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PY365 Quality Of Sterile Medicines > Heat Sterilisation > Flashcards

Heat Sterilisation Flashcards

1
Q

what are the 2 categories of heat sterilisation

A

Moist heat sterilisation and dry heat sterilisation

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2
Q

what is the flowchart process of moist heat sterilisation

A
  1. heat sterilisation
  2. thermostable products
  3. moisture resistant items
  4. moist heat sterilisation
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3
Q

what is the flowchart process of dry heat sterilisation

A
  1. heat sterilisation
  2. thermostable products
  3. moisture sensitive items
  4. dry heat sterilisation
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4
Q

what is the most heat resistant microbe

A

prions and endospores

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5
Q

what is the least heat resistant microbes

A

protozoa, algae and viruses

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6
Q

what are the 3 stages in heat sterilisation profile

A
  1. heating stage
  2. holding stage (sterilisation)
  3. cooling stage
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7
Q

what is dry heat sterilisation and when is it used

A

sterilisation by thermal conduction
- heat stable, moisture sensitive products
- action through coagulation and oxidative processes
- killing less effective in absence of moisture, reflected in processing times

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8
Q

What is the sterility assurance level to aim for in dry heat sterilisation

A

10-6 or better

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9
Q

outline the sterilisation parameters for dry heat

A
  1. reference conditions: 160 degrees for 2 hours
  2. 170 degrees for 1 hour
  3. 180 degrees for 30 mins
  4. 250 degrees for 30 mins for endotoxin removal
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10
Q

what is depyrogenation

A

removal of pyrogens from a solution
- pyrogen is any substance that can cause fever (eg. endotoxins)

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11
Q

outline some features of dry heat sterilising ovens

A
  1. open mesh shelving
  2. temperature recorder with no control
  3. overheat cut out
  4. thermally insulated chamber
  5. cycle counter
  6. forced cooling and filtered air
  7. fault indication
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12
Q

what are other alternative dry heat sterilisers

A
  1. unidirectional airflow tunnels- allows for continuous throughput of material
  2. radiant heat tunnels
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13
Q

what are the applications of dry heat sterilisation

A
  1. heat stable, non aqueous materials that cannot be sterilised by steam
  2. glassware
  3. metal instruments
  4. non aqueous thermostable liquids (some oily injections)
  5. thermostable solids
  6. depyrogenation of glassware
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14
Q

what are the advantages of dry heat sterilisation

A
  1. simple method
  2. effective method- heat conduction reaches all surfaces
  3. where hydration is undesirable
  4. protection of cutting edges (eg. sharps)
  5. avoid wet pack problems
  6. no chemical residue
  7. depyrogenation possible
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15
Q

what are the disadvantages of dry heat sterilisation

A
  1. less efficient than steam at the same temperature
  2. limitations for plastic/rubber items
  3. uneven/slow heat transfer
  4. cost of prolonged cycles
  5. limited packaging materials due to high temperatures
  6. oxidation may occur
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16
Q

where is moist heat sterilisation carried out

A

carried out in an instrument called autoclave
- autoclaves use dry saturated steam

17
Q

what is saturated steam

A

in thermal equilibrium with the water which has produced it

18
Q

what is dry steam

A

water vapour, no liquid water

19
Q

what is superheated steam

A

inefficient sterilising agent

20
Q

what is crucial to the process of steam sterilisation

A

air removal
- steam containing air will be at a lower temperature than pure steam

21
Q

what are the key parameters in moist heat sterilisation

A

steam, pressure, temperature, time

22
Q

what are the types of autoclaves

A
  1. downwards displacement (bench top autoclaves)
  2. porous loads (high speed pre vacuum sterilisers)
  3. steam in place systems
23
Q

what are the stages in the process of moist heat sterilisation

A
  1. air removal and steam admission
  2. heating up and sterilising stage
  3. drying/cooling
24
Q

what are the main constructional features of a large scale steam steriliser

A
  1. exhaust valve to remove steam after sterilisation
  2. pressure gauge
  3. operating valve- controls steam from jacket to chamber
  4. steam chamber
25
Q

outline the parameters for steam sterilisation

A
  1. reference conditions: 121 degrees for 15 mins, 15 PSI
  2. 126 degrees for 10 mins, 20 PSI
  3. 134 degrees for 3 mins, 30 PSI
    - SAL of 10-6 or better
26
Q

what are the adverse effects of air on steam

A
  1. air is driven off from water and can be trapped in items such as porous loads
  2. air is a poor conductor of heat and inhibits heat flow
  3. air reduces steam temperature at a given pressure (not saturated)
  4. the sterilisation temperature will not be achieved
27
Q

what are the applications of gravity displacement autoclaves

A
  1. laboratory media
  2. water
  3. pharmaceutical products
  4. medical waste
  5. non porous articles
28
Q

what are porous loads

A

high speed pre vacuum sterilisers (HPV)
- contain trapped air which must be removed for efficient sterilisation
- achieved with a vacuum pump
- requires contact between materials and steam
- may be operated at 134 degrees for 3 mins

29
Q

what are the applications of porous loads

A
  1. heat stable items
  2. dressings
  3. gowns
  4. plastics
  5. packaging materials permeable to steam and air
30
Q

what are the stages in the process of the HPV cycle

A
  1. pre-vacuum
    - steam replaces vacuum
  2. holding time
    - vacuum pulled
  3. drying cycle
    - entry of filtered air
31
Q

what are the advantages of steam sterilisation

A
  1. non toxic
  2. inexpensive
  3. rapidly microbiocidal
  4. sporicidal
  5. efficient at heating and penetrating the load
32
Q

what are the disadvantages of steam sterilisation

A

deleterious effects on materials
- eg change of shape, corrosion

PY365 Quality Of Sterile Medicines (19 decks)

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