Medication Description: Phenobarbital (Phenobaritalum)
PHENOBARBITAL (Phenobaritalum). 5-Ethyl-5-phenylbarbituric acid.
Synonyms: Luminal, Adonal, Aephenal, Barbenyl, Barbinal, Barbiphen, Dormiral, Epanal, Episedal, Fenemal, Fenobarbital, Gardenal, Hypnotal, Lepinal, Luminal, Mephabarbital, Neurobarb, Nirvonal, Omnibarb, Phenobarbitone, Zerphalb, Neurobarb, Nirvonal, Omibarb, Phenobarbital, Nepharbal others
White crystalline powder of slightly bitter taste, odorless. Very little soluble in cold water, difficult to boil (1:40), easily soluble in alcohol and alkali solutions.
Usually, phenobarbital is considered a hypnotic. Indeed, it has a pronounced hypnotic effect and is used in sleep disorders. However, at present, this drug is of the greatest importance as an antiepileptic drug.
In small doses, phenobarbital has a calming effect and in combination with other drugs (antispasmodics, vasodilators) is used in neuro-vegetative disorders.
In connection with the anticonvulsant effect, phenobarbital is also prescribed for chorea, spastic paralysis, various convulsive reactions.
When ingestion, phenobarbital is completely but relatively slowly absorbed. Peak blood concentrations are observed 1–2 hours after ingestion. About 50% is bound by plasma proteins. The drug is evenly distributed in different organs and tissues; lower concentrations of it are found in brain tissue. The half-life period in the blood plasma in adults is 2-4 days (up to 7 days in newborns). Is excreted from the body slowly, which creates prerequisites for cumulation. Metabolized by liver microsomal enzymes. An inactive metabolite (4-oxyphenobarbital) is excreted by the kidneys as a glucuronide, and about 25% is excreted.
As a hypnotic, phenobarbital is prescribed to adults at a dose of 0.1-0.2 g per reception, usually 1/2 to 1 hour before sleep. Duration of the hypnotic effect is 6-8 hours. Depending on age, children are prescribed from 0.005 to 0.0075 g.
The hypnotic effect of phenobarbital is similar to that of other barbiturates. An undesirable property of phenobarbital is that when it is used, a pronounced after-effect can be observed: general depression, continued drowsiness, nystagmus, ataxia, etc.
As a sedative and antispasmodic, phenobarbital is prescribed in a dose of 0.01-0.03 - 0.05 g 2 - 3 times a day. It is usually used in combination with antispasmodic, vasodilators, and other means (see Andipal, Bellatamininal, Teofedrin, and others). It is part of the preparations of Corvalol and Valocordin.
Long-term use of phenoarbital and drugs containing it as hypnotic and sedatives should be avoided due to the possibility of their accumulation and the development of addiction.
Recently, a number of finished dosage forms containing phenobarbital (Piraminal, Diafein, Lupaverin, Theodinal tablets, Microdiode with phenobarbital, etc.) have been excluded from the range of drugs.
For the treatment of patients with epilepsy, phenobarbital was first used in 1912.