Flashcards in ADME Four Deck (14):
What are the sites of drug excretion?
- Biliary Excretion (MW>400 & Ionized drugs e.g Drug-glucuronide conjugates)
What is the product of metabolism
What is the kidneys main homeostatic role?
Regulates blood volume and fluid composition
IN relation to drugs what does the kidney do?
Removes water soluble drugs and metabolites ((excretion)) (depends on physico-chemico properties)
Up to what MW is filtered by the kidney
What is the average Glomerular filtration rate in an adult?
130mL per min
What are the three steps of drug excretion by the kidney?
2) Active secretion of free and protein bound drugs by transporters
3) Filtrate is concentrated in the Tubules for favorable reabsorption conditions
What anions and cations are secreted into the tubules?
Anions- Glucuronide and sulphate conjugates
Cations- Histamine, basic drugs
Are drugs bound to plasma proteins filtered?
No their MW is too high, thus only free plasma drugs filtered.
What are some factors influencing renal excretion?
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
How can renal excretion be changed with drugs?
Competitive inhibition of tubular secretion
Influence of urinary pH
Influence of urinary flow rate
How does competitive inhibition of tubular secretion effect renal excretion of drugs?
Can prevent up to 90% of drug secretion (as at least 10% is always filtered
How does influence of urinary pH effect renal excretion?
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)