Exam I Terms/Definitions Flashcards
Pharmacology
The study of drugs and their interactions with the human body
Drug
Any chemical agent that affects a living protoplasm
Adverse Drug Reaction (ADR)
Any response to a drug which is harmful and unintended
Pharmacokinetics
The action of body on the drug
ADME - Absorption, Distribution, Metabolism, Elimination
Absorption
Movement of a drug from its site of administration into the central compartment (systemic system) and extent to which this occurs
Bioavailability
Measure of the amount of drug that is BIO AVAILABLE –> i.e., available to exert a systemic effect on the body
In other words:
The fractional extent to which a dose of drug reaches site of action
Cp max
Maximum concentration
T max (hrs)
Time to achieve maximum concentration after administration
Distribution
Following absorption (or systemic administration into bloodstream) when a drug distributes into interstitial and intracellular fluids
Volume of Distribution (Vd)
To account for observed initial drug concentrations following drug administration, researchers calculate an “apparent” volume
This is NOT a true physiologic volume
Biotransformation
Drug is chemically altered to form a metabolite that is more “excretable” than parent drug
Excretion
Removal of a drug or metabolite from the body via an organ
Drug Clearance
The volume of blood that is cleared of drug per time
Elimination/Drug Half-Life
The time it takes for the concentration of drug to reduce by 50%
Pharmacodynamics
Effects of drug on the body
In vitro and in vivo
Receptor
A molecule to which a drug binds to bring about a change in function of the biological system
Receptor Site
Specific region of receptor molecule to which the drug binds
Inert Binding Molecule or Site
A molecule to which a drug may bind without changing any function
Spare receptor
Receptor that does not bind drug when drug concentration is sufficient to produce maximal effect
This is present when Kd > EC50
Effector
Component that accomplishes the biologic effect and the receptor is activated by an agonist
examples:
- Channel
- enzyme molecule
Efficacy, maximal efficacy (E max)
The maximum effect that can be achieved with a particular drug, REGARDLESS OF DOSE
Potency
The amount of drug needed to produce a given effect, determined mainly by the affinity of the receptor for the drug and the number of receptors available
Graded dose-response curve
A graph of increasing response to increasing drug concentration or dose
Quantal dose-response curve
A graph of the fraction of a population that shows a specific response at progressively increasing doses
EC 50
The CONCENTRATION that causes 50% of the maximum effect or toxicity
ED 50
The DOSE that causes 50% of the maximum effect or toxicity
TD 50 (or TC 50)
The median toxic Dose (Concentration), the dose (concentration) at which toxicity occurs in 50% of cases
LD 50 (LC 50)
The median lethal dose (concentration)
The dose (concentration) required to kill half the members of a tested population after a specific test duration
Kd
The concentration of drug that binds 50% of the receptors in the system
B max
Maximal number of receptors bound
Partial agonist
A drug that binds to its receptor but produces a smaller effect at full dosage than a full agonist
Allosteric Agonist
A drug that binds to its receptor molecule without interfering with normal agonist binding BUT alters the response to the normal agonist
Competitive antagonist
A pharmacologic antagonist that can be overcome by increasing the concentration of agonist
Irreversible antagonist
A pharmacologic antagonist that cannot be overcome by increasing agonist concentration
Physiologic antagonist
A drug that counters effects of another by binding to a different receptor and causing opposing effects
Chemical antagonist
A drug that counters effects of another by binding the agonist drug (not the receptor)
Allosteric antagonist
A drug that binds to a receptor molecule without interfering with normal agonist binding BUT alters the response to the normal agonist
Therapeutic Index (TI)
TD 50 : ED 50
