Introduction to PK

Question 1

What are invasive measurements

Answer 1

plasma, serum, blood

Question 2

What are non-invasive measurements

Answer 2

milk, saliva, urine, feces

Question 3

difference bet plasma and serum (how do you collect it)

Answer 3

plasma = added an anticoagulant (e.g. heparin/citric acid); contains bound and unbound drug

serum = no anticoagulant added; fibrinogen and fibrin is removed

Question 4

how to find kpRBC (RBC-to-unbound plasma drug conc ratio)

Answer 4

Crbc/Cu

Question 5

what does kpRBC reflect?

Answer 5

affinity of RBC for drug

Question 6

What does ADME stands for?

Answer 6

Absorption (systemic)
Distribution
Metabolism
Excretion

Question 7

What does disposition consist of?

Answer 7

DME

Question 8

What does elimination consist of?

Answer 8

ME

Question 9

What is systemic absorption?

Answer 9

Unchanged drug proceeds from site of administration (extravascularly via non-intravenous routes) to site of measurement within the body, usually plasma in arm vein

Question 10

fraction unbound is usually

Answer 10

constant

Question 11

when can fu change?

Answer 11

when protein binding is altered

e.g renal/hepatic disease, surgery, severe burns, preg

Question 12

What are some examples of extravascular routes?

Answer 12

Via Alimentary Canal (Buccal, Rectal, Oral, Sublingual)
Other routes (Inhalation, SC, IM, Transdermal, Intranasal)

Question 13

What is enterohepatic cycle?

Answer 13

Process where drug is secreted into bile, stored in and released from the gallbladder, transit into the small intestine, and reabsorbed there back into circulation.

Question 14

Which component (A,D,M,E) does enterohepatic cycle fall under?

Answer 14

Distribution

Question 15

What is elimination?

Answer 15

Irreversible loss of drug from site of measurement?

Question 16

what does AUC represent in exposure-time profile

Answer 16

total systemic exposure

Question 17

F =

Answer 17

AUCoral/AUCiv

Question 18

How does oral absorption works?

Answer 18

Drug enter gut lumen (some move to faeces, some gets metabolised) –> enter gut wall (some get metabolised) –> drug enters portal vein (some get metabolised or go to biliary excretion) –> to site of measurement which is the PORTAL VEIN
anything after portal vein is already intravascular/systemic abs

Question 19

2 organs of elimination:

Answer 19

Liver (Metabolise)

Kidney (Excretion)

Question 20

How does the drug gets metabolised by liver?

Answer 20

Conversion of one chemical species to another

Question 21

How does the kidney excretes the drug?

Answer 21

Irreversible loss of chemically unchanged drug

Question 22

What is metabolism?

Answer 22

Conversion of parent drug to another chemical species (metabolite)

Question 23

when is it considered to be systemic absorption?

Answer 23

after passing the heaptic vein

Question 24

distinguishing ____ and ____ is difficult when there is a decline in the plasma drug conc

Answer 24

Elimination and distribution

Question 25

Metabolism usually renders a drug ___ and ready for excretion

Answer 25

inactive

Question 26

Major sites of metabolism

Answer 26

Intestinal mucosa and liver

Question 27

Major sites of drug excretion:

Answer 27

1. Kidneys (glomerular filtration, tubular filtration)
2. Biliary tract in liver (high MW drugs, conjugate metabolites)
3. Lungs for volatile agents (anesthetics)

Question 28

Renal and biliary excretion often involves drug transporters that can ______

Answer 28

concentrate drug in urine and bile

Question 29

First order Kinetics equation (for curve)

Answer 29

A = Ao x e^-kt

Question 30

First order Kinetics equation (for linear)

Answer 30

In A = In Ao - kt

Question 31

half life equation

Answer 31

t1/2 = In2/k

Question 32

how to find k (elimination rate constant)?

Answer 32

gradient of linear graph