Methohexital or methohexitone, (marketed under the brand name Brevital) is a drug which is a barbiturate derivative. It is classified as short-acting, and has a rapid onset of action. It is similar in its effects to sodium thiopental, a drug with which it competed in the market for anaesthetics.
Pharmacology
Methohexital binds to a distinct site which is associated with Cl− ionophores at GABAA receptors.[1] This increases the length of time which the Cl− ionopores are open, thus causing an inhibitory effect.
Metabolism of methohexital is primarily hepatic (i.e., taking place in the liver) via demethylation and oxidation.Side-chain oxidation is the primary means of metabolism involved in the termination of the drug’s biological activity.
Protein binding is approximately 73% for methohexital.
Indications
Methohexital is primarily used to induce anesthesia, and is generally provided as a sodium salt (i.e. methohexital sodium). It is only used in hospital or similar settings, under strict supervision.[citation needed] It has been commonly used to induce deep sedation or general anesthesia for surgery and dental procedures. Unlike many other barbiturates, Methohexital actually lowers the seizure threshold, a property that make it particularly useful when anesthesia is provided for a electroconvulsive therapy (ECT). And rapid recovery rate with consciousness being gained within three to seven minutes after induction and full recovery within 30 minuntes is a major advantage over other ECT barbiturates (Schulgasser and Borowitz 1963).
Synthesis
Methohexital, 5-allyl-1-methyl-5-(1-methyl-2-pentinyl barbituric acid, is synthesized in the classic manner of making barbituric acid derivatives, in particular by the reaction of malonic ester derivatives with derivatives of urea.
Methohexital synthesis: W.J. Doran, U.S. Patent 2,872,448 (1959).
The resulting allyl-(1-methyl-2-pentynyl) malonic ester is synthesized by subsequent alkylation of the malonic ester itself, beginning with 2-bromo-3-hexyne, which gives (1-methyl-2-pentynyl)malonic ester, and then by allylbromide. In the final step, reaction of the disubstituted malonic ester with N-methylurea gives desired methohexital.
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| Systematic (IUPAC) name | |
|---|---|
| 5-hex-3-yn-2-yl-1- methyl-5-prop-2-enyl-1, 3-diazinane-2,4,6-trione | |
| Clinical data | |
| AHFS/Drugs.com | Consumer Drug Information |
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| Legal status |
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| Routes | Intravenous, rectal |
| Pharmacokinetic data | |
| Bioavailability | I.V. ~100% Rectal ~17% |
| Metabolism | Hepatic |
| Half-life | 5.6 ± 2.7 minutes |
| Excretion | ? |
| Identifiers | |
| CAS number | 151-83-7  |
| ATC code | N01AF01 N05CA15 |
| PubChem | CID 9034 |
| DrugBank | DB00474 |
| ChemSpider | 8683 |
| UNII | E5B8ND5IPE |
| KEGG | D04985 |
| ChEBI | CHEBI:102216 |
| ChEMBL | CHEMBL7413 |
| Chemical data | |
| Formula | C14H18N2O3 |
| Molecular mass | 262.304 |
References
- Katzung, Bertram G., Basic and Clinical Pharmacology, 10th ed., p. 406-407
External links
- RxList.com – Methohexital
- Drugs.com – Methohexital Sodium
- DrugLib.com – Brevital (Methohexital Sodium)
