Med Chem Refresher

Question 1

Importance of pKa

Answer 1

The lower the pKa the stronger the acid

The pKa of the acid is the pH where it is exactly half dissociated

Question 2

Pka equation

Answer 2

pKa = -log Ka

Question 3

What does an acids pKa depend on

Answer 3

It depends on the stability of its conjugate base.
The stronger the acid HA, the weaker it’s conjugate base A-
The stronger the base A- the weaker it’s conjugate acid HA

Question 4

Benzoic acid (E210)

Answer 4

Preservative in soft drinks

pKa = 4.2

Question 5

pHs above the pKa of the acid means..

Answer 5

It will be more water soluble

Question 6

pH range of some body fluids

Blood plasma, saliva, gastric juice, duodenal contents

Answer 6

Blood plasma 7.4
Saliva 6.2-7.2
Gastric juice 1.0-3.0
Duodenal contents 4.8-7.2

Question 7

Where are weak acids and babies absorber well and poorly?

Answer 7

Weak acids tend to be well absorbed from the stomach and poorly absorbed from the small intestine
Weak babies tend to be well absorbed from the small intestine

Question 8

Hydrophobicity

Answer 8

Effects the ability of the drug molecule to cross cell membrane and or perform a suitable bonding interaction
High p = hydrophobic compound
Low p = hydrophilic compound

Question 9

Partition coefficient equation

Answer 9

P = [drug] octanol / [drug] aqueous