Ch 49 -Drugs Used To Treat Anemias Flashcards
What is anemia? What is the etiology of anemia? Types of Anemia?
Anemia results from some alteration in erythropoiesis, the process of RBC production, which occurs in the myeloid tissue of the bone marrow. The rate of RBC production is controlled by the glycoprotein erythropoietin, which is released from the kidneys in response to dec blood flow or dec oxygen tension in the kidneys. Average lifespan of RBC is 120 d
Etiology is anemia can occur if erythropoietin levels are low. To produce healthy RBC the bone marrow must have - adequate amounts of iron, minute amounts of vit b12 and folic acid, essential amino acids and carbohydrates to complete the hemoglobin rings, cell membrane, and basic structure. Mostly the body is able to supply from diet alone but if it can’t it can develop into anemia. Three anemia’s - iron deficiency anemia - is a common problem in certain groups menstruating women, pregnant and lactating women, rapidly growing adolescents, pts with gi bleeding. Megaloblastic anemia - result from insufficient amounts of folic acid or vit b12 to adequately create the stomach structure needed in the healthy RBC, causing a slowing of nuclear DNA synthesis. This effect occurs in rapidly dividing cells such as the bone marrow. It contains a large number of megaloblasts (immature RBCs) they become crowded in the bone marrow and fewer RBC are produced, increasing the amount of immature cells in circulation. Malabsorption is the major cause (pernicious anemia is when the gastric mucosa cant produce intrinsic factor to absorb vit b12). Sickle cell anemia is a chronic hemolytic anemia that occurs almost exclusively in African Americans and is characterized by a genetically inherited hemoglobin S,which gives RBC s a sickle shaped appearance.
What are erythropoiesis - stimulating agents? Epoetin alfa
Pts who are no longer able to produce enough erythropoietin in the kidneys may benefit from treatment.
Epoetin Alfa - 50-100 units/kg IV or sc 3 x week, 300 units/kg/d sc for 15d
Indications: Treatment of anemia associated with chronic renal failure, related to treatment of HIV infection or to chemotherapy in cancer pts; to reduce the need for allogenic blood transfusions in surgical pt.
Actions: Natural glycoprotein that stimulates RBC production in the bone marrow.
Pharmacokinetics: Route SC Onset 7-14 d, Peak 5-24 hr, Duration 24 h.
T1/2: 4-13 hrs; metabolized in the serum and excreted in the urine.
Adverse effects: Headache, arthralgias, fatigue, Athenian, dizzziness, hypertension, edema, chest pain, nausea, vomiting, diarrhea.
What are agents used of iron deficiency anemia? Ferrous fumarate, Ferrous sulfate.
Although most people get enough iron through diet some situations diet alone may not be adequate.
Ferrous fumarate - 100-200mg/d Po. Treatment of iron deficiency anemia.
Ferrous sulfate - 100-200 mg/d Po.
Indications: Prevention and treatment of iron deficiency anemia; dietary supplement for iron.
Actions: Elevates the serum iron concentration and is then converted into hemoglobin or stored for eventual conversion to a usable form of iron.
Pharmacokinetics: Route PO, Onset 4 d, Peak 7-10 d, Duration 2-4 mo.
T1/2: Not known; recycled for use, not excreted.
Adverse effects; Gi upset, anorexia, nausea, vomiting, constipation, diarrhea, CNS toxicity progressing to coma and death with overdose.
Drug-drug: iron absorption dec if taken with anti acids, tetracyclines, or cimetidine if used should be administered 2 hours apart.
Drug-food: iron is not absorbed if taken with antacids, eggs, milk, coffee or tea.
What are agents for megaloblastic anemia’s? Folic acid Derivatives (folic acid), Vitamin B12.
Is treated with folic acid and vitamin B12. They usually occur secondary to inc demand; as a result of absorption problems in the small intestine; because of drugs that cause folate deficiencies; or secondary to the malnutrition of alcoholism. Vitamin B12 can be result from poor diet or inc demand but they are usually caused by lack of intrinsic factor in the stomach.
Folic acid - 1 mg/d PO,IM, SC or IV.
Vitamin B12 - nasal spray (cyanocobalamin) one spray in one nostril once a week. - Hydroxocobalamin - 30 mcg/d IM for 5-10 d, then 100-200 mcg, mo IM
Folic acid
Indications: Treatment of megaloblastic anemia due to spruce, nutritional deficiency.
Actions: Reduced form of folic acid, required for nucleoprotein synthesis and maintenance of normal erythropoiesis.
Pharmacokinetics: Route PO, IM SC, IV; Onset Varies; Peak 30-60 min
T 1/2: Unknown; metabolized in the liver and excreted in the urine.
Adverse effects: Allergic reactions, pain and discomfort at injection site.
Hydroxocobalamin
Indications: Treatment of vitamin B12 deficiency; to meet pregnancy or blood loss.
Actions: Essential for nuclei acid and protein synthesis used for growth, cell reproduction, hematopoiesis, and nucleoprotein and myelin synthesis.
Pharmacokinetics: Route, IM; Onset Intermediate; Peak 60 mins.
T1/2: 24-36 hours; metabolized in the liver and excreted in the urine.
Adverse effects: Itching, transitory exanthema, mild diarrhea, anaphylactic reaction, heart failure, pulmonary edema, hypokalemia, pain at injection site.
What is the agent for sickle cell anemia? Hydroxyurea.
They are treated with antibiotics to help fight the infections that can occur when blood flow is dec to any area; with pain-relieving activities to help alleviate the pain associated with the anoxia to tissues, which can range from heat applied to the area to OTC pain meds to prescription opioids and hydroxyurea.
Hydroxyurea
Indications: Reduction of frequency of painful crisis and need for blood transfusions in adult pt with sickle cell anemia.
Actions: Inc fetal hemoglobin production in the bone marrow and dilutes the formation of abnormal hemoglobin S.
Pharmacokinetics: Route PO; Onset Varied; Peak 1-4 h; Duration 18-20 h.
T1/2: 3-4 hours; metabolized in the liver and excreted in the urine.
Adverse Effects: Dizziness, headache, rash, erythema, anorexia, nausea, vomiting, stomatitis, bone marrow depression, cancer.
