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Airborne Particle Counting for Pharmaceutical Facilities
Airborne Particle Counting for Pharmaceutical Facilities: Update 2008, EU GMP Annex 1
Morgan Polen - VP of Applications Technology, LighthouseWorldwideSolutions
On February 14th, 2008, The European Commission updated Volume 4EUGuidelines to Good Manufacturing Practice Medicinal ProductsforHuman and Veterinary Use, Annex 1: Manufacture of SterileMedicinalProducts.
This update comes into operation on March 1st, 2009.
(With the provisions on capping of freeze – dried vialsimplementedby March 1st, 2010)
CleanroomandClean Air Device Classification:
The formal cleanroom testing for classification should be doneperthe EN ISO 14644-1 standard.
Another key point stated in this update is thatclassificationshould be clearly differentiated from the operationalprocess ofenvironmental monitoring.
The maximum permitted airborne particle concentration is givenintable 1.
Airborne Particle Counting for Pharmaceutical Facilities
Table1:Updated limits in particle counts per Grade.
ComparisonAnnex1, to ISO 14644-1
To note the Particle Classifications are NOT Exactly perISO14644-1, but the amount of difference is listed in Table 2forGrades C and D (note areas in BOLD)
For cleanroom certification testing of Grade A zones, aminimumsample volume of 1m3should be taken per samplelocation.
It should be noted that this follows the sampling guidelines ofENISO 14644-1. For Grade A, the airborne particle classificationis*ISO 4.8 and is dictated by the limitforparticles≥5.0um, which is 20 particles per cubic meter.
*(EN ISO 14644-1 allows intermediate classifications withtheminimum increment of 0.1)
For Grade B (at rest) the airborne particle classification is ISO5for both particle sizes and in operation, the airborneparticleclassification is ISO 7 for both particle sizes.
For Grade C at rest, the airborne particle classification is ISO7and in operation the airborne particle classification isISO8.
For Grade D (at rest) the airborne particle classification is ISO8and it is not defined for in operation.
For the classification of a cleanroom or clean air device,EN/ISO14644-1 defines:
● The minimum number of sample locations
● The sample size (volume) based on the class limit of thelargestparticle size under consideration
● The means of evaluating the data
MinimumNumberof Sample Locations
The minimum number of sample locations for cleanroomcertificationtesting per EN ISO 14644-1 is a simplecalculation
Where NL is the minimum number of sample locations (rounded uptothe nearest whole number), and A is the area of the cleanroomorclean zone in square meters.
The minimum sample volume for cleanroom certification testing perENISO 14644-1 is determined by largest considered particle sizeforthat particular environment. The Grade A environmentat5.0um is classified as an ISO 4.8 cleanroom or clean air device. Thisiswhere the 1 cubic meter of air / location comes from.
EN ISO 14644-1 states that, for each sample location, sampleasufficient volume of air that a minimum of 20 particles wouldbedetected if the particle concentration for the largestconsideredparticle size were at the class limit for the designatedISO Class.The Sample volume or Vs per location is determined by theequationbelow:
● Vs is the minimum single sampling volume per location, expressedinliters
● Cn,m is the class limit (number of particles per cubic meter)forthe largest considered particle size, specified for therelevantclass.
● 20 is the defined number of particles that could be counted iftheparticle concentration were at the class limit.
(See EN ISO 14644-1 Section B.4.2 for details)
Per ISO 14644-1 the minimum sample volumes for each of theGradeareas in liters is listed in Table 3, based upon thelargestconsidered particle size.
*the volume sampled at each location shall be at least 2 liters, with a minimum sample time of 1 minute.
The minimum sample volume presents an unusual situation wheretheminimum number of sample locations is 1. Per EN ISO 14644-1whereonly one sampling location is required, take a minimum ofthreesingle sample volumes at that location. For a small GradeAenvironment where only one sample location is needed, a minimumof3 cubic meters of air must be tested (see EN ISO 14644-1 AnnexB3.4.3 for details).
For the classification testing, portable particle counters withashort length of sample tubing should be used. Thisrequirementexists because of the loss of large sizedparticles(≥5.0um) in the sample tubing.
Isokinetic sample probes must be used in unidirectionalairflowsystems. Lighthouse Worldwide Solutions recommends usinganisokinetic probe in non-unidirectional airflow systemsaswell.
The in-operation classification may not always be possibleduringnormal operations. This classification may be demonstratedinsimulated operations, during media fills ornormaloperations.
In order to demonstrate continued compliance, EN ISO14644-2provides information on this testing. The frequency of suchtestingis in the Table 4.
Grade A and B cleanrooms or clean air devices must bere-testedevery 6 months. Grade C and D must be recertified at aminimum ofevery year.
CleanroomandClean Air Device Monitoring:
Particle monitoring during the operational process is differentfromthe particle monitoring for classification oftheenvironment.
All Grade environments should be routinely monitored while theyarein operation. The locations selected for this particlemonitoringshould be chosen based upon a formal risk analysis andthe resultstaken during the cleanroom classification testing of thecleanroomor clean air device.
In Grade A zones, particle monitoring should be done duringtheentire operation of a critical process, includingequipmentassembly aand setup stages.Justifiable exceptions arewhere thecontaminates in the process would damage the particlecounter orpresent a hazard. Examples of such a hazard are whenworking withlive organisms or radiological hazards.
Grade A zone shouldbemonitored continuously in such a manner that any interventionsinthe process, transient events, or air system deteriorationisdetected, recorded and, if necessary, appropriate alarmsorwarnings are triggered.
Though not specifically stated in Annex 1, dedicated fixedpointRemote particle counters with 1 minute sample times havebeendemonstrated to adequately monitor Grade A Environments.Thesedevices provide adequate sampling frequency to detectalloccurrences.
Some operations may generate particles or droplets from theproduct,thus making the demonstration of low levels ofparticles≥5.0μm not possible. Annex 1 states this is acceptable, especiallyatthe point of fill, when filling is in process. It is stillnecessaryto monitor these locations, both at rest and duringsetup.
Particle monitoring of the Grade B zone should be similar toGradeA; however, the sample frequency may be decreased. Theimportanceof the Grade B monitoring is determined by the degreeofsegregation between the Grade A and B zones.
The Grade B zone should be monitored so that changes in theparticlelevels or any system deterioration would be detected, andalarm andwarnings triggered and recorded if limits areexceeded.
For the particle monitoring system, fixed point remoteparticlecounters, or sequential sampling systems (manifold),attached to aparticle counter or a combination may be used.
Regardless of the system used, it must be appropriate fortheparticle size considered. When using any system, thelossof≥5.0μm particles in the sample tubing is a concern. The length ofthetubing used, the number of bends and the radius of these bendsmustbe considered.
The system should take into account any risk from the materialsusedin the operation. An example of the risk is with liveorganisms orradioactive materials.
The sample size of sample volume for monitoring using anautomatedsystem does not necessarily the same sample volume usedfor theformal classification of the cleanroom or clean air device.Whereasthe classification of a Grade A environment requires aminimumsample (per location) of 1 cubic meter of air, forenvironmentalmonitoring a smaller sample volume may be used.
Particles that are ≥5.0μm are important as they can provide early indication offailurein the environmental system. Occasional≥5.0μm particle counts may be false counts because ofelectronicnoise, stray light or the sudden release of particlesfrom thesample tubing. But Annex 1, states that consecutive orregularcounting of low levels of ≥5.0μm particles is an indication of a possible contaminationeventand should be investigated.
These counts might indicate a failure of the HVAC system,fillingequipment failure or poor practices during routine operationorequipment set up.
For all Grades, the clean-up time between the “operationalstate”and the “at-rest” state should be 15-20 minutes in anunmannedstate after the completion of operations. This period isreferredto as a guidance value.
ParticleMonitoringof Grade C and D Areas.
These areas should be monitored for particles in operation and,forGrade C, also at rest. The frequency of such monitoringisdetermined by quality risk management. The alert/action limitsaredependent on the types of operations carried out.
Examples of operations carried out for products are listed inTable5.
The background classification for the isolator environmentdependson the isolator design and the type of application. Thebackgroundshould be a controlled environment. For an asepticprocess itshould at least be a Grade D.
The transfer of materials into and out of the unit is one ofthegreatest potential sources of contamination, as the area insidetheisolator is the local zone for high risk manipulations.
Routine monitoring of isolators should be carried out andincludefrequent leak testing of the glove/sleeve system.
Partially stoppered freeze drying vials should be maintainedunderGrade A conditions at all times until the stopper is fullyinserted(this part of Annex 1 will be effective March 1,2010).
Crimping of the cap should take place as soon as possible afterthestopper has been inserted. As the crimping process cangeneratelarge numbers of non-viable particles, it should be done atadifferent station.
For aseptic processing, vial capping can be done as anasepticprocess or as a clean process outside the aseptic area. Whenvialsleave the aseptic area for capping in the clean area, theyshouldbe protected by Grade A conditions up to the point of leavingtheAseptic area, thereafter stoppered vials should be protectedwith aGrade A air supply until the cap has been crimped. Note thataGrade A air supply is differentiated from a GradeAenvironment.