Drug Groups

approved

Description

A barbituric acid derivative that acts as a nonselective central nervous system depressant. It promotes binding to inhibitory gamma-aminobutyric acid subtype receptors, and modulates chloride currents through receptor channels. It also inhibits glutamate induced depolarizations. [PubChem]

Indication

For the treatment of all types of seizures except absence seizures.

Pharmacology

Phenobarbital, the longest-acting barbiturate, is used for its anticonvulsant and sedative-hypnotic properties in the management of all seizure disorders except absence (petit mal).

Toxicity

CNS and respiratory depression which may progress to Cheyne-Stokes respiration, areflexia, constriction of the pupils to a slight degree (though in severe poisoning they may wshow paralytic dilation), oliguria, tachycardia, hypotension, lowered body temperature, and coma. Typical shock syndrome (apnea, circulatory collapse, respiratory arrest, and death) may occur.

Affected Organisms

Biotransformation

Hepatic (mostly via CYP2C19).

Absorption

Absorbed in varying degrees following oral, rectal or parenteral administration. The salts are more rapidly absorbed than are the acids. The rate of absorption is increased if the sodium salt is ingested as a dilute solution or taken on an empty stomach.

Half Life

53 to 118 hours (mean 79 hours)

Protein Binding

20 to 45%

References

External Links