Pentobarbital

Pentobarbital (previously known as pentobarbitone in Britain and Australia) is a short-acting barbiturate typically used as a sedative, a preanesthetic, and to control convulsions in emergencies. It can also be used for short-term treatment of insomnia but has been largely replaced by the benzodiazepine family of drugs.
In high doses, pentobarbital causes death by respiratory arrest. It is used for veterinary euthanasia and is used by some U.S. states and the U.S. federal government for executions of convicted criminals.
Pentobarbital was widely abused and known on the streets as "yellow jackets" due to the yellow capsule of the Nembutal brand. Pentobarbital in oral (pill) form is no longer commercially available. The death of Marilyn Monroe in 1962 was ruled as probable suicide due to an overdose of pentobarbital.
Uses.
Medical.
Typical applications for pentobarbital are sedative, short term hypnotic, preanesthetic, insomnia treatment, and control of convulsions in emergencies. Abbott Pharmaceutical discontinued manufacture of their Nembutal brand of Pentobarbital capsules in 1999, largely replaced by the benzodiazepine family of drugs. Pentobarbital was also widely abused, known on the street as "yellow jackets". They were available as 30, 50, and 100-milligram capsules of yellow, white-orange, and yellow colors, respectively.
It is also used as a veterinary anesthetic agent.
Pentobarbital also has an application in reducing intracranial pressure in Reye's syndrome, traumatic brain injury and induction of coma in cerebral ischemia patients. Pentobarbital-induced coma has been advocated in patients with acute liver failure refractory to mannitol.
Euthanasia.
Pentobarbital can cause death when used in high doses. It is used for euthanasia for humans as well as animals. It is also used by itself, or in combination with complementary agents such as phenytoin, in commercial animal euthanasia injectable solutions.
In the Netherlands, it is part of the standard protocol for physician-assisted suicide for self-administration by the patient.
It is also used by mouth for physician-assisted death in the United States states of Oregon, Washington, Vermont, and California (as of January, 2016). 
The oral dosage of pentobarbital indicated for physician-assisted suicide in Oregon is typically 10 g in liquid form.
Execution.
Pentobarbital has been used or considered as a substitute for other drugs traditionally used for capital punishment in the United States when they are in short supply. Such use however is illegal under Danish law, and when this was discovered, after public outcry in Danish media, Lundbeck, the owner of the drug, stopped selling it to US states that impose the death penalty. US distributors of the drug are forbidden by the owner to sell it to any customers, such as several state authorities, that practice or participate in executions of humans.
Texas began using pentobarbital for executing death-row inmates by lethal injection on July 18, 2012. The use of pentobarbital has been considered by several states, including Ohio, Arizona, Idaho, and Washington; those states made the decision to switch following shortages of pancuronium bromide, a muscle paralytic previously used as one component in a three-drug cocktail.
In October 2013, Missouri changed its protocols to allow for a compounded pentobarbital to be used in a lethal dose for executions and it was first used in November 2013.
According to a December 2019 ProPublica article, by 2017, the Bureau of Prisons (BOP) in discussion with then Attorney General Jeff Sessions, had begun to search for suppliers of pentobarbital to be used in lethal injections. The BOP were aware that courts would challenge the use of pentobarbital as their "new drug choice" as some lawyers have said that "pentobarbital would flood prisoners’ lungs with froth and foam, inflicting pain and terror akin to a death by drowning." BOP said that these concerns were not justified and that their two expert witness said that the use of pentobarbital was "humane". On July 25, 2019, US Attorney General William Barr directed the federal government to resume capital punishment after 16 years. The drug of choice for these executions is pentobarbital.
Metabolism.
Pentobarbital undergoes first-pass metabolism in the liver and possibly the intestines.
Drug interactions.
Administration of ethanol, benzodiazepines, opioids, antihistamines, other sedative-hypnotics, and other central nervous system depressants will cause possible additive effects.
Chemistry.
Pentobarbital is synthesized by methods analogous to that of amobarbital, the only difference being that the alkylation of α-ethylmalonic ester is carried out with 2-bromopentane in place of 1-bromo-3-methylbutane to give pentobarbital.
Society and culture.
Names.
Pentobarbital is the INN, AAN, BAN, and USAN while pentobarbitone is a former AAN and BAN.
One brand name for this drug is Nembutal, coined by John S. Lundy, who started using it in 1930, from the structural formula of the sodium salt—Na (sodium) + ethyl + methyl + butyl + al (common suffix for barbiturates). Nembutal is trademarked and manufactured by the Danish pharmaceutical company Lundbeck (now produced by Akorn Pharmaceuticals) and is the only injectable form of pentobarbital approved for sale in the United States. Abbott discontinued their Nembutal brand of Pentobarbital capsules in 1999, largely replaced by the Benzodiazepine family of drugs. Abbott's Nembutal brand of Pentobarbital capsules known on the streets as "yellow jackets" were widely abused. They were available in 50 and 100 Mg strength yellow capsules.
Pentobarbital can occur as a free acid, but is usually formulated as the sodium salt, pentobarbital sodium. The free acid is only slightly soluble in water and in ethanol.
Notable overdoses.
The death of Marilyn Monroe in 1962 was ruled as probable suicide due to an overdose of pentobarbital. Kenneth Halliwell's death is also attributed to an overdose of pentobarbital. Oscar-winning British actor George Sanders died of a suicidal overdose of Nembutal in Spain.