Exam 3

Question 1

Digoxin is a ____ molecule

Answer 1

polar molecule and has erratic or incomplete oral absorption

Question 2

Riboflavin

Absorbed by?

What are some possible reasons for its decreased absorption percentage as dose increases?

Polar non polar? All B vitamins are?

Answer 2

• By transporters not very permeable
• Location of carriers, at high doses the rate is maximum and the carriers are saturated, due to GI transit time the drug passes the anatomical carrier site prior to being absorbed

Question 3

Thiamine

Polar non-polar?

When intake of thiamine is high?

At low physiological concentrations?

Answer 3

• Polar B vitamin
• When intake is high absorption is passive
• When intake is low absorption is by active transport

Question 4

Ascorbic acid Vit C

Transport of Vit C is a _____ and _____ process that occurs by?

At the ___ and cells AA is ____ to DHAA which is?

Once inside the tissue or intestinal epithelium?

Absorption is greater when?

Answer 4

• Polar
• Saturable and dose dependent process occurs by active transport
• Intestine and cells AA is oxidized to DHAA which is more quickly transported across membrane
• It is reduced back to AA
• Greater when several individual doses of Vit C are taken through the day

Question 5

Lipinskis Rule of 5 Predicts poor membrane permeation when?

Answer 5

1. 5 H bond donors
2. 10 H bond acceptors
3. MW> 500
4. Log p > 5
5. This doesnt apply to drugs involving transporters