Drugs used to treat anaemias. Hematopoetic growth factors

Question 1

Classification?

Answer 1

1. Drugs for treatment of iron deficiency anaemia (Iron supplementation)
2. Drugs for treatment of megaloblastic anaemia (B12 and B9)
3. Erythropoietin substitutes (Epoetin alfa and Darbepoetin)
4. Iron Chelators (Iron Overload treatment)
5. Hematopoietic growth factors

Question 2

Explain the drugs used for the treatment of iron deficient anaemias?

Answer 2

2 types of preparations are used namely “oral” and “parenteral” preparations.

Oral = Ferrous sulphate, ferrous gluconate and ferrous fumate. Rate of oral absorption depends on the status of iron deposits. Low iron deposits cause a fast absorption.

Parenteral = Iron dextran and sodium ferric gluconate

parenteral treats iron deficiency rapidly, whereas oral takes a few weeks to take effect.

Adverse Effects:

Oral = Dark stools and GI disturbances ( abdominal pain, nausea, diarrhoea and constipation).

Parenteral = Fatal hypersensitivity and anaphylactic reactions. Should be used carefully in the presence of an active infection.

Overall these drug preparations contain iron, which acts as a form of iron supplementation for the treatment of iron deficient anaemias.

Question 3

Explain the treatment of “megaloblastic anaemias”? (EXPLAIN B9 ONLY)

Answer 3

Vit. B9 and vit.B12 supplementations treat MBA.

Folic acid (B9) is responsible for normal DNA synthesis and hence normal erythropoiesis.

1. Increase Demand (pregnancy)
2. Reduced absorption (Malabsorption syndromes)
3. Alcoholism
4. Inhibitors of dihydrofolate reductase inhibitors (Methotrexate and trimethoprim)

Oral/parenteral administration, excessive vitamin is lost in the urine. Hypersensitivity reactions to parenteral administration may be observed.

Primary outcome of B9 deficiency is MBA due to reduced purine/pyrimidine synthesis by the B9.

Question 4

Explain the drugs used to treat “megaloblastic anaemias”? (EXPLAIN B12 ONLY)

Answer 4

1. Reduced dietary intake
2. Malabsorption syndromes
3. Reduced intrinsic factor production from the parietal cells (in pernicious anaemia, caused by atrophic gastritis).

Drugs can be taken orally (for dietary deficiency) or via (subcutaneous/IM) for pernicious anaemia (as there is no gastric absorption).

“Hydroxycobolamine” is preferred as it has good plasma protein distribution, maintains plasma concentrations for long periods of time.

“Cyanocobolamine” is used through oral administration as a high daily oral dose.

Question 5

Explain how “Epoetin alfa” and “Darbepoetin” is used to replace erythropoietin function?

Answer 5

Epoetin alfa is produced by recombinant DNA technology is used for the treatment of anaemia that is caused by bone marrow disorders, HIV, malignancy and end-stage renal disease.

Darbepoetin and epoetin alfa can be given intravenously for renal dialysis or subcutaneously for other indications. They are not indicated for the acute treatment of anaemia as they have delayed onset of action. Iron supplementation and these drugs may be used in combination for the effective treatment of erythropoietin deficiency.

Question 6

Explain Iron Chelation?

Answer 6

Are used in treatment of chronic iron overload

Question 7

Explain Hematopoietic growth factors.

Answer 7

Stimulate the
formation and proliferation of colony forming cells, leading to formation
of granulocytes, macrophages, eosinophils and megakaryocytes.

Examples are : colony-stimulating factors, such as
1.granulocyte colony-stimulating factor.

2. granulocyte/macrophage colony-stimulating factor.
3. monocyte/macrophage colony-stimulating factor.
4. stem cell factor.
5. erythropoietin, and a number of interleukins.