Stability of drugs Flashcards Preview

The Medicine (Y2) > Stability of drugs > Flashcards

Flashcards in Stability of drugs Deck (18):
1

Lactams are more susceptible to hydrolysis than esters. True or false?

True

2

Imides are less susceptible to hydrolysis than amides. True or false?

True

3

Which are most susceptible to hydrolysis, esters or amides?

esters

4

Hydrolysis is a zero order reaction. True or false?

False - first order

5

Hydrolysis is pH dependent - so the lower the logK, the higher the rate of hydrolysis and so the more the drug will degrade. True or false?

False - the higher the logK the more the drug will degrade

6

Oxidation is promoted in the presence of oxygen. What else promotes oxidation?

presence of oxidising agents
light
trace metals

7

Highly conjugated metals are susceptible to photodegradation. True or false?

True

8

Energy increases as wavelength increases. True or false?

False - energy increases with decreasing wavelength

9

What is light induced degradation called?

Photolysis

10

Isomeric change may affect pharmacological and toxicological activity. True or false?

True

11

The L form of adrenaline is more active than the D form. True or false?

True

12

Optical rotation is used to detect isomeric change because there is no change in mass so mass spec etc. is not useful. True or false?

True

13

The chemical stability of proteins and peptides is dependent on amino acid composition and sequence. True or false?

True

14

How do inert gases stabilise pharmaceutical preparations?

They protect from auto-oxidation

15

Why is procaine more prone to hydrolysis than lidocaine?

Procaine is an ester so more prone to hydrolysis than lidocaine, an amide

16

What is the equation for half life of a first order reaction?

T1/2 = In(2)/k

17

What is the equation for shelf life of a first order reaction?

T90 = In(1.11)/k

18

What are the limitations of accelerated stability testing?

Kinetics of degradation may change at higher temps
Additional complex reactions may take place at higher temps
Temp may change nature of dosage form
Change in physical properties with unpredictable effect