Renal Impairment

Question 1

Renal clearance = glomerular filtration + tubular secretion - ?

Answer 1

Renal reabsorption

Question 2

Normal eGFR?

Answer 2

Around 100 mL / min

Question 3

Why can’t protein-bound drugs be filtered at the glomerulus?

Answer 3

Bc they are too large. Glomerular filtration is a passive process that filtered small MW molecules out of blood into filtrate

Question 4

CL renal (filtration) = GFR x fu. Define fu

Answer 4

Fraction of unbound drug

Question 5

Is tubular secretion active or passive?

Answer 5

Active. It is a saturatable energy dependent process that uses transport proteins

Question 6

Tubular reabsorption involves drug moving in which direction?

Answer 6

From the renal filtrate back into circulation.
Driven by concentration gradient

Question 7

How does urine flow rate alter tubular reabsorption?

Answer 7

Higher flow rate = less water being filtered = drug is less concentrated in urine = less reabsorption = more drug excretion

Question 8

Are unionised or ionised drugs more likely to be reabsorbed?

Answer 8

Unionised - better membrane permeability

Question 9

High urine pH would result in more excretion of which type of drug?

Answer 9

A weak acid. Because they are more ionised at higher pH’s so less likely to be reabsorbed

Question 10

Low urine pH has what effect on drugs that are weak bases?

Answer 10

At low pH’s weak bases will be more ionised, meaning they will be excreted rather than reabsorbed