percentage of medication that reaches the systemic circulation
bioavailability
Name the 7 ways drugs can be absorbed into the body:
oral
sublingual
inhalation
intramuscular
subcutaneous
intravenous
transdermal or topical
drugs absorbed through this route
- must be lipid soluble
- are absorbed through passive diffusion
oral
drugs absorbed through this route:
- can not be taken orally because will be destroyed by stomach acid
sublingual
-nitroglycerin
drugs absorbed through this route:
- are delivered directly to site of action via small particles
- have minimized side effects
Inhalation
-bronchodialators
drugs absorbed through this route:
- have rapid absorption
- should avoid high fat distribution which can slow down absorption
intramuscular
Drugs absorbed through this route:
are consistent, reliable with good bioavailability
subcutaneous
drugs absorbed through this route:
have instantaneous systemic absorption
intravenous
Pharmokinetic terms for drugs
: % of med that reaches systemic circulation
: method by which drug is administered into body
: method by which drug gets to site of action
: elimination of drugs to maintain proper levels of medications
: clearance of drug from the body by volume of blood/unit of time
bioavailability
absorption
distribution
metabolism
elimination
Distribution ( drugs ability to get to site of action) is affected by:
1) local blood flow
2) plasma protein binding
1) ischemia can result in treatment failure
2) drugs NOT protein-bound are ACTIVE and THERAPEUTIC
too much free drug can be toxic
liver and kidneys produce proteins for binding to keep drug toxicity down
enzymes in liver transform drugs to less active or inactive drug compounds or to another substance.
: this drug is inactive when administered and metabolized into an active form by the liver.
Prodrug
ie: cortisone is administered inactive and converted to active hydrocortisone
this is a phenomenon occurs when an oral drug is metabolized by the liver before it enters the systemic circulation therefore decreases bioavailability.
First pass
drug elimination occurs in this organ
kidney
the amount of time it takes for plasma concentration to drop to 50%
half life
drugs and receptors/receptor sites:
can bind with or block receptors
can avoid receptors and directly attack foreign organisms
act chemically
:endogenous substances and drugs that bind with appropriate receptors to produce some effect.
agonist: affinity to bind may be strong or weak
: ability to cause a response at a receptor site
efficacy
: comparing two drugs and their ability to produce the same response.
Potency
: subtances or drugs that fit into and bind to receptor sites to block the receptor and not allow it to be activated.
have an affinity for site but no efficacy
therapeutic in that they may increase or decrease a certain biological process