L3 Drug movement in the body

Question 1

What are the 3 physicochemical factors controlling drug absorption?

Answer 1

Solubility, Chemical stability, Lipid to water partition coefficient and degree of ionisation

Question 2

What does solubility mean?

Answer 2

the drug within a medication must dissolve (dissolution) in order to be absorbed

Question 3

What is chemical stability in a drug?

Answer 3

Some drugs are destroyed by acid in the stomach, or enzymes in the gastrointestinal tract

Question 4

what does the degree of ionisation depend on ?

Answer 4

pKa (pH at which 50% is ionised and 50% is unionised) and local pH

Question 5

what does the henderson hasselbalch equation stand for?

Answer 5

the proportions of ionised and unionised drugs can be calculated by the henderson hasselbach equation

Question 6

T/F-Absorption of weak acids is facilitated by the pH of the stomach lumen

Answer 6

true

Question 7

T/F- Bases are not readily absorbed until they reach the small intestine

Answer 7

true

Question 8

Define the term oral availability?

Answer 8

is the fraction of drug that reaches the systemic circulation after oral ingestion

Question 9

Define the term systemic availability?

Answer 9

is the fraction that reaches the systemic circulation after absorption

Question 10

What are examples of route of drug administration?

Answer 10

enteral (via the GI tract), parenteral (not via the GI tract)

Question 11

What are examples of enteral and parenteral routes of drug administration?

Answer 11

enteral- oral, sublingual, rectal

pararental- Intravenous, intramuscular, subcutaneous, inhalation, transdermal, topical

Question 12

What are the pros and cons of enteral oral route?

Answer 12

pros-simple, convenient, non-sterile route, good absorption for most drug
cons-inactivation of some drugs by acid/enzymes; food binding; variable absorption;first pass metabolism; GI irritation; at the extremes of age, swallowing solid meditations become tough

Question 13

What are the pros and cons of sublingual buccal ?

Answer 13

pros-rapid absorption; by passes portal system and avoids first pass; avoids gastric acid. cons- infrequent route; few sublingual, buccal preparations available

Question 14

what are the major fluid compartments?

Answer 14

body water is distributed into 4 main compartments.
1- plasma water
2-interstitial water 
3-intracellular water
4-transcellular water

Question 15

what is the apparent volume in which a drug is dissolved in the volume of distribution?

Answer 15

VD= DOSE/PLASMA CONC