| Clinical data | |
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| Trade names | Brevital Sodium |
| Other names | Methohexitone |
| AHFS/Drugs.com | Consumer Drug Information |
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| Routes of administration | Intravenous,rectal |
| Drug class | Barbiturate |
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| Pharmacokinetic data | |
| Bioavailability | I.V. ~100% Rectal ~17% |
| Metabolism | Liver |
| Eliminationhalf-life | 5.6 ± 2.7 minutes |
| Excretion | excreted in feces |
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| ECHA InfoCard | 100.005.272 |
| Chemical and physical data | |
| Formula | C14H18N2O3 |
| Molar mass | 262.309 g·mol−1 |
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Methohexital ormethohexitone (marketed under the brand namesBrevital andBrietal) is a drug which is abarbiturate derivative. It is classified as short-acting, and has a rapid onset of action.[2] It is similar in its effects tosodium thiopental, a drug with which it competed in the market foranesthetics.
Methohexital binds to a distinct site which is associated with Cl−ionophores at GABAA receptors.[3] This increases the length of time which the Cl− ionopores are open, thus causing aninhibitory effect.
Metabolism of methohexital is primarily hepatic via demethylation and oxidation.[1] Side-chain oxidation is the primary means of metabolism involved in the termination of the drug'sbiological activity.
Methohexital is primarily used to induceanesthesia, and is generally provided as a sodium salt (i.e. methohexital sodium). It is only used inhospital or similar settings, under strict supervision.[1] 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 makes it particularly useful when anesthesia is provided for anelectroconvulsive therapy (ECT).[4] Its rapid recovery rate with consciousness being gained within three to seven minutes after induction and full recovery within 30 minutes is a major advantage over other ECT barbiturates.[4]
Methohexital can be synthesized in the classic manner of making barbituric acid derivatives, in particular by the reaction of malonic ester derivatives with derivatives ofurea.[5] 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 withN-methylurea gives methohexital.