缬沙坦原料药中为什么会出现杂质NDMA？
基于公司目前的调查，NDMA是按照现行注册工艺生产过程中产生的意料之外的微量工艺杂质。原因是在特定的工艺中，溶剂降解产生的微量杂质与后一步试剂产生的副反应。现行工艺经过相关国家药品监管部门批准。
NDMA（N-亚硝基二甲胺）分子式C2H6N2O，分子量74.08，黄色液体，可溶于水、乙醇、乙醚、二氯甲烷，由二甲胺与亚硝酸盐在酸性条件下反应而生成。该物质在环境中广泛存在。
缬沙坦原料药为什么要改变工艺？变更过程是否合规？
公司原有工艺存在工艺转化率低、“三废”产生量大、异构体杂质水平波动等问题。改变缬沙坦原料药生产工艺后，工艺转化率提高约30%、“三废”产生量降低约30%、异构体杂质也得到了有效控制。基于上述原因，公司于2012年开始，按照相关国家药品监管部门工艺变更的法规要求，将工艺变更为现行工艺。
企业是如何发现缬沙坦原料药中存在杂质NDMA的？
2018年6月15日，公司在对缬沙坦原料药生产工艺进行优化评估过程中，发现并检定其中一未知杂质为N-亚硝基二甲胺（NDMA）。NDMA是按照现行注册工艺生产过程中产生的意料之外的微量杂质。事件发生之前，各国药品监管机构均未对该杂质提出检测要求。
药物中未知杂质能否检出主要依赖于人类的认识认知水平，以及检测手段的发展水平。关于基因毒性杂质的控制指南“ICH M7”2010年被ICH管理委员会正式提出，于2013年定稿，这才逐步引起医药业的重视。公司从2004年开始研发缬沙坦，对基因毒性杂质的研究方面是一个逐渐深入的过程；从最初的叠氮残留研究，到后期的溴化物系列杂质的残留研究，再到本次NDMA的发现和检定。鉴于当时的研究和认知水平，基因毒性杂质研究是根据潜在基因毒性警示结构指南开展的，在起始物料、中间体、主成分、主反应副产物及直接使用的试剂这条主线上使用业界通行的排查、检测手段进行风险评估和控制。由于本次NDMA是溶剂降解物质与后一步的反应试剂反应产生的，且在产品中残留量极微，按照当时注册批准的分析方法无法检出，也就无法对该基因毒性杂质进行针对性的控制。因此，NDMA这个杂质是随着产品科学认知的深入、科学技术的发展以及检测手段的提升而新发现的。
公司是否及时向药品监督管理部门报告？
7月6日，公司就出口缬沙坦原料药中检出微量N-亚硝基二甲胺 (NDMA)杂质的情况向国内药监部门进行了报告。
为什么中国和美国召回公告晚于欧洲？
在公司自主发现该杂质前，各国监管部门均未对该杂质制定可接受的控制限度标准。此事件发生后，公司主动与相关客户及监管机构进行技术沟通，由于各国药品监管机构对此事件的评估及监管要求各有不同，公告发布时间也略有差异。公司基于风险防范的考虑，于2018年7月13日中午主动发布有关召回在国内外上市的缬沙坦原料药和使用公司缬沙坦原料药生产的在国内上市的制剂产品公告。北京时间2018年7月14日，发布召回本公司在美国上市的缬沙坦制剂产品公告。
华海：缬沙坦事件美国FDA最新,20180727
OnJuly 13th, FDA announced a recall of certain batches of valsartan tablets because of an impurity, a chemical known as N-nitrosodimethylamine (NDMA). Valsartan is a medication commonly used to treat high blood pressure and heart failure.
NDMA has been found to increase the occurrence of cancer in animal studies. These animal studies were done using amounts of NDMA much higher than the impurity levels in recalled valsartan batches. Based on these animal studies, the U.S. Environmental Protection Agency considers NDMA a probable human carcinogen—a chemical that can increase the risk of cancer in humans. NDMA is found in some water supplies and in some foods. Consuming up to 96 nanograms NDMA/day is considered reasonably safe for human ingestion. It is estimated that over the course of a person’s lifetime, consuming this amount of NDMA would result in less than one additional case of cancer for every 100,000 people. To put this in context, currently one out of every three people in the US will experience cancer in their lifetime.
The amounts of NDMA found in the recalled batches of valsartan exceeded these acceptable levels. The agency wanted to put some context around the actual potential risk posed to patients who used versions of valsartan that may have contained high levels of NDMA. Based on records from the manufacturer of the recalled valsartan, some levels of the impurity may have been in the valsartan-containing products for as long as four years. FDA scientists estimate that if 8,000 people took the highest valsartan dose (320 mg) from the recalled batches daily for the full four years, there may be one additional case of cancer over the lifetimes of these 8,000 people. This assessment led to FDA’s decision to have these batches recalled.
Patients taking valsartan from a recalled batch should continue taking their current medicine until their doctor or pharmacist provides a replacement or a different treatment option. It is important to know that not all valsartan products contained NDMA, so pharmacists may be able to provide a refill of valsartan medication from batches that that are not affected by the recall, or doctors may prescribe a different medication that treats the same indications.
FDA continues to evaluate the safety of valsartan-containing products and will update the list of products included in the recall and the list of products not included in the recall as more information becomes available. If you are taking a valsartan product, be sure to check to back as the lists may change.
For more information, please visit: FDA Updates on Valsartan Recalls.
注：除华海外，印度HETERO生产的缬沙坦API中NDMA也是超标范围(超过0.3ppm)。
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