Drug administration

Question 1

define absoprtion?

Answer 1

drug enters plasma

Question 2

drug transported to and from sites of action

Answer 2

distribution

Question 3

biotransformation (metabolism)

Answer 3

chemical structure of drug changed

Question 4

excretion

Answer 4

irreversible loss of drug

Question 5

loss of drug concentration or effect

Answer 5

elimination

Question 6

enteral

Answer 6

• via GI tract
• sublingual, oral, rectal

Question 7

paraenteral

Answer 7

• via injection
  -intravenous, intramuscular, subcutaneous, intrathecal

Question 8

local routes of drug admin

Answer 8

• topical
• intradermal
  -intrasynovial

Question 9

Oral route

Answer 9

• convenient and economical
• requires patient compliance
• absorption variable
  -safest

Question 10

factors of oral route

Answer 10

• gastric emptying time
• gastric acidity
• first pass effect
• greater absorption from small intestine

Question 11

intravenous route

Answer 11

• Into the vein (not artery)
• Absorption circumvented; potentially immediate effects
• Useful in emergencies
• Permits titration of dose
• Suitable for large volumes or irritating substances if diluted

Question 12

downside to intravenous

Answer 12

-Not suitable for oily solutions or insoluble substances
-Dangerous; expensive
-Must inject slowly
-Usually required for high molecular weight protein or peptide drugs

Question 13

Intramuscular route

Answer 13

-Into the muscle (not vein)
-Prompt absorption from aqueous solution
-Slow and sustained absorption from repository preparations
-Suitable for moderate volumes; oily vehicles
Painful; tissue damage

Question 14

subcutaneous route

Answer 14

-Beneath the skin
-Absorption similar to intramuscular (at rest)
-Useful for insoluble suspensions or solid pellets
-Painful; tissue damage
Vasoconstrictors can slow absorption

Question 15

Other common routes

Answer 15

inhalation, topical, transdermal

Question 16

topical

Answer 16

designed for local actions

Question 17

transdermal

Answer 17

designed for systemic actions

Question 18

inhalation

Answer 18

very rapid distribution to CNS

Question 19

drug movement: membrane

Answer 19

-lipid
-pores
-channels
-transporters
-carrier proteins

Question 20

drug transport mechanisms

Answer 20

active or facilitated

Question 21

aqueous channels

Answer 21

filtration

Question 22

facilitated diffusion

Answer 22

-carrier mediated transport
- does NOT require energy

Question 23

active transport

Answer 23

• requires energy
• ATP binding cassette (ABC)
• solute carrier transporter (SLC)

Question 24

passive diffusion

Answer 24

• most common
• high to low concentration

Question 25

passive diffusion is proportional to

Answer 25

- concentration gradient of unionized drug - lipid water partion coefficient - membrane surface area - pH gradient

Question 26

weak acids _____

Answer 26

dissociate

Question 27

weak bases ___

Answer 27

dissociate

Question 28

weak acids absorbed more at a ____ pH

Answer 28

low

Question 29

weak bases absorbed more at a ____ pH

Answer 29

high

Question 30

factors that affect drug distribution

Answer 30

-Blood perfusion rate -Membrane characteristics -Intracellular / extracellular pH -Sequestration in fat -Protein binding - plasma - tissues

Question 31

drug distribution

Answer 31

Process by which absorbed drug in plasma gains access to sites of action

Question 32

weak acids bind to serum ____

Answer 32

albumin

Question 33

weak bases bind to ____

Answer 33

glycoproteins

Question 34

plasa protein binding is

Answer 34

- non-specific - levels change with age and disease

Question 35

displacement of bilirubin by sulfonamides will cause ____

Answer 35

kernicterus

Question 36

blood brain barrier

Answer 36

- restricts drug distribution into brain - drugs must be very lipid soluble to cross - inflammation may increase permeability

Question 37

placental barrier

Answer 37

- tissue layers become thinner during gestation - distribution of drug to baby increases as term approaches

Question 38

apparent volume for drug distribution

Answer 38

D/Vd = Co (concentration)

Question 39

plasma water ____ L

Answer 39

3

Question 40

interstitial fluid ____ L

Answer 40

9

Question 41

intracellular fluid ___ L

Answer 41

29

Question 42

total body water ___ L

Answer 42

41

Question 43

drug binding to tissues ____ apparent volume of distribution

Answer 43

elevates

Question 44

drug binding to plasma proteins _____ apparent volume of distribution

Answer 44

depresses

Question 45

redistribution

Answer 45

drugs administered to vessel rich areas and then move to less vascularized tissue serving as a drug elimination mechanism example: thiopental

Question 46

Thiopental

Answer 46

- weak acid - crosses BBB - acidosis increases in plasma