Exam 4 - Growth Factors Flashcards
DRUG LIST
Iron, Folic Acid, Hydroxycobalamine,
Epoetin alpha, Darbepoetin, G-CSF, GM-CSF
Hematopoiesis Required Nutrients (3)
- iron (better absorbed as ferrous ion; Vit C/HCl aid)
- folic acid
- B12
Hematopoiesis
Growth Factors
- GCSF
- GM-CSF
- Epoetin
Iron
Metabolism
- absorbed best as Ferrous ion
- Acidity/Vit C aid in absorption
- no excretion; only lost by bleeding or sloughing
- transferrin transports iron to tissues
- ferritin protein is storage form
- apoferritin responds to iron levels
Iron
Acute Toxicity
- young children
- necrotizing gastroenteritis
- tx w/ chelation (deferoximine)
Iron
Chronic Toxicity
- “hemochromatosis”
- iron deposition in tissues
- tx w/ chelation, phlebotomy
Iron Therapy
Indications
- infants, children, pregnant/lactating women
- absorption (gastrectomy) d/o
- chronic bleeding
Iron Therapy
ADME
- Iron salts 25% absorbed
- GI distress may preclude optimal dose
- multiple salts available
- titrate dose up gradually
Iron Therapy
Tox/Side Effects
- epigastric distress
- abdominal cramps
- black stools
- take with meals (tho descreases absorption)
Iron Therapy
Alternatives
- for GI intolerance
- IM or IV Iron dextran
B12 Biochemistry
- B12 necessary for Methionine synth (SAM)
- B12 necessary for Purine Synth (via tetrahydrofolate)
- Deficiency inhibits DNA synth
- Deficiency has CNS effects
B12 Deficiency
- Dietary deficiency takes years
- Usually caused by IF deficiency (absorption)
- Recall: IF from parietal cells
- Aborption of IF/B12 complex in ileum
- transported on transcobalmin II
B12 Therapy
Administration Form
- inactive forms (Cyano- and Hydroxycobalamin)
- usually on tx for life for absorption pathology
- Folate tx can mask B12 deficiency (CNS sx not corrected)
Folate Deficiency
Clin/Sx
- neural tube defects in pregnancy
- anemia
- 400mcg needed/day to maintain levels
Folate
metabolism
-stored as polyglutamate
Folate Deficiency
Susceptible
elderly, alcoholics, pregnant, hemolytic anemia,
malabsorption syndromes, dialysis, phenytoin,
oral contraceptives, isoniazid
Folate Therapy
- pteroylglutamic acid
- folate reductase reduces x2 to tetrahydrofolate
Epoeitin A
Administration
- Medical recombinant version of erythropoietin
- different glycosylation patterns, seen on assay
- degraded in liver
- pair with Folate supplement
Epoeitin A
Indications
- anemia due to renal failure
- anemia due to AZT tx
- other anemias
Epoetin A
Toxicity
- HTN, thrombosis
- titrate slowly
- HTN-ive encephalopathy, seizures (w/ dialysis)
Darbopoetin alpha
- similar to epoetin A
- different glycosylation pattern, longer half-life
G-CSF/ GM-CSF
- produced in yeast/bacteria
- stims stem cells multiple lineages
- reduces neutrpenia after chemotx
- G-CSF more commonly used
G-CSF
- mobilizes ALL stem cells
- fewer adverse effects than GM-CSF
- bone pain, necrotizing vasculitis
GM-CSF
- worse side effects than G-CSF
- fewer stem cell lines stimulated
- flu-like syndrome
- prescribed far less often
- not sure why this is on the drug list
