Pharmacology for Hematology Flashcards
how does erythropoietin affect RBC values?
anemia is caused by low RBC production, causing low oxygen capacity of the blood and decreased tissue oxygenation, this sends a signal to the kidneys causing the kidneys to increase secretion of EPO which stimulates production of RBCs
what is required for RBC production?
Iron, B12, Folic acid and Heme
where does Heme iron come from?
diet and meat, has a 30-40% absorption
where does non Heme iron come from?
vegetarian diet, lentils, 10% absorption
where is iron absorbed?
duodenum and proximal jejunum
what is iron absorption regulated by?
hepcidin made by liver
how is iron replaced?
oral (preferred), IV
who needs IV iron?
intolerance to oral products, malabsorption due to IBD or gastric bypass, nonadherence, refusal for blood transfusions
how do you increase iron absorption when takin iron PO?
take on empty stomach and with vitamin C
what are some examples of oral iron preparations?
ferrous fumarate, ferrous gluconate, ferrous sulfate
what drugs decrease iron absorption?
aluminum, magnesium and calcium containing antacids, tetracycline and doxycycline, histamine 2 antagonists, PPI, cholestyramine
when should iron PO be taken?
1-2 hours separate from other medications
question about
IV iron
question about
iv iron
question about iv iron
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question about
iv iron
what are adverse reactions associated with PO iron?
constipation, tarry stool, nausea, epigastric pain, cramps, diarrhea
what are adverse reactions associated with IV iron?
infusion reactions, arthralgia, myalgia, fever, costly
when do you follow up for PO iron and what labs do you get?
2 weeks, CBC and reticulocyte count, assess tolerance
when do you follow up for IV iron and what labs do you get?
4-8 weeks, CBC, reticulocyte count and iron panel
what are the different colorectal screening guidelines for different organizations?
USPSTF: (B) 45, (A) 50
ACG: 45
ACS: (B) 45, (A) 50
ACP/AAFP: 50
discontinue at 75 unless greater than 10 year life expectancy
describe acute iron posioning
most commonly an accidental overdose by young children, direct caustic injury to GI mucosa, cellular toxin impairing metabolism
how do you treat acute iron poisoning?
whole bowel irrigation NOT activated charcoal, IV iron chelating agents, supportive therapy
describe stage 1 of iron toxicity
30 mins - 6 hours
local toxicity, n/v, diarrhea, abdominal pain, GI bleeding
describe stage 2 of iron toxicity
6 - 24 hours
latent toxicity, resolution of local toxicity with ongoing cellular toxicity, hypovolemia, poor tissue perfusion, metabolic acidosis and high lactate
describe stage 3 of iron toxicity
12- 24 hours
systemic toxicity, shock, acidosis, coagulopathy, coma, multisystem failure
describe stage 4 of iron toxicity
2-3 days
hepatic failure
describe stage 5 of iron toxicity
3-6 weeks
long term sequelae, gastric outlet obstruction, small bowel obstruction, CNS sequelae
what can cause megaloblastic anemia?
vitamin B12, folate or copper deficiency, medications that interfere with DNA synthesis
what are the symptoms of macrocytic anemias?
decreased WBC, glossitis, neurocognitive changes with B12 deficiency, neural tube defects with folate deficiency during embryogenesis
describe pernicious anemia
auto antibodies against parietal cells that make intrinsic factors causing B12 to not be able to be absorbed
how do you treat vitamin B12 deficiency?
supplement - 1000 mcg daily or 2000 if impaired absorption
IM - 1000 mcg weekly for 4 weeks and then monthly
how do you treat folate deficiency?
0.2 mg PO is recommended daily for all people, 1-5 mg for deficiency and 0.4 mg for pregnancy, IV
what is important to note in concomitant B12 and folate deficiency?
folate supplementation may reverse hematological abnormalities but will not correct or stop neurological manifestations of B12 deficiency
what medications can interfere with folate metabolism?
methotrexate, antibiotics (trimethoprim, pyrimethamine), antiseizure agents (phenytoin, valproate, carbamezepine)
when should erythropoietin stimulating agents be considered?
when hemoglobin is <10gm/dL, use smallest dose to prevent repeat RBC transfusions
what are erythropoietin stimulating agents contraindicated in?
patients with active or recent malignancy due to risk of progression and recurrence
why is there an FDA black box warning for erythropoietin stimulating agents?
chronic kidney disease patients experienced greater risks for death, serious adverse cardiovascular reactions and stroke when administered to target a hemoglobin level of greater than 11
describe erythropoietin stimulating agents
all are subq
epoetin alfa (epogen, procrit)
epoetin alfa-epbx (retacrit)
darbepoetin alfa (aranesp)
methoxy PEG - epoetin beta (mircera)
dosed 3 times weekly to monthly depending on medication