Biomedical Engineering Reference
In-Depth Information
In addition to sample stability assessment, poststained cell stability, with or
without fixatives, should also be examined. Data collected from immediate acquisi-
tion after staining and samples stored at 4
C at various times prior to being acquired
should be compared with reference baseline values (at H, M, and L); recovery within
80-120% is considered acceptable.
11.3.6 Control Reference Ranges
QC samples (at H,M, and L) tested invalidation studiesmay be used to establish control
reference ranges. Due to inherent variability seen inflowcytometricmethods in general,
at least 20 data values for each drug level from multiple analysts over a period of time
are recommended. MFI values typically showed higher degree of variability in part due
to instrument drifting as a result of decreased laser power output over time. Therefore,
establishing control ranges on the basis of MFI would take this variability into account.
Calculation of interpolated concentration (H, M, and L) inherently corrects for this
variability. In general, control range setting for flow cytometric PKmethod is similar to
practices for other analytical methods (see details in Section 11.2.7.7).
11.4 CONCLUSIONS AND DISCUSSION
Flow cytometry is an alternative technology platform that can be used for PK studies.
The examples discussed demonstrate the utility of this approach relative to other PK
methods. Both flow cytometric methods (for drug X and drug Y) were validated and
met the proposed validation criteria. To further our understanding of its utility, a
comparative study of the validated flow cytometric PK method for drug Y to an
electrochemiluminescence (ECL)-based PK assay was completed. Results are shown
in Table 11.1 for key performance parameters. Both assays are accurate and precise.
The ECL PKmethod is more sensitive than the flow cytometric PK method primarily
due to the use of an anti-idiotypic monoclonal antidrug antibody with high affinity as a
capture reagent. Both methods were deemed acceptable for use in evaluating clinical
samples.
In summary, flow cytometric PK methods can be successfully validated and hence
assay performance meets validation criteria based on regulatory guidelines and
published papers for analytical method validation [3-7].
REFERENCES
1. Current Protocols in Cell Biology, Juan S. Bonifacino, Mary Dasso, Joe B. Harford, Jennifer
Lippincott-Schwartz, and Kenneth M. Yamada Editors, Wiley, Inc., 2010.
2. Anderson MJ, Whitcomb PJ. DOE Simplified: Practical Tools
for Effective
Experimentation, Productivity Inc., 2000.
3. FDAGuidance for Industry: Bioanalytical Method Validation. FDACDER, US Department
of Health and Human Services, 2001. Available at http://www.fda.gov/downloads/Drugs/
GuidanceComplianceRegulatoryInformation/Guidances/UCM070107.pdf.
Search WWH ::
Custom Search