|Common names||Phenobarbital, phenobarbitone, Luminal, phenobarb|
phenobarbital, also known as phenobarbitone in british english and by the brand name luminal, is a long-acting psychoactive drug of the barbiturate class which produces powerful anxiolytic, hypnotic, muscle relaxant and amnesic effects. phenobarbital is used medically as an anticonvulsant, and occasionally in the short term treatment of insomnia. phenobarbital works in a similar fashion to benzodiazepines, however barbiturates bind to a distinct allosteric site on the gabaa receptor.
phenobarbital, like most long-acting barbiturates, can be deemed moderately addictive. the abrupt discontinuation of phenobarbital in dependent individuals may be life-threatening and lead to seizures and even death. phenobarbital drastically enhances the effects of other depressants such as alcohol, and concurrent use may lead to respiratory depression and possibly death.
phenobarbital is a drug of the barbiturate class. barbiturate drugs contain the backbone of barbituric acid. phenobarbital has a 5-ethyl, 5-phenyl substitution on the 5-position of the barbituric acid backbone which gives it its unique pharmacological effects. phenobarbital empirical formula is c12h12n2o3 and has a molar mass of 232.235 grams per mole.
barbiturates behave similarly to benzodiazepines. phenobarbital binds to an allosteric site on the gabaa receptor and potentiates the effects of the endogenous ligand, gamma-aminobutyric acid. when barbiturates bind to the gabaa receptor, it causes the ion pore to open for extended periods of time, causing an increase of intracellular chlorine ion concentrations. as this site is the most prolific inhibitory receptor set within the brain, its modulation results in the sedating (or calming effects) of barbiturates on the nervous system.
phenobarbital has a bioavailability of around 95%. 20%-45% of phenobarbital will bind to proteins. phenobarbital’s biological half life is 53-118 hours. it is metabolized by the liver and excreted by the kidneys and intestines.