Pharmacodynamics Flashcards by Brooke Thornburg

Pharmacodynamics

-concentration and effect relationship
-actions of drug on body
-receptor interaction
-efficacy, toxicity (dose-response)
-mech of therapeutic and toxic effects

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PK PD venn diagram

-PK: dosage regimen
-both: drug exposure
-PD: effects

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Importance of PK/PD

-relate patterns of response to drug admin following dosing
-rationale for drug design/selection/dosage regimen
-aid in design of protocols to view in vivo effects

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Exposure

-any dose or drug input to the body or various measures of acute or integrated drug concentrations in plasma or other biological fluid

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Reponse

-measure of pharmacologic observation
-desired vs harmful

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Effect

-change in response from one time to another
-gonna use interchangably with “response” tho

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Relating exposure to effect

-exposure: time vs concentration
-effect: % effect vs time
-combined: % effect vs concentration

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Drug-receptor interactions

-form drug-receptor complex
=initiate response

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Drug action is mediated by

-free drug concentrations

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Effect equation

do i need to know??

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Graded response

-continuous scale
-measured in single biologic unit (person)
-relates dose to INTENSITY of effect

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Quantal response

-all or nothing effect
-measured in more than one individual
-relates dose to FREQ of effect

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Graded dose-response relationship

-inc curve over time until it hits max

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Clinical stress testing

-dobutamine for pt that cannot get on treadmill for cardiac stress test
-synthetic cholamine to assess inc in heart rate
-inc dose inc HR

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Concentration-effect relationship (parameters)

-Emax: peak effect
-EC50: concentration for half max effect

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Emax

-max effect
-NOT concentration units

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EC50

-CONCENTRATION units
-concentration for half max response

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Receptor parameter

-% receptors bound vs dose
-Bmax and kd

Doxorubicin

-cardiotoxin
-chemo
-quantal response
-heart either fails or it doesnt
-put population data together to get an individual graph
-how much can we give someone before they develop heart failure

Clinical quantal

-50mg per treatment * 8 treatments = 400mg lifetime dose

Efficacy (Emax)

-max effect
-Emax

Potency

-sensitivity to drug
-EC50

Agonist vs partial vs antagonist

-agonist: max effect
-partial: part effect
-antagonist: no effect

When an antagonist is added to an agonist

-make agonist less POTENT
-shifts curve right

Effect of kidney disease on PD

-Na secretion effect on plasma log -dec response -gonna need to inc dose or freq

effect of disease on PD

-effect response

Linking concentration to response

-GRAPHS HUH -slide 45

Response vs time

-predicts response will decline linearly -one-compart -linear log-dose relationship -dec in effect is impact by k (PK) and m (PD)

What happens to time course of response if k is increased

-Slope declines more quickly -Eo unchanged -m unchanged -time course changed due to change in PK

What if dose is changed?

-slope same -y-intercept diff

what could cause a change in m?

idk

Non-compartment PK/PD modeling

-PK: Cmax, AUC, fu -PD: Cmax/MIC, AUC/MIC, t>MIC (time above MIC)

graph graph graph

slide. 50

PD models

-linear -Emax -Sigmoid Emax

Linear model

-Effect = Eo (intercept) + S(slope)*C(concentration)

Log-linear model

-effect = Eo + S * logC

Emax model

E=(Emax*C)/(EC50+C)

Sigmoid Emax model

E = (Emax * C^h)/(EC50^h + C^h) -h is constant -high h is gonna be steeper slope -EC50 stays same

Ketamine example

-sigmoidal model -S ketamine more effective

Direct effect model

-peak concentration happens around the same time as peak response

Dysequilibrium in concentration-effect relationship

-peak effect is NOT at same time as peak concentration =LOOP

hysteresis loop

-delay in response causes graph to loop

Potential reasons for delay in response

-delay in drug reaching effect site/biophase -production of active metabolite that produces response similar to parent -up-regulation of receptor response or sensitixation -indirect effect