Drug Elimination Flashcards
Excretion
Removal of drugs or metabolites from the body.
Elimination
Excretion or inactivation of drug by metabolism
Hydrophilic drugs
can be excreted via urine w/out metabolism
Kidneys
Major route of excretion of most drugs.
Most have to be metabolized b4.
High blood flow
Clears blood of drug by FILTRATION and ACTIVE SECRETION
The three processes that predominate excretion via the kidney;
Filtration, Reabsorption, Secretion
Filtration via the kidney
Same clearance of plasma compounds (creatinine is classic clearance substance).
What is favoured to be excreted by the kidney?
Polar drugs and metabolites
The low pH of urine traps weak bases, which can speed up elimination/detox.
Secretion via the kidney
Some drugs secreted into proximal tubules.
Penicillin 90% of elimination is secretion.
Secretion results:
Rapid elimination and high concentrations in bladder.
In the liver:
Elimination: deactivates through metabolism.
Prepars many lipophilics for renal excretion.
Prepares some drugs for biliary excretion.
Hepatic metabolism/biotransformation:
Enzymes breakdown or transform drug molecules.
Elimination by the liver
Can secrete drugs or its metabolites into bile which is then secreted into intestines.
Enterohepatic cycling:
most of what is secreted with the bile into the intestines is reabsorbed by the intestines.
Unabsorbed drugs or drugs not reabsorbed:
Go out with feces.
Elimination by lungs
Important for elimination of general anesthetics.
Lungs eliminate gases and not much else