DRUG DISPOSITION AND FATE OF DRUGS 1

Question 1

Drugs MUST have some ability to dissolve______ to move around (be absorbed, reach sites of action.)

Answer 1

WATER

Question 2

drugs must also have a
certain degree of_____, to (leave and enter capillaries,
enter and leave cells.)

Answer 2

LIPID SOLUBILITY

Question 3

is a preference not an absolut?

Answer 3

SOLUBILITY

Question 4

drug concentration are measured in what?

Answer 4

SERUM or PLASMA

Question 5

Drug dissolve in?

Answer 5

BODY FLUID

Question 6

Drugs enter the circulatory system as fluid enters the?

Answer 6

CIRCULATORY SYSTEM

Question 7

Drugs must enter the________ before they can distributed to sites of
action.

Answer 7

CIRCULATORY SYSTEM

Question 8

drugs are not IN the body until they are IN the?

Answer 8

BLOOD STREAM

Question 9

Advanatges of oral administration:

Answer 9

1. CONVENIENT
2. CHEAP
3. NO NEED FOR STERILIZATION
4. VARIETY OF DOSE FORM

Question 10

Disadvantages pf oral administartion:

Answer 10

1. Variability due to physiology, feeding, disease, etc.
2. Intractable patients
3. First-pass effect
4. Efficiently metabolized drugs eliminated by the liver before they reach the systematic circulation.

Question 11

The bolus remains relatively spherical. Mixing and
dissolution in tissue fluid occurs from surface of bolus, so entry of drug into
circulatory system limited by rate of drug “dissolution”

Answer 11

LIPID SOLUBLE VEHICLE

Question 12

Can be given by the owner (small patients); also
Vasoconstrictor can be added to prolong effect at site of interest

Answer 12

SUBCUTANEOUS ADMINISTRATION

Question 13

disadvantage of subcutanous administartion:

Answer 13

1. VARIABILITY

Question 14

2 types of TOPICAL ADVANTAGES :

Answer 14

1. IF systemic therapy – easy painless application
2. IF skin therapy – reduced systemic effects/enhanced skin effects

Question 15

-Larger absorptive surface are than IM / Subcutaneous
-drugs & vehicles may cause peritonitis
-restricted to labortory animals

Answer 15

intraperitoneal

Question 16

Direct delivery to site of action. High concentrations can be produces in the joint.

Answer 16

intra-actular

Question 17

Direct delivery to site of action, via an injection into the spinal canal, or into the subarachnoid space so that it reaches the cerebrospinal fluid (CSF)

Answer 17

intrathecal

Question 18

Absorption from the site to systemic is variable but often quite fast.

Answer 18

intra-actular

Question 19

Produce extremely high concentrations “pointed at” (the tissue of interest. Used primarily for anti-tumor therapy and infectious disease therapy when blood supply is questionable.

Answer 19

intra-arterial

Question 20

Animals may not willingly retain the drug, it has an advantages of Access to GI absorption in unconscious or vomiting patients

Answer 20

per rectum

Question 21

Includes plasma, plasma water, and red blood cells. Equilibria occur between water and various plasma proteins, ionized and unionized drug, and plasma and cells. Distribution occurs within 10 to 30 minutes due to mixing

Answer 21

vascular spaces

Question 22

Represents 7% of body weight. Equilibria occur between ionized and unionized drugs, and between plasma and cells. Distribution occurs within 10 to 30 minutes due to mixing.

Answer 22

tissue space

Question 23

Special barriers exist between plasma and tissue fluids, such as cerebrospinal fluid (CSF), aqueous humor, and prostatic fluid. Distribution occurs in minutes to never, indicating limited or no permeability in some cases.

Answer 23

reserved spaces

Question 24

Exists in both vascular and tissue spaces, constituting 35-45% of body weight. Equilibria occur between ionized and unionized drugs. Intracellular pH is lower than extracellular pH. Distribution takes 30 minutes to over 12 hours.

Answer 24

intracellular spaces

Question 25

Occurs through transcytosis, endothelial junctions (in inflammation), and diffusion across endothelial cell membranes.

Answer 25

Vascular to tissue space

Question 25

Includes extracellular fluid in both vascular and tissue spaces, constituting 15-20% of body weight. Equilibria occur between water and proteins, and ionized and unionized drugs. Distribution takes 30 minutes to 1.5 hours.

Answer 25

extracellular spaces

Question 25

Involves diffusion through the lipid bilayer of cells. Drugs can move from vascular extracellular space to vascular intracellular space, with the possibility of active acquisition by white blood cells.

Answer 25

Extracellular to Intracellular Space

Question 26

Brain and liver concentration rise faster than muscle or fat

Answer 26

true

Question 26

Diffusion can be rapid and is controlled by the rate of drug delivery to the tissue, determined by blood flow per gram of tissu

Answer 26

Blood Flow Limited Distribution

Question 27

Diffusion is relatively slow compared to mixing within the vascular system.

Answer 27

diffusion limited to distrubution

Question 28

This process leads to lower drug elimination rates and a higher volume of drug distribution.

Answer 28

Enterohepatic Circulation

Question 29

This process is crucial in treating mammary gland infections and ensuring that nursing animals are not exposed to toxic drug levels in milk.

Answer 29

Mammary Excretion:

Question 30

normal milk pH

Answer 30

6.6 (slightly acidic versus blood)

Question 31

Drug in saliva passes into GI tract, Ruminants can recycle certain drugs (similar to enterohepatic circulation) and trap drugs in the rumen based on pH, affecting elimination.

Answer 31

Salivary excretion

Question 32

chemical mechanism involves in biotransformation:

Answer 32

1. oxidation 2. hydroxylation 3. hydrolysis 4. reduction 5. conjugation

Question 33

converts drugs into metabolites, often inactivating them but sometimes activating them

Answer 33

BIOTRANSFORMATION

Question 34

Involves drugs with molecular weights > 300, usually conjugates of the original drug.

Answer 34

ACTIVE SECRETION

Question 35

Involves drugs with molecular weights < 300, with biliary concentrations similar to plasma water.

Answer 35

PASSIVE SECRETION

Question 36

passive elimination of drug dissolved in plasma water.

Answer 36

Glomerular excretions

Question 37

energy dependent excretion by proximal kidney tubule

Answer 37

Tubular secretions

Question 37

drug movement from renel tubule back to blood stream

Answer 37

passive reabsorption

Question 38

renal elimination of aspirin can go from?

Answer 38

2% to 30% of total elimination