Membrane filtration is the pharmacopoeial method of choice for sterility testing. Viscous products, for example creams and ointments, can be difficult to filter and are therefore normally diluted in a sterile solvent such as isopropyl myristate (IPM). Testing such products may be problematic if specific testing procedures are not implemented and the appropriate devices not used. The Steritest® NEO device TZHVSL210 is the perfect choice for testing solvents, creams, ointments and veterinary injectables due to its solvent-resistant nylon canister, Durapore® (PVDF) membrane, reinforced base structure and canister connection.
This article describes one possible test set-up to dilute a product in IPM, filter it and rinse the membrane to eliminate residues that may inhibit microbial growth. Depending on the nature of the product, the method may have to be adapted to pass the necessary method suitability test (see “pharmacopoeia acceptance criteria and method suitability test” below).
Figure 1.Isopropyl Myristate and Green base Steritest® NEO filtration device (TZHVSL210).
The new Steritest® NEO device is upgraded with new improvements such as colored clamps, graduations for accurate volume measurement, optimized identification, and traceability with the new peel-off label. The test system offers an optimized and fully compliant testing process, when used with the Steritest® Symbio pump, specific accessories and high-quality culture media and rinsing fluids.
Figure 2.Schematic diagram of sterility testing using Steritest® NEO devices.
The following procedure is an example of a test method that will serve as a base during method development. It should be validated afterward following the instructions mentioned in pharmacopeia before use in routine.
Note: In our experiments, poor rinsing was observed when the membrane filter remained covered with liquid throughout the filtration and rinsing steps. To avoid this, the entire volume of diluted sample should be filtered through the Steritest® NEO devices (step 7), followed by the entire volume of each Fluid K rinse (step 8).
According to the pharmacopoeias, recovery must be tested to ascertain that the method is suitable. To do so, inoculate the last Fluid K rinse with no more than 100 CFUs of the microorganisms as recommended in the pharmacopoeias. Environmental isolates can also be tested this way. When filtration is complete, add media (TSB and either FTM or CTM) to the canisters and incubate for the time and temperature that the pharmacopoeias recommend. Then observe the canisters to see if the pharmacopoeia acceptance criteria for growth have been met.
Note: Microbiological recovery tests are performed to demonstrate the ability to detect microorganisms in the presence of IPM. If IPM is directly inoculated with microorganisms, add 9% of NaCl peptone buffer to generate an IPM/water emulsion (e.g., 9 mL NaCl peptone buffer, add microorganism suspension and fill up to 100 mL with IPM) and perform the filtration within 10 minutes to increase the survival rate of challenging microorganisms. Under these conditions recovery rates of ≥50% must be obtained.
Our team of expert engineers will assist you in implementing method development and validation within your QC microbiology lab. Additionally, you will be provided with basic and advanced technical training on sterility testing, on-site or remotely.
Rely on our expertise to support you in various situations including:
如要继续阅读,请登录或创建帐户。
暂无帐户?