Exam 2: Dosage adjustment in kidney failure and disease DSA Flashcards
What are patient risk factors for developing drug-induced nephrotoxicity?
- “Absolute” or “effective” intravascular volume depletion
- Age older than 60 years
- Diabetes
- Exposure to multiple nephrotoxins
- Heart failure
- Sepsis
- Underlying renal insufficiency (glomerular filtration rate < 60 mL per minute per 1.73 m 2)
What are common prevention strategies to avoid drug-induced nephrotoxicity?
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Adjust medication dosages using
- the Cockcroft-Gault formula (in adults)
- or Schwartz formula (in children).
- Assess baseline renal function using the MDRD equation
- consider patient’s renal function when prescribing a new drug.
- Avoid nephrotoxic combinations.
- Correct risk factors for nephrotoxicity before initiation of drug therapy.
- Ensure adequate hydration before and during therapy with potential nephrotoxins.
- Use equally effective non-nephrotoxic drugs whenever possible.
Name some classes of medications that are known to cause drug-induced nephrotoxicity.
medications that are inherently nephrotoxic and prevention strategies:
ACE inhibitors, ARBs, NSAIDs
- Use analgesics with less prostaglandin activity (acetaminophen, aspirin, sulindac [Clinoril], nabumetone [Relafen; brand not available in the United States])
- Correct volume depletion before initiation of drug, especially if used on a chronic basis
- Monitor renal function and vital signs following initiation or dose escalation, especially if used in at-risk patients
medications that are inherently nephrotoxic and prevention strategies:
Cyclosporine, tacrolimus
- Monitor serum drug concentrations and renal function
- Use lowest effective dose
medications that are inherently nephrotoxic and prevention strategies:
Acetaminophen, aspirin, NSAIDs
- Avoid long-term use, particularly of more than one analgesic
- Use alternate agents in patients with chronic pain
medications that are inherently nephrotoxic and prevention strategies:
Lithium
- Maintain drug levels within the therapeutic range
- Avoid volume depletion
medications that are inherently nephrotoxic and prevention strategies:
Acyclovir (Zovirax), methotrexate, sulfa antibiotics, triamterene (Dyrenium)
- Discontinue or reduce dose
- Ensure adequate hydration
- Establish high urine flow
- Administer orally
If you needed to start a patient on Gentamicin, what would you do?
- First get all necessary information
- My motto is “ No labs???? – No gent”
- I also get the height, weight, allergies first
- Calculate my dose
- I will spare you the pain of dosing gent! Order written “Gent per pharmacy”
- Common strategy give 6-8 mg/kg IBW (Ideal body weight) or ABW (Adjusted body weight), do a level around 10 hours, use a chart and figure out dosing interval
- Monitor BUN/Scr 2-3 times/week
- Monitor gent trough levels 2-3 times/week
- Give in the morning
- If the treatment has a treatment range, give for shortest length possible
- If range is 4-6 weeks, give only 4 weeks
- Use extended-interval dosing
- Basically means use the longest dosing interval
- If package inserts says Q8h-q12h, give q12h
medications that are inherently nephrotoxic and prevention strategies:
Aminoglycosides
- Use extended-interval dosing
- Administer during active period of day
- Limit duration of therapy
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Monitor serum drug levels and renal function
- 2-3 times per week
- Maintain trough levels ≤ 1 mcg per mL
If you needed to start a patient on Amphotericin B, what would you do?
- Would call the doctor and say “Are you sure? —O.K. —What are we treating?”
- I call this Ampho-terrible?
- I would get a height, weight, allergies, medical diagnosis
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Make sure patient is stable before administering medication.
- cardiac, resp, renal
- Most infectious disease doctors only order the liposomal product due to less risk of nephrotoxicity.
- Make sure of this with clinician because they are dosed differently.
- Give a test dose if possible.
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Hydrate patient before and after dose.
- Usually 250 ml NS before and after if patient can tolerate it. If not, administer as a continuous infusion.
- Make sure we are giving the smallest dose in our range and for the shortest duration in our range.
- Consider administering as a continuous infusion over 24 hours
- Example 200-400 mg continuous infusion for 2-4 weeks
- Give 200 mg continuous infusion for 2 weeks
- Read package insert carefully !
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Re-educate my pharmacists/technicians making the medication. Educate my nurse
- that this medications requires a filter
- by phone AND by label!
If you needed to perform a CT scan with IV Contrast on a patient, what would you do?
- First, I check their medications.
- Are they on any medications that should not be given within 48 hours of contrast media? (mainly metformin)
- Second, allergies. Do they have ANY allergies? Have they ever received contrast media and did they have a reaction?
- What co-morbidities do they have and what do we need to do about it? (diabetes, kidney disease, pheochromocytoma, solitary kidney, transplant patient, myeloma)
- Any chance they may be pregnant? Still get a pregnancy test.
- Can cause hypothyroidism in the neonate
- Do I need to check Scr before giving contrast media? If they have any of these risk factors, I would.
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Risk factors:
- > 60 years old, history of renal insufficiency, DM, hypertension
- Can I give dye in patients with risk factors? YES…. But….
- Adequate hydration
- Give a smaller dose of contrast
- Discontinue other nephrotoxic drugs
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Risk factors:
- Use low-osmolar contrast in the lowest dose possible and avoid multiple procedures in 24 to 48 hours
- 0.9% saline or sodium bicarbonate (154 mEq per L) infusion before and after procedure
- Withhold NSAIDs and diuretics at least 24 hours before and after procedure
- Monitor renal function 24 to 48 hours postprocedure
- Consider acetylcysteine preprocedure
We adjust most medications by?
- Decreasing the dose
- Increasing the dosing interval
Calculating Creatinine Clearance
Calculate BMI
Metric BMI Formula
BMI = weight (kg) ÷ height2 (m2)
Imperial BMI Formula
BMI = weight (lb) ÷ height2 (in2) × 703
