Microbial Stability Flashcards Preview

Drug Delivery II > Microbial Stability > Flashcards

Flashcards in Microbial Stability Deck (24)
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0
Q

How can you tell when a product is microbial instable?

A

Localised or gross spoilage.
Release of unpleasant smelling or tasting.
Discolouration and pigmentation.

1
Q

What defines microbial instability?

A

Microbial growth and initiation of physics-chemical deterioration of the product.

Survival of pathogenic microorganisms

Presence of toxic metabolites

2
Q

Name 5 consequences of microbial instability

A

1) Safety
2) Efficacy
3) Quality
4) Patient’s acceptability
5) Commercialisation

4
Q

Briefly, what is the difference between Sterile products and Non-sterile products, on terms of microbial instability?

A

Sterile product should have “no organism” present.

Non-sterile products should have limited of micro-organism present, but must have an absence of ‘objectional’ organisms.
E.g. Staph aureus, E. Coli, Salmonella, Pseudomonas

5
Q

What organisms does the TGA restrict for products for oral use in non-sterile products?

A

E. coli

Salmonellae

6
Q

What organisms does the TGA restrict for products for topical use in non-sterile products?

A

Pseudomonads

Staph Aureus

7
Q

Briefly explain how Microbial limit testing methods (2 methods)

A

1) Product is sampled
2) Diluted or dissolved in a suitable solvent (e.g. water)
3) Aliquots are poured or plated onto nutrient agars
4) Incubated to detect the colony-forming unit/gram or mL

or membrane filtration method:

1) Product solution is filtered using a sterile membrane filter
2) Membrane filter is then incubated on the surface of the nutrient agar place or added into the nutrient broth to detect growth

8
Q

List some sources of microbial contamination (8)

A

1) Raw materials - drugs, excipients
2) Environment
3) Personnel
4) Equipment and containers
5) Packaging materials
6) Manufacturing process
7) Storage
8) Usage and handling

9
Q

What 4 things does microbial stability depend on?

A

1) Physico-chemical properties of the formulation ingredients
2) Type of contaminants
3) Quantity of contaminants
4) Risk of contamination

10
Q

What can lead to microbial instability?

A

Product ingredients and metabolites are sources of energy and precursors for micro-organism survival and multiplicaiton

11
Q

List some susceptible formulation ingredients that can either be metabolised by micro-organisms or used as a substrate for growth.

A
Drug molecules
Sweeting, flavouring and colouring agents
Fats and Oils
Preservatives and disinfectants
Humectants
Surfactants
Polymers
12
Q

List the 5 factors that affects microbial instability

A

1) Growth factors in the formulation
(e. g. nutrients as substrates for growth)

2) Risk of contamination
(level of exposure)

3) Temperature
(m. o. can grow between 20-60°C)

4) pH
(neutral pH promotes growth)

5) Packaging materials
(prevents m.o. entry, but can be nutrients as well)

13
Q

What are the 7 formulation considerations for microbial stability?

A

1) Preservatives
2) pH of formulation
3) Additives
4) Packaging design
5) Storage conditions
6) QA/QC
7) Postmarketing surveillance

14
Q

What is the purpose of preservatives? (3)

A

Antimicrobial agents to:

1) Protect from microbial spoilage during storage and use
2) Protect from contamination during manufacture
3) Protect the user from infections

15
Q

What does Preservative activity depend on? (4)

A

1) Type and Concentration of preservative
2) Number and Type of micro-organisms
3) Ionisation state of preservative
4) Temperature

16
Q

How might addition of preservative compromise the chemical stability of the drug?

A

It can alter the formulation of the pH

17
Q

How does temperature affect preservatives?

A

Warmer temperatures (e.g. room temp) can decrease the preservative concentration, thus decreasing its antimicrobial activity

18
Q

What’s one common conflict that may arise when using buffers in formulations?

A

A buffer can create an unfavourable growth environment. But buffers are also required to adjust pH to stabilise the formulation. This can be an issue when it’s microbial stability vs. chemical stability.
E.g. a formulation is stable under basic conditions (high pH), but the preservative is no longer effective under these conditions.

19
Q

What are Additives?

A

Ingredients added to reduce water activity
(free water concentration available for growth)

E.g. PEG, sorbitol, glycerol

20
Q

How can foil or seal packaging protect from microbial instability?

A

Reduces moisture content & prevents contamination

21
Q

How can packaging increase microbial instability? (2)

A

1) Adsorption and partitioning of preservatives

2) Packaging materials may also support growth

22
Q

What might refrigerating a product (4-8°C) help prevent?

A

Warm-cold cycles that might lead to crystal growth. Thus it has an effect on drug solubility

23
Q

What is the difference between QA & QC?

A

Quality Assurance (QA) involves planning and monitoring of all stages of product manufacturing (e.g. sterilisation methods, training & education, and environmental monitoring of air, surfaces)

Quality Control (QC) involves end product testing (e.g. sterility testing & endotoxin testing)

24
Q

Briefly explain Postmarketing surveillance and how it helps microbial stability.

A

Monitor product in-use performance.

Procedures for responding customer feedback or complaints about the product.

Data modification of design and processing to improve microbial stability profile of produce