The Kidney & Drugs

Question 1

Why is the kidney imporant?

Answer 1

eliminates drugs, if it doesnt work there is toxicity

Question 2

Most important way of eliminating drug from the body is…..

Answer 2

renal clearance

Question 3

Glomerular Filtration Rate- GFR

Answer 3

measure of how well the kidney is filtering blood

Can not measure GFR- but can measure creatine clearence

Question 4

Decrease in GFR=

Answer 4

kidney dysfunction

Question 5

Creatinine

Answer 5

prodcut of creatine which is produced by the liver

Creatinin is filtere at glomerulus where it is secreted

Question 6

As SCR increases

Answer 6

GFR decrease

Question 7

Good range of GFR

Answer 7

1-1.4

Question 8

Stages of Kidney Function

Answer 8

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:

Question 9

Second way of classifying Kidney Function

Answer 9

Renal insufficiency 30-90cc/min (Stage 2 & 3)

Renal failure

Question 10

3 Ways of Measuring CrCl

Answer 10

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

Question 11

Cockcroft-Gault Equation

Answer 11

Estimate GFR from serum CR

Question 12

Approach to adjusting meds

Answer 12

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

Question 13

Chronic Renal Failure Adjustment

Answer 13

if kidney failure- estimate CrCl w/ equation- review drugs and dose based on literature

monitor for response and toxicity
get serum drug level

Question 14

How should you change the dose?

Answer 14

decrease mg each time dosed

OR

increase dosing interval- this is prefered- easier- especialy for ABX and KILL ZONE

Question 15

Hypoglycemic med needed to decrease of kidney disfunction are…

Answer 15

Acarbose, chlorpropamide, glyburide, glipizide, insulins, and metformin

Question 16

Drug induced kidney disease

Answer 16

common, devastating

Question 17

symptoms of drug induced kidney dysfunction

Answer 17

malaise, anorexia, HTN, edema, decreased urine

often pts. have no symptoms and only diagnosed by elevated serum Cr

Question 18

What are the two Cr patterns of Kidney dysfunction?

Answer 18

If Cr at baseline 2.0 & increases by 30% or >1mg/dl

Question 19

What are the 3 common forms of Renal Failure?

Answer 19

1) Acute tubular necrosis (ATN)
2) Hemodynamically mediated injury [ACE inhibitors NSAIDs]
3) Interstitial nephritis

Question 20

Acute Tubular Necrosis

Answer 20

• 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

Question 21

treatment for Acute Tubular Necrosis

Answer 21

• stop drug
• hydrate
• support

Question 22

Drugs that cause Hemodynamic- Mediated Injury

Answer 22

AceI, ARBs, NSAIDs

Question 23

ACEI Induced Renal Failure

Answer 23

-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

Question 24

Risk Factors fo renal Failure from ACEI

Answer 24

-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

Question 25

Captopril

Answer 25

ACEI- start at low dose and slowly

Question 26

4 ways to prevent Renal Failure from ACEI

Answer 26

1_ initiate low dose and itrate up

2) switch to longer acting agent once tolerated
3) monitor kidney function and SCR
4) Avoid diuretics

Question 27

How to treat RF caused by ACEI

Answer 27

Stop ACEI or ARB during GI ilness

Question 28

NSAIDS and COX-2s RF

Answer 28

Increased Cr is not expected & not part of how drug works so if increased Cr occurs immediately stop the drug!

Question 29

Mechanisms of RF with NSAIDS

Answer 29

NSAIDs inhibit prostaglandins that regulate renal blood flow to the kidney, inhibiting the formation of these prostaglandin inhibits kidney blood flow, decreasing function

Question 30

Presentation of NSAID RF

Answer 30

• occur within days
• low urine v. and low sodium
• increased BUN, SCr, potassium, edema, weight

Question 31

Treatment of NSAID RF

Answer 31

• avoid NSAID if on ACEI or ARB
• use low dose of NSAID if not avoidable
• Keep well hydrated

Question 32

Interstitial Nephritis

Answer 32

inflamation of interstitium- not as comm on has hemodynamic causes

most are allergic drug cases

2 weeks after med is started

fever, rash, pyuria (looks like an allergy_

Question 33

treatment of interstitial nephritis

Answer 33

stop drug and put on corticosteroids

Question 34

How to avoid drug induced kidney disease.

Answer 34

• Do not give nephrotoxic drugs unless needed
• monitor closely people on these drugs
• hydrate until you get high urine flow rates