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Flashcards in ADME Four Deck (14)
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1
Q

What are the sites of drug excretion?

A
  • Kidney
  • Biliary Excretion (MW>400 & Ionized drugs e.g Drug-glucuronide conjugates)
  • Lungs
2
Q

What is the product of metabolism

A

metabolites

3
Q

What is the kidneys main homeostatic role?

A

Regulates blood volume and fluid composition

4
Q

IN relation to drugs what does the kidney do?

A

Removes water soluble drugs and metabolites ((excretion)) (depends on physico-chemico properties)

5
Q

Up to what MW is filtered by the kidney

A

30,000MW

6
Q

What is the average Glomerular filtration rate in an adult?

A

130mL per min

7
Q

What are the three steps of drug excretion by the kidney?

A

1) Filtration
2) Active secretion of free and protein bound drugs by transporters
3) Filtrate is concentrated in the Tubules for favorable reabsorption conditions

8
Q

What anions and cations are secreted into the tubules?

A

Anions- Glucuronide and sulphate conjugates

Cations- Histamine, basic drugs

9
Q

Are drugs bound to plasma proteins filtered?

A

No their MW is too high, thus only free plasma drugs filtered.

10
Q

What are some factors influencing renal excretion?

A

Gender (F have 0.8 function of males)
Age (50% decrease by 75)
Pregnancy (increased by 50%)
Disease (renal failure, heart failure- decreased blood to kidney

11
Q

How can renal excretion be changed with drugs?

A

Competitive inhibition of tubular secretion
Influence of urinary pH
Influence of urinary flow rate

12
Q

How does competitive inhibition of tubular secretion effect renal excretion of drugs?

A

Can prevent up to 90% of drug secretion (as at least 10% is always filtered

13
Q

How does influence of urinary pH effect renal excretion?

A

E.g Sodium bicarbonate is used to increase pH which increases ionization of weak acids and thus decreases tubular re-absorption = increase excretion

e.g Ammonium Cl used to increase tubular pH which increases excretion of basic drugs (e.g meth)

14
Q

How does urinary flow rate increase renal excretion?

A

(more water) increase urinary flow rate which decrease concentration of tubular fluids, decreasing the concentration gradient for passive reabsopriton of drug thus increased secretion.