Chapter 49: Drugs Used to Treat Anemias

Drugs Used to Treat Anemias , addressing the pharmacology of agents used to treat anemias, defines anemia as a disorder involving too few or ineffective red blood cells (RBCs) that compromises the blood’s capacity to transport oxygen. The production and life cycle of RBCs, termed erythropoiesis, occur in the bone marrow and are critically regulated by the renal glycoprotein, erythropoietin. Successful RBC formation requires essential factors including iron, amino acids, carbohydrates, vitamin B12, and folic acid. The chapter details three main categories of anemia: iron deficiency anemia, resulting from low iron availability due to high demand, poor diet, or poor absorption, which is typically treated with iron replacement agents such as ferrous sulfate; megaloblastic anemia, caused by insufficient folic acid or vitamin B12, leading to large, weak RBCs with shortened lifespans; and hemolytic anemias, such as sickle cell anemia, a genetic disorder where abnormal hemoglobin S causes RBCs to become sickle-shaped, leading to vessel occlusion, tissue anoxia, and severe pain crises. Pharmacological interventions include Erythropoiesis-Stimulating Agents (ESAs), such as epoetin alfa and darbepoetin alfa, which are used primarily for anemia associated with renal failure or chemotherapy where erythropoietin production is low. A vital safety guideline for ESAs is maintaining a maximum target hemoglobin level of 11 g/dL, as levels higher than this are associated with severe cardiovascular events, deep vein thrombosis, and increased tumor growth in cancer patients. For pernicious anemia, a type of megaloblastic anemia where lack of intrinsic factor prevents vitamin B12 absorption, B12 replacement (e.g., hydroxocobalamin or cyanocobalamin nasal spray) must be given parenterally or intranasally for life to bypass the gastrointestinal tract and prevent potential central nervous system (CNS) myelin sheath damage. Hydroxyurea, a cytotoxic drug, is utilized in adults with sickle cell anemia to increase fetal hemoglobin and dilute abnormal hemoglobin S, thereby reducing painful crises. Nursing management for iron replacement requires warning patients about common gastrointestinal upset, dark stools, and ensuring the drug is taken properly (e.g., liquid forms through a straw to prevent teeth staining; avoiding administration with milk, eggs, tea, or coffee). Furthermore, patients receiving iron therapy must be warned about the serious, life-threatening CNS toxicity resulting from iron overdose, sometimes necessitating emergency treatment with chelating agents. Proper nursing care involves continuous monitoring of lab values and awareness of racial variations in hematological test results.