influence of renal insufficiency on drug elimination and response

Question 1

Cl(drug)

Answer 1

volume of plasma cleared of drug per unit time

Question 2

adjusting doses

Answer 2

estimate drug clearance as a proportion of normal

then adjust dose proportionally

Question 3

glomerular filtration rate

Answer 3

Cl(creatinine)

volume of plasma cleared of creatinine per unit time

Question 4

tubular reabsorption

Answer 4

100% of sugars and 99.5% of salts are reabsorbed
only excess amounts of required substances are not absorbed
waste products are not reabsorbed and eliminated as urine

Question 5

only thing that can reflect GFR

Answer 5

creatinine

Question 6

adjusting doses

Answer 6

estimate GFR as creatinine clearance
take ratio of creatinine clearance to normal creatinine clearance
assume normal clearance of drug is proportionally reduced

Question 7

estimating creatinine clearance

Answer 7

pathology serum creatinine level resports are now routinely accompanied by an estimated GFR
calculated using
- serum creatinine
- patients age and sex

Question 8

creatinine clearance is useful for

Answer 8

getting a good idea of renal function in older age
tracking changes in renal function over time
roughly estimating renal clearance for common drugs

Question 9

Cockcroft gault equation is more frequently used for

Answer 9

more critical dosing eg. oncological drugs
but
- not proven more accurate than CKD-EPI in all circumstances
- no consensus in dealing with obesity

Cockcroft gault was used at the time the dose-creatinine equations were researched, so the creatinine clearance is estimated this way

Question 10

morphne

Answer 10

metabolised to morphine-6-glucuronide and morphone-3-glucuronide which is really excreted
morphone-6-glucuronide is a ligand for the target receptor and is accumulated in patients with renal impairment aadn experience toxicity (despite being hepatic ally cleared drug)

Question 11

K+ sparing diuretics

Answer 11

more toxic for patients with poor renal function