F and CL part 4

Question 1

Renal clearance

Answer 1

CLR= fe X CL

Question 2

Secretion

Answer 2

active carrier-mediated process; saturable

neutral drugs are not secreted

If rate of excretion>rate of filtration, then infer that secretion has
occurred. If CLR > fu ⋅GFR, then assume that secretion has occurred

High Er are good substrates for renal transporters and dissociate rapidly from plasma proteins so as not to limit secretion

depends on fu and kidney blood flow

Question 3

Secretion drug-drug interaction

Answer 3

renal excretion of amoxicillin affected by co administration of probenecid

Question 4

Reabsorption

Answer 4

Occurs along the length of the nephron, associated with reabsorption of
water.

Passive process for exogenous products including drugs. Active process
for many endogenous compounds, e.g., vitamins, electrolytes, amino
acids, glucose

If rate of excretion < rate of filtration, then infer that reabsorption has
occurred. If CLR < fu ⋅GFR, then reabsorption has occurred

Question 5

Factors affecting renal reabsorption of drugs

Answer 5

polarity and ionization

polar compounds are not reabsorbed
ionized compounds are not reabsorbed

urine flow and urine pH

Clr= fu X urine flow

Question 6

When do you want to manage overdose of renally excreted drugs

Answer 6

acidification of urine will increase renal excretion of methamphetamine

overdose is involved in urine pH involvement