pharmacodynamics Flashcards
pharmacodynamics
what the drug does to the body
pharmacodynamics is determined by: (2)
- changes in the environment surrounding the cells
- Change in cellular function
effects via change in the environment surrounding cells
drugs can illicit effects by changing the environment surrounding the cells via physical or chemical means
–> does not bind to receptors to elicit effects
change in the environment: physical processes
- changes in surface tension
- lubrification
- adsorption (binding to a drug)
change in the environment: chemical processes
- neutralization
- change in pH
- changes in bodily fluids
can a drug illicit pharmacological effects without binding to receptors?
yes –> changes in environment surrounding cells (physical or chemical)
effects via change in cellular function
interactions occur between drugs and its site of action (target receptor) to illicit effects
site of action (4)
a. specific cellular receptors - most common
b. enzyme
c. transporter
d. ion channel
receptor
part of a cell or tissue to which a drug can bind and impart an effect
ligand
the molecule (drug) that binds to a receptor
affinity
the probability of a drug occupying a receptor at any given instant
(force of attraction between a receptor and a drug)
receptors have _ capacity and _ affinity
low capacity, high affinity
selectivity
degree to which a drug acts on a given target relative ot other sites
agonism
when a drug binds to a receptor –> illicit a response
antagonism
when a drug binds to a receptor –> does not illicit a response
when is the effect of an antagonism felt?
the intensity of the effect depends on the concentration of agonist present in the system being antagonized
–> the more agonist present, the more the inaction of the antagonist is felt (rather than the action of the agonist)
relationship between the size of an administered dose and the intensity of the response produced
dose is directly proportional to the activity of the receptors –> the intensity of the response
increased dose =
increased activity of the receptors –> increased response (effect)
decreased dose =
decreased activity of the receptors –> decreased response (effect)
the relationship between the size of an administered dose and the intensity of the response produced determines (3)
- maximum drug needed to reach therapeutic minimum
- maximum response each drug can elicit (max number of receptors)
- how much to increase the dose to produced the desired increase in response
Efficacy
–> dose
the largest effect (response) a drug can produce
Potency
–> response
the amount (dose) of a drug that must be given to elicit an effect
(dose needed to reach therapeutic minimum)
Therapeutic Drug Monitoring (TDM)
managing medication regime with the help of measured drug concentrations to keep drug levels within a therapeutic range
what can TDM provide information on? (3)
- patient compliance
- drug interactions
- dosing adjustments required
when should sampling occur to measure maximum drug plasma concentration?
1-2 hours post administration
when should sampling occur to measure minimum drug plasma concentration?
just prior to/ 1 hours before next dose
purpose of therapeutic drug monitoring
to ensure drug plasma levels are within therapeutic index
what drug classes are often monitored with TDM?
- analgesics
- antimicrobials
- anticonvulsants
- chemotherapeutics
- bronchodilators
- cardiovascular drugs
- immunosuppressant drugs
what class of drug is theophylline?
bronchodilator
what class of drug is digoxin?
cardiovascular
what class of drug is cyclosporine?
immunosuppressant
what class of drug is vancomycin?
antimicrobials
what class of drug is aminoglucosides?
antimicrobials
