MODULE 2

Question 1

what is pharmicokinetics?

Answer 1

study of drug movement in the body
what the body does to the drug
adme

Question 2

what is absorption?

Answer 2

movement of the drug from the site of administration into blood
rate of absorption determines how quickly how quickly the drug effect will occur
the amount of drug absoprtion determines how intense the effect of the drug will be

Question 3

what is the greatest determinant of absorption?

Answer 3

surface area
larger SA= quicker absorption

Question 4

why does high blood flow increase absorption?

Answer 4

high blood flow maintains a concentration gradient because it whisks away drugs

Question 5

does a lipophillic drug or hydrophillic absorb quicker

Answer 5

lipohillic - penetrates the membrane

Question 6

how does pH partitioning affect absorption?

Answer 6

there is increased absoprtion when theres a difference between pH at the site of admin and the blood- such that the drug is ionized in the blood

Question 7

what do uptake and efflux drug transporters do

Answer 7

there is uptake (increased absorption of drugs) and efflux (decreased absorption)

Question 8

why is a weakly acidic drug not absorbed better in the stomach rather than the intestine

Answer 8

stomach would not ionize the drug and would absorb well. HOWEVER the stomach has a layer of mucus and the intestine has a way larger surface area

Question 9

what is the pharmaceutical phase?

Answer 9

-occurs after the patient swallows a tablet
-involves disintegration and dissolution of a drug
-if the drug does not disintegrate, absorption is reduced

Question 10

what increases gastric emptying?

Answer 10

-taking medications on an empty stomach
-taking medications with cold water
-lying down on the right side
-high osmoslity feeding
-taking a prokinetic drug (drug that increases GI)

Question 11

what is decrease gastric emptying?

Answer 11

high fat meal, heavy exercise, lying down on left side, taking a drug that inhibits the vagus nerve

Question 12

what is enteric coating?

Answer 12

-prevents dissolution in the acidic environment of the stomach
-once passes into the more alkaline intestine, the enteric coating dissolves

Question 13

what is bioavailability?

Answer 13

the fraction of a dose of drug that reaches the systemic circulation unchanged

Question 14

what is bioavailability influenced by?

Answer 14

1. drug formulation
2. route of admin
3. degree of metabolism

Question 15

how does transdermal absoprtion occur?

Answer 15

epidermis provides a lipid barrier

must be lipophilic to pass through the epidermis lipid barrier but must be hydrophilic in order to dissolve in extracellular fluid

usually small molecule

Question 16

characteristics of a transdermal preparation

Answer 16

-provides constant plasma levels
-need to remove for 6-10 hours to avoid ointments

Question 17

what affects transdermal absorption?

Answer 17

1. thickness - thicker the skin, the less absoprtion
2. hydration - increased when the skin is hydrated
3. follicles - more follicles = increased absoprtion
4. area - more area = more absorption
5. integrity - worse skin - better absorption

Question 18

description of rectal absorption

Answer 18

-50% of rectal drugs bypass the liver
-incomplete absorption and may irritate the rectal
mucosa

Question 19

description of subcutaneous

Answer 19

-only barrier to absorption is the capillary wall
-irritant drugs must not be injected subcutaneously as
this tissue will cause severe pain and/or tissue
sloughing
-the primary determinants of rate of absorption are blood flow and water solubility