Amobarbital (formerly known as amylobarbitone or sodium amytal as the soluble sodium salt) is a drug that is a
barbiturate
Barbiturates are a class of depressant drugs that are chemically derived from barbituric acid. They are effective when used medically as anxiolytics, hypnotics, and anticonvulsants, but have physical and psychological addiction potential as ...
derivative. It has
sedative
A sedative or tranquilliser is a substance that induces sedation by reducing irritability or excitement. They are CNS depressants and interact with brain activity causing its deceleration. Various kinds of sedatives can be distinguished, but ...
-
hypnotic
Hypnotic (from Greek ''Hypnos'', sleep), or soporific drugs, commonly known as sleeping pills, are a class of (and umbrella term for) psychoactive drugs whose primary function is to induce sleep (or surgical anesthesiaWhen used in anesthesia ...
properties. It is a white crystalline powder with no odor and a slightly bitter taste. It was first synthesized in
Germany
Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...
in 1923. It is considered a short to intermediate acting barbiturate. If amobarbital is taken for extended periods of time, physiological and
psychological dependence can develop. Amobarbital withdrawal mimics
delirium tremens
Delirium tremens (DTs) is a rapid onset of confusion usually caused by withdrawal from alcohol. When it occurs, it is often three days into the withdrawal symptoms and lasts for two to three days. Physical effects may include shaking, shiver ...
and may be life-threatening. Amobarbital was manufactured by
Eli Lilly and Company
Eli Lilly and Company is an American pharmaceutical company headquartered in Indianapolis, Indiana, with offices in 18 countries. Its products are sold in approximately 125 countries. The company was founded in 1876 by, and named after, Colon ...
in the US under the brand name Amytal in bright blue bullet shaped capsules (known as Pulvules) or pink tablets (known as Diskets) containing 50, 100, or 200 milligrams of the drug. The drug was also manufactured generically. Amobarbital was widely misused, known as "Blue Heavens" on the street. Amytal, as well as Tuinal, a combination drug containing equal quantities of
secobarbital and amobarbital, were both manufactured by Eli Lilly until the late-1990s. However, as the popularity of benzodiazepines increased, prescriptions for these medications became increasingly rare beginning in the mid to late-1980s.
Pharmacology
In an ''
in vitro
''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology and ...
'' study in fat thalamic slices amobarbital worked by activating
GABAA receptors, which decreased input resistance, depressed
burst and tonic firing, especially in
ventrobasal and intralaminar neuron
A neuron, neurone, or nerve cell is an membrane potential#Cell excitability, electrically excitable cell (biology), cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous ...
s, while at the same time increasing burst duration and mean
conductance at individual
chloride channel
Chloride channels are a superfamily of poorly understood ion channels specific for chloride. These channels may conduct many different ions, but are named for chloride because its concentration ''in vivo'' is much higher than other anions. Several ...
s; this increased both the amplitude and decay time of
inhibitory postsynaptic
Chemical synapses are biological junctions through which neurons' signals can be sent to each other and to non-neuronal cells such as those in muscles or glands. Chemical synapses allow neurons to form circuits within the central nervous syste ...
currents.
Amobarbital has been used in a study to inhibit mitochondrial electron transport in the rat heart in an attempt to preserve mitochondrial function following
reperfusion.
A 1988 study found that amobarbital increases
benzodiazepine receptor
The GABAA receptor (GABAAR) is an ionotropic receptor and ligand-gated ion channel. Its endogenous ligand is γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Upon opening, the GABAA receptor on ...
binding ''
in vivo
Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and ...
'' with less potency than secobarbital and
pentobarbital
Pentobarbital (previously known as pentobarbitone in Britain and Australia) is a short-acting barbiturate typically used as a sedative, a preanesthetic, and to control convulsions in emergencies. It can also be used for short-term treatment o ...
(in descending order), but greater than
phenobarbital
Phenobarbital, also known as phenobarbitone or phenobarb, sold under the brand name Luminal among others, is a medication of the barbiturate type. It is recommended by the World Health Organization (WHO) for the treatment of certain types of ep ...
and
barbital
Barbital (or barbitone), marketed under the brand names Veronal for the pure acid and Medinal for the sodium salt, was the first commercially available barbiturate. It was used as a sleeping aid (hypnotic) from 1903 until the mid-1950s. The chemic ...
(in descending order). (Secobarbital > pentobarbital > ''amobarbital'' > phenobarbital > barbital)
It has an in mice of 212mg/kg s.c.
Metabolism
Amobarbital undergoes both
hydroxylation
In chemistry, hydroxylation can refer to:
*(i) most commonly, hydroxylation describes a chemical process that introduces a hydroxyl group () into an organic compound.
*(ii) the ''degree of hydroxylation'' refers to the number of OH groups in a ...
to form 3'-hydroxyamobarbital, and
N-glucosidation to form 1-(beta-D-glucopyranosyl)-amobarbital.
Indications
Approved
*
Anxiety
Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil
Turmoil may refer to:
* ''Turmoil'' (1984 video game), a 1984 video game released by Bug-Byte
* ''Turmoil'' (2016 video game), a 2016 indie oil tycoon video ...
*
Epilepsy
Epilepsy is a group of non-communicable neurological disorders characterized by recurrent epileptic seizures. Epileptic seizures can vary from brief and nearly undetectable periods to long periods of vigorous shaking due to abnormal electrical ...
*
Insomnia
Insomnia, also known as sleeplessness, is a sleep disorder in which people have trouble sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia is typically followed by daytime sleepiness, low energy ...
*
Wada test
Unapproved/off-label
When given slowly by an intravenous route, sodium amobarbital has a reputation for acting as a so-called
truth serum. Under the influence, a person will divulge information that under normal circumstances they would block. This was most likely due to loss of inhibition. As such, the drug was first employed clinically by Dr.
William Bleckwenn at the University of Wisconsin to circumvent inhibitions in psychiatric patients. The use of amobarbital as a truth serum has lost credibility due to the discovery that a subject can be coerced into having a "
false memory" of the event.
[ ]
The drug may be used intravenously to interview patients with
catatonic
Catatonia is a complex neuropsychiatric behavioral syndrome that is characterized by abnormal movements, immobility, abnormal behaviors, and withdrawal. The onset of catatonia can be acute or subtle and symptoms can wax, wane, or change during ...
mutism Muteness or mutism () is defined as an absence of speech while conserving or maintaining the ability to hear the speech of others. Mutism is typically understood as a person's inability to speak, and commonly observed by their family members, caregi ...
, sometimes combined with
caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine t ...
to prevent sleep.
It was used by the
United States armed forces
The United States Armed Forces are the military forces of the United States. The armed forces consists of six service branches: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard. The president of the United States is ...
during
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
in an attempt to treat
shell shock
Shell shock is a term coined in World War I by the British psychologist Charles Samuel Myers to describe the type of post-traumatic stress disorder (PTSD) many soldiers were afflicted with during the war (before PTSD was termed). It is a rea ...
and return soldiers to the
front-line duties. This use has since been discontinued as the powerful sedation, cognitive impairment, and dis-coordination induced by the drug greatly reduced soldiers' usefulness in the field. Amobarbital was once manufactured in the US by Eli Lilly Pharmaceuticals under the brand name Amytal in capsule form. It was discontinued in the early 80s largely replaced by the benzodiazepine family of drugs. Amobarbital was also widely abused, known on the streets as "blue heavens" because of their blue capsule.
Contraindications
The following drugs should be avoided when taking amobarbital:
*
Antiarrhythmics, such as
verapamil
Verapamil, sold under various trade names, is a calcium channel blocker medication used for the treatment of high blood pressure, angina (chest pain from not enough blood flow to the heart), and supraventricular tachycardia. It may also be ...
and
digoxin
*
Antiepileptics, such as
phenobarbital
Phenobarbital, also known as phenobarbitone or phenobarb, sold under the brand name Luminal among others, is a medication of the barbiturate type. It is recommended by the World Health Organization (WHO) for the treatment of certain types of ep ...
or
carbamazepine
Carbamazepine (CBZ), sold under the trade name Tegretol among others, is an anticonvulsant medication used primarily in the treatment of epilepsy and neuropathic pain. It is used as an adjunctive treatment in schizophrenia along with other medi ...
*
Antihistamine
Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provide ...
s, such as
doxylamine and
clemastine
*
Antihypertensive
Antihypertensives are a class of drugs that are used to treat hypertension (high blood pressure). Antihypertensive therapy seeks to prevent the complications of high blood pressure, such as stroke and myocardial infarction. Evidence suggests that ...
s, such as
atenolol and
propranolol
*
Ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a h ...
*
Benzodiazepine
Benzodiazepines (BZD, BDZ, BZs), sometimes called "benzos", are a class of depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat conditions such as anxiety disorders, ...
s, such as
diazepam,
clonazepam,
nitrazepam,
alprazolam, or
lorazepam
Lorazepam, sold under the brand name Ativan among others, is a benzodiazepine medication. It is used to treat anxiety disorders, insomnia, trouble sleeping, Psychomotor agitation, severe agitation, active Epileptic seizure, seizures including ...
*
Chloramphenicol
Chloramphenicol is an antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medica ...
*
Chlorpromazine
*
Cyclophosphamide
*
Ciclosporin
*
Digitoxin
*
Doxorubicin
*
Doxycycline
*
Methoxyflurane
Methoxyflurane, sold under the brand name Penthrox among others, is an inhaled medication primarily used to reduce pain following trauma. It may also be used for short episodes of pain as a result of medical procedures. Onset of pain relief is ...
*
Metronidazole
Metronidazole, sold under the brand name Flagyl among others, is an antibiotic and antiprotozoal medication. It is used either alone or with other antibiotics to treat pelvic inflammatory disease, endocarditis, and bacterial vaginosis. It is e ...
*
Narcotic analgesic
An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...
s, such as
morphine
Morphine is a strong opiate that is found naturally in opium, a dark brown resin in poppies ('' Papaver somniferum''). It is mainly used as a pain medication, and is also commonly used recreationally, or to make other illicit opioids. Ther ...
and
oxycodone
Oxycodone, sold under various brand names such as Roxicodone and OxyContin (which is the extended release form), is a strong, semi-synthetic opioid used medically for treatment of moderate to severe pain. It is highly addictive and a commonly ...
*
Quinine
Quinine is a medication used to treat malaria and babesiosis. This includes the treatment of malaria due to '' Plasmodium falciparum'' that is resistant to chloroquine when artesunate is not available. While sometimes used for nocturnal leg ...
*
Steroid
A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and ...
s, such as
prednisone
Prednisone is a glucocorticoid medication mostly used to suppress the immune system and decrease inflammation in conditions such as asthma, COPD, and rheumatologic diseases. It is also used to treat high blood calcium due to cancer and adren ...
and
cortisone
Cortisone is a pregnene (21-carbon) steroid hormone. It is a naturally-occurring corticosteroid metabolite that is also used as a pharmaceutical prodrug; it is not synthesized in the adrenal glands. Cortisol is converted by the action of the ...
*
Theophylline
*
Warfarin
Warfarin, sold under the brand name Coumadin among others, is a medication that is used as an anticoagulant (blood thinner). It is commonly used to prevent blood clots such as deep vein thrombosis and pulmonary embolism, and to prevent ...
Interactions
Amobarbital has been known to decrease the effects of hormonal birth control.
Overdose
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). Severe overdose may result in death without intervention.
Chemistry

Amobarbital (5-ethyl-5-isoamylbarbituric acid), like all barbiturates, is synthesized by reacting
malonic acid derivatives with
urea derivatives. In particular, in order to make amobarbital, α-ethyl-α-isoamylmalonic ester is reacted with urea (in the presence of
sodium ethoxide).
Society and culture
It has been used to convict alleged murderers such as
Andres English-Howard, who strangled his girlfriend to death but claimed innocence. He was surreptitiously administered the drug by his lawyer, and under the influence of it he revealed why he strangled her and under what circumstances.
On the night of August 28, 1951, the housekeeper of actor
Robert Walker found him to be in an emotional state. She called Walker's psychiatrist who arrived and administered amobarbital for sedation. Walker was allegedly drinking prior to his emotional outburst, and it is believed the combination of amobarbital and alcohol resulted in a severe reaction. As a result, he passed out and stopped breathing, and all efforts to resuscitate him failed. Walker died at 32 years old.
The British actor and comedian
Tony Hancock took his own life in Australia in 1968 using the drug in combination with alcohol.
Eli Lilly manufactured amobarbital under the brand name Amytal, it was discontinued in the 1980s replaced largely by the benzodiazepine family of drugs. Amytal was also widely abused. Street names for amobarbital include "blues", "blue angels", "blue birds", "blue devils", and "blue heavens" due to their blue capsule.
Cultural references
In
Len Deighton
Leonard Cyril Deighton (; born 18 February 1929) is a British author. His publications have included cookery books, history and military history, but he is best known for his spy novels.
After completing his national service in the Royal Air F ...
's 1967 novel ''
An Expensive Place to Die
''An Expensive Place to Die'' is a 1967 novel by Len Deighton. It is set initially in Paris and takes its title from an Oscar Wilde quotation about the said city. ("Dying in Paris is a terribly expensive business for a foreigner.") The action co ...
'', a combination of amytal and
LSD is used to make the unnamed protagonist respond to questioning about his activities.
In
Thomas Pynchon
Thomas Ruggles Pynchon Jr. ( , ; born May 8, 1937) is an American novelist noted for his dense and complex novels. His fiction and non-fiction writings encompass a vast array of subject matter, Literary genre, genres and Theme (narrative), them ...
's 1973 novel ''
Gravity's Rainbow'', sodium amytal is used by a military intelligence unit as some kind of truth serum to extract Tyrone Slothrop's (the novel's protagonist) ideas on racism of white Americans against Afro-Americans during the 1930s in his home state of Massachusetts (Chapter 1).
In 2001, the ''
Law & Order: Special Victims Unit'' episode "Repression" (
Season 3, Episode 1), a therapist (
Shirley Knight) treats her patient with "sodium amytal". The character Dr.
George Huang (
BD Wong) claims that the drug leaves a patient so susceptible to
suggestion, that the therapist is able to implant false memories in the patient.
In 2022, in "Diophantine Pseudonym", Episode 06 of
Dan Brown's ''
The Lost Symbol'', sodium amytal is used by the CIA as a truth serum.
See also
*
Blue 88
Blue 88 was a blue-colored pill that was a mix of calming drugs, mainly barbiturates such as sodium amytal, used to treat American soldiers in the Second World War who suffered from battle fatigue. In most cases, it was used to induce sleep.
Use ...
*
Depressant
A depressant, or central depressant, is a drug that lowers neurotransmission levels, which is to depress or reduce arousal or stimulation, in various areas of the brain. Depressants are also colloquially referred to as downers as they lower the ...
*
Tuinal
Notes
{{GABAAR PAMs
Hypnotics
Barbiturates
GABAA receptor positive allosteric modulators
German inventions
Eli Lilly and Company brands
Substances discovered in the 1920s