Contamination Control Flashcards
What is the difference between Non-sterile vs. Sterile products?
Non-sterile products:
- Limited microbial burden
- Absence of “objectionable” organisms (e.g. E. coli, Salmonella)
- Products include oral, topical, nasal, oitc, vag & ass
Sterile products:
- Free from micro-organisms, pyrogens & particulates
- Safe, Stable & Therapeutically effective
- Acceptable quality for administration to the patient
Define sterilisation
A process intended to kill or remove all micro-organisms (with an acceptable low probability of an organism surviving) e.g. 1 in a million
List two things that product sterility depends on
- Contamination control and sterility assurance procedures and practices
- Knowledge, skills and attitude of staff
Identify 8 sources of contamination
1) Air
2) Surfaces
3) Operator
4) Equipment
5) Containers
6) Drugs
7) Excipients
9) Vehicle (water)
What are some contamination control of area methods(6)
1) Segregated
2) Limited and authorised entry
3) Operational arrangement
4) Sterile production cleanrooms
5) Maintenance and monitoring
6) cGMP standards
What are some properties of a cleanroom that controls its contamination?
- Class 3.5, 350, 3500
- Positive pressure differential
- Air supply via HEPA filter
- Constant flushing of room with clean air
- Smooth impervious surfaces
What are some differences between Horizontal Flow Cabinet and Down Flow Cabinet?
Horizontal:
- Unidirectional horizontal air flow, with the cleanest zone being the Inner zone (closest to the HEPA filter)
- Protects the product FROM the operator
- Compounds non-toxic sterile products
Vertical (Down):
- HEPA filtered vertical air flow (downwards)
- Protects the product AND protects the operator from contamination
- Aseptic preparation of Cytotoxic drug
- Glass shield covers
- Cytotoxic cleanroom has negative pressure than the cytotoxic anteroom (airlock)
Describe the 3 zones of the Horizontal flow LFC and their purpose
Inner zone:
- Closest to the HEPA filter (cleanest zone)
- Set up of sterile work items
- Avoid shadowing of critical areas
Middle:
- For aseptic assembly
Outer:
- Finished and seal product
List 3 monitoring methods of LFC
1) Air flow tester
- to show air currents/pattern
2) Smoke test for HEPA filter leaks
- 0.5 micron particules
3) Microbiological monitoring
- Air sampling
- Surface sampling
- Sterile and Fertile nutrient agars
List some ways contamination can be reduced in an operator
- Hand washing
- Gowning procedure
- Aseptic techniques
- Training and checks
- Report medical conditions
- Remove cosmetics and jewellery
What are some container considerations? (5)
- Not interact with the fill contents
- Not generate particles or pyrogens
- Not retain any ingredients from the product
- Not release any substances into the product
- Heat stable for heat sterilisation
List 3 sterile manufacturing methods
1) Terminal Sterilisation
2) Aseptic Filtration
3) BFS - Blow Fill Seal technology
What are some main differences between terminal and aseptic filtraions
Terminal:
- Filtration with 0.45 micron filter and sealing in LFC
- Sterilisation of finished product in HEAT steriliser
Aseptic:
- Strict aseptic techniques (e.g. sterile equipment, containers, etc) where WFI must be used
- Sterilisation by filtration with a 0.22 micron filter
Both:
- Sterility testing of the finished product
List 8 contamination control in sterile dispensing
- Clean rooms
- Air quality
- Pressure differentials
- Operator and clean room procedures
- Equipment/containers
- Method of sterile manufacture
- Quality control of water
What are two readily applied checks of water quality?
- pH testing
(For acidity or alkalinity) - Conductivity testing
(For ion load of +ve or -ve ions)
What are the 5 types of water?
- Tap water
- De-ionised water
- Purified water (distilled)
- Water for irrigation
- Water for injection
How is ‘De-ionised water’ made? Are bacteria removed?
Prepared by passing tap water through synthetic ion exchange resin beds.
This removes cations and anions.
But it does not remove any bacteria.
NOT for oral formulations, but topical is okay.
What are some properties of ‘Purified water’?
- Prepared by distillation
- Apyrogenic (but NOT STERILE)
- Free from micro-organism
- Used for oral & topical preparations
- Not suitable for parenteral products
Properties of ‘Water for Irrigation’?
- STERILE & Pyrogen-free
- Prepared by Terminal heat sterilisation of the purified water
- Used for oral & topical preparations AND irrigation of wounds & body cavities
- Not suitable for injection or parenteral products
Properties of ‘Water for Injection’?
- STERILE, FILTERED & pyrogen-free
- Used for injections, eye drops & parenteral solutions
List 5 types of water contaminants
1) Particulate matters
2) Micro-organisms
3) Pyrogens
4) Endotoxin
5) Organic and Inorganic substances
What are 3 types of Particulate contamination checks?
1) Coulter Counter
2) Light Obstruction
3) Microscopic Count
How do you remove microbial contamination in water?
Distillation or filtration to remove micro-organism.
Subsequent contamination in cooling, distribution or storage systems.
Freshly distilled water is stored at 65C degrees prior to sterilisation
How do you monitor microbial contamination?
Membrane filtration method.
Membrane filter retains micro-organisms from the water during filtration. Filter is then incubated in a microbial culture medium to detect and identify colonies
What are some methods of removing pyrogens from water?
1) HEAT
- 250 degrees for 45 mins
- 180 degrees for 4 hours
2) CHEMICAL
- Heating with strong alkali or oxidants
3) PHYSICAL
- Distillation
- Reverse Osmosis
What is reverse osmosis?
A semi-permeable membrane that retains all molecules with MW>300 as waste water. It rejects pyrogens and bacteria.
What are two ways of testing for pyrogens?
1) Rabbit Test
2) Limulus Amoebocyte Lysate (LAL) Test
Briefly explain the Rabbit Test
- Test solution is injected into the ear vein of rabbits
- Rectal temperature is measured pre and post injection
- Product passes if there is only an increase in temperature for each rabbit < 1.4 degrees Celsius.
Explain the LAL test
1) Mix the LAL reagent (pro-clotting enzymes, clotting proteins & Ca++) with the test solution (e.g. water)
2) Reaction between reagent and the test solution
3) If bacterial endotoxin is present, then LAL enzyme recognises and activates enzymes in a cascade to cleave the clotting protein. This results in:
a) Gel formation (Gelatoin method)
b) Change in turbidity (Turbidimetric)
c) Change in colour (Chromogenic)
What are some characteristics of LAL test
- Perform tests in duplicate
- Positive and negative controls
- Equipment/container shall not adsorb of generate endotoxin
What are some limitations of LAL test
- Product interference
- pH & Temperature
- Reconstitution of lysate
- Sensitivity and limit of detection
Describe how to quantitatively determine the endotoxin level of water used for sterile products
Calibration curve
- [endotoxin] vs [reaction time]
Turbidimetric kinetic
- time needed for the development of turbidity of solution
Chromogenic kinetic
- time needed for liberation of coloured dye
