Pentobarbital sodium

Описание

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.

Химические свойства

A white or almost white, crystalline powder, hygroscopic.

Использование

Sedative, hypnoyic. Controlled substance (depressant).

Общее описание

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

Реакции воздуха и воды

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

Профиль безопасности

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.

Экологическая судьба

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.