Medical Issues Ch. 4 Flashcards
what is a drug
a chemical that interacts with and affects living organism to produce a biological response
who regulates drugs
FDA
DEA
drug nomenclature and classifications
identified by -chemical name -generic name -brand name classifications -prescription drugs -over-the-counter drugs -controlled substances
Prescription drug
prescribed by Doctor, NP, or PA
OTC products
no prescription necessary
FDA must approve ingredients and label information
Controlled Substances
-schedules
high risk for abuse schedule 1: high potential for abuse -marijuana, LSD schedule 2 -cocaine, riddalin schedule 3 -anabolic steroids, prescription pain killers schedule 4 -xalium schedule 5 -codein
routes of administration
enteral
-alimentary canal
-digestive system
parenteral
-pathway other than the alimentary canal or digestive system
-usually allows drug to be delivered directly to the tissue sight
enteral and parenteral types
enteral -oral -rectal parenteral -inhalation -intravenous -intramuscular -transdermal -sublingual
oral
most common slow release preparation (+) -easy -convenienti -nexpensive (-) -variability in absorption -gastric irritation -may take longer to produce therapeutic effects
rectal
(+) -quick acting and doesn't interfere with digestive system -good for those with nausea and vomiting (-) -can't control absorption rate
inhalation
(+)
-quick delivery of medication for quick relief of symptoms
(-)
-not as convenient
injection types
-(+) and (-)
types -intravenous -intramuscular -intraarticular -subcutaneous tissue (+) -no barriers -rapid onset (-) -cost and risk of infection -discomfort -inconvenient
sublingual
-pros and cons
(+) -absorbed rapidly (-) -uncomfortable -expensive
topical
- types
- pros and cons
types -creams -gels -lotions -patches -drops -sprays (+) -effective locally (-) -only effective locally
primary vs. secondary effect
primary
-desired therapeutic effect of the drug
secondary
-everything else (side effects)
pharmacokinetics
how the body acts on and processes a drug
4 distinct processes of pharmacokinetics
absorption
distribution
metabolism
elimination
absorption
for a drug to produce a therapeutic effect, it must be absorbed into the blood stream and distributed through the circulation
2 types of drug solubility
hydrophilic
-water soluble
lypophilic
-fat soluble
types of movement across cell membranes
passive diffusion
active transport
facilitated diffusion
passive diffusion
most common mechanism of transport across membranes
lypophilic drugs will diffuse more quickly
movement of drug molecules across membranes based on concentration
move to equilibrium
active transport
requires a protein to move the drug across a membrane
protein and drug bind
selective diffusion
facilitated diffusion
active transport + passive diffusion
selective process
protein involvement
high conc. –> low conc.
oral absorption
- pathway
- effect of absorption rate
- take with…
stomach –> small intestine –> circulatory system
the quicker the drug dissolves, the quicker it can be absorbed
take with a full glass of water
extended release drugs
enteric coating
-prevents dissolving in the stomach and takes it to the stomach
effects of exercise on absorption
decreases effects of oral drugs
blood flow diverted
medication should be taken at least 30 minutes prior to exercise
sublingual and buccal (cheek) absorption
dissolve directly in the mouth
rapid absorption –> rapid therapeutic effect
nitroglycerin
rectal absorption
drug dissolves in the rectum
absorbed into the hemerrhoidal veins
injection (intravenous, intramuscular, subcutaneous) absorption
very fast
topical absorption
slow absorption
inhalation absorption
rapid absorption (<5 minutes)
distribution factors
solubility
target tissue and blood-flow
distribution onset of action
the time it takes for drug molecules to reach their site of action in sufficient quantities to produce a therapeutic effect
duration of action
the period of time when concentration levels are sufficient enough to produce a therapeutic effect
effects of exercise on distribution
increase in blood flow
may increase distribution rate
dependent on site of action
metabolism
drugs inactivated
droken down into water-soluble metabolites for excretion
metabolism
- primary site
- secondary
primary -liver secondary -kidneys -GI tract
metabolism and exercise
exercise can decrease the clearance of some drugs due to blood being diverted away from the GI, kidneys, and liver to the skeletal muscles
however
-drug’s effects are usually longer than exercise session
therefore effect on metabolism is negligible
elimination
the process by which a drug leaves the body
elimination
- primary site
- secondary
primary -kidneys secondary -intestines -sweat -lugns
elimination and exercise
can decrease the rate of renal excretion
elimination can also be influenced by…
the drug’s half-life
bioavailability
-factors
amount of the drug actually available to target tissue
factors
-rate at which a drug dissolves in the GI tract
-amount and rate of drug absorbed
-formulation (capsule, tablet, injection)
half-life
the time required for the body to eliminate 1/2 of a dosage of a drug by the regular physical processes
half-life and water- and fat-soluble drugs
water
-move through faster
fat
-stay in system longer
half-life steady state
some drugs will be taken on a consistent basis
ongoing process of drug absorption and removal
amount going in = amount going out
5-6 half-lives of a medication to reach steady state
pharmacodynamics
how a drug acts on the body
receptor theory
for a drug to work, it must bind to a receptor
receptor may be within a cell or on a cell membrane
lock and key
agonist drug
a drug that interacts with a receptor to produce a pharmacological response
antagonist drug
a drug that binds with a receptor but does not produce a pharmacological response or prevents a response
-may be blocking other chemicals from attaching to receptors
drug dosing
- based on
- increased dose =
based on -potency of the drug -patient's age -patient's condition increased dose = increased receptors -until steady state is reached
drug interactions
occur when one drug alters the effect of another drug
may change how the body handles one or both drugs
may change the way the drug acts on the body
additive interactions
agonistic
two of the same type of drug taken together
effects of the drug “add together”
inhibitory effects
antagonistic
can occur between two unrelated drugs
adverse drug reactions
range from side effects to hypersensitivity
side effects
common effects with use of certain medications
hypersensitivity
allergic reactions
may be local or anaphylactic shock
