Pentobarbital sodium

Description

Barbituric acid, the precursor of barbiturates, was first produced in 1864 by condensation of malonic acid and urea; it had no central nervous system (CNS) effects. In 1903, diethyl barbituric acid (barbital) was created as the first barbiturate with CNS inhibitory effects. Barbiturates were commonly used as sedative-hypnotics in the mid-twentieth century; meantime they were abused by some people as sold on the street. Use of barbiturates quickly dropped after introduction of benzodiazepines as the safer sedative-hypnotics. However some of the barbiturates are still used as anticonvulsants and some for euthanasia.

Chemical properties

A white or almost white, crystalline powder, hygroscopic.

Originator

Nembutal,Abbott,US

The Uses of Pentobarbital sodium

Sedative, hypnoyic. Controlled substance (depressant).

The Uses of Pentobarbital sodium

Human
Pentobarbital as sodium salt has been used as a sedative and hypnotic in the short-term management of insomnia. Pentobarbital sodium has also been used for premedication in anesthetic procedures. Pentobarbital is FDA-approved for the emergency control of certain acute convulsive episodes, e.g., those associated with status epilepticus, cholera, eclampsia, meningitis, tetanus, and toxic reactions to strychnine or local anesthetics. The other indications for pentobarbital include treatment of nonfatal submersion and traumatic/nontraumatic raised intracranial pressure.
Animal
Intraperitoneal (IP) injection of pentobarbital is used in experimental medicine as an anesthetic in small animals such as rat and mouse. Pentobarbital is an important drug for relieving convulsive seizures, especially when caused by strychnine.

Definition

ChEBI: Pentobarbital sodium is an organic molecular entity.

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).

Therapeutic Function

Hypnotic, Sedative

General Description

Crystalline granules or white powder. Used as an anesthetic and sedative.

Air & Water Reactions

Freely soluble in water. Aqueous solutions are unstable upon storage.

Safety Profile

Poison by ingestion, intraperitoneal, subcutaneous, intravenous, intraduodenal, intramuscular, intracerebral, parented, and rectal routes. An experimental teratogen. Other experimental reproductive effects. Human systemic effects by ingestion: wakefulness, change in motor activity, ataxia, and antipsychotic effects. Mutation data reported. When heated to decomposition it emits toxic fumes of NOx and Na2O.

Environmental Fate

Routes and Pathways Relevant Physicochemicals Properties
Pentobarbital sodium, with a molecular weight of 248.3, consists of white, crystalline granules or white powder with a slight characteristic odor. The melting point equals 130 °C and respective vapor pressure is 3.02 × 10¹⁰ mmHg at 25 °C. Pentobarbital is very soluble in water (679 mg l1), freely soluble in alcohol, and practically insoluble in ether. pH of a 10% solution in water is between 9.8 and 11.0. Its dissociation constant (pK) and octanol/water partition coefficient (log Kow) are 7.88 and 2.10, respectively. Henry’s law constant is 8.5  108 Pa m3 mol1 at 25°C.
Environmental Persistency Due to lack of hydrolyze-prone functional groups, pentobarbital is not expected to undergo hydrolysis in the environment. Also, pentobarbital does not contain chromophores to absorb wavelengths higher than 290 nm and therefore is not susceptible to direct photolysis by sunlight.
Environmental Degradation
Pentobarbital has been positively identified (not quantified) in a ground-water sample collected from a well 300 m from a landfill which received wastes between 1968 and 1969 and re-sampling 21 years later (in 1991) revealed the presence of pentobarbital at a concentration of 1 mg l^-1 which shows persistency of pentobarbital in the environment.

storage

Store at RT