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Amobarbital chemical structure

IUPAC name
CAS number
ATC code


Chemical formula
Molecular weight 226.272
Bioavailability ?
Metabolism Hepatic
Elimination half-life 8-42 hours
Excretion Renal
Pregnancy category ?
Legal status Schedule II/Schedule III (US)
Routes of administration Oral, IM, IV, Rectal

Amobarbital (formerly known as amylobarbitone) is a drug that is a barbiturate derivative. It has sedative-hypnotic and analgesic 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 can develop.


According to an in vitro study conducted at the University of British Columbia, amobarbital works by activating GABAA 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 inhibitory postsynaptic currents.[1]

It has an LD50 in mice of 212 mg/kg s.c.


Amobarbital undergoes both hydroxylation to form 3'-hydroxyamobarbital,[2] which has both levorotatory and dextrorotatory isomers[3] and N-glucosidation[4] to form 1-(beta-D-glucopyranosyl)amobarbital.[5]


Amobarbital DOJ.jpg



A vial of amytal sodium.

  • 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 claimed innocence. He was surreptitiously administered the drug, by his attorney, and under the influence of it he revealed why he strangled her and under which circumstances. A year later he confessed, on the stand, and was convicted on the basis of these statements; he later committed suicide in his cell.[6] The use of amobarbital as a truth serum has lost credibility due to the discovery that the subject can be coerced into having a 'false memory' of the event. In controlled doses, it is used in the Narco Analysis test to trace crime and criminals in modern forensics.[How to reference and link to summary or text]
  • It was also used in the Battle of the Bulge as a healing pill to send people back to the front.[8]


The following drugs should be avoided when taking amobarbital:

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).[9]


Some side effects of overdose 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). Death can result.

See also

References and End Notes

  1. 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
  2. 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
  3. Chemicals: 3'-hydroxyamobarbital The Comparative Toxicology Database.
  4. 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
  5. 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
  6. Truth Serum: A Possible Weapon, 60 minutes, April 23, 2003.
  7. McCall WV. "The addition of intravenous caffeine during an amobarbital interview." Journal of Psychiatry & Neuroscience. 1992 Nov;17(5):195-7. PMID 1489761
  8. Use of sodium amytal during WWII
  9. Miller LG, Deutsch SI, Greenblatt DJ, Paul SM, Shader RI (1988). Acute barbiturate administration increases benzodiazepine receptor binding in vivo. Psychopharmacology (Berl) 96 (3): 385-90. PMID 2906155
  1. Controlled Substances in Schedule II Office of Diversion Control, Drug Enforcement Administration.
  2. Controlled Substances in Schedule III Office of Diversion Control, Drug Enforcement Administration.

External links

Barbiturates edit

Allobarbital, Amobarbital, Aprobarbital, Barbexaclone, Barbital, Butabarbital, Butalbital, Butobarbital, Cyclobarbital, Ethallobarbital, Heptabarbital, Hexobarbital, Mephobarbital, Metharbital, Methohexital, Methylphenobarbital, Pentobarbital, Phenobarbital, Primidone, Proxibarbal, Reposal, Secobarbital, Talbutal, Thiobarbital, Thiopental, Vinbarbital, Vinylbital

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