D7 Intro to stability

Question 1

what are the 3 types of stabilities in medicines?

Answer 1

• chemical
• physical
• microbiological

Question 2

what is degradation? what could it be a change in?

Answer 2

• any chance that adversely affects the properties of the medicine

could be a change in:
- chemical composition (eg. amount of drug)
- physical characteristics (eg. caking or suspension separating)
- performance of the medicine (eg. rate of drug release)
- microbial contamination

Question 3

describe the pharmaceutical term: pack

Answer 3

• the container, wrapper, leaflets etc.
• the whole packaging, everything you require to give to the patient

Question 4

describe the pharmaceutical term: container

Answer 4

• the first layer the medicine comes into contact with
• the barrier that provides the main protection to the formulation against the environmental factors that cause degradation
• eg. for Calpol, amber glass bottle

Question 5

describe the pharmaceutical term: shelf life

Answer 5

• the time over which a medicine in a specified pack remains stable when stored under the recommended conditions
• it’s the whole medicine / pack combination that provides the stability
• over the whole shelf life the medicine must remain stable as long as in the correct conditions

Question 6

describe the pharmaceutical term: expiry date

Answer 6

• the ‘use by’ date on label
• tells the user the shelf life

Question 7

describe the pharmaceutical term: storage conditions

Answer 7

• conditions under which the medicine should be stored to achieve its shelf life
• expiry only applies if kept within the conditions

Question 8

what is potency?

Answer 8

• the amount of drug remaining in the medicine after storing it
• in stability testing, usually expressed as a percentage of the original drug content (‘label claim’)

Question 9

what is the label claim of a medicine?

Answer 9

what the manufacturer is claiming is in the medicine

Question 10

what is considered a ‘stable’ medicine?

Answer 10

• 90% of label claim must be retained by the end of the shelf life (10% loss is allowed)
• reduces to 5 or 3% loss allowed if toxic products are produced

Question 11

what are stability tests?

Answer 11

• provide scientific evidence for shelf life and storage conditions
• manufacturer undertakes stability tests to prove the product is stable for how long they’re stating it will be

Question 12

what is the desired effect of a product/pack combination?

Answer 12

• designed to maximise stability
• 4 factors work together to maximise shelf life for as long as possible

Question 13

what are the 4 factors within a product/pack combination that work together to maximise shelf life?

Answer 13

• pack design
• drug and medicine stability
• storage conditions
• medicine design (formulation)

Question 14

state some physical mechanisms that can give rise to instability

Answer 14

absorption
diffusion / partition
evaporation
particle size changes
separation
solubility changes

Question 15

state some chemical mechanisms that can give rise to instability

Answer 15

hydrolysis
photolysis
oxidation
enzymes from microbes

Question 16

state some consequences of instability

Answer 16

• changes in the rate of drug release from a medicine
• dose uniformity problems (over or under dosing)
• changes in the colour, smell and texture
• changes you cannot detect easily
• microbial growth

Question 17

explain how colour, smell and texture can change in medicines and what these mean

Answer 17

• usually indicate chemical degradation
• can be a sign of microbial growth
• loss of drug and excipients
• loss of palatability
• medicine can’t be used

Question 18

consequences of microbial growth in injections

Answer 18

• blood infections
• growth up catheters into bloodstream

Question 19

consequences of microbial growth in eye and nose drops

Answer 19

• transfer of infections
• are they being used on other family members?

Question 20

consequences of microbial growth in oral medicines

Answer 20

• sickness and nausea
• food poisoning
• loss of drug and excipients
• nasty smells and taste

Question 21

what are the dose uniformity problems in solutions?

Answer 21

• precipitation due to solubility limit
• eg. paracetamol syrups in the fridge