Pharm Flashcards
form of iron most easily absorbed
Ferrous iron Fe2+
Goals of therapy for iron deficient anemia
- Replenish iron stores
- Improve sx
- Treat underlying cause of IDA (must ID cause!!). In men and non-menstruating women new onset IDA need to rule out blood loss from occult GI malignancy or other bleeding lesion
- Prevent organ damage, ischemia, progression of anemia
Iron deficient anemia Indications for Oral therapy for
- IDA
- IDA w/o anemia
- Nutritional support to prevent deficiency
Iron deficient anemia
indications for parenteral therapy
- GI intolerance of oral iron therapy
- Preference to replenish iron stores in 1-2 visits vs. several months
- Mal-absorption syndromes
- Long-term non-adherence
- Ongoing blood loss that exceeds the capacity of oral iron to meet needs
- Refusal to accept blood transfusions for a significant blood loss
- Anemia due to chronic kidney disease, esp undergoing hemodialysis
- CA pts receiving chemo on EPO-stimulating agents
- Co-existing inflammatory state that interferes with iron homeostasis
How is dietary supplementation used in treatment of iron deficient anemia
Never used alone, only in addition to iron supplementation
Recommendations for children dietary intake to avoid iron deficient anemia
- <12 months fed breast milk or iron-fortified formula
- cow’s milk ok if no evidence of cow’s milk protein-induced colitis
- Infants should not be given low-iron formula or unmodified cows milk
- 6+ months, esp breastfed, ensure adequate iron consumption in food (fortified cereals, meats)
- 12+ months: cow’s milk limited to no more than 20 oz a day (higher intake of milk related to increased risk for iron deficiency)
Oral Iron
- OTC
- Avoid slow release or sustained-release products
- Soluble Fe2+ iron salts are best
- % of elemental iron will differ by salt
Oral Iron Dosing
- Depends on age, estimated iron deficit, speed needs to be corrected, and tolerance - Traditional: 150-200 mg elemental iron daily in 2-3 divided doses
- Fall 2017 Update: lower dose (40-80 mg/daily) every other day
Older patient oral iron dosing
lower doses may be needed to avoid toxicity and ADE
Children patient oral iron dosing dose forms
tabs
liquid (drops, elixer, syrup)
duration of oral iron therapy
- Differs among experts and in different settings
- Some stop when hgb normalizes bc allows earlier detection of recurrent anemia
- Others treat 6 montsh past hgb normalization to completely replenish iron stores and to prevent relapse
** Might take 6-8 weeks to fully ameliorate anemia and as long as 6 months to replete iron stores
monitoring parameters oral iron therapy - adults
list two labs and one other thing to check
- Hgb
- Reticulocytes
- Ability to tolerate iron
Monitoring parameters for oral iron therapy
- Hgb
- will rise slowly after 1-2 weeks of treatment
- should rise by 2 g/dL over three weeks
- 50% correction after a month
- normal after 6-8 weeks
Monitoring parameters for oral iron therapy
- reticulocyte count
should peak 7-10 after treatment initiated, is a good sign of response to therapy (mod to severe)
Monitoring parameters children with mild anemia
(Hgb ≥ 9 g/dL)
Hgb or CBC 4 weeks after therapy, should see hgb rise of >1g/dL
Monitoring parameters children with moderate to severe anemia
(Hub < 9 g/dL)
- Rise in retic in 72 hours
- Check Hgb or CBC 1-2 weeks after treatment starts, Hgb should rise at least 1 g/dL within 2 weeks
- Check CBC, Hgb, MCV, RDW, serum ferritin 3 months after starting treatment
- Continue iron supplements additional month after all parameters normalize to ensure replacement of body stores
- F/u essential to confirm anemia was due to iron deficiency and that it was adequately treated (neuro deficits d/t iron deficiency!!)
Potential oral iron drug interactions
- Aluminum, magnesium, calcium containing antacids (give Fe 2 hrs before or 4 hrs after ingestion of antacids)
- Tetracycline and doxycycline
- OTC acid blockers (ranitidine, famotidine)
- PPI (omeprazole)
- Cholestyramine (bile acid binder)
How to calculate amount of elemental iron in a dose of oral iron salt
% elemental Fe X dose
Ferrous sulfate example of how to calculate elemental iron
Dose - 325 mg
% elemental Fe - 20-30%
Fe per tablet
(325)(20%) = 64 mg
what factors affect bioavailability and absorption of iron
- Some foods inhibit absorption
- vitamin C enhances absorption
- best absorbed as Fe2+ in mildly acidic stomach (empty stomach)
- divide daily dose into multiple doses: percent of iron decreases as the dose increases
Foods to avoid with oral iron
- calcium containing foods like milk, yogurt, cheese
- calcium supplements including antacids
- dietary fiber
- tea and coffee
- eggs
List 5 reasons for oral iron treatment failure
- Non-adherence!!
- Misdiagnosis
- Mal-absorption due to previous gastrectomy, celiac disease, inflammatory bowel disease,
- Blood loss equal to rate of production
- Impaired response when coexisting cause for anemia exists
List of 3 common reasons for oral iron treatment in kids
- Cow’s milk protein-induced colitis
- Celiac disease
- Inflammatory bowel disease
- ID the foods that should be recommended to improve iron deficient anemia
Animal products (heme) are more easily absorbed
- Meat
- Fish
- Poultry
Plant products (non-heme)
- Eggs (not a plant but non-heme)
- Vegetables
- Fruits
- Legumes
- Enriched breads and cereals
- Other: molasses, peanuts, pine nuts, etc.
oral iron therapy ADE
- GI side effects most common (dark feces, constipation/diarrhea, nausea, vomiting
- Metallic taste
- Epigastric distress
- Flatulence
- Black/green tarry stools that stain clothing ☹
- Children: liquid preps can stain teeth and hands if suck
Strategies to improve tolerability of oral iron
- Take iron with meals or reduce daily dose
- Gradually increase dose of iron to minimize GI effects (easier to titrate on liquid than tablet)
- Stool softeners are largely ineffective
- Make dietary modification: take with food or milk (might reduce absorption)
- Switch to formulation with lower amt of elemental iron
- Consider IV iron which does not have GI side effects (if switch, discontinue oral iron)
Goal of Vitamin B12 therapy
- Reverse hematologic manifestations
- Replace vitamin B12 body stores
- Prevent or resolve neurologic manifestations
Foods that should be recommended to improve vitamin B12 deficiency
- Meat, organs, clams
- Fortified breakfast cereals
- Fish: rainbow trout, sockeye salmon, canned tuna
- Milk and yogurt
Vitamin B12 forms
- Liquid
- Tablet
- Lozenge
- Injection
- Nasal spray
- Sublingual tablet
Pernicious Anemia B12 treatment dose
- 1000 mcg every day for a week
- then 1 mg every week for four weeks
- 1 mg for month if needed
Bariatric surgery B12 treatment dose
- Oral 350 – 500 mcg daily
- 1000 mcg IM of SQ monthly
- 1 per week nasal spray
Oral B12
- good for what diet
- what is required
- avoid what
- Good for vegetarians
- Requires much greater adherence
- Avoid timed release
Response to B12 tx
- Markers of hemolysis: serum iron, indirect bilirubin and LDH will fall rapidly after parental B12
- Retic count changes from megaloblastic to normoblastic within 3-4 days
- Anemia improves 1-2 week and normalizes 4-8 weeks. Will feel better before any blood work changes
- Hypokalemia during first week due to increase in K+ use during production of new hematopoietic cells
- Neuro abnormalities, if present, improve over 3 months, max improvement 6-12 months
Goals of folic acid deficiency anemia treatment
- Induce hematologic remission
- Replace folic acid body stores
- Resolve signs & symptoms of folic acid deficiency
drugs that may either interfere with the absorption of or antagonize the actions of folic acid
a. Phenytoin and other anticonvulsants
b. Oral contraceptives
c. Methotrexate
d. Trimethoprim
e. alcohol
Three factors that place pt at risk for folic acid deficiency
- Impaired absorption
- Increased requirement
- Impaired utilization
Impaired absorption for folic acid
- Intestinal short circuits
- Celiac disease
- Inflammatory bowel disease, infiltrative bowel disease
Increased requirement for folic acid
- Pregnancy
- Infancy
- Growth spurts in adolescent
- Hemolytic anemia
- Neoplastic disease (leukemia, lymphoma)
- Chronic inflammatory diseases
Impaired utilization of folic acid
- Folic acid antagonists
- Increased loss
- hemodialysis
foods that should be recommended to improve folic acid deficiency
- Dark leafy greens, broccoli, asparagus, carrots, celery, avocado, beets
- Fruit: papaya, orange, grapefruit, strawberries
- Legumes
common signs and symptoms of folic acid deficiency
- Fatigue, pallor, tachycardia, pale mucous membranes, SOB, cardiac decompensations, dizziness, lightheadedness, weakness
- Dysphagia, anorexia, weight loss, beefy red tongue, personality changes, ecchymosis, purpura
- Loss of skin elasticity, early graying hair
What is major sx diff between vitamin B12 deficient anemia and folic acid deficient anemia
neuro sx in B12 but not folic acid
Folic acid deficient anemia lab findings
- Increased MCV, MCH (macrolytic anemia)
- Decreased serum folic acid level, retic count, Hgb, Hct, RBC
Folic acid dosing
- Deficient anemia
- Megaloblastic anemia from anticoag therapy
- Pregnant/lactating women
- Women of childbearing age
- High risk females
- 1 mg daily for megaloblastic and macrolytic anemia due to folic acid deficiency
- 0.5 mg daily for megaloblastic anemia from anticonvulsive therapy
- Pregnant/lactating women: 800 mcg/day
- Females of childbearing potential: 400 to 800 mcg/day to prevent neural tube defects
- High risk females (previous preg with neural tube defects, hx of neural tube defects) 4 mg/day
Duration of folic acid treatment
- 1-4 months to restore folic acid stores
- chronic therapy when not possible to correct underlying problem
Monitoring parameters for folic acid treatment
- Should feel better in 2-3 days
- Peak retic response in 7-10 days
- Hct and Hgb should increase within two weeks
(Recheck in 2-4 weeks after starting therapy)
Mechanism of ESA (anemia of chronic disease)
- Same biological effect as EPO produced by the kidney
- Stimulates division/differentiation of erythroid progenitors in bone marrow
Monitoring parameter for anemia of chronic disesae
- Hgb must be monitored
What are Hgb goals for anemia of chronic disease treatment
- Not to exceed 12 g/dL with treatment
- Hgb should not increase more than 1 g/dL every two week
