Renal Pharm Flashcards
GFR is estimated by? How do we acquire this?
Creatinine Clearance
Acquire this by..
-direct collection (24 hr urine collection)
-Serum creatinine (requires adjustments)
The higher the Creatinine clearance the ____ kidney function The higher the serum creatinine the ____ kidney function?
WHats normal CrCl?
The higher the CrCl the better the kidney function.
The higher the SCr the worse the kidney function.
Normal SCr 0.6-1.3mg/dl
How do you calculate creatinine clearance?
CrCl (male)= [(140-age) x ideal weight (kg)]/72 X SCr(mg/dL)
CrCl (female) = 0.85 x male CrCl
- use ideal body weight unless their actual body weight is less than ideal.
- in pts over 18yrs old, if SCr less than 1.0, use 1.0
Example CrCl calculation
-83 yo female, SCr = 1.0, wt 103lbs, ht 5’3”
= [(140-83) x (46.2kg)] / (72 x 1.0mg/dl)] (0. 85)
= 31.5ml/min
Can you use serum creatinine as an accurate measure of renal function?
NOOOO WAAAYYYYY !!!!!!!
What would happen to creatinine clearance if you increased the age? decreased the weight?
- increase age: CrCl would be lower (think less nephrons)
- decreased weight: CrCl would be higher (think more muscle mass)
Do we calculate GFR on everyone??? Why?
NO! we only need to calculate GFR on pts who are older than 65 or w/ SrCr greater than 1.5.
Nephrotoxic agents causing Chronic Kidneys Dz
NSAIDS (blocks prostaglandins causing vasoconstriction of afferent arteriole leading to kidney damage)
Aminoglycosides (topicals do not have effects on kidneys)
Heavy Metals (Lead, gold, mercury)
Radiocontrast
Ethylene glycol (antifreeze)
How does Uremia affect protein/drug binding?
Uremia may inhibit or enhance protein binding, therefore more active drug is in the system
*drug is not active when bound to the protein
Why does decreased kidney function produce adverse reactions?
Because drugs that are usually filtered and excreted accumulate and could lead to AE and toxicity.
Some drugs have toxic effects at peak concentrations and some at trough concentrations. Example of each, please.
Imipenem can induce seizures at high concentrations.
Aminoglycosides can cause nephrotoxicity and ototoxicity with sustained trough levels above 2mcg/mL
What are the two methods of dose adjustment in Chronic Kidney Dz?
Smaller dose (reduce amount of each dose but interval time remains the same)
longer interval between doses (Q 24hrs instead of Q 12hrs, dose remains the same)
Is loading dose affected in patients with chronic kidney dx?
Despite renal failure, the loading dose is usually not different from normal….even though it should be adjusted.
In absence of loading dose, maintenanec doses will achieve 90% of their steady state level in ___ half lives?
-3.3 half lives
When do we give medications to dialysis patients?
-AFTERWARDS!!!!!!!!!
Unless otherwise noted, one can assume that dose modification is not necessary for patients with GFR of _____.
greater than 50
Drugs that should be avoided in severe kidney dz?
- Metformin
- Aspirin, NSAIDS
- Acetazolamide
- Spironolactone
- Thiazide Diuretics
- Bretylium
Abx drugs that do NOT require dosage adjustment with chronic kidney dz
Azithromycin (Macrolide; protein synthesis inhibitor)
Ceftriaxone(Rocephin) (Cephalosporin, interferes with Cell wall synthesis, 3rd gen)
Moxifloxacin (FQ, tendone rupture, inhibit DNA gyrase)
Doxy (tetracycline, gray teeth and weak bones less than 8 yrs)
What is the GFR at each stage of kidney disease?
- Kidney damage w/ normal or increased GFR
- Kidney damage with mild or decreased GFR
- Moderate decreased GFR
- severely decreased GFR
- Kidney failure
- GFR greater than or equal to 90ml/min
- 60-89ml/min
- 30-59ml/min
- 15-29ml/min
- less than 15ml/min
