Fundamentals

Question 1

What is enternal route of drug administeration

Answer 1

Across a membrane (oral, topical etc)

Question 2

What is the perenteral route of druug administeration

Answer 2

Administeration bypasses membrane

IV, Intrathecal into spinal cord etc

Question 3

What is the main site of drug bio transformation

Answer 3

liver

Question 4

What are the 2 reasons a liver changes parent drug to metabolites

Answer 4

• generally (but not always) liver turns parent drug into something that is toxicologically inactive
• Increase water solubility for allowing easy excretion via kidneys

Question 5

What is free drug vs bound drug

Answer 5

free- disolved in the blood

Bound- distribibuted via plasma proteins (attached to albuminin)

creating free:bound

Question 6

free vs bound drug biotransformations + excretion

Answer 6

free drug is type that undergoes biotransformation in liver by entering hepatocytes (bound to large to enter)

-Kidney glomerus allows movement/filtration of drugs up to 1000da and bound drg is too large for this

Question 7

What is the drug receptor complexes

Answer 7

is at site of action formed with free drug (initiates pharmacological action)

Question 8

Most drugs are what weight

Answer 8

40-450 daltons

Question 9

To be pharmalogically active a drug must have these 2 characteristics

Answer 9

Some solubility within aqueos fluids of body in order to reach site of action + some lipid solubility to cross membrane barriers

Question 10

what is ionization

Answer 10

When a substance releases or accepts ions

Question 11

What will acid and basic drugs do with there protons in low ph env

Answer 11

Acidic drugs will keep proton (unionized)

Basic drugs will accept proton (becoming pos- ionized)

Question 12

How does ionization affect solubility

Answer 12

A substance that is ionized will prefer to disolve in highly polar area (water)

A substance that is unionized will prefer to disolve in more lipid areas

Question 13

What does pKa represent

Answer 13

ratio calculated to understand what fraction of the drug is ionized (water solube) vs unionized (lipid soluble)

Question 14

What will acid drugs tend to do in high ph environments

Answer 14

donate proton and become ionized (more soluble in water)

Question 15

What happens when acid drugs enter the stomach

Answer 15

Will encounter low ph and stay unionized and easily be able to move thru lipid mucosa
-when ionized form encounters high ph of plasma it donates H and becomes ionized at high amount (do calculation)

Question 16

Acid and base formula for ionization

Answer 16

Acids- pKa-pH=log (unionized/ionized)

Bases- Pka-ph=log(ionized/unionized)

Question 17

when basic drug eneters stomach what happens

Answer 17

Will enter as unionized form and accept protons becoming ionized form and only small amount of unionized form will cross

When unionized form reaches high ph of plasma it will convert to ionized at lower level

Question 18

When Pka=ph what does it mean for ionized and unionized forms of druge

Answer 18

50/50 distribution

Question 19

If ph

Answer 19

Pronated forms predominat

low ph environment favours movement of acid drugs across biological membranes

Question 20

if ph>pka

Answer 20

depronated forms predominant

High ph environment favours basic movement

Question 21

What are anatomical vs functional barriers

Answer 21

Anatomical- formed by cells that are linked together in ways that block passage of drugs they intercellular spaces

Functional-Formed by drug transport systems that carry drug molecules out agains a drug conc

Question 22

Capillaries w/ maculae- what can pass thru

Answer 22

has transient intercellular spaces present allowing movement of free drug molecules (bound is too big)

Question 23

What can move thru fenestrated capillaries and where are they present

Answer 23

Present usually in excratory and secretory organs (urine system)

-Only allows free drugs to move thru it

Question 24

Capilaries with occluding zones are in all areas of the brain except (5)

Answer 24

choroid plexus
median eminence
area postrema
pineal gland 
pituitary gland

Question 25

What is the cut off phenomenon of solubility

Answer 25

absorbtion rate of a substance in ralation to its partition coefficient (lipid:aques)
-as partition coefficient increases solubility will increase to a certain point then drop off quick (results in need for some h2o solubility

Question 26

What are the 3 major aspects that influence absorbtion

Answer 26

Molecular size
solubilutu
degree of ionization