PHARMACOLOGY Flashcards
what are pharmacodynamics?
what the drug does to the body
i.e. what does the drug do once it is in the body?
what factors affect the pharmacodynamics?
affinity
efficacy
potency
what are pharmacokinetics?
what the body does to the drug
i.e. what does the body do once the drug is in it?
what factors affect pharmacokinetics?
- absorption - gut vs parenteral
- distribution
- metabolism - first pass metabolism
- excretion - usually renal
what is affinity?
it is how well a drug will bind to a receptor
high affinity = binds well
low affinity = binds less well
what is efficacy?
it is the degree to how well a drug works on a specific receptor
it can be seen as the maximum effect a drug can have in the body
what is potency?
it is the amount of the drug needed to achieve a response
what is an agonist?
a molecule that attaches to a receptor, causing a reaction in the cell
- it stimulates the receptor
what is a partial agonist?
a molecule that attaches to a receptor, causing the same reaction as a full agonist, to a lesser extent
what are competitive inhibitors?
molecules that block other things from binding to the receptor by sitting in it’s action site
what are non-competitive inhibitors?
- molecules that block other things from binding to the receptor but not by sitting in it’s action site
- it may attach to a different part of the receptor and cause the action site to change shape
what factors affect distribution in pharmacokinetics?
- blood flow
- molecular weight/size
- how lipophilic/phobic a drug is
- blood brain barrier/blood testicle barrier
where does first pass metabolism occur?
in the liver
what is bioavailability?
the proportion of the drug given that enters circulation and so can exert an effect on the body
why are different doses of the same drug prescribed when given orally vs IV?
- with oral medications, first pass metabolism via the liver will reduce how much enters circulation - reduces bioavailability
- giving mediations IV means drug enters straight into circulation - bioavailability = 100%
what are the main routes of drug administration?
- oral
- IV
- subcutaneous
- intramuscular
- topical
- rectal
- intrathecal
- sublingual/buccal
- inhalation
what does parenteral drug administration?
non-oral drug administration routes
what is intrathecal drug administration?
into the spinal column for anaesthesia, chemotherapy or pain management
what is oral drug administration?
drugs taken orally
undergoes first pass metabolism - reduced bioavailability
what is IV drug administration?
drugs enter directly into circulation
what is subcutaneous drug administration?
drugs have to diffuse through subcutaneous fat
- drug is absorbed more slowly
what is intramuscular drug administration?
muscle tissue is vascular so it is rapidly absorbed
what is topical drug administration?
- directly onto skin/mucosa
- avoids first pass metabolism
- slowly absorbs into circulation
what is rectal drug administration?
can be used when patient is unable to tolerate oral route
highly vascular tissue so absorbs quickly