Phamacokinetics & Pharamacodynamics Flashcards
How does body handle drug
absorption, distribution, metabolism, excreation
maximum therapeutic concentration
drug become toxic beyond that point
minimum effective conc
minimum con where drug effect is observed
pharmacodynamics
drug receptor theory- signalling- biological response
therapeutic index
TD50/ED50, range of dose at which medication is effective without unacceptable adverse effect
TD50
toxic dose 50
ED50
effective dose 50
higher TI
safer the drug
Pharmacokinetics
absorption, distribution, metabolism, excretion,
need to know to identify the dosage
pharmacokinetics vs pharmacodynamics
- dose resulting in conc vs time
- effect vs conc
drug receptor theory
drug and recepetor bind to for DR complex nd cause impact on effector
resulting in response
affinity
measure of the probability that a drug molecule will interact with its receptor to form a DR complex
- both agonist and antagonise must have affinity to the receptor
efficacy
intrinsic activity
the ability of bound liganf to activate the receptor
agonist
interact with receptor and elicits a direct response
antagonist
interact with receptor without eliciting a direct response
receptor
any cmoponent of biologial system that interacts with drug and thereby leads to drug effect
protein base targets
receptors, enzyme,s ion channels, transporters
DNA target
inhibit replication and trasncrition
-antitumour :cispatin
- antibiotics: streptomycin
drug that bind to osmotic diuretics
mannitol
drug that bind to bulk laxative
agar and methyl cellulose
Antaacids
against overproduction of acid in stomach
aluminium or magnesium hydroxide
factors that affect the binding of drug to receptors
size, receptor drug interaction(ionic, covalent, hydrophobic interaction) and drug shape(complementary to receptor)
law of mass
rate of checmical rxn is proportionate to the product of the concentrations of reactants
kf: forward
kr: reverse
measure of affinity
K=Kf/Kr
Kd, dissociation constant
[d][r]/[dr] = kr/kf= kd
smaller the kd, the higher the affinity
affinity and response
same conc, a drug with higher affinity will form more DR
receprot affinity determine the conc of drug required to form a significant number of drug receptor complexes
magnitude of response to receptor occupation
proportional
formula assocated with affinity
[DR]=b=(bmax*[d]free)/(d free + kD)
bmax when Dr approached R[t]
efficacy(a)
measure of biological effectiveness of the DR complex the drug forms with its receptor
full agnosit : 1
partial: 0 to 1 , can be negative as well
antagonist : 0
effficacy higher
higher then Emax
who elicit diret respose and why
agonist bc of their efficacy
who cannot product direct response
antagonist with no efficacy at the receptor thus no signaling mechanism
potency
related to thedose requrired ot product a given degree of response >EC50
factors affecting potency
affinity and efficacy
dose required relation with potency
higher the potency, lower dose required
calculated with EC50 and IC40 for antagnonists
y axis and x axis of log, con of drug and response curve
x- potency difference
y- efficacy difference
how to choose drug of varying potency
look at the respose we want as well, and then the conc needed to obtain it
- higher response vs lower response
response equation
emax*[d]/[d]+ec50
