RPA pharmacology

Question 1

first pass metabolism

Answer 1

everything that happens from consuming the drug until the drug reaches the rest of the body
digestive -> portal system -> liver

Question 2

oral bioavailability

Answer 2

AUC oral/ AUC IV x 100%

Question 3

clearance in pharmacology

Answer 3

CL is expressed in L/min

the volume from which the drug is cleared per unit time

Question 4

first order kinetics

Answer 4

clearance is related to the concentration of the drug

there is an exponential decay

Question 5

zero order kinetics

Answer 5

the amount that is removed from the body is fixed

e.g. if an enzyme system is saturated

Question 6

what are examples of drugs that operate at zero order kinetics

Answer 6

alcohol, aspirin, phenytoin, theophylline

Question 7

does metabolism make the drug more polar or non polar

Answer 7

more polar so they can be excreted in urine

Question 8

extraction ratio

Answer 8

fraction of drug removed from blood in one passage across organ (liver)

ER = (drug in - drug out)/(drug in)

Question 9

what is flow dependent kinetics

Answer 9

when all drug is removed in the liver

clearance is approaching hepatic blood flow

Question 10

what is capacity limited metabolism

Answer 10

when the ER approaches 0

Question 11

examples of low extraction ratio

Answer 11

diazepam, carbamazepine phenytoin, warfarin

Question 12

examples of high extraction ratio

Answer 12

morphine
propranolol
gtn
CCB
antidepressants
levodopa

Question 13

volume of distribution

Answer 13

theoretical volume that would be necessary to contain the total amount of an administered drug at the same concentration that it is observed in the blood plasma

volume distribution - amount in body/plasma concentration

Vd is defined as the apparent volume into which a drug disperses in order to produce the observed plasma concentration”

Question 14

how to calculate loading dose

Answer 14

volume distribution x plasma concentration

Question 15

greatest impact on pharmacokinetics in older people

Answer 15

decreased hepatic flow

age selective impairment of phase I>II (CYP >conjugation)

Question 16

doxycycline birth defects

Answer 16

third trimester

teeth

Question 17

what happens to volume distribution in pregnancy

Answer 17

increases

Question 18

what happens to protein binding in pregnancy

Answer 18

decreased protein binding

need to think about when interpreting drug concentrations

Question 19

p glycoprotein

Answer 19

drug transporters that determine the uptake and efflux of a range of drugs. This process affects their plasma and tissue concentrations and ultimately their final effects. P-glycoprotein functions as a transmembrane efflux pump, pumping its substrates from inside to outside the cell.

drugs are often both substrates of CYP3A4 and P-glycoprotein

Question 20

what drug is most likely to cause addisonian crisis on adrenal replacement

Answer 20

rifampicin

Question 21

pharmacodynamics

Answer 21

impact of the drug on the body
can be divided into effect and potency
potency is how quickly you get a response initially
effect is total effect on the body

Question 22

hysteresis - negative vs positive hysteresis

Answer 22

negative hysteresis is where the drug effect increases despite same concentration because it is reaching the appropriate compartments over time

positive hysteresis is where the drug effect decreases despite the same concentrations due the toleration developing

Question 23

Type A, B, C, D adverse drug reaction

Answer 23

type A is dose related

type B is idiosyncratic
anaphylaxis

C - chronic

D- delayed