Amobarbital

Amobarbital (formerly known as amylobarbitone) is a drug which is a barbiturate derivative. It has sedative-hypnotic and analgesic properties, but lacks anxiolytic properties. It is a white crystalline powder with no odor and a slightly bitter taste. If amobarbital is taken for extended periods of time, physical and psychological dependence may develop.

Pharmacology

According to an in vitro conducted at the University of British Columbia, amobarbital works by activating GABA_A receptors, which decreases input resistance, depresses burst and tonic firing, especially in ventrobasal and intralaminar neurons, while at the same time increasing burst duration and mean conductance at individual chloride channels; this increases both the amplitude and decay time of inhibit postsynaptic currents.

Metabolism

Amobarbital undergoes both hydroxylation to form 3'-hydroxyamobarbital, which has both levorotatory and dextrorotatory isomers and N-glucosidation to form 1-(beta-D-glucopyranosyl)amobarbital.

Indications

Approved

Anxiety
Insomnia
Epilepsy
Catatonic mutism, sometimes combined with caffeine to combat somnolence.

Unapproved/Off-Label

Sodium amobarbital has a reputation for having activity as a truth serum, where the person under the influence of the drug will submit to almost any request given by another person. It has been used to convict murderers such as Andres English-Howard, who strangled his girlfriend to death but pleaded innocent. He had surreptitiously been administered the drug, under the influence of which he revealed why he strangled her and under which circumstances. He was convicted on the basis of these statements, and committed suicide in his cell.

Contraindications

The following drugs should be avoided when taking amobarbital:

Alcohol
Caffeine
Chloramphenicol
Chlorpromazine
Cyclophosphamide
Ciclosporin
Digitoxin
Doxorubicin
Doxycycline
Methoxyflurane
Metronidazole
Quinine
Theophylline
Warfarin
Sedatives, such as zolpidem and flunitrazepam
Anxiolytics, such as diazepam and lorazepam
Antiepileptics, such as phenobarbital, carbamazepine or clonazepam
Antihistamines, such as doxylamine and clemastine
Analgesics, such as morphine and oxycodone
Steroids, such as prednisone and cortisone
Antidepressants
Antihypertensives, such as atenolol and propranolol
Antiarrhythmics, such as verapamil and digoxin

Amobarbital has been known to decrease the effects of hormonal birth control, sometimes to the point of uselessness. Being chemically related to phenobarbital, it might also do the same thing to digitoxin, a cardiac glycoside.

In 1988, Miller et al reported that amobarbital increases benzodiazepine receptor binding in vivo with less potency than secobarbital and pentobarbital (in descending order), but greater than phenobarbital and barbital (in ascending order).

Overdose

Some side effects of overdose may include confusion (severe); decrease in or loss of reflexes; drowsiness (severe); fever; irritability (continuing); low body temperature; poor judgment; shortness of breath or slow or troubled breathing; slow heartbeat; slurred speech; staggering; trouble in sleeping; unusual movements of the eyes; weakness (severe).

References and End Notes

Controlled Substances in Schedule II Office of Diversion Control, Drug Enforcement Administration.
Controlled Substances in Schedule III Office of Diversion Control, Drug Enforcement Administration.
Kim HS, Wan X, Mathers DA, Puil E. "Selective GABA-receptor actions of amobarbital on thalamic neurons." British Journal of Pharmacology. 2004 Oct;143(4):485-94. Epub 2004 Sep 20. PMID 15381635 Fulltext
Maynert EW. "The alcoholic metabolites of pentobarbital and amobarbital in man." Journal of Pharmacology and Experimental Therapeutics. 1965 Oct;150(1):118-21. PMID 5855308
Chemicals: 3'-hydroxyamobarbital The Comparative Toxicology Database.
Tang BK, Kalow W, Grey AA. "Amobarbital metabolism in man: N-glucoside formation." Research Communications in Chemical Pathology and Pharmacology. 1978 Jul;21(1):45-53. PMID 684279
Soine PJ, Soine WH. "High-performance liquid chromatographic determination of the diastereomers of 1-(beta-D-glucopyranosyl)amobarbital in urine." Journal of Chromatography. 1987 Nov 27;422:309-14. PMID 3437019
McCall WV. "The addition of intravenous caffeine during an amobarbital interview." Journal of Psychiatry & Neuroscience. 1992 Nov;17(5):195-7. PMID 1489761
Truth Serum: A Possible Weapon, ''60 minutes, April 23, 2003.
PMID 2906155

External links

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