Embutramide is a veterinary, central nervous system active medicine used for euthanasia in dogs. The drug is marketed under the name Tributame in the USA and under the name Tanax in Europe. Human consumption of the drug is usually associated with suicide attempts.

Excerpt from NCATS:
https://drugs.ncats.io/drug/3P4TQG94T1

Embutramide Safety Data Sheet (PDF 7 pages):
https://hybris-static-assets-production.s3-eu-west-1.amazonaws.com/sys-master/pdfs/h19/h3a/9669392498718/EN_ST-WB-MSDS-2594097-1-1-1.PDF

Embutramide is a potent opioid pain releiver and sedative drug that is structurally related to methadone. It was found to have a very narrow therapeutic window, with a 50 mg/kg dose producing effective sedation and a 75 mg/kg dose being fatal. Along with strong sedative effects, embutramide also produces respiratory depression and ventricular arrhythmia. Because of these properties, it was never adopted for medical use as an anesthetic as it was considered too dangerous for this purpose. Instead it is used for euthanasia in veterinary medicine, mainly for the euthanization of dogs. Embutramide is used for euthanasia of a range of different animals, mainly small animals kept as pets rather than large farm animals. It may cause significant pain to the animal being euthanized and so may be less humane than older drugs used for this purpose such as pentobarbital.