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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).

Figure 11–1.

Drugs used in the treatment of anemia. The hematopoietic factors are initially classified based on the blood component stimulated. Erythrocyte factors are subsequently divided into nutrients such as iron or vitamins and erythropoietin, a growth factor that stimulates erythrocyte formation.

Figure 11–2.

Drugs used in the treatment of altered hemostasis can be divided into those that inhibit thrombosis and those that facilitate clotting. Those used to prevent or dissolve blood clots are divided into three classes that describe their mechanisms of action: anticoagulants, antiplatelet agents, and thrombolytics. Drugs to prevent excessive bleeding are divided into three classes. These classes are replacement of clotting factors, vitamin K supplementation (required for manufacture of clotting factors), and drugs that inhibit plasmin (an enzyme that degrades blood clots).

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.

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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