Pharmacokinetics

Question 1

What is pharmacokinetics

Answer 1

what the body does to the drug

Question 2

ADME;

Answer 2

absorption distribution, metabolism, excretion

Question 3

How do drugs get administered?

Answer 3

Intral;po (orally), rectal, Intradermis, sub-Q, intra-muscle, topical, intravenous, inhaled, buccal(between teeth), sublingual.

Question 4

how do drugs get absorbed?

Answer 4

Passive diffusion, facilitated diffusion, Active transport, endostosis.

REMEMBER: This is only when a drug is not taken in intravenously.

Question 5

Passive diffusion

Answer 5

High to low concentration

Has to be small + hydroliphic

Can pass through cell membrane and through the basal lateral membrane into the blood

Question 6

Facilitated diffusion

Answer 6

High to low concentration

Needs a protein to pass through the concentration

Large: or hydrophilic

Question 7

Active transport

Answer 7

Low to high concentration

Large or hydrophillic drug

Needs to be pumped via ATP

Question 8

Endocytosis

Answer 8

Too big to be transported.

Needs receptor mediated endocytosis

binds onto receptors on the outside of the membrane which will trigger endocytosis which is the drug being taken into the cell, and then exocytosed into the blood stream. Ex. B12

Question 9

What can impact absorption?

Answer 9

Ph, Blood flow, TSA + contact time, P-glycoprotein

Question 10

pH

Answer 10

Charged molecules are more difficult to be absorbed: want nonpolar elements which are easier to be moved.

Weak acids need to be put in an acidic environment in order for it to be absorbed

Weak bases needs you to shift the reaction; needing to make the environment more alkaline for the drugs to be absorbed

Question 11

Blood flow

Answer 11

Need good blood flow;

less blood flow: less absorption

Diseases which decrease blood flow means any orally or rectally or through the skin cannot ensure that it can be absorbed

Question 12

Total surface area and contact time

Answer 12

not enough time for it to absorb

Ex: diarrhea you are decreasing absorptioin because you’re decreasing the contact that the drug will have.

Ex. Constipated- tons of contact time with an increase of absorption

the intestines: increases the total surface area… any intestinal diseases decrease the TSA which means it decreases the absorption

Question 13

p-Glycoprotein

Answer 13

Drug resistance… from

A special p-glycoprotein on the apical surface and it just spits it back out and then you will poop the drug out

So it decreases the absorption

Question 14

Bioavailability (F)

Answer 14

Fraction of the drug that actually does enter into the systemic circulation

IV = 100% bioavailability

Any other way will have not 100% because of all of the factors

Orally: the concentration will rise but it will start to fall because of metabolism. 100Mg but possibly only 50Mg get into the system. F=Auc oral/Auc IV. F=50mg/100mg= 50% is the bioavailability

Question 15

Solubility

Answer 15

Hydrophobic, small: easily pass and there can be more bioavailability and absorption

Hydrophilic, large drug: lower absorption, lower bioavailability

Question 16

Instability w/ insulin

Answer 16

oral: pen G is not good orally= it has a bunch of protons that get destroyed before it can move into the blood stream; lower bioavailability

Insulin is also something that will get broken down; so it is never given orally

Question 17

First Pass Effect

Answer 17

Mostly happens from orally (PO)

Once it moves across GIT into the blood steam, which then goes into the portal steam into the liver, the liver always takes a portion and it metabolizes inactivate, which means even less is passed on.

Ex: start with 100, but then pH, blood flow, p-glycoproteins, surface area, stability, instability, all take 10%, then after the portal stream it goes into the liver which always takes a part- 60mg in this case and then that means only 30% is left

Question 18

what makes a good drug

Answer 18

-goes to its specific target (and has a selective mechanism of action)
-able to reach the target (absorption/metabolism)
-Few off targget effects (toxicities and side effects)
-improves the condition
(physiology and efficacy)