introduction to pharmacology Flashcards
what is a drug
any compound used to treat disease
common drugs
paracetamol, ibuprofen, cannabis, nicotine, alcohol
what are the three different sources of drugs
-plants and natural products-digoxin for heart conditions from foxglove plant
-micro-organisms- penicillin from mould
animals- insulin from pancreas of various animals
factors important to consider when producing a drug
mechanism
dose
selectivity
side effects
risk/benefit ratio
what is a receptor
protein that has a structure that enables it to bind to a drug
agonist function
to activate receptors
what are antagonists
-block receptor so that the agonist cannot bind
what are the two types of agonists
-full agonists
-partial agonists
what is a full agonist
-fully binds to and activates the receptor
-produces a maximum response
examples morphine- bind to opioid receptors
what is a partial agonist
binds to receptors but activates them to a lesser extent
produces a weaker response despite occupying the same receptor
example is buprenorphine which binds to opioid receptors
what are the three types of antagonists
reversible competitive antagonists
irreversible competitive antagonists
non competitive antagonists
what are reversible competitive antagonists
bind at the site of agonist so competes with it
increasing concentration of agonist can overcome effect
what are irreversible competitive antagonists
bind to receptor via strong covalent bonds
increasing concentration of agonist has no effect, so to overcome the effect, new receptors must be synthesised
what are non competitive antagonists
bind to a distinct site
alter function of the receptor
what does potency mean
concentration of drug needed to produce a desired effect- effectiveness
low concentration of drug needed- higher potency
what does the ec50 mean
the concentration of a drug needed to produce half of its maximum effect
increase in potency- lower ec50
what happens to the ec50 as the potency increases
ec50 lowers
what does efficacy mean
magnitude of effect a drug can produce
the ability of a drug to activate a receptor once it binds to it
what is the efficacy of full agonists
1
what is the efficacy of partial agonists
between 1 and 0
what is the efficacy of an antagonist
0
what is the TI therapeutic index
measure of drug safety
margin between therapeutic and toxic effect
TI= TD50/ED50
what is the TD50
dose toxic to 50% population
what is the ED50
dose effective in 50% of the population
what does a lower therapeutic index mean
more likely for toxicity to be a problem
what are allosteric modulators
act at distinct sites to which the agonist (neurotransmitter) binds to
negative- non competitive antagonists
positive- increase potency of agonist
dose response curve shifts to left
what is an example of a positive allosteric modulator
diazepam
what is an example of a negative allosteric modulator
GABA
