pharmacology definitions Flashcards
used all lecture notes to combine important definitions. checked against spec
define drug interactions
how one drug affects the action of another drug,
can be positive or negative,
3 main classes
what are the 3 main classes of drug interactions
- physiochemical
- pharmacodynamics
- pharmacokinetics
describe the drug interaction: physiochemical
2 drugs reacting, completely independent of what’s happening in the body
eg. same effect in test tube as body
give an example of a physiochemical reaction
Overdose of paracetamol →
given ‘activated charcoal’ in hospital →
it sticks to the paracetamol and prevents it from being absorbed
this is ADSORPTION
what’s the difference between adsorption and absorption?
Adsorption compounds cling to the surface of the molecule,
whereas absorption substances enter the bulk phase of a liquid or solid.
define bioavailability
how much a drug is available for use over a period of time.
is the fraction of an administered drug that reaches the systemic circulation unaltered
when is bioavailability always 100%?
when a medication is administered intravenously, its bioavailability is 100%.
because it all reaches the systemic circulation
define pharmacodynamic
Any effect the drug has on the human body (intended or not)
define Pharmacokinetics
what the body does with the drug , the action of drugs in the body
(the disposition of a compound within an organism)
aka. the study of drug metabolism
what is an enzyme inhibitor?
An enzyme inhibitor is a molecule that binds to an enzyme and decreases its activity.
It prevents the substrate from entering the enzyme’s active site and prevents it from catalysing its reaction
define transport
when molecules move across a cell membrane
define active transport
moves ions from a lower concentration to a higher concentration. Needs energy from ATP
define xenobiotics
compounds foreign to an organism normal biochemistry
such as any drug or poison
define a drug
a medicine or other substance which has a physiological effect when ingested or otherwise introduced into the body
define pharmacology
the branch of medicine concerned with the uses, effects and modes of action of drugs
what is meant by Drugability?
the ability of a protein target to bind small molecules with high affinity (sometimes called ligandability).
A protein is ‘druggable’
what is a receptor?
a component of a cell that interacts with a specific ligand and initiates a change of biochemical events leading to the ligands observed effects.
what is a ligand?
a molecule that binds to another (usually larger) molecule
can be exogenous or endogenous
what is an agonist?
a compound that binds to a receptor and activates it
can be full or partial
what is an antagonist?
a compound that reduces the effect of an agonist
(DOES NOT ACTIVATE A RECEPTOR)
what does EC50 on a log dose response curve mean?
‘half maximal effective concentration’
ie. the concentration of a drug needed to cause half of the maximum possible effect/response
define potency
a measure of drug activity expressed in terms of the amount required to produce an effect of given intensity.
A highly potent drug evokes a given response at low concentrations
whether a drug is ‘strong’ or ‘weak’ relates to how well the drug binds to the receptor, the binding affinity.
define affinity
describes how well a ligand binds to the receptor
(agonists and antagonists both have affinity)
define efficacy
describes how well a ligand activates the receptor
( agonists have efficacy, antagonists have 0 efficacy)
this is the concept of full or partial agnostic
what is a receptor reserve?
Some agonists only need to activate a small fraction of the existing receptors to produce maximal response.
Have SPARE
Partial agonists don’t have a receptor reserve
what is signal transduction?
a basic process involving the conversion of a signal from outside the cell to a functional change within the cell.
(After a ligand interaction with receptor on cell surface)
what is signal amplification
action to increase the strength of a signal
define tolerance
biological response to a drug diminishes SLOWLY
down regulation of the receptors with prolonged use, Need higher doses to achieve the same effect
define desensitisation
biological response to a drug diminishes RAPIDLY
what is parenteral administration?
administration that bypasses digestive system
ie. not orally given
define partial agonists
drugs that bind to and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist
not picked up by all receptors to
define and ADR?
Adverse drug reactions:
unwanted or harmful reactions following the administration of drugs or combination of drugs under normal conditions of use and are suspected to be related to the drug.
Has to be noxious and unintended .
define side effects
an unintended effect of a drug related to its pharmacological properties
can include unexpected benefits of treatment
define hypersensitivity
= objectively reproducible symptoms or signs, initiated by exposure to a defined stimulus at a dose tolerated by normal subjects’ and may be caused by immunologic (allergic) and non‐immunologic mechanisms’
define Anaphylaxis
an acute allergic reaction to an antigen to which the body has become hypersensitive
define Cholinergic
Cholinergic medications act upon the neurotransmitter acetylcholine (ACh) and its receptors
define Adrenergic
Adrenergic medications bind to adrenergic receptors throughout the body.
(these are adrenaline and noradrenaline receptors)
define afferent nerves
signal towards the brain/spinal cord
define efferent nerves
signal away from the brain/spinal cord
define stereoisomers
have the same molecule formula and sequence of bonded atoms, but differ in the 3D orientations of their atoms in space
define absorption
the process of transfer from the site of administration into the general or systemic circulation
define elimination
The removal of a drugs activity from the body
define half life
this is the time taken for a concentration to reduce by one half
define drug distribution
Rate and extent of movement of a drug into tissues from blood
define an inverse agonist
a drug that binds to the same receptor binding site as an agonist, but induces an opposite response to that agonist
define a competitive antagonist
directly competes with the agonist by binding to the same active site and blocking it
it inhibits (does not activate)
is reversible and surmountable
define a non competitive antagonist
A non-competitive antagonist binds to an allosteric binding site on the receptor, to block its activation
It does not completely block the effect of the agonist
and it isn’t competing with the antagonist for the same binding site
define selectivity
refers to a drug’s ability to preferentially produce a particular effect
its the degree to which a drug acts on a given site relative to other sites.
Relatively nonselective drugs affect many different tissues or organs.
better term to use (over specificity)
define specificity
the capacity of a drug to cause a particular action in a population.
compounds are nerve 100% specific
the measure of a receptors ability to respond to a single ligand
example of an agonist
Adrenaline is an agonist at beta adrenoceptors
Opioids are agonists for opioid receptors in the brain
define: first pass metabolism
rapid uptake and metabolism of an agent into inactive compounds by the liver, immediately after enteric absorption and before it reaches the systemic circulation
i.e. concentration of the drug is greatly reduced before it reaches systemic circulation.
