The Kidney & Drugs Flashcards
Why is the kidney imporant?
eliminates drugs, if it doesnt work there is toxicity
Most important way of eliminating drug from the body is…..
renal clearance
Glomerular Filtration Rate- GFR
measure of how well the kidney is filtering blood
Can not measure GFR- but can measure creatine clearence
Decrease in GFR=
kidney dysfunction
Creatinine
prodcut of creatine which is produced by the liver
Creatinin is filtere at glomerulus where it is secreted
As SCR increases
GFR decrease
Good range of GFR
1-1.4
Stages of Kidney Function
Stage 1: 90-120cc/min (or ml/min) normal function
Stage 2: 60-89cc/min=mild dysfunction
Stage 3: 30-59cc/min=moderate dysfunction
Stage 4: 15-29cc/min=severe dysfunction
Stage 5:
Second way of classifying Kidney Function
Renal insufficiency 30-90cc/min (Stage 2 & 3)
Renal failure
3 Ways of Measuring CrCl
1) Serum Cr- rough estimate, basic metabolic panel, draw blood, LEAST ACCURATE
2) Equations- serum Cr plugged into equation
3) 24 hour urin collection- not acurate b/c hard to do
Cockcroft-Gault Equation
Estimate GFR from serum CR
Approach to adjusting meds
figure out CrCL
acute change (acute renal failure)- equation does not work, need to see specialist
chronic change- chronic renal insufficiency or chronic renal failure
Chronic Renal Failure Adjustment
if kidney failure- estimate CrCl w/ equation- review drugs and dose based on literature
monitor for response and toxicity
get serum drug level
How should you change the dose?
decrease mg each time dosed
OR
increase dosing interval- this is prefered- easier- especialy for ABX and KILL ZONE
Hypoglycemic med needed to decrease of kidney disfunction are…
Acarbose, chlorpropamide, glyburide, glipizide, insulins, and metformin
Drug induced kidney disease
common, devastating
symptoms of drug induced kidney dysfunction
malaise, anorexia, HTN, edema, decreased urine
often pts. have no symptoms and only diagnosed by elevated serum Cr
What are the two Cr patterns of Kidney dysfunction?
If Cr at baseline 2.0 & increases by 30% or >1mg/dl
What are the 3 common forms of Renal Failure?
1) Acute tubular necrosis (ATN)
2) Hemodynamically mediated injury [ACE inhibitors NSAIDs]
3) Interstitial nephritis
Acute Tubular Necrosis
- most common reason for renal failure
- direct toxicity or ischemia to the cells that line the renal tubules, dead cells are shed and then block tubules so can’t make urine
- aminoglycoside, radio contrast media, cisplatin, amphotericin B, foscarnet, osmotic active agents
treatment for Acute Tubular Necrosis
- stop drug
- hydrate
- support
Drugs that cause Hemodynamic- Mediated Injury
AceI, ARBs, NSAIDs
ACEI Induced Renal Failure
-most pts increase Cr from baseline when one ACEIs, expected do not need to stop
- expected to rise 30% in 5 days
- stabilizes in 3 weeks
- detrimental if rise is more than 30%
- reversible with discontinuation
Risk Factors fo renal Failure from ACEI
-CHF kidney disease -renal a. stenosis -v. depletion -cirrhosis
Even if pt. has risks, ACE is still used because decreases mortality and time until dialysis
