Folinic Acid (Calcium Folinate / Leucovorin)

How it works

As a ready-made reduced folate, it bypasses the dihydrofolate reductase block produced by methotrexate, restoring folate-dependent synthesis in normal cells (folinic acid 'rescue').

Prescribing in practice

• In methotrexate toxicity, start rescue promptly and continue according to methotrexate levels and renal function, as delay reduces its protective effect.
• Do not use folinic acid to treat overdose of trimethoprim-related antifolates without specialist advice, and distinguish it from folic acid, which is not an adequate rescue agent.
• Refer to current prescribing references and toxicology services for regimen selection in high-dose methotrexate and accidental overdose.

Monitoring

Monitor methotrexate levels, renal function and full blood count when used as rescue from antifolate toxicity.

Counselling the patient

• Explain that this medicine protects healthy cells from the side effects of certain chemotherapy or methotrexate.
• Stress the importance of taking rescue doses exactly on schedule.
• Advise reporting mouth ulcers, sore throat or feeling unwell, which may indicate toxicity.

Evidence & guidelines

Folinic acid rescue is a well-established component of high-dose methotrexate therapy and of the management of methotrexate toxicity.