结论：等同性论证的关键不是「像不像」，而是「差异会不会影响生物学安全」
企业常问：我这个产品用的材料和另一个已经做过试验的产品一样，能不能不重做？
答案取决于能否论证：两者的差异不会影响生物学安全。 注意这个表述——不是论证「完全相同」，而是论证「差异无影响」。完全相同的情形很少，多数情况是有差异而需要评估差异。
论证的质量决定了能否被接受。 论证充分的可以大幅减少试验；论证草率的不但不被接受，还会引出对整体评价质量的质疑。
判断的维度
| 维度 | 需要比较什么 |
|---|---|
| 化学组成 | 基体材料、添加剂种类与含量 |
| 加工工艺 | 成型方式、温度、助剂 |
| 表面处理 | 涂层、清洗、处理剂 |
| 灭菌方式 | 方式、参数、残留 |
| 物理形态 | 表面粗糙度、孔隙、几何 |
| 接触条件 | 部位、时间、面积 |
注意后三项常被忽略。 同样的材料，用不同方式灭菌，残留物和降解产物可能不同；同样的材料，表面粗糙或多孔与光滑致密，生物学反应可能不同。
所以「材料牌号相同」只是等同性的一个方面，不构成完整论证。
需要的证据
论证等同性通常需要这几类证据：
材料规格文件。 两者的材料牌号、供应商、规格说明。
配方信息。 添加剂的种类和含量。这部分往往需要供应商配合。
化学表征对比。 两者的可提取物谱对比。这是最有说服力的证据 ——如果化学表征结果高度一致，说明释放物质相近。
加工与灭菌参数对比。 说明工艺条件的一致性。
物理特性对比。 表面特性、形态。
接触条件对比。 说明使用方式的一致性或差异。
化学表征对比是这几项里性价比较好的。 它直接反映了「会释放什么」这个核心问题，比逐条比较配方更有说服力，尤其在供应商不愿提供完整配方的情况下。
论证的写法
建议按这个结构写：
第一，说明比较对象。 参照产品是什么、它的评价数据是什么、数据是否可靠。
第二，逐维度比较。 按上面的六个维度，逐项说明相同还是有差异。
第三，对每个差异做影响分析。 差异是什么、为什么不影响生物学安全、依据是什么。
第四，给出综合结论。 哪些终点可以引用参照数据、哪些仍需试验。
第三步是论证的核心，也是最容易写空的地方。 写「差异较小，不影响安全」而不说理由，等于没论证。
常见的论证漏洞
只比牌号不比配方。 同一牌号不同批次的添加剂可能有调整；不同供应商的同类牌号差异更大。
忽略加工差异。 注塑温度、模具、脱模剂都可能影响释放物。
忽略灭菌差异。 前面提过。
参照数据本身不可靠。 引用的数据来源不明或质量存疑。
接触条件不同。 材料相同但一个短期接触一个长期接触，不能直接引用。
未考虑规模差异。 小批量试制与量产的工艺可能不同。
最后一项在新产品上容易出现。 用试制样品做的评价，量产后工艺变了，原评价可能不再适用。
适用与不适用的情形
比较适用的情形： 同一企业的系列产品，材料和工艺一致，只是规格尺寸不同；材料供应商和牌号未变，只是产品外形改变；以及有完整的化学表征对比数据支撑。
不适用或需谨慎的情形： 更换了材料供应商；加工工艺有实质改变；灭菌方式改变；接触性质或时间改变；参照数据年代久远或来源不明；以及涉及高风险接触类别（血液、植入）的产品。
高风险类别的产品，论证被接受的门槛明显更高，因为失误的后果更严重。这类产品做等同性论证时要准备更充分的证据。
与变更管理的结合
等同性论证的思路同样适用于变更评估。产品发生变更时，要回答的是同一个问题：变更是否影响生物学安全。
建议在变更评审中固定这个动作：
列出变更内容；按六个维度判断影响；对有影响的维度做进一步评估；决定是否需要补充试验；以及记录判断过程。
把这个动作固化下来，能避免「小变更逐渐累积成大变更」的问题。 每次变更都判断「影响不大」，累积几次之后，产品与原评价的基础已经差别明显，而中间没有任何一次触发重新评价。
供应商信息的获取
等同性论证依赖材料信息，而信息在供应商手里。实务中的做法：
在采购合同中约定信息提供义务。 包括配方变更的告知义务。这是最有效的手段，但要在合作开始时就谈。
要求提供材料声明。 供应商出具的成分与合规声明。
保密安排。 供应商不愿直接提供配方时，可以通过保密协议，或者由供应商直接向评价方提供。
用化学表征绕过。 拿不到配方时，用表征数据代替，直接看释放了什么。
关注变更告知。 供应商变更配方而不告知，是等同性论证失效的常见原因。合同中应当明确这一点。
第五项是实务中最大的风险。 材料牌号没变、供应商没变，但配方悄悄调整了，而下游完全不知情。定期做化学表征对比可以发现这类变化。
论证的时效
等同性论证是基于某个时点的信息，它会过期：
供应商配方调整；加工设备或参数改变；灭菌设备或参数改变；参照产品本身发生变更；以及评价要求更新。
建议定期复核论证是否仍然成立，并在每次重大变更或续期前做一次确认。复核成本不高，但能避免用失效的论证支撑现行产品。
我们的做法
遇到委托方希望引用已有数据的情况，我们会先看现有数据的完整性和可靠性，再看两者的差异在哪里。如果差异集中在材料或工艺上，通常建议做一次化学表征对比 ——成本不高，但能把论证建立在数据上而不是描述上。
如果论证确实不成立，我们会说清楚哪些终点必须重做，而不是含糊带过。含糊的结论在审查环节会被追问，最终还是要补。
如果你在考虑引用已有数据，不确定论证能不能站住，可以把两个产品的材料和工艺信息发过来一起评估，或者直接联系：132 4819 8029。能力范围见服务介绍，送检要求见送检要求，其他问题见常见问题。
English version
Conclusion. Manufacturers regularly ask whether testing can be avoided because their product uses the same material as another product already tested. The answer depends on whether it can be argued that the differences do not affect biological safety. Note the formulation: the argument is not that the materials are identical but that any differences have no effect. Identity is rare; in most cases differences exist and must be assessed. The quality of the argument determines whether it is accepted. A thorough argument can reduce testing substantially; a careless one is not only rejected but raises questions about the quality of the evaluation as a whole.
Dimensions of comparison. Chemical composition compares base material and the identity and content of additives. Processing compares forming method, temperature and processing aids. Surface treatment compares coatings, cleaning and treatment agents. Sterilisation compares method, parameters and residues. Physical form compares surface roughness, porosity and geometry. And contact conditions compare site, duration and area. The last three are commonly overlooked: the same material sterilised differently may carry different residues and degradation products, and the same material with a rough or porous surface rather than a smooth dense one may provoke a different biological response. Identical material grade is therefore only one aspect of equivalence and does not constitute a complete argument.
Evidence needed. Material specification documents covering grade, supplier and specification for both. Formulation information covering additive identity and content, which usually requires supplier cooperation. Comparative chemical characterisation setting the extractables profiles side by side, which is the most persuasive evidence, since closely matching profiles indicate similar released substances. Comparison of processing and sterilisation parameters. Comparison of physical characteristics. And comparison of contact conditions, stating consistency or difference in manner of use. Comparative characterisation offers the best value among these: it addresses directly what is released, which is the core question, and is more persuasive than clause-by-clause formulation comparison, particularly where suppliers will not disclose full formulations.
How to write the argument. Identify the comparator, stating what the reference product is, what evaluation data exist for it, and whether those data are reliable. Compare across the six dimensions, stating for each whether it is the same or differs. Analyse the effect of each difference, stating what it is, why it does not affect biological safety, and on what basis. And give an integrated conclusion identifying which endpoints may rely on the reference data and which still require testing. The third step is the heart of the argument and the easiest to leave empty: writing that the difference is minor and does not affect safety, without reasons, is not an argument.
Common weaknesses. Comparing grade without formulation, when additive packages may be adjusted between batches of the same grade and differ more between suppliers of nominally similar grades. Ignoring processing differences, since moulding temperature, tooling and release agents all affect what is released. Ignoring sterilisation differences, as noted. Relying on unreliable reference data of unclear provenance or questionable quality. Differing contact conditions, where the material is the same but one product contacts briefly and the other for long periods. And ignoring scale, since pilot processes may differ from production. The last arises easily with new products: an evaluation performed on pilot samples may no longer apply once the production process differs.
Where it applies and where it does not. It applies comparatively well to a family of products from one manufacturer with consistent materials and processes differing only in size; to products where supplier and grade are unchanged and only the form differs; and where complete comparative characterisation data support the argument. It applies poorly, or demands caution, where the material supplier has changed; where processing has changed substantively; where the sterilisation method has changed; where contact nature or duration has changed; where reference data are old or of unclear origin; and for products in high-risk contact categories such as blood contact and implantation. For high-risk categories the bar for acceptance is distinctly higher, because the consequences of error are more serious, and equivalence arguments for such products need fuller evidence.
Connection to change management. The same reasoning applies to assessing change, where the question is identical: does the change affect biological safety. Fix the action within change review: list what changed, judge the effect across the six dimensions, assess further where an effect exists, decide whether supplementary testing is needed, and record the reasoning. Fixing the action prevents small changes accumulating into a large one, where each is judged individually to have little effect while, several changes later, the product differs markedly from the basis of the original evaluation and no single step ever triggered re-evaluation.
How we handle it. Where a client hopes to rely on existing data we look first at the completeness and reliability of those data and then at where the differences lie. Where differences concentrate in material or process we usually suggest comparative chemical characterisation: the cost is modest and it puts the argument on data rather than description. Where the argument genuinely does not hold we say plainly which endpoints must be repeated rather than leaving it vague, because vague conclusions attract questions during review and the work has to be done anyway.
Send us the material and process information for both products and we will assess whether the argument stands. Phone or WeChat: +86 132 4819 8029.