Exam 1: Pharmacology Flashcards
specified amount of medication/substance administered at one time
amount of drug per body weight (mg/kg)
- achieve EQUAL blood concentration of drug
dose
amount, number, and frequency of doses over a specific period
dosage
specific molecular changes produced by a drug when it binds to target site/receptor
- physically in body
- more or less likely an action potential would occur
- inc or dec in a neurotransmitter
drug actions
alterations in physiological or psychological functions
- effects of drug depend on dose
- in general as dose inc effects inc to maximum effect and then effects decrease
drug effects
pharmacokinetics
what the body does to drugs
how drugs are absorbed by and pass through the body
ADME
(absorption, distribution, metabolism, excretion)
bioavailability
- amount of drug in blood free to bind at target sites
- factors affecting drug’s action in body, excluding the chemical structure of the drug
- pH and where it is absorbed from, age, gender, fast distribution
absorption
movement of drug from site of administration to circulatory system
- not all will be absorbed
- need to get to bloodstream to be psychoactive
- absorbed at diff rates - speed can alter strength of drug effects
rate of absorption into blood stream and bioavailability depend on _____
route of administration
- path drug takes into body
enteral route
passes through GI tract
oral, rectal administration
generally slow to be absorbed and produces variable concentrations of drug in the blood
parenteral route
injection, pulmonary, topical administration
avoids GI tract
enteral administration: oral
drug dissolves in stomach fluids, passes through stomach wall to reach capillaries
- drug must be resistant to stomach acid, enzymes
- first pass metabolism
enteral administration: rectal
inserting drug directly into rectum (suppositories)
AVOIDS first pass metabolism
first pass metabolism
- liver essential for processing/filtering substances consumed orally
- dugs absorbed by gut are carried directly to liver via portal vein
- liver breaks down some of drug before released to circulation
like squid games red light green light
parenteral administration - types
Injections: - Intravenous (IV)
- Intramuscular (IM)
- Subcutaneous (SC)
inhalation
topical
intranasal
Intravenous injection
injected directly into vein
drug immediately enters bloodstream, reaches brain in seconds - super fast and accurate
danger: hard to correct if give too much of the drug - little time to fix since it acts so fast
intramuscular injection
injected into muscle
upper arm, thigh buttocks
subcutaneous injection
injection into space beneath skin before it hits the muscle
- slower than IV - longer period of absorption
inhalation
fast like IV
absorbed by the lungs - to some extent the muscous membranes of mouth, throat, nose
rapid absorption because lungs have large SA and many capillaries!!!
drug effect is rapid
topical
drug applied to the mucous membranes
- mostly local effects but can get into bloodstream
transdermal!!! - through the skin, usually patches (hormones, nicotine, pain killers)
sublingual administration
drug placed under the tongue
- let it dissolve
- avoids gastric acid, enzymes, and first pass metabolism
(does not lose any of the drug’s ability to act)
intranasal
nasal passage contains mucosal membranes that can absorb drugs into capillaries like sublingual or transdermal routes
- avoids 1st pass metabolism, bypasses BBB!!! - allows high brain concentration
- snorting things, nasal sprays
What does the route of administration effect?
the rate of absorption and blood levels of the drug
- each method has advantages and disadvantages
Factors that effect the drug absorption process (5)
- lipid solubility
- active transport
- ionization
- rate of GI emptying
- size and sex of individual
degree to which a substance dissolves in fat
lipid solubility
consumes energy but can move larger molecules and work against concentration gradient
- allows drugs to build up in someone’s system
active transport
pH alters drug solubility
acidic drugs absorbed better in acidic environments
alkaline drugs absorbed better in alkaline environments
ionization
small intestine has large SA, substances move through it slowly
- greater absorption than in the stomach
rate of GI emptying
process through which the bloodstream carries drug to site of action
must penetrate membranes
distribution
amount of drug that can have action on targets
effected by distribution
bioavailability
selectively permeable membrane that separates the blood supply from direct contact with brain tissue
- prevents most pathogens and toxins from entering brain
- regulates entry of nutrients into brain
BBB
what can easily cross the BBB
- lipid soluble substances, certain gases (NO), water
what can not easily cross BBB
large molecules and ones with high electrical charge
components of BBB
- endothelial cells
- astrocytes
- pericytes
line inside of blood vessels avoiding edges fuse to form tight junctions that prevent flow of most substances into and out of both
- “walls of a castle”
endothelial cells
glial cells responsible for formation and maintenance of BBB
wrap around endothelial cells to restrict entry of pathogens
release secretion factors to maintain tight junctions
astrocytes
wrap around endothelial cells
contract to regulate blood flow
speed at which drugs move through circulatory system
pericytes
not as strong as BBB
placenta
fat diffuses through placental barrier quickly
teratogens
placental barrier
stimuli that cause developmental abnormalities in fetus (drugs, xrays)
inc susceptibility in 1st trimester
teratogens
non-specific binding - proteins in blood, fat, bones
drugs stuck in these cannot reach active sites or be metabolized by liver
drug depots
what does depot binding effect
magnitude and duration of drug action
- reduces bioavailability - delays drugs effects
- varies across people
can result in drugs staying in body for prolonged periods of time - THC
drug broken down into metabolites by enzymes
biotransformation - metabolism
main site for metabolism
makes drugs more water soluble
liver
main enzyme family responsible for breaking down psychoactive drugs
cytochrome p450s
repeated use of a drug increases number of enzyme molecules and speeds biotransformation
- speeds transformation of other drugs that enzyme acts on reducing effects
- drugs lose effectiveness with repeated use
enzyme induction
a drug may inhibit n enzyme, which reduces metabolism of other drugs
- effects more intense or prolonged, toxicity is possible
enzyme inhibition
