chapter 55
DESCRIPTION
Chapter 55. Drugs for Deficiency Anemias. Anemias. Decrease in erythrocytes (RBCs) Number Size Hemoglobin content Causes Blood loss Hemolysis Bone marrow dysfunction Deficiency of substances essential for RBC formation and maturation. Red Blood Cell Development. - PowerPoint PPT PresentationTRANSCRIPT
Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Chapter 55
Drugs for Deficiency Anemias
2Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Anemias Decrease in erythrocytes (RBCs)
Number Size Hemoglobin content
Causes Blood loss Hemolysis Bone marrow dysfunction
• Deficiency of substances essential for RBC formation and maturation
3Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Red Blood Cell Development Development begins in the bone marrow Matures in the blood Evolves through four stages Healthy development requires:
Healthy bone marrow erythropoietin, iron, and other factors to support DNS synthesis
4Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Biochemistry and Physiology of Iron
Metabolic functions Fate in the body
Uptake and distribution• Uptake into mucosal cells in small intestine• Undergoes storage within mucosal cells• Undergoes binding to transferrin
Utilization and storage• Taken up by cells of the bone marrow• Taken up by the liver and other tissues• Taken up by muscle
5Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Iron in the Body Fate in the body (cont’d)
Recycling: undergoes continuous recycling Elimination: 1 mg of iron excreted each day Regulated through control of intestinal absorption
6Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Iron Deficiency Most common nutritional deficiency and
cause of nutrition-related anemia Causes Consequences Diagnosis
7Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Iron Daily requirements
Determined by rate of erythrocyte production Increased requirement during pregnancy
Dietary sources Available in foods of plant and animal origin
8Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Iron Deficiency: Causes, Consequences, and Diagnosis
Results from an imbalance in iron uptake and iron demand
Causes Pregnancy (blood volume expansion) Infancy and early childhood Chronic blood loss
Consequences Microcytic, hypochromic anemia
9Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Iron Deficiency: Causes, Consequences, and Diagnosis
Diagnosis Presence of microcytic, hypochromic erythrocytes Absence of hemosiderin in bone marrow Other laboratory work
• RBC count • Reticulocyte count• Hemoglobin• Hematocrit• Serum iron• Increased serum iron-binding capacity (IBC)
10Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Oral Iron Preparations I: Iron Salts Ferrous sulfate
Indications—drug of choice Prophylactic therapy
Adverse effects GI disturbances Staining of teeth Toxicity
11Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Oral Iron Preparations I: Iron Salts Drug interactions
Antacids Tetracycline Ascorbic acid
Other oral iron salts Ferrous gluconate, ferrous fumarate, and ferrous
aspartate Carbonyl iron
12Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Parenteral Iron Preparations I: Iron Dextran
Iron dextran (INFeD, DexFerrum) Used for patients who have experienced
intolerable or ineffective oral dosing Adverse effects
Anaphylactic reactions Hypotension Persistent pain with IM injection
13Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Parenteral Iron Preparations II: Sodium Ferric Gluconate Complex and Iron Sucrose
Alternatives to iron dextran Sodium ferric gluconate (SFGC) (Ferrlecit)
• Low risk of anaphylaxis Iron sucrose (Venofer)
• Limited to patients undergoing chronic hemodialysis• All patients must also receive erythropoietin
Most common side effects Hypotension Cramps
Ferumoxytol Approved in 2009 Iron deficiency anemia, chronic kidney disease (CKD)
14Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Iron Deficiency Treatment Guidelines Assessment Routes of administration Duration of therapy Therapeutic combinations
15Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Vitamin B12 (Cobalamin)
Essential for synthesis of DNA Absorption requires intrinsic factor Elimination takes place very slowly Daily requirement Dietary sources
Limited to microorganisms Animal products (liver, dairy products) Fortified foods
16Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Vitamin B12 (Cobalamin)
Fate in the body Absorption Distribution and storage Elimination
17Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Vitamin B12 Deficiencies: Causes, Consequences, and Diagnosis
Causes Usually result of impaired absorption Regional enteritis Celiac disease Absence of intrinsic factor
18Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Vitamin B12 Deficiencies: Causes, Consequences, and Diagnosis
Consequences Megaloblastic anemia Neurologic damage
• Demyelination of neurons GI disturbances
Diagnosis Measurement of plasma B12
Schilling test
19Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Vitamin B12 Preparations: Cyanocobalamin
Administration• Oral, parenteral, intranasal
Adverse effects • Hypokalemia
Long-term treatment• With lack of intrinsic factor, vitamin B12 therapy
lifelong• Potential hazards of folic acid
20Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Guidelines for Treating Vitamin B12 Deficiency
Route of B12 administration Treatment of moderate B12 deficiency Treatment of severe B12 deficiency Long-term treatment Potential hazard of folic acid
21Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Folic Acid Deficiency Folic acid
Essential factor for DNA synthesis• DNA replication• Cell division cannot proceed
Absorbed in the early segment of the small intestine
Significant amounts excreted daily Daily requirements Dietary sources: all foods
22Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Folic Acid Anemia: Causes and Consequences
Causes Poor diet (malnutrition and alcoholism) Malabsorption syndrome (sprue)
Consequences for developing fetus Neural tube defects (eg, spina bifida,
anencephaly) Adequate intake before conception is critical The USPSTF now recommends that women of
child-bearing age consume 400 to 800 mcg of supplemental folate each day, in addition to the folate they get in food
23Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Folic Acid Anemia:Causes and Consequences
Consequences for anyone Megaloblastic anemia Leukopenia, thrombocytopenia, injury to the oral
and GI mucosa May increase risk of colorectal cancer and
atherosclerosis
24Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Folic Acid Preparations Nomenclature Folic acid (pteroylglutamic acid)
25Copyright © 2013, 2010 by Saunders, an imprint of Elsevier Inc.
Guidelines for Treating Folic Acid Deficiency
Choice of treatment modality Route of administration Prophylactic use of folic acid Treatment of severe deficiency