Pentobarbital

Absorption

Barbiturates are absorbed in varying degrees following oral, rectal, or parenteral administration.

Toxicity

Symptoms of an overdose typically include sluggishness, incoordination, difficulty in thinking, slowness of speech, faulty judgment, drowsiness or coma, shallow breathing, staggering, and in severe cases coma and death.

Description

Pentobarbital (CRM) (Item No. 20966) is a certified reference material categorized as a barbiturate. Pentobarbital is regulated as a Schedule II compound in the United States. Pentobarbital (CRM) (Item No. 20966) is provided as a DEA exempt preparation. This product is intended for research and forensic applications.

Description

Pentobarbital is in the barbiturate family. It usually is used as its sodium salt: as a short-term sedative and hypnotic; a veterinary anesthetic; and, in emergencies, an anticonvulsant. The salt is marketed under trade names such as Nembutal and Embutal.
Pentobarbital sodium also has been used in animal and, where legal, human euthanasia—and as an injectable drug for capital punishment. Its use in lethal injections has been in the news because producers of pentobarbital refused to sell it (specifically Nembutal) for this purpose. Similar shortages of other lethal injectables have caused some states to eliminate this form of capital punishment, adding another layer to the discussion about this controversial topic.
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Chemical properties

A white or almost white, crystalline powder or colourless crystals

Originator

Nembutal,Abbott,US

The Uses of Pentobarbital

Sedative-hypnotic.

Indications

For the short-term treatment of insomnia.

Background

A short-acting barbiturate that is effective as a sedative and hypnotic (but not as an anti-anxiety) agent and is usually given orally. It is prescribed more frequently for sleep induction than for sedation but, like similar agents, may lose its effectiveness by the second week of continued administration. (From AMA Drug Evaluations Annual, 1994, p236)

Definition

ChEBI: A member of the class of barbiturates, the structure of which is that of barbituric acid substituted at C-5 by ethyl and sec-pentyl groups.

Manufacturing Process

Sodium (9.6 parts) was dissolved in butanol (192 parts) and di-n-butyl ethyl 1-methyl-n-butylmalonate (62.8 parts) and urea (14.4 parts) were added to the warm solution with agitation. The mixture was then heated to reflux temperature in three quarters of an hour and maintained for 2 hours. The reaction mass was kept, water (150 parts) added, the aqueous portion separated, and the butanol layer extracted with water (3 x 50 parts). The combined aqueous extracts were then given 3 small extractions with benzene, the aqueous liquors separated, charcoaled, filtered and precipitated with concentrated hydrochloric acid (acid to congopaper). The solid was collected, washed with water, dissolved in N-sodium hydroxide and reprecipitated with carbon dioxide. On recrystallization, from aqueous alcohol, the pentobarbitone was obtained.

brand name

Nembutal(Ovation)[Name previously used: Pentobarbitone.];Aethaminalum;Barbityral;Barbopent;Burtylonel;Cafergot p.b.;Calpental;Di-barbs;Dipental;Distonocalm;Ergobel plus;Hypnol;Hypnotal;Hyptonal;Insom rapido;Isoamytal;Isom rapido;Iturate;Narcoren;Nembudeine;Nicaphlogyl;Novarectal;Nova-rectal;Novopentobarb;Novo-pentobarb;Or-trin;Palpent;Pembul;Penbon;Pentalgin;Pentanca;Pentodormol;Pentogen;Pentolos;Petab;Petonel;Praecicalm;Prodormol;Somnophyt;Somnotol;S-spac;Stopp-15;Wans;Wigraine-pb;Yastyl.

Therapeutic Function

Hypnotic, Sedative

World Health Organization (WHO)

Pentobarbital is a short-acting barbiturate which is controlled under Schedule III of the 1971 Convention on Psychotropic Substances. See WHO comment for barbiturates. (Reference: (UNCPS3) United Nations Convention on Psychotropic Substances (III), , , 1971)

Pharmacokinetics

Pentobarbital, a barbiturate, is used for the treatment of short term insomnia. It belongs to a group of medicines called central nervous system (CNS) depressants that induce drowsiness and relieve tension or nervousness. Little analgesia is conferred by barbiturates; their use in the presence of pain may result in excitation.

Metabolism

by hepatic microsomal enzyme system

Purification Methods

A solution of the sodium salt in 10% HCl is prepared, and the acid is extracted with ether. Evaporation of the extract gives a solid which is then purified by repeated crystallisation from CHCl3. It sublimes at 95-105o/10-12mm. [Bucket & Sandorfy J Phys Chem 88 3274 1984.] The (+)-and (-)-enantiomers crystallise from 50% aqueous EtOH with m 120-121o and have [] 25 +4.73o to –4.93o (EtOH) [Kleiderer & Shonle J Am Chem Soc 56 1772 1934]. [Beilstein 24