D7: Introduction to stability

Question 1

types of stability?

Answer 1

Chemically stable
Physically stable
Microbiologically stable

Question 2

A change could be in…

Answer 2

-chemical composition e.g amount of drug
-physical characteristics
-performance of the medicine e.g rate of drug release
-microbial contamination

Question 3

what is the pack in pharmaceutical terms?

Answer 3

Pack (the whole packaging): the container, wrapper, leaflets, etc.

Question 4

function of the first layer, the container?

Answer 4

Provides the main protection against the environmental factors (e.g. O2, light) that cause degradation

Question 5

what is the self life

Answer 5

The time over which a medicine, in a specified pack remains
stable when stored under the recommended conditions. medicine/ pack combination provides stability. Expiry date tells user self life.

Question 6

What is the definition of stability (USP definition)

Answer 6

The extent to which a medicine retains, within specified limits, and throughout its shelf life, the same properties and characteristics that it possessed at the time of its manufacture. The ‘specified limits’ ensure quality, safety & efficacy of a medicine

Question 7

what is potency

Answer 7

The amount of drug remaining in the medicine after storing it. usually expressed as percentage in stability testing

Question 8

what is a stable medicine in terms of potency

Answer 8

-BP and USP both allow 10% loss in most medicines, over their shelf life.
-5% or 3% when there are degradent toxic products

Question 9

Describe stability testing

Answer 9

The manufacturer undertakes stability tests (chemical, physical and microbiological analytical tests) after storing the product/pack combination at internationally agreed temperatures and humidities. This provides evidence for self life and storage conditions

Question 10

what are the most common storage condition and self life

Answer 10

3 Years when stored between 15-25 ºC (room temp)

Question 11

what chemical mechanisms lead to chemical instabilities

Answer 11

-oxidation
-photolysis
-hydrolysis
-enzymes from microbes

Question 12

consequences of instability?

Answer 12

-Changes in the rate of drug release from a medicine
-Dose uniformity problems
-Changes in the colour, smell and texture
-Changes that you cannot detect easily i.e chemical degradation: loss of potency & therapeutic effect
-Increase in toxicity & adverse effect (rare)
-Microbial growth in medicines.

Question 13

Describe dose uniformity problems with bulk powder mixtures

Answer 13

Can separate with movement or vibration
-problem usually after long distance transport

Question 14

Describe dose uniformity problems with suspensions

Answer 14

Separation
Caking
Ostwald ripening
Degradation of suspending agent by microbes
-problem usually after a long period of time

Question 15

Describe dose uniformity problems with emulsions and creams

Answer 15

Creaming and cracking
Temperature cycling
Freezing
-problem due to travel in cold places e.g fridge, freezer

Question 16

Describe dose uniformity problems with solutions

Answer 16

precipitation due to solubility limit
-problem usually due to travelling in cold place

Question 17

what do changes in the colour, smell, texture of a medicine indicate?

Answer 17

-chemical degradation of drug or medicine
-microbial growth
loss of drug and excipients

Question 18

consequences of microbial growth?

Answer 18

Cross infection, septicaemia, food poisoning, degradation
(one note for specific examples)

Question 19

Describe medicine stability in practice, issues?

Answer 19

-Short shelf life (may be reduced further when opened)
-Medicines may not have been stored correctly
-There may be significant degradation after date
Remove them immediately from your stock