Protak Scientific were instructed by The Royal Liverpool University Hospital (RLUH) NHS Trust to validate the Isolator vaporised hydrogen peroxide (H2O2) decontamination cycles and loading patterns of their new Pharmacy Aseptic Production Unit (PAPU).
This activity included the assessment of H2O2 exposure levels for both load item interaction and personnel safety.
To achieve this objective, Protak Scientific employed the use of the Picarro PI2114 Gas Concentration Analyser (Ref.1/Fig.1 ).
Figure 1a: Picarro P12114 Gas Concentration Analyser: performance specifications
Figure 1b: The Picarro Analyser connected to the PAPU Isolator
The new Pharmacy Aseptic Production Unit (PAPU) at The Royal Liverpool University Hospital (RLUH) will house aseptic dispensing services including preparation of Central Intravenous Additives (CIVAs), Total Parenteral Nutrition (TPN), Intravenous Cytotoxic medication (Cytotoxic) and clinical trial (Gene Therapy) medication.
The new PAPU facility houses a number of bespoke, production Isolators with dedicated H2O2 generators supplied by Envair Technologies (Ref.2).
The importance of establishing that the aeration phase is of suitable duration to return to safe operation levels before an isolator can be used and, additionally, the potential risk of residual levels with load items was factored into the validation strategy created by Protak Scientific.
The validation strategy assessed the following considerations:
- The aeration process was required to be effective in achieving <1ppm of H202 at the end of the cycle as a minimum but due to potential medicinal product interactions, the measurement of this needed to be accurately recorded and determined.
- Materials of construction for H2O2 compatibility, permeability and also safety for personnel and product exposure required a robust risk assessment of all items to be used within the isolator (Ref.3,4).
Once the strategy was complete, a method was needed to conduct the testing. The solution was determined by using the Picarro PI2114 Gas Concentration Analyser. An extremely sensitive, continuous, real-time H2O2 monitoring system with a low detection limit of <3 ppb (parts per billion)
Product and Personnel Safety Study
Upon completion of the risk assessment, 3 high risk areas of testing were determined and became the objectives of the study:
Objective 1: To ascertain the efficacy of the degassing – aeration phase on the worst case gassing cycle (loaded to full loading pattern with maximum permeable wrapping materials).
Objective 2: To assess the impact from off gassing of consumables upon unloading from the Rapid Gassing Chamber (RGC) used for Material transfer into the Isolator Chamber (Fig.2).
Objective 3: To assess the potential ingress of hydrogen peroxide into high risk consumable items.
The study was executed and provided results as follows:
Objective 1 – Aeration Phase:
The final developed gassing cycle was run on the isolator with the Picarro activated towards the end of the aeration phase (as per test schematic Fig.3b below) to measure the residual hydrogen peroxide concentration (Fig.3a).
The accuracy of the Picarro analyser meant that it was possible to ascertain the aeration phase duration could be set to confidently achieve 824ppb (0.8ppm) prior to the isolator chamber being available for operation.
Figure 3a: Picarro results for objective 1 study: Aeration phase
Results prove that the aeration phase reduces the residual H2O2 concentration to <1ppm
Figure 3b: Schematic of Experimental Set-Up for objective 1 study: Aeration phase
Objective 2 – Gassed Items:
The Picarro analyser was set up to measure inside the isolator chamber as per experimental set-up (Fig.4b)
The RGC was loaded with a maximum load which included worst case/absorbent materials described in the strategy (e.g. Tyvek) and gassed with the qualified gassing cycle twice, using back-to-back cycles. This ensured that the worst case levels of H2O2 was present within the load items at the end of aeration.
Figure 4a: Picarro results for objective 2 study: Unloading of the RGC into chamber.
Results prove that unloading of the RGC into the chamber does not raise the H2O2 concentration above <1ppm
Upon completion the racking was instantly moved from the RGC into the isolator chamber in front of the Picarro sensor with items removed from the racking to simulate the unloading.
The Picarro sensor did not detect any H2O2 above 1.0ppm (Fig.4a).
Objective 3 – Opened Gassed Items:
The high risk (higher potential for ingress of hydrogen peroxide) items such as membrane filters, packaging of medicinal product bags, syringes were assessed for H2O2 residues by gassing each packaging material twice, using back to back RGC runs to ensure a worst case challenge, and then simulating their opening or intended operation in front of the Picarro sensor (Fig.5b).
The Picarro sensor confirmed that none of the items showed any distinguishable change from background (air) hydrogen peroxide concentration therefore confirming all load consumables to
be suitable for decontamination by gaseous hydrogen peroxide and also minimising the risk for forward processing use (Fig.5a).
Figure 5a: Picarro results for objective 3 study: opening of gassed item
Results show no distinguishable evidence of H2O2 ingress.
Figure 5b: Schematic of Experimental Set-Up for objective 3 study: opening of gassed items
The isolator H2O2 decontamination cycles and loading patterns of the new Pharmacy Aseptic Production Unit at The Royal Liverpool University Hospital were validated and the additional 3 objectives relating to personnel and product safety also passed.
Reliability of the data was confirmed as the data was gathered towards the end of cycle development, to ensure that the data gathered reflected the routine running of the isolators. All data was gathered from within the Isolator, which had been leak tested prior to use in all of the studies, to ensure all residual gas would be captured by the sensor. One operator performed the study with an additional operator observing to validate that the study had been performed correctly, and the results were unbiased and reflective of the objectives set by the study.
The use of the Picarro analyser meant a greater accuracy of H2O2 detection, resulting in a suitable and justifiable aeration phase duration (Obj.1) required for the safe operation and exposure of potentially H2O2 sensitive medicinal products.
The use of the Picarro analyser also confirmed that at the end of a gassing cycle, any consumable products unloaded (Obj.2) and/or opened (Obj.3), would not have any level of hydrogen peroxide above 1.0ppm, ensuring that the safety of the operations and status requirements at the end of the cycle were maintained.
In addition to this study’s objectives, the Picarro analyzer, and its extremely sensitive monitoring capabilities supported the validation strategy for the overall cycle development/qualification goals.
Protak Scientific’s Enzyme Indicator technology was used to provide accurate cycle efficacy data to minimise the amount of overkill applied to the H2O2 decontamination process. However, there are no ppm sensors installed in the Isolator Chambers. Therefore, without the support of the Picarro analyser there would have been no way to ensure that the most critical area maintained the required <1ppm.
This means the customer can be assured that only the necessary amount of hydrogen peroxide is used, the isolators are working only for as long as they need to preserving the longevity of the isolators and related equipment from unnecessary wear or damage.
The new Pharmacy Aseptic Production Unit at The Royal Liverpool University Hospital will now be capable of completing their required daily gassing targets whilst ensuring the utmost safety to product, patients and staff.
https://www.legislation.gov.uk/eur/2012/528/contents – Regulation (EU) No 528/2012 March 2015 – Evaluation of active substances assessment Report: Hydrogen Peroxide.
Hubbard A, Roedl T, Hui T, Knueppel S, Eppler K, Lehnert S & Maa Y. (2018) Vapor Phase Hydrogen Peroxide Decontamination or Sanitization of an Isolator for Aseptic Filling of Monoclonal Antibody Drug Product—Hydrogen Peroxide Uptake and Impact on Protein Quality. PDA J Pharm Sci Technol 72: 348-366.