In this essay we will discuss about the drugs used for the treatment of anemia.
1. Ferrous Sulphate:
Ferrous sulphate is the drug of choice and is given in doses of 325 mg (65 mg elemental iron) three times daily. Other iron preparations include ferrous gluconate, ferrous fumarate and compound preparations such as ferrous glycine sulphate, polysaccharide iron complex and sodium iron edetate. The incidence of side effects is related to the content of elemental iron. Iron salts are astringent and may cause nausea, vomiting and constipation.
2. Parenteral Iron:
The only valid reason for parenteral iron is failure of oral therapy. Parenteral iron does not cause any significant faster hemoglobin response than oral therapy and should not be considered as a more rapid cure of the anemia. Iron sorbitol citrate is given by deep intramuscular injection, while iron sucrose is given by slow intravenous injection or infusion.
Parenteral iron may rarely be complicated by anaphylaxis, and therefore a 0.5 ml (25 mg) IV iron (test dose) should be administered 1 hour before therapy is initiated. Adrenaline should be available in hand to treat any anaphylactic reaction. Delayed reactions to IV iron, such as arthralgia, myalgia, fever, pruritus, and lymphadenopathy, may be seen within 3 days of therapy and usually resolve spontaneously or after treatment with NSAIDs. They are contraindicated in pregnancy, history of allergic disorders and liver disease.
Iron overdose may be accidental in children or may occur in aplastic and other refractory anemias with hyperplasic bone marrow (especially thalassemia major) due to repeated blood transfusion and excessive iron absorption from the gut. Desferrioxamine, an iron chelating is given parentally in iron poisoning.
3. Folic Acid:
Cyanocobalamin (vitamin B12) is required for the maturation of the red blood cells. The deficiency of vitamins B12 leads to a failure in the production of erythrocytes and those, which do manage to mature, are abnormal, large and irregular in size and shape. Primitive red cells may also appear in the blood.
Vitamin B12 deficiency also leads to glossitis and degenerative changes in the nervous system.
The syndrome produced by vitamin B12 deficiency is known as pernicious anemia or Addison’s anemia. Vitamin B12 deficiency is due to failure of its absorption from the intestine due to lack of a factor (intrinsic factor) produced by the stomach.
Hydroxocobalamin has completely replaced cyanocobalamin as the form of vitamin B12 used for pernicious anemia. It is ineffective orally and is given in doses of 1 mg by intramuscular injection. Folic acid is necessary for the maturation of red blood cells, and its deficiency will produce changes in the blood similar to those found in pernicious anemia. However, it has no effect on the degenerative changes in the nervous system of pernicious anemia.
Folic acid has few indications for long term therapy since most causes of folate deficiency yield to short course of treatment. It is contraindicated in pernicious anemia, because it will improve the anemia but will worsen the neurological complications of pernicious anemia.
Therapeutic uses:
Folic acid is given orally in doses of 5 to 15 mg daily in folate deficiency megaloblastic anemia (e.g. due to poor nutrition, pregnancy or antiepileptics). Prophylactically, it is used in chronic hemolytic states, in renal dialysis and during the first 3 months of pregnancy to minimize the risk of neural tube defects, which occur very early in pregnancy. Folic acid is also believed to reduce the incidence of cardiovascular disease.
4. Folinic Acid:
Folinic acid is also effective in the treatment of folate deficient megaloblastic anemias but it is generally used in association with cytotoxic drugs (methotrexate) to prevent methotrexate induced mucositis and myelosuppression. Erythropoietin is a hormone manufactured by the kidney, which is necessary for erythrocyte formation. Epoetin is a recombinant (DNA prepared) human erythropoietin and is available into two forms- alpha and beta.
Epoetin is used in anemias associated with chronic renal failure parenterally until a satisfactory hemoglobin level is maintained. Side effect is mainly hypotension which may be severe. Occasionally thrombosis and flu like symptoms may occur.