Regulatory Expectations and Industry Practices for Recovery Studies

Purpose and Introduction

This reference document discusses the regulatory expectation for performing recovery studies. This document also includes Hyde Analytical Lab’s position on selecting soils to perform recovery studies on.

Scope / Background

Demonstration of cleaning process efficacy requires that the surface sampling methods are developed along with an appropriate analytical method by which acquired samples can be assayed. Sampling is generally accomplished by either indirect or direct sampling methods. Rinse sampling, an indirect method, is employed to sample large surface areas and equipment surfaces that are otherwise inaccessible. Surface swab sampling is a direct method commonly employed for assessing surface cleanliness and is the most preferred by regulatory health authorities. To develop these methods, input can be drawn from both regulatory requirements and industry best practices. Given that there are losses in the amount of material recovered from surfaces, regulatory health authority guidance documents broadly recommend the conduct of recovery studies. The FDA Guide to Inspections: Validation of Cleaning Processes, states that firms should “show that contaminants can be recovered from the equipment surface and at what level…” [1]. Further, both the Pharmaceutical Inspection Convention and Pharmaceutical Inspection Co-operation Scheme (PIC/S) and Eudralex Volume 4, Annex 15 provide more explicit guidance that “recovery should be shown to be possible from all materials used in the equipment with all sampling methods used” [2, 3]. Health Canada’s guidance also requires that recovery studies be completed [4]. Clearly, recovery studies are a regulatory expectation, however regulatory guidance does not mandate the specific residues or analytes for these studies. In the absence of direct regulatory specification and requirements, manufacturers should employ a combination of published industry best practices and logical assessments founded on product knowledge and scientific understanding of the process. There are varying approaches regarding the recommended soil for spiking coupons in a recovery study. The first approach concentrates on confirming that the analytical and sampling method can reliably and reproducibly quantify the amount of residual drug substance residue since this is the residue of concern for cross contamination. The second rationale, one of several approaches discussed in PDA Technical Report 49 [5], suggests that recovery studies should be conducted using the same residue present on the process equipment surfaces at the conclusion of the cleaning process (if it were ineffective), i.e., residue that has been degraded by the cleaning agent. Technical Report 49 also states that it is common practice to spike coupons using the native protein active since it is simpler and represents a worst case [5], i.e., non-degraded residue.

Results / Discussion

In conducting studies for our clients, Hyde uses the native proteins or in-process samples rather than degraded residues for spiking coupons during recovery studies. The general rationale points for this recommendation are as follows: Conservatively, the use of the worst-case post-production soil from the standpoint of solubility and recovery will result in a more robust sampling method capable of recovering soils that pose a lesser challenge. Spiking coupons with the native soil represents a worst case as the physical and chemical changes associated with protein drying lead to an overall increase in the molecular weight distribution resulting from oligomerization, denaturation, entanglement, and aggregation. Kimble et al. have noted that these structural changes correlate with reduced solubility [7]. Exposure to alkaline cleaning agents facilitate hydrolysis reactions that in turn cleave proteins into smaller peptides, however the extent to which this proceeds is dependent on concentration, temperature, and exposure duration. Generating the degraded material can be difficult depending on the protein and can be inconsistent for future study executions unless the degradation parameters are tightly controlled. After a prescribed degradation duration, if an alkaline cleaning agent is neutralized, protein fragments can in some cases exhibit agglomeration or precipitation. As TOC is a non-specific method, it will not differentiate between multiple carbonaceous materials within the same sample. Accordingly, common practice is to assume that any TOC detected in a sample is attributable entirely to the material of concern (likely drug product) rather than other more benign materials within the product stream. While the method is non-specific it must be capable of delivering reliable results from a representative sample matrix. Using TOC to gauge the recovery of degraded material would require additional development work to ensure that the cleaning agent matrix does not interfere with the analysis. Additionally, if alkaline materials used to degrade the residues are not neutralized, work needs to be performed to confirm the samples are sufficiently acidified to compensate for the additional atmospheric carbon dioxide (inorganic carbon) absorbed into the samples.

Conclusions

Recovery studies are included as part of a holistic approach to providing evidence of cleanliness within process equipment. Sampling studies should be combined with other studies, such as visual residue assessments to provide orthogonal means to confirm minimal risk of cross contamination. When selecting soils for the small-scale recovery studies, Hyde recommends the use of native proteins or in-process samples rather than degraded residues.

References

1. The FDA Guide to Inspections : Validation of Cleaning Processes https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/inspection-guides/validation-cleaning-processes-793
2. Eudralex Volume 4, Annex 14, Section 10.12, https://health.ec.europa.eu/system/files/2016-11/2015-10_annex15_0.pdf, accessed July 14, 2023
3. PICS Annex 15, https://picscheme.org/docview/4590
4. Health Canada’s Cleaning Validation Guide (GUI-0028), https://www.canada.ca/en/health-canada/services/drugs-health-products/compliance-enforcement/good-manufacturing-practices/validation/cleaning-validation-guidelines-guide-0028/document.html#s9-1, accessed November 14, 2022
5. PDA Technical Report No. 49 (TR 49) Points to Consider for Biotechnology Cleaning Validation, 2010
6. Kimble A, Ratanski C, Kremer TA. Chemical Changes Over Time Associated with Protein Drying. Biomed Instrum Technol. 2023;57(2):52-57. doi: 10.2345/0899-8205-57.2.52. Epub 2023 Jun 21. PMID: 37343070