Anemia: Hematopoietic Growth Factors, Myeloid Growth Factors, Megakaryocyte growth factors, Sickle Cell

Question 1

Next in the anemia section we will discuss Hematopoietic growth factors. Several growth factors produced by recombinant DNA technology have been approved to treat patients with blood cell deficiencies. The first is erythropoietin. What are the pharmacodynamics for this?

Answer 1

Erythropoietin is produced in the kidney

–in response to tissue hypoxia and this will correct anemia

Question 2

Normally an inverse relationship exists between the hematocrit or hemoglobin levels and the serum erythropoietin level.

Answer 2

As the hematocrit and hemoglobin levels fall and anemia becomes more severe the serum erythropoietin level rises

Question 3

What is the most important exception to the inverse relationship?

Answer 3

Anemia of chronic renal failure

• -erythropoietin levels are usually low because the kidneys can not produce the growth factor
• –these patients are most likely to respond to treatment with exogenous erythropoietin

Question 4

What is darbepoetin?

Answer 4

Long acting version of erythropoietin that differs from erythropoietin by addition of two carbohydrate chains
–decreased clearance and a half life three times that of erythropoietin

Question 5

What is a common adverse effect of erythropoietin?

Answer 5

HTN

Thrombotic complications

Question 6

Next drug is myeloid growth factors for anemia. Includes two drugs Filgrastim and Sargramostin. How do these drugs work?

Answer 6

Stimulate production and function of neutrophils

Also stimulate production of other myeloid and megakaryocyte progenitors

Question 7

Myeloid growth factors stimulate proliferation and differentiation by interacting with specific receptors on various myeloid progenitor cells. These receptors are members of what?

Answer 7

JAK/STAT superfamily

Question 8

Both drugs for growth factors are used for what?

Answer 8

Accelerate recovery of neutrophils after cancer chemotherapy and to treat other forms of secondary and primary neutropenia

Question 9

The next growth factor has to do with megakaryocyte growth factors. Interleukin-11, what does this drug do?

Answer 9

Stimulates growth of primitive megakaryocytic progenitors and increases the number of peripheral platelets.
Use:
prior episode of thrombocytopenia after a cycle of cancer chemotherapy
(reduces the need for platelet transfusions)

Question 10

Finally the last drug to discuss is an agent used to treat sickle cell disease called hydroxyurea. what is the use?

Answer 10

Relieve painful clinical course of sickle cell disease
–increases fetal hemoglobin levels, thus diluting the abnormal hemoglobin S
–takes several months
Also used to treat chronic myelogenous leukemia and polycythemia vera