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Drug classes presented in this chapter include nutrients and
growth factors affecting formation of blood cells and platelets
(hematopoiesis) (Figure 11–1) and drugs used in the control
of blood clotting (hemostasis) (Figure
11–2).
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Hematopoiesis is the production of circulating erythrocytes (red
blood cells, RBCs), platelets, and leukocytes from undifferentiated
stem cells. This remarkable process produces over 200 billion new
blood cells per day in the normal person and even greater numbers
of cells in people with conditions that cause loss or destruction
of blood cells. The hematopoietic machinery resides primarily in
the bone marrow in adults and requires a constant supply of essential
nutrients such as iron, vitamin B12, and folic acid. Hematopoietic
growth factors, proteins that regulate the proliferation and differentiation
of hematopoietic cells, are also required. The circulating blood
cells play essential roles in oxygenation of tissues, coagulation,
protection against infectious agents, and tissue repair. Blood cell
deficiency is a relatively common occurrence that can have profound
effects on health. Inadequate supplies of either the growth factors
or, much more commonly, the essential nutrients, result in deficiency
of functional blood cells.
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Anemia is a deficiency of oxygen-carrying
erythrocytes. Regardless of the cause, anemia presents clinically
with pallor, fatigue, dizziness, exertional dyspnea, and tachycardia.
The most common causes of anemia are insufficient supply of iron,
vitamin B12, or folic acid. Treatment of these types of
anemia involves replacement of the missing nutrient. Treatment of
certain forms of anemia and treatment of deficiency of other types
of blood cells requires transfusion of the appropriate cell type
or administration of recombinant hematopoietic growth factors. These
growth factors stimulate the production of various lineages of blood
cells and regulate blood cell function. Almost a dozen glycoprotein
growth factors regulate the differentiation and maturation of stem
cells within the bone marrow. Several growth factors, produced by
recombinant DNA technology, have Food and Drug Administration (FDA)
approval for treatment of patients with blood cell deficiencies.
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