1: Principles of Pharm Flashcards
Pharmacokinetics
study of how a drug is absorbed, distributed, or eliminated from the body
threshold dose
minimum dose of a drug needed to cause cellular changes (aka minimal effective dose)
potency / potent
amount of a drug needed to produce a given effect / powerful in small doses
pharmacotherapeutics
drugs used to prevent, treat, or diagnose a disease (therapeutic impact of medications)
pharmacodynamics
analysis of what the drug does to the body at the systemic and cellular level (what is the effect of the drug on the body)
What group monitors and approves new drugs in the U.S.?
the FDA
how are animals involved in the drug creation process?
they are the initial testing phase, before human tests
what are the 3 phases of drug testing (number of subjects)?
Phase 1 - 10-100 subjects
Phase 2 - 50-500
Phase 3 - hundreds to thousands
What portion of drugs tested in clinical trails reach the marketplace?
less than 1/3
controlled substances
medications with strict regulations in order to try to prevent drug abuse
drug toxicity
drug level exceeds therapeutic range; body reacts to higher rate of intake before the body can metabolize or excrete
TI equation
TD50 / ED50
non-receptor drugs
some drugs exert their effects without interaction with a receptor
neurotransmitters
released by neurons to cause excitation or inhibition to other neurons
ceiling effect
maximum dose of a drug where increased doses will not result in further change
median effective dose (ED50)
the dose at which 50% of the population responds to it in the expected manner
median toxic dose (TD50)
the dose at which 50% of the population exhibits the specific adverse effect
median lethal dose (LD50)
the dose that causes death in 50% of the animals it was tested on
therapeutic index
an indicator of the drug’s safety; determined by the median effective dose and toxic dose. safer drugs have higher TI value (larger margin for error)
drugs with highest vs. lowest TI
highest: OTC
lowest: chemo
enteral drug administration
drug intake that involves the GI system; oral, sublingual, buccal, rectal
parental drug administration
drug intake that is not associated with the GI system; inhalation, injection, topical, transdermal
oral administration
- swallowing drug, absorbed by GI lumen
- most common enteral method
- must be lipid-soluble so that it is absorbed into mucosa and bloodstream
- may be slower and less complete than some parenteral routes
first-pass effect
when a significant amount of the drug is metabolized by the liver before it ever reaches its site of action
sublingual and buccal administration
- drugs placed under tongue
- drugs placed between cheek and gums
- NOT subject to first-pass effect
- will be ineffective if swallowed
rectal administration
- inserted via suppositories
- poor absorption, irritation of rectal mucosa
- partial avoidance of first-pass effect
parenteral admin compared to enteral admin
- parenteral methods deliver drugs to the action site more directly
- quantity of parenteral drug that reaches the site is more predictable
- not effected by first-pass effect of liver
inhalation administration
- drugs in aerosol form
- drugs diffuse into pulmonary circulation through alveoli
- commonly used with pulmonary medications and general anesthetics
injection administration
- used for systemic or local drugs
- can be through veins, arteries, skin, muscle, spinal subarachnoid space, bursae
- IV commonly used in ER because it is fast
topical administration
- drug applied to the surface of the skin or mucous membrane
- used to treat skin conditions
- not well absorbed across the epidermis
- includes eye & ear drops
transdermal administration
- drugs applied to the surface of the skin
- designed to be absorbed into skin
- allows for slow controlled release of drug (medicine patches)
- absorption & effect of drug depends on local blood flow at the site
- includes ionto & phonophoresis
bioavailability
the extent to which the drug reaches the systemic circulation (expressed as a percentage of the amount of drug administered)
factors that affect distribution of a drug
tissue permeability, blood flow, plasma proteins, subcellular components
What is the problem with drugs binding to plasma proteins?
drugs can form irreversible bonds with proteins in the bloodstream which renders them essentially ineffective
volume of distribution
amount of drug administered / concentration of drug in the plasma (used to estimate how well a drug was distributed throughout the body)
locations drugs may be stored after being absorbed
adipose tissue (most common), bone, muscle, organs
controlled-release substances
drugs that are designed to have a slower and prolonged absorption from the GI tract or other routes (common in meds for cardiovascular, pain, and parkinson’s)
implanted drug devices
surgically inserted container in the abdomen that has a reservoir of the drug and releases in small, measured doses on a schedule; can be controlled by remotes
two ways of drug elimination
biotransformation and excretion
biotransformation
chemical changes that take place which alter the drug into a metabolite which is inactive
site for most drug biotransformation
liver
methods of drug excretion
kidneys (most common), lungs, GI tract, sweat, saliva, breast milk
tolerance
prolonged use of a drug induces the body to adjust and break down the drug faster
clearance
elimination of a drug (can be used to describe specific organs or the whole body)
half-life
the amount of time required for 50% of the drug in the body to be eliminated
factors that affect how an individual responds to drugs
genetics, disease, drug interactions, age, diet, sex, exercise, smoking, alcohol, obesity, SCI
