For folinic acid (calcium folinate), used to counteract the folate-antagonistic action of methotrexate in cancer treatment, refer to 8.4.6 Drugs for cytotoxic-induced side effects

Folic acid

• Tablets 400micrograms (£3.27 = 90 tablets)
• Tablets 5mg (£0.68 = 28 tablets)
• Oral solution sugar free 2.5mg/5ml, 400 microgram/5ml (£9.16 = 150ml x 2.5mg/5ml)
• Injection 15mg/ml (unlicensed preparation)

Indications and dose

• Folate-deficient megaloblastic anaemia, oral, 5mg daily for 4 months (until term in pregnant women); up to 15mg daily may be required in malabsorption states
• Prevention of neural tube defects, see Neural tube defects (prevention in pregnancy)
• Prevention of methotrexate-induced side effects (off-label use), oral, 5mg at least once weekly (more frequent dosing is often routinely recommended, refer to individual methotrexate shared care guidelines / specialist advice). Folic acid should be taken at least 24 hours after previous methotrexate administration. Be aware that methotrexate and folic acid tablets look alike.
• Prophylaxis in chronic haemolytic states, oral, 5mg every 1–7 days depending on underlying disease
• Prophylaxis of folate deficiency in dialysis, oral, 5mg every 1–7 days

Notes

1. Care should be taken in giving folic acid on its own in megalobastic anaemia. Patients given folic acid alone must have a proven high/normal B12 level before folic acid is started or else both must be given jointly until the level has come back, if there is urgency in starting treatment. A ferritin level should also be done before treatment is given and one month after starting in case there is an occult iron deficiency which may become evident after B12 and folate replacement.
2. There is no justification for prescribing multiple-ingredient vitamin preparations containing vitamin B12 or folic acid.

Hydroxocobalamin

• Injection 1mg/1ml (£2.37 = 1ml amp)

Indications and dose

• Pernicious anaemia and other macrocytic anaemias without neurological involvement, initially 1mg 3 times a week for 2 weeks then 1mg every 3 months
• Pernicious anaemia and other macrocytic anaemias with neurological involvement, initially 1mg on alternate days until no further improvement, then 1mg every 2 months
• Prophylaxis of macrocytic anaemias associated with vitamin B12 deficiency, 1mg every 2–3 months
• Long-term supplementation following gastric bypass or sleeve gastrectomy: 1mg every 3 months

Notes

1. Hydroxocobalamin injections are normally given every three months; more frequent administration is rarely justified
2. MHRA Drug Safety Update (December 2023): Vitamin B12 (hydroxocobalamin, cyanocobalamin): advise patients with known cobalt allergy to be vigilant for sensitivity reactions

Cyanocobalamin

• Tablets 50micrograms (£14.41 = 150micrograms daily)

Indications

• Vitamin B12 deficiency of dietary origin

Dose

• 50–150micrograms daily taken between meals

Notes

1. MHRA Drug Safety Update (December 2023): Vitamin B12 (hydroxocobalamin, cyanocobalamin): advise patients with known cobalt allergy to be vigilant for sensitivity reactions