Pharmacodynamics
what a medicine does to the body
Ligand
a substance usually a molecule that forms a complex with a body protein to serve a biological purpose
three ways medicines may be in the body
- free
- bound to a receptor
- bound to a non-functional molecule in a cell/tissue
ligand-gated ion channel
Type of membrane receptor that has a region that can act as a "gate" when the receptor changes shape.
G-protein coupled receptors
sense molecules/lipids outside the cell and activate the g-protein, inside the cell, in which then stimulates cellular responses. (e.g enzymes)
Enzyme-linked receptors
binding of a ligand to an enzyme-linked receptor stimulates intracellular enzymatic activity. The enzyme-linked receptor has two functions- it is the receptor and possesses enzymatic activity.
stimulate, inhibit
When the medicine is distributed to the body. The medicine receptor complex initiates physiochemical reactions that stimulate or inhibit cellular functions.
why do some medicines inhibit while some stimulate cellular functions by binding to the same receptor?
some drugs (agonsit) bind to receptors and activate the receptor. other drugs (antagonist) can bind to the same receptor but block receptor activation
Antagonist
when a frug binds to a receptor but blocks its activation. as a result, the effects observed are often opposite to the stimulation of the receptor
agonist
when a drug stimulates a receptor. it mimics the engogenous transmitter.
affinity
refers to the strength of attraction between a drug on its receptor. drugs that are high in this are strongly attracted to their receptors
Specficity
related to a degree of selectivity. a drug is highly specific if it only interacts with one receptor type.
efficacy
is the ability of a drug to produce an effect at a receptor. it is a measure if the maximum biology effect resulting from a drug binding to its target e.g morphine is much more higher in this compared to paracetamol as it is a much more stronger pain kill
potency
describes the amount of drug needed to produce a desired effect. if you use more of this type of drug. a lower dose should be administered to produce the desired effects.
misuse
inappropriate use of medicines
drug dependence
the condition is which administration fo a substance is compulsory sought in the absence of a therapeutic indication e.g abuse of a pain killer
drug tolerance
is when repeated doses of a drug cause decreasing effects or if doses gave to be increased to maintain the same affect,
used to describe a medicine that has the same effect on a receptor as the endogenous chemical messenger?
agonist
used to describe a medicine that binds to a receptor, fails to activate it and prevents the endogenous chemical messenger from binding?
antagonist
used to describe a medicine that binds to a receptor, and activates it, but to a lesser extent than the endogenous chemical messenger?
partial agonist
inverse agonist
binds to a receptor and stabalises the inactive form of the protein such that endogenous messenger cannot bind
the maximum biological effect resulting from a medicine binding to its target
efficacy
the measure of how strongly a medicine binds to a receptor?
affinity
applies to the amount of medicine required to produce a defined biological effect?
potency
name the four main protein targets (receptor types) that ligands can bind to
ligand-gated channels, enzyme-linked receptor, G-protein linked receptor, and intracellular receptor.
Endogenous
produced from within; due to internal causes