Indications
Calcium Folinate serves the following purposes:
- Countering the immediate adverse effects of folic acid antagonists, such as methotrexate.
- Implementing calcium folinate rescue, a treatment method combining calcium folinate with folic acid antagonists like methotrexate to minimize overall toxicity.
- Treating megaloblastic anemias caused by various factors including sprue, nutritional deficiencies, pregnancy, infancy, liver disorders, and malabsorption syndrome.
Composition
Each tablet comprises:
- Calcium Folinate Hydrate BP 6.249 mg, equivalent to Folinic Acid 5 mg.
- Calcium Folinate Hydrate BP 18.746 mg, equivalent to Folinic Acid 15 mg.
Pharmacology
This formulation contains Calcium Folinate Hydrate, the calcium salt of folinic acid, which is a crucial metabolite and active form of folic acid. It acts as a cofactor in 1-carbon transfer reactions during the synthesis of nucleic acids’ purine and pyrimidine. The impairment of thymidylate synthesis in individuals with folic acid deficiency leads to defective DNA synthesis, resulting in megaloblast formation and megaloblastic, macrocytic anemias. Calcium Folinate serves as a potent antidote against the hematopoietic and reticuloendothelial toxic effects of folic acid antagonists, such as methotrexate. It is also postulated to protect normal cells from the toxic effects of folic acid antagonists in some cancers, a principle underlying high-dose methotrexate therapy with “Folinate rescue.”
Dosage & Administration
For calcium folinate rescue, treatment should commence as soon as possible after an accidental overdose of methotrexate and within 24 hours of methotrexate administration in cases of delayed excretion. The dosage of methotrexate triggering automatic subsequent Folinic Acid administration varies and depends on multiple factors. Typically, Folinic Acid is administered at a dose of 15 mg (approximately 10 mg/m2) every 6 hours for 10 doses.
Interaction
Large amounts of folinates may counteract the antiepileptic effect of phenobarbitone, phenytoin, and primidone, and increase seizure frequency in susceptible patients. Caution is advised during concurrent administration of calcium folinate with fluoropyrimidine due to associated seizures and syncope.
Contraindications
Calcium folinate is contraindicated in patients with known hypersensitivity to it or any other components of the product. It should not be used in pernicious anemia or other megaloblastic anemias where vitamin B12 deficiency exists. Patients with rare hereditary conditions of galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption should avoid calcium folinate tablets.
Side Effects
Common side effects include mucositis, stomatitis, leukopenia, and/or diarrhea, which may limit dosage.
Pregnancy & Lactation
The safety of calcium folinate in pregnant women hasn’t been established through adequate clinical studies. Its use during pregnancy should be carefully considered, weighing potential benefits against risks to the fetus. It’s unknown whether the drug is excreted in human milk, so caution is advised when administering it to nursing mothers.
Precautions & Warnings
Calcium folinate should only be used with methotrexate or 5-FU under the direct supervision of experienced clinicians in cancer chemotherapeutic agent usage. When treating inadvertent overdoses of folic acid antagonists, folinate should be administered as soon as possible, ideally within 4 hours. Concurrent administration with folic acid antagonists like methotrexate to abort clinical toxicity is generally not recommended, although concurrent use with other folate antagonists such as pyrimethamine and trimethoprim doesn’t inhibit their antibacterial activity.
Overdose Effects
There have been no reported sequelae in patients receiving significantly more calcium folinate than the recommended dosage. However, excessive amounts may nullify the chemotherapeutic effect of folic acid antagonists. There’s no specific antidote to calcium folinate overdose, so supportive care is essential in such cases.
Therapeutic Class
Supportive Care Therapy
Storage Conditions
Store below 30°C, away from light, and out of reach of children.
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