Drugs Used in Megaloblastic and Pernicious Anaemia

Classification of Drugs Used in Megaloblastic and Pernicious Anaemia

Megaloblastic anaemia is caused by impaired DNA synthesis, leading to large, abnormally shaped red blood cells. Pernicious anaemia is a form of megaloblastic anaemia due to vitamin B12 deficiency caused by the lack of intrinsic factor.

Drugs Used in Megaloblastic Anaemia

Folic Acid (Vitamin B9): Used in folate deficiency-induced megaloblastic anaemia. It aids in DNA synthesis and red blood cell production.
Vitamin B12 (Cobalamin): In cases of vitamin B12 deficiency, this drug helps in preventing megaloblastic anaemia and neurological symptoms.
Combined Therapy: In some cases, both Vitamin B12 and folic acid are used for treatment.

Drugs Used in Pernicious Anaemia

Vitamin B12 (Cobalamin): The main treatment for pernicious anaemia. Typically administered through intramuscular injections or sublingual tablets due to impaired absorption.

Why Large Amounts of Folic Acid Should Not Be Given in Pernicious Anaemia

In pernicious anaemia, excessive folic acid may correct megaloblastic anaemia but can mask the neurological symptoms caused by vitamin B12 deficiency. High doses of folic acid do not address the underlying B12 deficiency, which can result in irreversible neurological damage if not treated appropriately.

Therapeutic Uses of Folic Acid and Vitamin B12

Folic Acid (Vitamin B9)

Treatment of Folic Acid Deficiency: Used to treat megaloblastic anaemia due to folate deficiency.
Prevention of Neural Tube Defects: Recommended for women of childbearing age to prevent fetal neural tube defects.
Management of Homocystinuria: Used to reduce elevated homocysteine levels, which can cause cardiovascular problems.
Treatment in Methanol Poisoning: Folic acid can be given as part of the treatment for methanol poisoning to prevent the formation of toxic metabolites like formic acid.
Rescue for Methotrexate Therapy: Folic acid is used to reduce the toxicity of methotrexate, particularly in high-dose chemotherapy, where it helps protect healthy cells from the drug's toxic effects.

Vitamin B12 (Cobalamin)

Treatment of Pernicious Anaemia: Vitamin B12 injections are the primary treatment for pernicious anaemia.
Management of Vitamin B12 Deficiency: Used in cases of vitamin B12 deficiency from various causes, including malabsorption.
Treatment of Neurological Disorders: Vitamin B12 helps prevent and treat neurological symptoms caused by its deficiency.

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