acid (Calcium folinate) is used for:
Colorectal cancer, Methotrexate toxicity, Megaloblastic anaemia
Adult Dose
Oral
Antidote for methotrexate toxicity
Adult: 15 mg every 6 hr for 10 doses starting 24 hr after the start of methotrexate infusion. Continue admin until serum levels of methotrexate is <0.05 micromolar.
May also be given via IM/IV inj.
Folate-deficient megaloblastic anaemia
Adult: 15 mg daily.
Intravenous
Adjunct to fluorouracil in colorectal cancer
Adult: 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.
Intramuscular
Folate-deficient megaloblastic anaemia
Adult: Up to 1 mg/day.
Child Dose
Renal Dose
Administration
Contra Indications
Hypersensitivity, pernicious anaemia and other megaloblastic anaemias secondary to vit B12-deficiency, intrathecal and intraventricular admin.
Precautions
Undiagnosed megaloblastic anaemia, folate dependent tumors; pregnancy. Monitor calcium levels in patients receiving combined 5-Fluorouracil/Folinic acid treatment. To be given parenterally in the presence of GI toxicity, nausea or vomiting. Monitor serum levels of methotrexate to determine the optimal dose and duration of folinic acid admin. Monitor CBC, electrolytes and liver function tests before and regularly during treatment.
Pregnancy-Lactation
Interactions
Fluorouracil: Folinic acid may increase the toxicity associated with fluorouracil if the two are administered together. Some adverse effects that have occurred, particularly in elderly patients, include severe enterocolitis, diarrhea, and dehydration.
Sulfamethoxazole-trimethoprim: A potential drug interaction exists with concomitant use of sulfamethoxazole-trimethoprim and folinic acid. Folinic acid has been shown to decrease the efficacy of sulfamethoxazole-trimethoprim in the treatment of pneumocystis carinii, a common cause of pneumonia in AIDs patients
Adverse Effects
Side effects of Folinic Acid (Calcium folinate) :
Allergic sensitisation, rash, pruritus, eythema, urticaria, nausea, vomiting, pyrexia.
Mechanism of Action
Calcium folinate enters the cells as 5-methyl tetrahydrofolate and supplies the cofactor blocked by methotrexate. It stabilises the binding of 5-dUMP and thrymidylate synthetase, enhances flourouracil activity and neutralises the effects of folic acid antagonists such as methotrexate but increases those of 5-fluorouracil.