sterility Flashcards
sterility
(WHO) absence of viable microorg
* Conditions that guarantee absolute sterility is too harsh for API
Relies on procedural measures for sterility
prevent contamination of biological materials
○1) Clean room technology
2) GOOD MANUFACTURING PRACTICES
§ Environment (door, walls, floor) , equipment, product □ Personnel, practices and training, engineering, weather
§ Avoid microbial contamination holistically: address supportive elements
□ Optimise both individually and collectively to provide greatest confidence in overall process
sterility assurance level (SAL)
PROBABILITY of 1 viable microorg in a certain number of drug products
acceptable safety level: 1 in 10^6 prob non-sterility
sterilie means no __
○ Without Microorganisms
○ Endotoxins inside limit
§ Pyrogens
○ No detectable particles
sterility prep for
Parenteral, EYE, Irrigation
sterilisation process vs process development
NOT REPLACEMENT
○ Bioburden minimised in manufacturing step BEFORE sterilisation
high bioburden critical
○ High risk of contamination with viable microorg
§ Must be removed in initial process (API, excipients)
○ High risk of contamination with pyrogens
pyrogens
§ Substances that produce fever
Eg: endotoxins: lipopolysaccharides produced by gram-ve, e.coli
inactivation factor
degree which viable organisms reduced by the sterilisation treatment applied
overkill for sterilisation
sterilisation process applied to reduce the Biological Indicator (particular microorg) by
factor of 10^12
○ Not always feasible, few API can withstand harsh conditions
○ Intensity and duration of sterilisation treatment too high for some pdts
SAL vs log 10 reduction
SAL: probability of microorg of surviving
Log reduction: efficiency of sterilization method
tests that affect qty of viable microorg
1) sterility test
2) endotoxin test
3) bioburden
4) visible/ non-visible particles
1a) validation of sterility test (suitability test)
1) final pdt + known qty (<100 cfu) of known microorg – anaerobe, aerobe, fungi
- Medium: trypticase soy broth // fluid thioglicollate medium
2) +ve control: only microog
3) -ve control: only final pdt
4) incubate for 3-5days
5) compare lvl of turbidity
- see if pdt has antimicrobial prop (leads to a false neg)
- turbidity of pdt COMPARABLE to +ve control
1b) validation of sterility test (growth promotion test) ensures
- Culture media must meet established performance criteria
*Ensure accuracy of results, for key QC tests, procedures will depend on culture
- Acceptability of each batch of medium
- Medium is “fit for purpose”
- Medium produce CONSISTENT results
steps for growth promotion test
1) Can support growth of <100 viable microorg (SPECIFIC)
a. Indicator microorg to grow vs contaminants etc
b. does it support growth of microog
2) Culture media assessed for sterility a. Based on incubation parameters (time, temp) of the method b. No contaminants
choice of microorg for test
1) environmental contamination
2) those that may have been found in final pdt
2) endotoxins test
eg: injectable
1) Limulus Amoebocyte Lysate Test
a. Reaction between LPS and clottable protein (substance)
i. Amoebocytes (blood cell of horseshoe crab)
b. Endotoxins presence lead to clot into gel like
2) Gel clot method
a. Qualitative method
b. Used for water
c. Sensitivity depends on lysate (but higher) 0.015-0.250 EU/mL endotoxins unit
3) Turbidimetric/ chromogenic method
a. Quantitative method based on ONSET time
b.Dedicate equip
c. sensitivity based on lower limit quantification
endotoxins limit
a) ELC = k (endotoxins kg)/ M (dose kg/hr)
b) MAX endotoxins possible in sample
i) Depends on dose of drug, time, weight, age
<5 EU/kg/h (usually)
Maximum valid dilution
a) MVD = ELC/ method sensitivity
b) Determine how much you can dilute the sample so you still can detect the endotoxins
c) Based on meter SENSITIVITY
safety factor
Safety factor = RANGE OF dilution b. MVD – 1st dilution fitting the spectrum
3) bioburden/ IPC testing
- Conc of microorg in material
(total org /ml or /g)- Microbial control during manufacturing for pdt quality & safety
- Sterile biologic drug pdt
○ Manufactured by sterile filtration
○ Aseptic filtration
○ Processing
Controls microbial load for each step for OVERALL microbial control
steps for bioburden test
1) Bioburden sample conducted before sterile filtration (in-process microbial control)
* Maximum bioburden: in control of sterile filtration step
* Accepted limits for
○ Number of CFU
○ Sample test vol (Not More Than of 10 CFU/100ml)
potential process design and control strategy risk mitigation measures (BIOBURDEN TESTING)
1) Reduce microbial load prior to and on sterile filter
a. Remove bioburden with pre-filters
2) Limit hold times and room temp storage
3) Implement aseptic handling techniques when appropriate
4) Select and validate sterile filter mem with high microbial retention capabilities
a. > 10^6 CFU/ cm3
5) Incr effective filter SA by using larger single filter/ multiple filters in series
6) Limit batch vol to be sterile filtered
7) Test integrity of sterilizing filters PRE-/ POST use
- Test and control bioburden THROUGHOUT manufacturing process
- Raw materials introduction too
Reduce bioburden breakthrough!
- Raw materials introduction too
calculate bioburden
LogN = logN0 - K*t
N (n.o. of cells surviving at time t) = SAL of 10-6
D-value (decimal reduction value), exposure required in sterilisation process to reduce pop by 90%
4) Visible/ non-visible particles
Sub-visible/ visible:
* Particulate contamination of IV solutions
○ Extraneous, mobile
Undissolved particles (x gas bubbles)
sources of visible particles
○ EXTRINSIC: environment contamination
§ Equipment
§ Primary packaging (stainless steel, hair, fibers, glass, rubbers)
○INTRINSIC: formulation (API, excipients, gas bubbles unstable and ppt)
effects of these visible particles
○ mechanical obstruction of lung (from inhalation)
○ Injection site reaction, phlebitis, granuloma
○ Lower therapeutic conc
2 tests for visible particles
Light obstruction particle count test
Microscopic particle count test
Light obstruction particle count test
- Preferred for inj, parenteral infusions of sub-visible particles
1. Make sample go through thin tube
2. Go through with laser
3. Receiver at the other end
4. Tells how much particles of various sizes - Apparatus is calibrated using dispersions of spherical particles of known sizes between 10-25um
- Determine size and number of particles (of that size)
light obstruction particle test formulation considerations
- Large vol: single units tested
- Small vol: <25ml, need combine 10 or more units until total of 25ml
- Powders: dissolved in particle free water (sterilised) / solvent –not contaminated
number of particles per container
○ < 6000 particles per container. Size of >10um
○ <600 particles per container. Size >25um
- free of visible particles
(method 2) Microscopic particle count test
- Suitable binocular microscope
○ Equipped with ocular micrometer calibrated with objective micrometer
○ Mechanical stage can hold, transverse entire filtration area od mem filter
○ Ocular micrometer circular diameter graticule
§ Large circle divided by crosshairs into quadrants
§ Transparent and black reference circles (10um and 25um) in diameter- To detect visible particles, aided illumination or comparable automated methods (>100um)
- Sample in plate, spread thin layer
- Take picture
- Image modification – colour
a. Until able to see the particles
b. Can see shape too - Count the particles + size
- To detect visible particles, aided illumination or comparable automated methods (>100um)
STERILE MANUFACTURING
STERILE PREPARATION
○ Sterile preparation: ensure there’s no microbial contamination on anyone/ anything involved with healthcare practices (surgeries, drug manufacturing)
considerations of sterile prep
§ Safety – adverse toxicological concerns
§ Sterility – free from microbiological contamination
§ Non pyrogenic – endotoxins from contamination
§ Particle free – visible particle contamination
§ Stability – chemical, physical, microbiological
§ Compatibility – formulation, package, other diluents
§ Tonicity – isotonic w/ biological fluids
sterilisation methods
1) dry heat
2) moist heat (autoclave)
3) aseptic filtration
4) gamma irradiation
5) ethylene oxide/ nitrous oxide, hydrogen peroxide fog
6) lyophilisation
aseptic process simulation
Validate aseptic process using microbiological growth medium (instead of product) that closely approximate those used during drug product process