What is the difference between reprocessing and reworking in pharma, and what approvals does each need?

1Reprocessing vs reworking: the difference.

ICH Q7 draws the line at the established manufacturing process. Reprocessing repeats a step the process already contains; reworking uses a step it does not. Both definitions apply to “an intermediate or API”.¹

Two consequences follow. A batch that passes can still be reprocessed, for example milled again for particle size, but only a failing batch can be reworked. And equipment outside the validated process makes a step rework, whatever the batch record calls it; FDA told an API maker so in 2022, quoted under what inspectors cite below.

For finished products the regulations use one word. Part 211 says “reprocessing” in 211.115, 211.165(f) and 211.204 and never “rework”; the EU glossary defines reprocessing as “The reworking of all or part of a batch of product of an unacceptable quality”.³⁴ So recoating a failed tablet batch is controlled as reprocessing in both regions, whichever step it uses. FDA’s 2021 biologics guidance does split the terms for drug product too, and says reworking operations are generally “developed post-approval” and added by prior approval supplement.⁵

2Reprocess, rework, recover or reject: which is it?

3Reprocessing and rework SOP: steps, owners and records.

Section 211.115(a) requires a written reprocessing procedure and ICH Q7 14.32 expects procedures for rework, so one SOP can cover both; a rework adds the protocol and the equivalence report. Nothing is charged before the quality unit approves, and nothing ships before the filing question is answered.

3.1Rework protocol and report checklist.

Copy these into the protocol and its report. Each line is what the cited rule asks for.

1. Reason (Q7 14.30): the investigation of the non-conformance, finished before the decision to rework.¹
2. Procedure (Q7 14.31): the rework steps, how they will be carried out and the expected results.¹
3. Risks (EU 5.67; Q7 14.22): what the extra step could do to quality, including by-products and over-reacted material where a reaction is repeated.⁶¹
4. Tests (Q7 14.32): the release specification, plus additional methods where routine ones cannot characterise the reworked batch.¹
5. Impurity profile (Q7 14.32): the reworked batch compared with batches made by the established process.¹
6. Stability (Q7 14.31; EU 6.33): stability testing if warranted, and whether the batch joins the ongoing stability programme.¹¹³
7. Conclusion (Q7 14.31): whether quality is equivalent to the original process. One batch can be released on a report once it is found acceptable.¹
8. Approval (Q7 2.22; 211.115(b)): the quality unit reviews and approves the protocol and the report before the charge and before release.¹²

4What each market files.

FDA’s 2004 guidance has binding effect where it adjusts reporting categories, so that prior approval route is not optional.¹⁰ The 2021 biologics guidance covers vaccines, plasma-derived products and cell and gene therapies, among others. For drug product it lists only prior approval cases, and an approved protocol is one FDA reviewed and approved in the BLA or a later submission, so filing it early saves a supplement.⁵ Monoclonal antibodies for in vivo use are specified products outside that guidance; the 1997 guidance for them makes “reprocessing of a product without a previously approved reprocessing protocol” a major change.¹⁶¹⁷

The UK keeps applying the EU GMP guidelines as they stood at the end of 2020 unless the MHRA replaces them, and Chapter 5, Annex 16 and Part II all predate that.¹⁸ PIC/S adopted ICH Q7 as its GMP guide for APIs, now Part II of PE 009.¹⁹

5Example: one failing API batch, two paths.

Batch API-26-114, 120.0 kg, fails its release limit for impurity B: 0.18% against not more than 0.15%. The investigation finds the cake wash in step 6, an ethanol crystallisation, ran 40% short of the master record volume.

Step 6 has now been reprocessed in 3 of the last 40 batches (7.5%). That is far from the majority at which ICH Q7 and EMA’s 2026 guideline say a step belongs in the standard process, but the trend belongs in the product quality review.¹¹⁵

6What inspectors cite.

In a pre-approval inspection, FDA investigators compare actual manufacturing records with the process described in the application, and FDA’s 2026 programme lists “Reworking or process modifications not adequately justified or appropriately reported” among possible signs of a data integrity problem.²⁰

“Your response repeatedly described the additional (b)(4) that was performed as reprocessing. However, the use of equipment that is not part of the validated manufacturing process is considered rework.” Bioiberica, SAU, warning letter 320-22-20, 30 June 2022²¹

The API maker had reworked about 23 batches in 2020 and 2021 after microbiological or residual solvent failures, some of them repeatedly until results passed, with no studies of the step’s effectiveness. The letter goes on:

“None of the reworked batches were placed on stability to ensure they were of quality equivalent to that produced by the validated process.” Bioiberica, SAU, warning letter 320-22-20, 30 June 2022²¹

FDA asked for a rework procedure describing how reworked batches would be shown equivalent to the validated process, and an assessment that covered “the need to revalidate your manufacturing process”.²¹

Finished products get the same scrutiny. Medical Products Laboratories, which makes prescription and OTC drug products, used an unvalidated treatment on filled batches that failed microbiological tests:

“Your response commits to revising your procedures to no longer allow (b)(4) treatment to rework batches after failing microbiological results and to place a reworked batch on real-time stability.” Medical Products Laboratories, Inc., warning letter 320-26-61, 9 April 2026²²

FDA judged that inadequate, because the risk assessment did not reach every product where the treatment had been attempted.²²

7Judgement calls.

• Retest or reprocess after an OOS result. Retesting analyses the original sample, for example after an instrument malfunction; reprocessing changes the batch. Neither ends the investigation, which must reach other batches that may be affected, and if material was reprocessed after additional testing, production and the quality unit comment and sign in it. Testing until a result passes is “testing into compliance”.²³ See OOS investigation.
• How many times. No regulation sets a number. Reprocessing used for most batches belongs in the standard process,¹ and repeating a step until results pass is the Bioiberica pattern. Set a maximum in the procedure and trend every use, as in the example.
• An expired API. The ICH Q7 Q&As say it may be acceptable to reprocess or rework an expired API where the manufacturer holds all the related historical GMP documentation and additional stability data on the reworked or reprocessed API, and that filing questions may arise beyond GMP.⁹
• Laboratory reprocessing. Re-integrating chromatography data is also called reprocessing, and FDA expects the audit trail to show it with a justification.²⁴ That is a data integrity question, covered in manual integration.
• Medical devices. Device rework is handled under ISO 13485 and FDA’s QMSR instead; see nonconformance report.

8How it runs in Seal.

In Seal, API manufacturing keeps reprocessing and rework as accountable decisions rather than corrections hidden in the original instructions: the original execution stays as it ran, and the approved branch gets its own operations, samples, results, yields and losses. Material entering the branch keeps its source state and quantity, and a stage that keeps needing reprocessing can prompt a process review or CAPA rather than being normalised by passing final tests. In the electronic batch record, authorised rework creates additional executable work without altering the original course.

The decision itself sits in nonconformance and material review, where a disposition such as rework or reprocess is a plan with instructions, quantities, owners and completion evidence, and release or closure follows verified execution and reconciliation, not the selection of an option.