L13-Dynamics of drug action Flashcards
what are the different types of response curves?
A) dose response curve
B) quantal dose response curve
what does the dose response curve study?
it studies the efficacy and potency of a drug acting on 1 organ or 1 person only
name the substance that gives the same effect as an endogenous ligand
agonist
name the drug that gives reduced effect as the endogenous ligand
Partial agonist
what is an antagonist?
substance that prevents the response (inhibits it)
what type of curve is the dose response curve?
it is a sigmoid curve.
what is the Emax of a drug?
it is the maximum response of the drug and if drug concentration increases no further response will occur. it appears as a plateau on the sigmoid curve
what is the EC50 of a drug?
its the concentration of the drug that produces half the EMax
what happens to the efficacy if the Emax increases
it will increase
what will happen to the potency if the EC50 increases?
the potency will decrease
what’s the effect of graph shifting to the left on potency?
it will increase the potency.
when can potency be compared
when its a drug acting on the same receptor
how to know if 2 drugs have the same receptor?
if they have parallel slopes then they are acting on the same receptor
what is clinically more important efficancy or potency?
efficancy is clinically more important
name the relation between 2 drugs that increase each others potency
potentiation relation
name the relation between 2 drugs that decrease the potency of each other
antagonist
what is a competitive reversible antagonist?
substance that decreases the potency but gives of the same Emax
what is a noncompetitive antagonist ?
something that causes the decrease of efficancy but have the same potency
name the relation between 2 drugs that increase the efficancy of each others
synergism or summation
what are 2 aspects of the quantal dose response curve?
Therapeutic effect and toxic effect.
wha is the ED50?
it is the concentration that gives of half of the maximum therapeutic response
what is the TD50?
the concentration that gives of half of the toxic effect
what is the safety of the drug?
it is a value to see how safe is the drug. it calculated by {TD50/ED50}. The greater the number the safer the drug is.
explain what’s meant by drug tolerance?
it indicates a need to increase the concentration of the drug to maintain the same response.
explain what is meant by tachyphylaxis.
it an acute rapidly developed drug tolerance caused by taking the same drug consecutively with quick successions.
explain what’s meant by refractoriness.
loss of the therapeutic efficacy of the drug.
explain what meant by drug resistance.
signifies the complete loss of effectiveness to antibiotic or anticancer
explain what’s meant by idiosyncrasy?
it is an abnormal response to a drug cause by genetic defect
explain what is hypersensitivity reaction
when the immune response develops due to the formation of antigen-antibody reaction (ANAPHYLAXIS)
explain what’s meant by drug dependance?
an adaptive state that develops due to repeated administration of that drug
what are the types of drug dependance?
physical and psychological dependence
explain whats meant by physical dependance?
there have been physiological changes and the body has been altered in ways that make it crave that drug. upon cessation the body will experience withdrawal symptoms.
explain what meant by psychological dependance
the patient have the urge to take the drug but their body has no change because of it
