Indicator Explainer
Phenobarbital
A long-acting barbituric acid derivative with antipsychotic property. Phenobarbital binds to and activates the gamma-aminobutyric acid (GABA)-A receptor, thereby mimicking the inhibitory actions of GABA in the brain. The activation effects of the phenobarbital-receptor-ionophore complex include increased frequency of chloride channel openings, membrane hyperpolarization and ultimately synaptic inhibition and decreased neuronal excitability. In addition, this agent inhibits glutamate induced depolarization.
This page explains what the indicator is and how results are interpreted in general terms. Reference ranges depend on the laboratory, the method, and your own situation — no single “normal value” applies to everyone. This page is health information, not a diagnosis. For symptoms, treatment, or urgent concerns, contact a healthcare professional.
When it is tested
Source: National Cancer Institute, NCI Thesaurus 26.09d, C739. NCI definition, reproduced without modification under CC BY 4.0. Source identity and definition checked automatically on 2026-10-20. No individual clinical interpretation or human reviewer is asserted.
Reading results
Reference intervals and interpretation depend on the laboratory, specimen, method and clinical context. This source definition is educational information; it does not establish a diagnosis, product approval or suitability for an individual.
Also Known As
References
- NCI Thesaurus 26.09d — Phenobarbital (C739)
- Source: National Cancer Institute, NCI Thesaurus 26.09d, C739. NCI definition, reproduced without modification under CC BY 4.0.
- Comparative Effectiveness of Phenobarbital vs Diazepam for Alcohol Withdrawal Syndrome. — JAMA Intern Med, 2026-10-12 (PMID 42862568; literature)
- The Growing Role of Phenobarbital in Managing Inpatient Alcohol Withdrawal Syndrome. — JAMA Intern Med, 2026-10-12 (PMID 42862564; literature)
- Hospitalist perspectives and practices in treating hospitalized patients with alcohol withdrawal syndrome in the era of phenobarbital re-emergence. — J Hosp Med, 2026-10-04 (PMID 42830611; literature)
- Haemolytic anaemia and thrombocytopenia following phenobarbital therapy for alcohol withdrawal. — BMJ Case Rep, 2026-09-17 (PMID 42754353; literature)