ST LOUIS (MD Consult) - On November 19, 2010, the US Food and Drug Administration (FDA) announced that Xanodyne Pharmaceuticals, which makes Darvon and Darvocet, the brand version of the opioid analgesic propoxyphene, has agreed to voluntarily withdraw the medication from the US market. This action is being taken at the FDA's request after the agency concluded that the risks of the medication outweigh the benefits.

The FDA sought market withdrawal of propoxyphene after receiving new clinical data showing that use of the drug puts patients at risk for potentially serious or even fatal heart-rhythm abnormalities. These data, combined with other information–including new epidemiologic data–led to the decision.

Since 1978, the FDA has received 2 requests to remove propoxyphene from the market. Until now, the FDA had concluded that the benefits of propoxyphene for pain relief at recommended doses outweighed the safety risks of the drug. The agency has since required Xanodyne to conduct a new safety study assessing unanswered questions about the effects of propoxyphene on the heart.

The agency now has reviewed the data from that study, which show that, even when taken at recommended doses, the use of propoxyphene causes significant changes to the electrical activity of the heart. These changes, which can be observed using electrocardiography, can increase the risk for the occurrence of serious abnormal heart rhythms that have been linked to serious adverse effects, including sudden death. The available data also indicate that the risk of adverse events for any particular patient (even patients who have taken the drug for many years) is subject to change in the event of even small changes in health status (eg, dehydration, medication changes, and decreased kidney function).

The FDA is advising health care professionals to stop prescribing propoxyphene to their patients, and patients who are currently taking the drug are being advised to contact their health care professional as soon as possible to discuss switching to another pain-management therapy.

圣路易斯(MD Consult)——2010年11月19日，美国食品药品管理局(FDA)宣布，达尔丰和达尔持特 (阿片类止痛药丙氧酚的商品名)的生产商Xanodyne制药公司已经同意主动将该药撤出美国市场。早先FDA断定其风险超过收益，而生产商就是应FDA的要求而采取了此项举措。

有新临床数据显示患者使用该药可能有严重或致死性心律失常的风险，FDA在收到此数据后要求丙氧酚撤市。以上数据连同新流行病学数据等其他信息共同促成了此项决定。
自1978年以来，FDA已经收到2项将丙氧酚撤市的请求。直到今天FDA才断定推荐剂量的丙氧酚在缓解疼痛方面的收益超过其安全风险。自此以来，FDA一直要求Xanodyne公司开展一项新的安全性研究，评估有关丙氧酚对心脏影响的疑虑。

这项新研究表明，即使以推荐剂量使用，丙氧酚也会使心脏电活动发生明显的变化，现在FDA已对这些数据进行了审查。这些变化可以借助心电图观察到，可增加与猝死等严重不良反应有关的严重心律失常的发生风险。现有的数据还表明，任何一例特定的患者(甚至是多年服用该药的患者)发生不良事件的风险均易受健康状况变化(如脱水、用药变化和肾功能下降等)的影响，即便是较小的变化。

FDA建议医护人员停止对患者开丙氧酚处方，并建议目前正服用该药的患者尽快联系其医护人员以讨论换用另一种疼痛处置方案。