Drugs For Anemia

DRUGS USED TO TREAT ANEMIA Classification: A. Erythropoietin 1. Darbopoeitin alfa 2. Epoetin alfa (Epogen, Procrit) B. Iron Preparations 1. Ferrous fumarate 2. Ferrous gluconate 3. Ferrous sulfate 4. Ferrous sulfate exsiccated 5. Iron dextran 6. Iron sucrose 7. Sodium ferric gluconate complex C. Folic Acid Derivatives 1. Folic Acid 2. Leucovorin D. Vitamin B12 1. Cyanocobalamin 2. Hydroxocobalamin

I. A. Blood Components Blood  contains oxygen & nutrients essential for cell survival  delivers these to cells & removes waste products from the tissues. Blood- composed of : a. Plasma  mostly water • Also contain glucose, electrolytes & proteins for immune response & for blood clotting. b. Formed elements • Leukocytes (WBC) – impt part of immune system. • Erythrocytes (RBC) – carry O2 to tissues & remove CO2 for delivery to lungs. • Platelets – impt. part of coagulation, blood clotting. B. Erythropoiesis • Process of RBC production. • Produced in myeloid tissue of the bone marrow. • Controlled by Erythropoeitin. • Is a constant process  1% of body’s RBC are destroyed & replaced each day. Erythropoeitin  Released from kidneys in response to decreased blood flow in the kidneys.

Insert fig 49-1 p668 Mature RBC – has no nucleus  thus cannot reproduce. - average lifespan  120 days. II. Anemia  Decrease in number of RBCs • when erythropoeitin are low . • or lack of components needed to produce RBCs .  To produce healthy RBCs, the bone marrow must have the FF : 1. iron  used in forming hemoglobin rings to carry O2. 2. Vit B12 & Folic Acid  form supporting structure 3. Essential amino acids & carbohydrates.  Normally, diet supplies adequate amount but if inadequate  deficiency anemia. A. Iron Deficiency Anemia  Excessive blood loss or inadequate Fe in diet or malabsorption  negative Iron balance  Fe Deficiency Anemia Iron (Fe)  all cells in body require this .  At high levels  very toxic to cells, esp neurons. thus need to avoid toxic levels.  Body regulates Fe absorption thru intestinal absorption  once Fe absorbed  carried by transferrin to tissues , stored & eventually recycled.  About 1 mg Fe lost each day ( sweat, sloughed skin, GI & urinary tract lining) Tx: Iron replacement therapy B. Megaloblastic Anemia  Lack of Vit B12 or Folic Acid  needed to produce strong structure in RBC to survive 120 days in vascular system.  Cause slowing of nuclear DNA synthesis of human cells.  Produce large & immature RBCs with short lifespan.  Seen in rapidly dividing cells (BM & GIT) 1. Folic Acid Deficiency  Folic Acid  essential for cell division.  sources: green leafy vegetables, milk, eggs & liver. st  Seen 1 in rapidly growing cells ( cancerous tissues, GIT & BM)  Occur • Malabsorption state (Celiac & Sprue disease) • Malnutrition • Alcoholism • Repeated pregnancy • Chronic Tx of some antiepileptic drugs Tx: Folic Acid or Folate 2. Vitamin B12 Deficiency

 Vit B12  used in small amounts & stored for use if inadequate dietary intake.  impt for a heathy RBC & formation of myelin sheath in CNS.  sources: meat, seafoods, eggs & cheese.  Occur • Strict vegetarians • Pernicious Anemia  gastric mucosa cant produce Intrinsic factor  thus Vit B12 cant be absorbed.  Sxs: fatigue, lethargy, numbness, tingling, lack of coordination & motor activity. Tx: Vit B12 injections I. ERYTHROPOEITINS 1. Epoeitin Alfa a. Epogen b. Procrit 2. Darbopoeitin Alfa fig 49-2 p 671 & fig 49-3 p 672 1. Epoeitin Alfa • Stimulate RBC production in bone marrow. a. Epogen 1. Tx of anemia associated with renal failure. 2. Reduction in need for blood transfusions in surgical pxs. 3. Tx of anemia associated with AIDS therapy. • Halflife- 3-4 hrs Given 3x a week by IV or SC. b. Procrit 1. Tx of anemia associated with cancer chemotherapy. • Half-life-3-4 hrs  Given 3x a week by SC. 2. Darbopoeitin Alfa • Erythropoeitin-like protein  stimulate RBC production. • Produced in Chinese hamster ovary cells • Half-life- 4-13hrs Given once a week by IV or SC. • Cross into breastmilk  Tx of anemia associated with Chronic renal failure & dialysis pxs. Nursing Considerations: A. Before administration 1. Confirm the chronic, renal nature of px’s anemia to ensure proper use of drug. 2. Arrange for hematocrit reading to determine correct dosage. If no response within 8 wks, re-evaluate cause of anemia. 3. Know contraindications:  Uncontrolled hypertension  worsen HPN with increase RBC.  Allergy to mammalian cell-derived products or to human albumin.  Lactation  potential allergic reaction in neonate.

.

B. During 1. Give Epoeitin Alfa 3x a wk, Darbopoeitin Alfa once a week. Give calendar marked days to increase compliance. 2. Donot give with other drug solution avoid interaction. 3. Maintain seizure precautions on standby. C. After 1. Monitor for adverse effects.  CNS – headache, fatigue, asthenia,dizziness, serious seizures  GIT – n & v, diarrhea  CVS- hypertension, edema, chest pain

II. IRON PREPARATIONS • Fe Deficiency Anemia common in:  menstruating women  lose RBC monthly  pregnant & nursing mothers  increase demands  rapidly growing adolescents  persons with GI bleeding (NSAID induced) • • •

1. 2. 3. 4.

Increase serum iron concentration  either converted to Hgb or stored in RES for eventual use. Primarily absorbed from small intestine by active transport system  transported in blood bound to transferring. Small amounts of iron lost daily in :  sweat, urine, sloughing of skin & mucosal cells, sloughing of intestinal cells, menstrual flow in women. Ferrous fumarate Ferrous gluconate Ferrous sulfate Ferrous sulfate exsiccated  Tx of Iron deficiency anemia (IDA) • Oral preparation • Mostly lost in feces but some absorbed in intestine  transported in bone marrow. • Takes 2-3 wks upto 6-10 months to return to stable iron level.

5. Iron dextran  Tx of IDA • Parenteral form  used when oral form cant be tolerated. • If given IM  use Z-track method  stain tissues brown & can be very painful. • Cause severe hypersensitivity reaction. 6. Iron sucrose 7. Sodium ferric gluconate complex  Tx of IDA in px’s on chronic hemodialysis & who are receiving supplemental erythropoeitin therapy. • Given IV

Nursing Considerations: A. Before administering 1. Assess for contraindications.  Hemochromatosis  Hemolytic anemia  may increase serum Fe  cuase toxicity  Normal Iron balance  drug wont be absorbed & will just pass thru body  Peptic Ulcer, Colitis or regional enteritis  directly irritate tissues 2. Confirm IDA before administering drugs to ensure proper use. 3. Arrange Hct & Hgb count to monitor drug effectiveness. 4. Caution that stool may be dark or green. B. During 1. Administer with meals to relieve GI irritation. ( Avoid eggs, milk, coffee & tea.) 2. Have px drink solutions thru straw to prevent staining of teeth. 3. Dissolve ferrous salts in orange juice to improve taste. 4. Place iron drops on the back of the tongue to prevent staining teeth. 5. Administer IM by Z-track method only to avoid staining of tissues. C. After 1. Monitor for adverse effects & toxicity:  GIT- direct GI irritation  anorexia, n & v, diarrhea, dark stools & constipation  CNS –directly toxic  coma , death  Parenteral iron Severe anaphylactic reactions, local irritation, staining of tissues & phlebitis 2. Counteract Fe toxicity by giving chelating agent.. Chelating agents  Counteract metal toxicity (Fe, lead, arsenic, mercury, copper, gold)  Grasp & hold toxic metal  carried out of the body  prevents further damge to cells.  Excreted by kidneys. a. Deferoxamine mesylate  Counteract Fe toxicity. • given IM, SC or IV • rash & vision changes are common. b. Calcium disodium edentate  Counteract Lead toxicity • given IM or SC • monitor renal & hepatic fxn. c. Dimercaprol  for Arsenic, Gold, & mercury toxicity • given IM only for 7-10 days. • Cardiovascular toxicity may occur. • Push fluids & alkalinize urine to increase excretion. Clinically Drug-drug /Food Interactions:

1. Decreased Fe absorption when taken with antacids, tetracyclines, or cimetidine. Thus should be spaced at least 2 hrs apart. 2. Decrease antiinfective response to ciprofloxacin, norfloxacin or ofloxacin if taken with Fe. 3. Increase Fe levels if taken with chloramphenicol  monitor for toxicity. 4. Decrease effects of levodopa if taken with Fe. 5. Iron not absorbed if taken with antacids, eggs, milk, coffee or tea. IV. FOLIC ACID DERIVATIVES & VITAMIN B12 Folate deficiencies • Occur secondary to increase demands  pregnancy or growth spurts. • Absorption problems • Malnutrition secondary to alcoholism. Vitamin B12 deficiencies • Poor diet • Increased demand • Usual cause  lack of intrinsic factor in stomach. Folic acid & Vit B12 • Essential for cell growth & division. • For production of strong stroma in RBC. 1. Folic Acid • Given oral, IM, SC, IV • Parenteral form preferred for pxs with absorption problems.  Use as replacement therapy & Tx of Megaloblastic Anemia. 2. Leucovorin • Reduced form of folic acid. • Given oral, IM , IV  Use as replacement therapy & tx of Megaloblastic Anemia  Use as rescue after high dose chemotherapy allow noncancerous cells to survive • Methotrexate for osteocarcinoma • Fluorouracil for colorectal cancer 3. Hydroxocobalamin • Given IM everyday for 5-10 days, then once a month for life. • Cant be taken orally. • Highly protein bound  slowly released for use.  Traditional Tx of Pernicious Anemia & Vit B12 deficiency.  Use as replacement therapy in states of increased demands or inadequate diet. 4. Cyanocobalamin • Given IM or SC, intranasal gel, intranasal spray • Not as tightly bound to proteins  does not last long in body. • Intranasal spray  given once a week in 1 nostril.  Use as replacement therapy.

 Tx of Megaloblastic Anemia. Nursing Considerations: A. Before administration. 1. Confirm the nature of megaloblastic anemia to ensure proper drug regimen. 2. Assess for contraindication:  Allergies to drug  Use with caution in pregnant & lactating mothers.  Use with caution nasal form in pxs with nasal erosion or ulcers. 3. Screen baseline status: VS, Hct., Fe levels etc. B. During 1. Give both types of drugs in cases of pernicious anemia to ensure therapeutic effectiveness. 2. Parenteral Vit B must be given IM each day for 5-10 days, then once a month for life, if used to tx Pernicious anemia C. After 1. Monitor for adverse effects.  Pain & discomfort at injection sites.  Nasal irritation.  Hypersensitivity reactions.

.