Pentobarbital
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| Clinical data | |
|---|---|
| AHFS/Drugs.com | Monograph |
| MedlinePlus | a682416 |
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| Routes of administration | Oral, Intravenous, Intramuscular, Rectal; also Intraperitoneal & Intracardiac (for animal euthanasia) |
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| Pharmacokinetic data | |
| Bioavailability | 70-90% oral; 90% rectal |
| Protein binding | 20-45% |
| Metabolism | Hepatic |
| Elimination half-life | 15-48 hours |
| Excretion | Renal |
| Identifiers | |
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| CompTox Dashboard (EPA) | |
| ECHA InfoCard | 100.000.895 |
| Chemical and physical data | |
| Formula | C11H18N2O3 |
| Molar mass | 226.27 g·mol−1 |
| 3D model (JSmol) | |
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Pentobarbital is a short-acting barbiturate that was first synthesized in 1928. Pentobarbital is available as both a free acid and a sodium salt, the former of which is only slightly soluble in water and ethanol.[1] One brand name for this drug is Nembutal, coined by Dr. 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).[2]
Synthesis
26.7 g of clean metallic sodium is dissolved in 400 g of anhydrous (dry) ethanol. To this, a solution of 100 g of 1-methylbutyl-ethyl malonic ethyl ester and 37.2 g of dry urea is added. The mixture is heated for 4 to 6 hours in an autoclave, or refluxed for 20 to 40 hours. The alcohol is then removed by distillation. The residue is dissolved in water and this aqueous solution is acidified with hydrochloric acid. The precipitated product is filtered, washed with cold water, and recrystallized from boiling water. Yield depends on one's ability to exclude water from the beginning of the reaction. Melting point is 127°C to 130°C.[3]
Uses
Approved
Pentobarbital's FDA-approved human uses include treatment of seizures and preoperative (and other) sedation; it is also approved as a short-term hypnotic.[4]
Unapproved / investigational / off-label
Off-label uses of pentobarbital include reduction of intracranial pressure in Reye's syndrome, traumatic brain injury and induction of coma in cerebral ischemia patients.[4] Pentobarbital-induced coma has been advocated in patients with acute liver failure refractory to mannitol.[5]
Veterinary medicine
In veterinary medicine, sodium pentobarbital is used as an anaesthetic. It is also used by itself, or in combination with complementary agents such as phenytoin, in commercial animal euthanasia injectable solutions. [6]
Human euthanasia
Pentobarbital has also been used for physician-assisted suicide.[citation needed] In the US state of Oregon "oral doses of a barbiturate" have been used for this purpose.[7]
Also in Switzerland[citation needed] and the Netherlands.[citation needed] It was also used in the Northern Territory of Australia, prior to euthanasia becoming illegal in that region.[citation needed]
Capital punishment
Pentobarbital has been approved or considered for use in executions in various U.S. states.[8]
The Danish manufacturer of pentobarbital, Lundbeck, expressed displeasure at this use of their product, and on July 1, 2011, announced they would block sales of the drug to U.S. prisons that carry out the death penalty.
Lundbeck is dedicated to saving people’s lives. Use of our products to end lives contradicts everything we are in business to do. Lundbeck is opposed to the use of its product for the purpose of capital punishment.[9]
They explained this decision with their commitment to UN human rights principles. [8]
Metabolism
Pentobarbital undergoes first-pass metabolism in the liver and possibly the intestines.[10]
Drug interactions
Administration of alcohol, opioids, antihistamines, other sedative-hypnotics, and other central nervous system depressants will cause possible additive effects.[4]
Recreational use
Pentobarbital is a drug that has been used recreationally.[11]
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 (not 1-bromo-3-methylbutane) to give pentobarbital.[12][13][14]
References
- ^ "Pentobarbital Compound summary (CID4737)". Pubchem. NCBI.
- ^ Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 9281913 , please use {{cite journal}} with
|pmid= 9281913instead. - ^ http://www.erowid.org/archive/rhodium/chemistry/barbiturates.html
- ^ a b c "Pentobarbital". Monograph. AHFS / Drugs.com.
- ^ Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 17901832 , please use {{cite journal}} with
|pmid= 17901832instead. - ^ "International". Drugs.com.
- ^ "presciption". Death with dignity act - FAQ. Public health Oregon.
- ^ a b "Detailed position (regarding the misuse of pentobarbital)". Lundbeck.
- ^ "Lundbeck's position regarding the misuse of pentobarbital" (Press release). Lundbeck. July 1, 2011.
- ^
Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 6777235 , please use {{cite journal}} with
|pmid= 6777235instead. - ^ Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 16336040 , please use {{cite journal}} with
|pmid= 16336040instead. - ^
Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi: 10.1021/ja01367a061 , please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with
|doi= 10.1021/ja01367a061instead. - ^ German imperial patent, D.R.P. 293163 (1916), Bayer
- ^ GB patent 650354, Wilde, B. E. & Balaban, I. E., "Improvements in the manufacture of substituted barbituric and thiobarbituric acids", issued 1951-02-21, assigned to Geigy