Which Tests Must Be Redone After a Material or Supplier Change

The decision rule: look at whether contact and exposure changed, not whether the part name changed

When you bring in a new supplier, switch to a different grade, or move sterilization to a different provider, the two habits you see most often in industry both end badly. One is to compare the BOM line by line and release anything whose description still matches, which quietly lets through the same name with a different formulation. The other is to retest everything the moment anything moves at all, spending budget and schedule on items the change could not possibly touch.

Narrowing the list down to the items that genuinely apply comes down to a single thread. Did this change alter the physical material that contacts the body, the nature of that contact, or its duration category? Did it alter the exposure route for chemical substances or energy? Did it alter what the sterile barrier is made of? A change that touches none of these can be closed out with a written rationale in the change review record. A change that touches any of them gets broken down into specific test items. Run the sequence in reverse and you end up in the familiar position of having tested a pile of items and then being unable to write down the basis for them.

Change grading reference table

The "how to handle it" column gives you a starting point, not a conclusion. When you actually fix the test list, add one more layer on top: did this change also alter the intended use, the contact site, or the duration of use? If any one of those three moved, you cannot borrow the row above as a "similar change" — you go back and redo the risk assessment.

Biological evaluation: the blind spot sits in "same name, different material"

Once the material of a body-contacting part changes in substance, biological evaluation is repeated against the corresponding parts of ISO 10993 and GB/T 16886, with the applicable parts confirmed against the current valid version of the standard text. There are a few judgement details here that anyone who has been through it will guard against in advance.

Same grade does not mean same formulation. One grade produced at different plants or in different countries may use a different additive package, and differences in antioxidants, slip agents and mould release agents all show up in the extract. What you want from the supplier is not verbal confirmation that "the grade is the same" but a written formulation-equivalence statement plus a commitment to notify you of changes. The case that is genuinely hard to cover is the supplier who changes the formulation and does not tell you.

Masterbatch is a material in its own right. Plenty of change reviews treat a colour change as a cosmetic adjustment and route it through the simplified path, but the colourant is itself a source of extractables, and a colour change on a body-contacting part should be treated as a new material. This one gets skipped often, and the cost lands directly.

The contact duration category sets the depth of evaluation. Limited contact and long-term contact are not in the same league in terms of how deep the evaluation goes. If the change comes bundled with an adjustment to the intended manner of use, re-establish the contact category first and fix the test list second; otherwise you finish testing, the category does not line up, and the data still cannot be used.

Existing data can be cited, but the case has to be made. Evaluation data generated for the same material on another product is not automatically unusable. The condition is that you write up and file a documented justification covering the comparability of contact site, contact area relationship, sterilization method and manufacturing process. If you cannot write the justification, you effectively have no data.

For the specific combination of tests that a material change drags in, start from the usual scope of biocompatibility testing and then trim it against your own product's contact category.

Sterilization and packaging: one change often pulls three threads

Sterilization and packaging are the parts of a change review where the workload is most often underestimated, because a single action sets off three threads at once.

Changing the sterilization provider means the sterilization validation is repeated at the new site even if the method is unchanged. Equipment, load configuration and chamber conditions all differ, and the validation conclusion from the old site does not transfer. Residual evaluation and a product performance recheck come along with it: what the sterilization process does to the material does not go away because a different company now runs it. See sterilization validation for the related scope of work.

Changing the sterilization method is a change with a wider footprint. Materials tolerate different sterilization methods differently, so performance testing, biological evaluation and packaging tolerance all need to be looked at again — plan for roughly the intensity of a new product.

Changing the packaging material or the sealing equipment means redoing packaging system validation in line with ISO 11607, with evidence supporting both the formation and the maintenance of the sterile barrier, and it knocks on to transport and ageing-related conclusions as well. Your existing shelf-life conclusion was built on the old packaging system; change the packaging and the conclusion needs fresh support. See packaging validation for the specific items.

These three threads have a dependency order. Run packaging validation before the sterilization method is locked down and you will probably run it twice. Drawing out the dependencies when you build the schedule saves more than squeezing the duration of each individual item.

When an equivalence justification is enough on its own

Not every change needs retesting. A change that can be closed with an equivalence justification instead of a new test campaign usually satisfies all of the following at once: the changed part does not contact the body and plays no role in the energy transfer path; the change does not alter the product's key performance characteristics or failure modes; the change does not affect the sterile barrier or sterilant accessibility; the supplier can provide traceable material information and a statement of consistency; and comparable historical data exists with the comparability written out.

Fail any one of these and the justification is downgraded to "partial retesting plus justification". When you make this call, write the conclusion and the supporting material into the change review record at the same time — it costs far less than reconstructing it later. During an audit, being able to produce the reasoning as it stood at the time carries a completely different weight from producing an explanation written after the fact.

The system side: your change control record decides how you explain yourself

What ISO 13485 cares about is whether the change control process itself closes the loop: change identification, impact assessment, verification or validation, approval, implementation, traceability, and notification where required. A test report is one piece of evidence inside that loop; it cannot stand in for the loop.

The common misreading is "the lab issued a conforming report, so the change is signed off". In reality a report only demonstrates that the submitted samples met the requirements applied, for the items tested. It does not take on the job of judging how far the effects of your change reach — that reach is something the client defines in its own change review. Get this backwards and the cost of explaining yourself during an audit goes up sharply.

One point worth stating plainly: laboratory accreditation marks only demonstrate that the laboratory holds the corresponding technical competence within its accredited scope; they do not constitute a commitment regarding market access outcomes. After a change, the compliance conclusion is still for the manufacturer to reach on the basis of a complete evidence chain.

Self-check sequence: work through it in this order, not backwards

One, write down exactly what changed: from which state to which state, which material codes, which process steps, which sites are involved. If you cannot describe the difference in states, everything downstream is guesswork.

Two, decide whether the change touches the main thread: contacting material, nature of contact, contact duration category, exposure route, sterile barrier composition — tick or cross each one.

Three, grade it against the table above and draft an initial test list.

Four, check the dependencies: get the order of sterilization method, packaging system and ageing validation straight.

Five, assess whether an equivalence justification can replace part of the test list; write the justification, and if it will not write, drop the idea.

Six, define the condition of the samples to be submitted: sterilized or not, in final packaging or not, production-representative or not, and whether they represent actual post-change manufacturing.

Seven, confirm the applied standards and acceptance criteria before the request form goes out, so the report's conclusion is expressed in a form you can actually use.

Eight, write the whole reasoning process into the change review record and file it.

Three failure scenarios and what they cost

Scenario one: a masterbatch change was never declared and went through the simplified route as a cosmetic change. Some time later a customer audit asked for the evaluation basis for the colourant, no record could be produced, and the line was stopped to complete the biological evaluation while an impact assessment was run on the batches already shipped. Handled at the review stage this is one document action; handled in front of a customer auditor it is a line stoppage plus traceability work.

Scenario two: the sterilization provider changed and the old packaging validation conclusion was carried over. Sampling inspection showed seal strength drifting, and the investigation traced it to a load configuration at the new site that differed from the old one. At that point packaging system validation has to be redone and the shelf-life conclusions are left hanging as well. Corrected at the planning stage this costs nothing; corrected once samples have arrived and tooling is cut, it means fresh scheduling and fresh material.

Scenario three: at second-source qualification the only thing obtained was the supplier's verbal "same grade", with no written formulation statement. The supplier later changed the additive package quietly, extraction results stopped matching the original data, the specific batches could not be traced, and the evaluation had to be reopened across a wider scope. The cost of one written statement and the cost of one traceability exercise with undefined boundaries are an order of magnitude apart.

What these three have in common is that what you saved was paperwork at the review stage, and what you paid was schedule and traceability at the production stage. A thorough change review is one of the better-value steps in the whole process.

If you need to turn a change list into a testing plan, talk to us

SUNGO Lab (Shanghai Shage Medical Technology Co., Ltd.) is a third-party testing laboratory for medical devices and assistive products, accredited by CNAS, CMA and IAS (USA), with laboratories in Shanghai and Hefei. Defining test scope and arranging submissions after material substitutions, supplier switches and changes to sterilization or packaging systems is routine work for us. Send over the before-and-after state description, the material information and the product's contact category, and we can help you narrow the list down to what actually needs doing, along with recommendations on sample condition and scheduling, so you do not finish testing only to find the basis does not fit.

Call +86 132 4819 8029, or request a quote and we will put together a concrete plan for your specific change.