System Suitability and Analytical Methods
Ed O'Connor
Open for contract remote work 1) GxP QA auditor. 2) GxP method Development. 3) GxP Method, Process, Software, Instrument and Computer System Validation. 4) Data Integrity. 5) Statistics- Minitab (ROC, etc.)
To say that bioanalytical method validation is a continually evolving process is an understatement.? With the current approved FDA guidance from May 2001 still in revision from Sep 2013 and white papers and workings groups moving in real time what is the bioanalytical scientist to follow.? The question of what to follow is beyond the scope of this article and has significant literature available to address this question and potentially confuse anyone.? Instead herein I would like to discuss one aspect of bioanalytical methods that is often underappreciated, system suitability.? System suitability is the testing that is conducted to determine that the instrument performance is suitable prior to the running of a sample set/batch.?
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System Suitability (SS) is a required component of regulated assays. ?The implication from the USP, citations and arguments is that they must precede validation and sample analysis runs in assays following FDA or EMA guidance. ?This discussion is a review of recent publications and focuses on descriptions in guidance and other documents pertaining to the “when” or “if” of system suitability.? The actual components of suitability may be found in the United States and European Pharmocopeia (1).
First, the predicate description from which FDA and EMA considerations of SS originates from the USP (1, 2) ?and EP(10).? The language is described below from USP and recent interpretations.
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USP:
System suitability tests are an integral part of gas and liquid chromatographic methods. These tests are used to verify that the chromatographic system is adequate for the intended analysis.
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The use of the word intended is not accidental but implies that suitability must be assessed before a run is initiated. ?It would be much clearer if the wording actually indicated that SS must precede runs. ?The USP also provides more resolution as to when suitability must be run.?
The closing sentence of the quote below is ambiguous in that here one could infer that suitability could be run without interpretation before sample analysis but that the acceptance of sample analysis requires acceptance of suitability.
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USP
Whenever there is a significant change in the chromatographic system (equipment, mobile phase component, or other components) or in a critical reagent, system suitability is to be re-established. No sample analysis is acceptable unless the suitability has been demonstrated.
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The statement above does not indicate any relative chronology.?? This does not indicate that SS need precede or even be concurrent with the assay only that SS must be accepted before the sample analysis is accepted.
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The Quote from the Perkin Elmer White paper (7) is more precise but it is a White paper not a guidance document:
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Perkin Elmer
The third layer of the data quality triangle is the system suitability test (SST). Again the basis for a SST working reliably is that the instrument is qualified and the method used is validated. USP defines this as “Verify that the system will perform in accordance with the criteria set forth in the procedure.” This really means: [sic]” is the method running on the system working as you expect on the day you want to analyze samples and before the samples are committed for analysis?” This approach is good analytical science and this should be the driver for SST rather than compliance with regulations.
This clearly dictates when suitability must occur and also indicates the dependency of analyses upon SST.? The Perkin Elmer White paper also offers this:
“In contrast, a system suitability test is a point of use check to confirm that the instrument and the analytical method are working correctly just before the analysis begins.”
This requirement is at least consistent with the earlier description of timing.?
Running a validation or sample analysis without running and reviewing system suitability puts those runs at risk.?? This can sacrifice analyst time which is considerable and sponsor time which is irreplaceable.?? Further this practice could result in a finding since running suitability without review is, in essence, not running suitability at all.? Ultimately, sample volume, sample availability and freeze thaws are more considerable limitations and have more considerable consequences; non clinical sample volumes are limited and patients in clinical trials would not necessarily agree to a willful waste of their irreplaceable contribution.?
Confirmatory test(s) procedures and parameters to ensure that the system (equipment, electronics, and analytical operations and controls to be analyzed) will function correctly as an integrated system at the time of use.
The 2001 guidance (3) is clearer and is in agreement with the position described in the Perkin Elmer paper.
FDA 2001 System suitability: Determination of instrument performance (e.g., sensitivity and chromatographic retention) by analysis of a reference standard prior to running the analytical batch.
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No real interpretation is needed here although how close in time to the running of the samples may be open to discussion.
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The 2013 draft Guidance (4) suggests in the first statement that suitability is optional:? “If system suitability is assessed” apparently contradicting the 2001 guidance.
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FDA 2013 Guidance: System suitability: If system suitability is assessed, a specific SOP should be used.? Apparatus conditioning and instrument performance should be determined using spiked samples independent of the study calibrators, QCs, or study samples. Data should be maintained with the study records.
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But the statement below- from the same guidance implies that SST is not optional.
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FDA 2013 Draft Guidance System suitability is routinely assessed before an analytical run. System suitability samples should be different from the study samples, standards, and QCs to be analyzed in the run. Therefore, study samples, standards, or QCs should not be used as their own system suitability samples within the analytical run.
Oddly enough, there is no discussion of suitability in the 2011 EMA Guidance (5) but The 28 February 2012 EMA/INS/GCP/532137/2010 GCP Inspectors Working Group Reflection paper for laboratories that perform the analysis or evaluation of clinical trial samples (6) states:
“Routine system suitability tests, such as the analysis of quality control (QC) samples, should be considered and included in the analytical methodology as required. It is important that analytical factors that may potentially affect clinical trial results are considered.”
Application to Dose formulation
A recent White paper describing dose formulation also described system suitability.? There is no clear guidance extant for this exercise and as such labs may use GLP or GMP approaches although dose formulation analysis is a described GLP exercise.?? That paper described the approach below:
System Suitability Test
The “system suitability” should be demonstrated before initiating a study sample batch analysis. The system suitability tests performance and criteria should have been demonstrated during validation and incorporated into the analytical method (8).
Agilent and Dr. Ludwig Huber, put together a good GLP analytical and bioanalytical guide (9). In that guide the role and description of suitability are well described.
“When the equipment and a particular method have been selected and found to be validated, the equipment for that method goes through a system suitability test before and during sample analysis.”
“Analytical methods should be validated prior to routine use and after changing method parameters. Analytical systems should be tested for system suitability prior to and during routine use, practically on a day by day basis.”
Another site- The Regulatory Forum provides the following:
“In addition, prior to the start of laboratory studies to demonstrate method validity, some type of system suitability must be done to demonstrate that the analytical system is performing properly. Examples include: replicate injections of a standard preparation for HPLC and GC methods.”
In summary, system suitability executed and reviewed before the run is initiated provides assurance that the analysts and sponsor’s time, and more importantly the subject’s (human or other) donation were not wasted by using a system that was not performing well.?? Granted, the run itself may fail but at the very least we can provide assurance that the time and material was not wasted because the system was not suitable.
Ligand based assays are seemingly excused from suitability.? Many labs refer to assay QCs as suitability samples.? They are not.? Few labs test the performance of plate readers for suitability but this is probably even more important there since ligand binding assays require significant time before the assay is read. ?Ignoring suitability may have an even greater impact on time.? Only a few CROs have adapted SST to plate readers.?? This is in light of the fact that the SST can be much simpler and can be limited to the assessment of a calibration plate or flood plate to determine that the reader and software are performing acceptably.?
In closing, system suitability tests are not peripheral to either instrumental or ligand binding assays but are the first test in committing and then accepting results from assays performed to support regulated studies.
[1] USP ?1058???????????????????????????????????????????????????????????????????? https://hmc.usp.org/sites/default/files/documents/HMC/GCs-Pdfs/c1058.pdf
[2] USP 621 ??????????????????????????????????????????????????????? ??????????????https://hmc.usp.org/sites/default/files/documents/HMC/GCs-Pdfs/c621.pdf
[3] FDA 2001 Guidance ??????????????????????????????????????????https://www.fda.gov/downloads/Drugs/Guidance/ucm070107.pdf
[4] FDA 2013 Draft Guidance https://www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation/guidances/ucm368107.pdf
[5] EMA 2011 Guidance https://www.ema.europa.eu/docs/en_GB/document_library/Scientific_guideline/2011/08/WC500109686.pdf
[6] EMA Notes to LabsLabhttps://www.ema.europa.eu/docs/en_GB/document_library/Regulatory_and_procedural_guideline/2012/05/WC500127124.pdf
[7] R.D.McDowall , Paul Smith, Nicola Vosloo,? System Suitability Tests and AIQ https://www.perkinelmer.com/lab-solutions/resources/docs/WTP_WhySSTisnosubstituteforAIQ.pdf
[8] Whitmire ML1, Bryan P, Henry TR, Holbrook J, Lehmann P, Mollitor T, Ohorodnik S, Reed D, Wietgrefe HD.? Nonclinical dose formulation analysis method validation and sample analysis. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2976985/
[9] Ludwig Huber: A primer Good laboratory practice and current good manufacturing practice https://www.agilent.com/cs/library/primers/Public/59886197.pdf