Formulation of Advanced or Complex Medicines 6

Question 1

What effects can organic contaminants have?

Answer 1

Pyrogens (bacterial toxins) - can induce fever
Amines - toxicity
Particulate materials - discolouration of packaging

Question 2

What effects can inorganic contaminants have?

Answer 2

Toxic metals (e.g. lead, mercury) - cumulative poisons
Calcium/magnesium - hardness deposits
Iron and chlorides - corrosion

Question 3

What are the advantages of moist heat sterilisation?

Answer 3

Well defined process
- reference method for sterilisation
- parametric release

Question 4

What are the disadvantages of moist heat sterilisation?

Answer 4

Does not destroy endotoxins
Impurities

Question 5

What products are sterilised using dry heat?

Answer 5

Powders
Glassware
Metal surgical instruments
- good penetrability
- non-corrosive
Non-aqueous thermostable liquids
Sterilisation of glass bottles filled aseptically

Question 6

What is the advantage of dry heat sterilisation over moist heat sterilisation?

Answer 6

Destroys bacterial endotoxins

Question 7

How is dry heat sterilisation carried out?

Answer 7

Usually uses temperatures in the range 160 - 180C
Requires exposure times of up to 2 hours
- temperature dependent

Question 8

How does dry heat sterilisation work?

Answer 8

Oxidative processes

Question 9

Why is dry heat sterilisation carried out for a long time at a high temperature?

Answer 9

Air is a less efficient conductor of heat than steam

Question 10

Give three designs of dry heat sterilisers

Answer 10

Hot air oven
Infrared conveyor oven
Depyrogenation tunnels

Question 11

What are the advantages of dry heat sterilisation?

Answer 11

Less expensive than moist heat sterilisation
Useful for moisture-sensitive items
No corrosion
Useful depyrogenation
- destruction of endotoxin

Question 12

What are the disadvantages of dry heat sterilisation?

Answer 12

High temperatures and long contact time
- compared to moist heat sterilisation
Higher temperatures/longer cycle times - damaging?

Question 13

What can gaseous sterilisation be used for?

Answer 13

Temperature-sensitive items
- medical devices
- endoscopes
Pharmaceutical products
Electrical equipment
Infusion giving sets, syringes, plastic containers
Some thermolabile powders

Question 14

Give four examples of gases that are used for gaseous sterilisation?

Answer 14

Ethylene oxide
Formaldehyde
- LTSF
Vapour phase hydrogen peroxide
- VHP
Gas plasma

Question 15

What is ethylene oxide?

Answer 15

Colourless gas at ambient temperature and pressure
Slightly sweet, aromatic odour
Used for sterilisation
- biocidal activity

Question 16

What is the mechanism of action of ethylene oxide?

Answer 16

Effective through alkylation
- alkylating agent
Reactions with lots of groups, converting them to hydroxyethyl adducts
- amino
- sulphydryl
- carboxyl
- hydroxyl
Results in cross-linking within/between proteins and nucleic acids
- inhibiting vital functions
- cell death

Question 17

How is ethylene oxide toxic?

Answer 17

Acute toxicity
Irritant
- eyes
- respiratory tract
Mutagenic
Carcinogenic

Question 18

What are the safe working levels of ethylene oxide?

Answer 18

Safe level in air = 5 ppm
Odour level > 250 ppm