NEWSLETTER
ISSUE
Jan to Apr, 2017 Volume 2
The safe and reliable testing of pharmaceutical
samples for sterility
Dr. Hans-Jürgen Bässler, SKAN AG
Key words
Aseptic isolator; Sterility testing; H2O2 decontamination; 6 log reduction; Short cycle time;
ABSTRACT
To perform testing of pharmaceutical samples for sterility in an aseptic isolator decontaminated with H2O2 is an unbroken trend in the pharmaceutical industry worldwide. Due to the strict separation of the process and the operator, false positive test results can be reduced to a minimum. The described isolator SKANFOG ® STI is a most advanced device for testing up to 15 samples in a batch mode with an efficient decontamination process of less than 30 minutes with a full 6 log reduction of Geobacillus stearothermophilus spores.
INTRODUCTION
Testing for sterility of a parenteral applicable product of the pharmaceutical industry is according to USP <71> and Ph. EUR. 2.6.1. applied to substances, .. which according to the Pharmacopeia are required to be sterile (parenterals, ophtalmics,..). It is the crucial test for the release of a produced batch to the market. [1] Sterility testing in an isolator is more and more recommended by the authorities in the USA and Europe. So says the FDA Guidance for industry: “A well-designed positive pressure isolator, .., monitoring and control, offers tangible advantage over classical aseptic processing including fewer opportunities for microbial contamination during processing” [2], so stated in the FDA Guidance for Industry (2004). In the US Pharmacopeia is a whole chapter referring to sterility testing in isolators.“The isolator for sterility testing need not to be installed in a classified clean room, but it is important to place the isolator in an area that provides limited access to nonessential staff.” [3] US Pharmacopeia 29 <1208>.
The ISOLATOR
The SKANFOG® STI is designed for the strict physical separation of the process and the product from the operator and thus the reduction of false positive test results caused by the sample handling in the laboratory. The inbuilt automatic H2O2 decontamination of all materials and samples used in the process leads to a high reproducibility of decontamination effect and the environmental parameter.
The SKANFOG® STI is constructed as a full welded stainless steel construction, using ASI 316L for the working chamber and ASI 304 for the support structure and the outer surfaces. The front door is made from safety glass and holds four shoulder rings for the gloves. The material of construction are chosen from a study which showed a good compatibility of stainless steel and glass with H2O2.[4] The gloves and sleeves are a three piece assembly; the sleeves are made from translucent PVC, the cove rings from grey PVC and the gloves from CSM (Chlorosulfonated Polyethylene) (Toso®). Glove stretchers are available to hold the gloves in position during H2O2 decontamination. The door opens in full with of the isolator chamber and is held in the open position by two gas dampers. A light bar on the outside of the door gives a good visibility inside the working zone; the light tube can be changed during the process without compromising the sterility. The height of the isolator can be adjusted by levelling pads in the support structure.
The air flow in the isolator is unidirectional from top down, which enables a good H2O2 reduction during aeration phase. The make-up air is taken from the room through an F9 prefilter and guided through an H14 HEPA filter into the working chamber. After passing the chamber at a speed of 0.2 m/s, the air is guided through five cartridge filters H 13 [4 ] in the back wall to the catalytic converter, where the H2O2 is broken down into water vapour and oxygen. After passing another HEPA filter, the air is released to the surrounding room. In the isolator is a constant overpressure of app. 100 Pa during operation mode. This helps to stay always in the positive pressure range during operation with the gloves. During operation mode the EU grade A (ISO 5) is achieved. There are no installations for an air exhaust necessary in the surrounding room.
The isolator is equipped with a H2O2 fogging system, which allows a decontamination of the main chamber including all necessary material for the test of sterility to 10-6 spores of Geobacillus stearothermophilus within less than 30 minutes including leak test and full aeration to less than 1 ppm H2O2.
To perform the test for sterility a peristaltic pump from any valuable supplier can be mounted in the centre of the base plate. This is recommended for nearly all applications, but on request the pump can also be moved to the left or right side. Near the pump a drain is welded in the base plate to remove the liquid waste from the isolator. The drain is either closed by a ball valve or a quick disconnect which fits to the sterile waste bags. It is recommended to use sterile bags for the collection of the liquid waste.
This has the advantage that the operator does not come in contact with the waste while changing the bag and it can be discharged in a contained way. If high active pharmaceutical ingredients are tested, the sterile closed bag is necessary.
Bothe side walls of the SKANFOG® STI are removable and can be equipped with all necessary sensors to monitor and control the isolator. As a standard, a pressure transmitter is included. Other sensors for temperature and humidity, air velocity, H2O2 concentration may be installed on request. The isokinetic probe for collecting particles as well as a sampling head for airborne viables may also be installed on one of the sidewalls.
The control system is a microprocessor with a colour touch panel as HMI, installed in the front of the isolator. Any data deriving from the sensors can be stored on a Yokogawa paperless recorder, which is CFR 21 part 11 compatible. The microprocessor itself is not storing any data.
Loading the isolator with the test material it is recommended to wipe all material with 70% isopropanol to remove any traces of impurities, which can cause microbial contamination if the H2O2 cannot reach the surfaces. The bottles are then stored on the integrated shelves, small items can be placed in baskets with little feed standing on the base plate or hang on the integrated bar. It is important to make sure that the bottles or other items do not touch each other to avoid blind spots for the H2O2. The shelves are made from stainless steel wire to allow the H2O2 to penetrate in the load. One isolator load can hold 15 tests with 20 samples each.
After loading is completed and the front door is closed, the glove stretchers are installed to hold the gloves in a fixed position during decontamination, in a way that the gloves are not touching any other surface. Now the decontamination can be started beginning with the leak test. Is the leak test, a pressure decay test at 220 Pa is successfully completed, the fogging starts automatically. The isolator with a full load needs app. 15 to 20 g of H2O2 in a concentration of 35%. The aeration starts automatically immediately after the holding phase and removes the H2O2 to a level of less than 1 ppm. After the decontamination with H2O2 the isolator switches automatically in the operation mode.
For the routine monitoring of the sterility test isolator the following tests are performed:
1. Leak test
2. Pressure differential between isolator and room
3. Glove testing and inspection
4. H2O2 monitoring I the room (TLV)
5. Microbial surface sampling on defined locations
6. Airborne viable sampling
LEAK TEST
The leak test of the SKANFOG® STI is performed automatically with the start of a decontamination process. A pressure drop of 50 Pa from a basic pressure of 220 Pa within 3 minutes is accepted as test passed. Any higher values have to be considered as the test failed. The decontamination process will not continue. The pressure differential between isolator working chamber and environmental room is 100 Pa in operation. Working in an isolator creates pressure alterations, ups and downs, depending on the movement. In order not to come in a critical negative pressure, the pressure difference is chosen to be 100 Pa.
GLOVE LEAK TESTING
For the glove testing in routine test covers to close the shoulder ring with an inflatable gasket hermetically are available. These covers have an integrated power supply and pumps which are able to autonomously pump up the seal and the glove assembly. The gasket up to 1.5 bars and the glove assembly up to 2500 Pa, which is enough to detect most, leaks. Pin holes in the gloves, especially on the finger tips where the material is in most gloves thicker than on the palm can only be detected with higher pressure or by well-trained operators who are able to perform a visual inspection. [6] The test covers wireless GT from SKAN AG is a complete autonomous system sending the test data wireless to a laptop or computer over a distance up to 15 m. Equipped with an RFID reader it also recognizes the glove port number, which is tested, that minimizes the risk for double work or missed glove ports.
Room monitoring with a TLV sensor for H2O2 is a requirement from health and safety department. H2O2is a vapour which can seriously affect the bronchial and lung system of people, therefore a threshold limit value (TLV) is set to 0.5 ppm. Draeger Polytron® 7000 is a useful device to monitor the content of H2O2 in the surrounding room of the isolator. It should be mounted close to the air exhaust.
SUMMARY
The use of the SKANFOG® STI for sterility testing offers tangible advantages over the use of a clean room class ISO 5 with a laminar flow bench for the testing of pharmaceutical samples for sterility:
1. A substantial reduction of false positive results resulting in a reduced retest effort and a reduced product loss.
2. A massive reduction of recurrent cost.
3. A reduction of clean room floor space between 25 and 50%.
4. Improved operator safety while testing samples with high active ingredients.
LITERATURE
1. Ph. EUR. European Pharmacopoeia 8th Edition 1/2014
2. Food and Drug Administration. Guidance for Industry, Sterile Drug Products Produced by Aseptic Processing. Sep 2004
3. USP XXXII NF 26 General Information. Chapter <1208> Sterility Testing Validation of Isolator Systems. p. 665-668
4. Lehmann F. and Luemkemann J.; Safe Change Filter Systems for Containments in the Pharmaceutical Industry, Pharm. Ind. 73 Nr. 9, 1683-1694 (2011)
5. Sigwarth V. and Staerk A. Effect of Carrier Materials on the Resistance of Spores of Bacillus stearothermophilus to Gaseous Hydrogen Peroxide, PDA Journal of Pharmaceutical Science and Technology, Vol. 57, No. 1, Jan/Feb 2003
6. Gessler A. et al. How Risky are Pinholes in Gloves? A Rational Appeal for the Integrity of Gloves for Isolators, PDA Journal of Pharmaceutical Science and Technology, Vol. 65, No. 3, May-June 2011
7. International Standard ISO 14644, Clean rooms and associated controlled environments. Geneva (Switzerland) International Organization for Standardization (ISO) 2004
8. Krebsbach T. Bässler H.J. Kostenvergleich zwischen Reinraum und Isolator als Prüfumgebung für die Durchführung für die Durchführung pharmazeutischer Muster auf Sterilität. Pharm. Ind. : 72[11]: 1980 – 1984
