9.12 Pharmacology Flashcards
Drugs must be eliminated from the body to: (2)
- terminate their effect
- prevent excessive accumulation of the drug
chemically altering the original compound so that the drug is no longer active
biotransformation
time frame for biotransformation
usually done within minutes or hours
What does biotransformation result in (product)?
metabolite
Metabolites are
inactive or greatly reduced form of a drug
Where are metabolites stored?
- fat
- bones
- muscles
- etc.
Can the active drug be excreted?
- yes, but generally, this process is too slow
- some compounds would stay in the body for several weeks
Primary location for drug metabolism
liver
In addition to the liver, where else does drug metabolism occur?
- lungs
- kidneys
- GI epithelium
- skin
lungs excrete:
aerosols, gas
Prolonged use of certain drugs “induces” the body to adjust and enzymatically destroy the drug more rapidly than expected. How might this happen?
- increasing the number of degrading enzymes
- destroying fewer enzymes
What may also cause enzyme induction?
- ETOH
- cigarette smoke
- herbal products
- environmental toxins
tolerance
need for increased drug dosages to maintain safe effect
Primary site for drug excretion
kidney
What are the mechanisms by which the kidney excretes drugs?
- tubular secretion
- glomerular filtration
Aside from the kidney, what are other sites of drug excretion?
- lungs (volatile drugs)
- GI tract
- sweat
- saliva
- breast milk
clearance
- organ and tissue ability to eliminate a drug
- can be systemic or specific to organ/tissue
Clearance includes excretion and elimination through _____
biotransformation
half-life
time required for 50% of the remaining drug to be eliminated from the body
Tylenol has a half-life of
2 hours (assuming normal fun)
half-life is a function of both
- clearance
- volume of distribution
