definitions Flashcards
clearance
relationship between drug concentration to the rate of elimination (rate out)
volume of distribution
relationship between concentration and the amount of a drug in the body
extend of absorption
reflects total amount of drug entering the body, is not time-dependent
rate of absorption
determines how quickly the drug enters the body. The rate typically changes with time.
fraction absorbed
how much of the drug gets from the gut into the portal venous system
first pass extraction
determined by blood flow and organ clearance
e.g. hepatic = amount of drug removed while passing through the liver
zero order input
means the absorption rate is constant for a defined period of time. Achieved by a constant rate IV infusion
first order input
means the absorption rate is proportional to the amount or concentration of drug at the absorption site. An example is an intra-muscular injection of a drug.
bolus input
absorption is instantaneous. Is approximated by rapid intravenous injection
half-life
the time taken for a concentration of a drug to fall to half its value. Describes first order process, which describes absorption and elimination
accumulation factor
is the ratio of the concentration at steady state to the concentration after the first dose at the same time after the dose.
affinity
a measure of how tightly a drug binds to a receptor.
Kd = concentration when 50% of the receptors are occupied. Higher Kd means lower affinity
potency
a measure of how much drug is required to produce a particular effect. EC50
efficacy
is the ability of a drug to produce a response. Emax
receptors
proteins which specifically recognise a particular neurotransmitter/hormone and upon binding undergo a conformational change leading to activation/inhibition of cell signalling.
types:
- ligand gated ion channels
- g-protien coupled receptors
- nuclear receptors
- tyrosine kinase receptors
full agonists
drugs that elicit the maximum tissue response
partial agonists
drugs that produce less than the maximal response
antagonists
a compound that binds to a receptor but does not activate or inactive the receptor
have affinity but no efficacy
irreversible antagonists
drugs that covalently bind to a receptor. They reduce the number of receptors available to the agonist
pharmacogenomics
the investigation of variations of DNA and RNA characteristics as related to drug response
drug interaction
a change in one drugs effect when administered with another drug, food or other substance
pharmacokinetic interactions
Drug-drug interactions that alter the plasma concentration of 1 or both drugs. Can occur at the level of absorption, distribution, metabolism or elimination
pharmacovigilance
monitoring of the safety of marketed medicines and taking action to reduce risk and promote safe use, thereby protecting public health
special authority medicines
prescriber requests government subsidy for a particular individual
specialist only medicines
only subsidised if prescribed by the appropriate specialist
surrogate
biomarker used for regulatory approval
biomarker
readily measurable marker of response
adverse drug reaction
a response to a drug which is noxious and unintended, and which occurs at doses normally used.
side effect
an expected and known effect of a drug that is not the intended therapeutic outcome.
target concentration intervention
links pharmacokinetics and pharmacodynamics to predict the right dose for a patient
rational prescribing
selection of the most appropriate therapeutic regimen for a specific patient
selective toxicity
is the goal of chemotherapy
achieved by exploiting differences between normal host cells and disease producing cells, when:
- there is a unique target in the pathogen
- the target is structurally different in the pathogen
- the target is functionally different in the host
therapeutic index
(important indicator for selective toxicity)
ratio of dose required to produce toxic effect divided by the dose required to produce desired effect
targeted cancer therapy
drug treatments that inhibit oncoproteins that drive tumour development and progression
