Paraldehyde is the cyclic form of three acetaldehyde molecules (a trimer). A colourless to pale yellow pungent liquid, it is sparingly soluble in water and highly soluble in alcohol. It has industrial and medical uses. It was first synthesized in 1829 by Wildenbusch. Paraldehyde decomposes in air, turning brown and producing an odour of acetic acid (and must then be disposed of). It quickly reacts with most plastics and rubber.

Medical applications

ToxicityOral rat LD50:
2711 mg/kg
Chemical Properties
Solubility in water1 in 10
Melting point12.5 C
Boiling point124 C
Flash point27.5 C
Specific gravity0.995
Paraldehyde was introduced into clinical practice in the UK by the Italian physician Vincenzo Cervello in 1882. It is a CNS depressant and was soon found to be an effective anticonvulsant, hypnotic and sedative. It was included in some cough medicines as an expectorant (though there is no known mechanism for this function beyond the placebo effect). It was commonly used to induce sleep in sufferers from delirium tremens but has been replaced by other drugs in this regard. It is one of the safest hypnotics and was regularly given at bedtime in psychiatric hospitals and geriatric wards up to the 1960s. Up to 30% of the dose is excreted via the lungs (the rest via the liver). This contributes to a strong unpleasant odour on the breath.

Today, paraldehyde is sometimes used to treat status epilepticus. Unlike diazepam and other benzodiazepines, it does not suppress breathing at therapeutic doses and so is safer when no resuscitation facilities exist or when the patient's breathing is already compromised.[1] This makes it a useful emergency medication for parents and other caretakers of children with epilepsy. Since the dose margin between the anticonvulsant and hypnotic effect is small, paraldehyde treatment usually results in sleep.

Generic paraldehyde is available in 5ml sealed glass ampoules. The tradename in the US is Paral®.

Paraldehyde was the last injection given to Edith Alice Morrell in 1950 by the suspected serial killer John Bodkin Adams. He was tried for her murder but acquitted.


Paraldehyde has been given orally, rectally, intravenously and by intramuscular injection. It reacts with rubber and plastic which limits the time it may safely be kept in contact with some syringes or tubing before administration.
  • Injection. Intramuscular injection can be very painful and lead to sterile abscesses, nerve damage, and tissue necrosis. Intravenous administration can lead to pulmonary edema, circulatory collapse and other complications.
  • Oral. Paraldehyde has a hot burning taste and can upset the stomach. It is often mixed with milk or fruit juice in a glass cup and stirred with a metal spoon.
  • Rectal. It may be mixed 1 part paraldehyde with 9 parts saline or, alternatively, with an equal mixture of Arachis or olive oil.

Industrial applications

Paraldehyde has numerous alternate chemical names including paracetaldehyde, s-trimethyltrioxymethylene, and trimethyl-1,3,5-trioxane. Paraldehyde is used in resin manufacture, as a preservative, and in other processes as a solvent.


1. ^ Norris E, Marzouk O, Nunn A, McIntyre J, Choonara I (1999). "Respiratory depression in children receiving diazepam for acute seizures: a prospective study". Dev Med Child Neurol 41 (5): 340-3. PMID 10378761. 
Acetaldehyde, sometimes known as ethanal, is an organic chemical compound with the formula CH3CHO or MeCHO. It is a flammable liquid with a fruity smell.
..... Click the link for more information.
Acetic acid, also known as ethanoic acid, is an organic chemical compound best recognized for giving vinegar its sour taste and pungent smell. Its structural formula is represented as CH3COOH.
..... Click the link for more information.
Toxicity is the degree to which something is able to produce illness or damage to an exposed organism. Toxicity can refer to the effect on a whole organism, such as a human or a bacterium or a plant, or to a substructure, such as a cell (cytotoxicity) or an organ (organotoxicity
..... Click the link for more information.
Solubility is a physical property referring to the ability for a given substance, the solute, to dissolve in a solvent.[1] It is measured in terms of the maximum amount of solute dissolved in a solvent at equilibrium. The resulting solution is called a saturated solution.
..... Click the link for more information.
Water (H2O, HOH) is the most abundant molecule on Earth's surface, composing of about 70% of the Earth's surface as liquid and solid state in addition to being found in the atmosphere as a vapor.
..... Click the link for more information.
The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. Although the phrase would suggest a specific temperature and is commonly and incorrectly used as such in most textbooks and literature, most crystalline compounds
..... Click the link for more information.
boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid.[1][2][3][4]
..... Click the link for more information.
The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. At this temperature the vapor may cease to burn when the source of ignition is removed.
..... Click the link for more information.
This article requires authentication or verification by an expert.
Please assist in recruiting an expert or [ improve this article] yourself. See the talk page for details. This article has been tagged since November 2006.
..... Click the link for more information.
The central nervous system (CNS) represents the largest part of the nervous system, including the brain and the spinal cord. Together with the peripheral nervous system, it has a fundamental role in the control of behavior.
..... Click the link for more information.
A depressant, referred to in slang as a "downer," is a chemical agent that diminishes the function or activity of a specific part of the body. (See also sedative.) The term is used in particular with regard to the central nervous system (CNS).
..... Click the link for more information.
The anticonvulsants, sometimes also called antiepileptics, belong to a diverse group of pharmaceuticals used in prevention of the occurrence of epileptic seizures. More and more, anticonvulsants are also finding ways into the treatment of bipolar disorder, since many seem to
..... Click the link for more information.
Hypnotic drugs are a class of drugs that induce sleep (which differentiates them from the sedative category), used in the treatment of insomnia and in surgical anesthesia. Often the treatment of insomnia will not begin with drugs at all.
..... Click the link for more information.
A sedative is a substance that depresses the central nervous system (CNS), resulting in calmness, relaxation, reduction of anxiety, sleepiness, and slowed breathing, as well as slurred speech, staggering gait, poor judgment, and slow, uncertain reflexes.
..... Click the link for more information.
cough medicine is a medicinal drug used to treat coughing and related conditions. Dry coughs are treated with cough suppressants (antitussives) that suppress the body's urge to cough, while productive coughs (coughs that produce phlegm) are treated with expectorants
..... Click the link for more information.
Placebo effect is the term applied by medical science to the therapeutical and healing effects of inert medicines and/or ritualistic or faith healing manipulations.[1] [2].
..... Click the link for more information.
MeSH D000430 Delirium tremens (colloquially, the DTs, "the horrors", "the shakes" or "rum fits;" literally, "shaking delirium" or "trembling madness
..... Click the link for more information.
worldwide view of the subject.
Please [ improve this article] or discuss the issue on the talk page.

A psychiatric hospital (also called, at various places and times, mental hospital or mental ward, historically often asylum,
..... Click the link for more information.
Geriatrics is the branch of medicine that focuses on health promotion and the prevention and treatment of disease and disability in later life. The term itself can be distinguished from gerontology, which is the study of the aging process itself.
..... Click the link for more information.
MeSH D013226 Status epilepticus (SE) refers to a life threatening condition in which the brain is in a state of persistent seizure. Definitions vary, but traditionally it is defined as one continuous seizure or recurrent seizures without regaining consciousness between
..... Click the link for more information.
Diazepam (IPA: /daɪˈæzɨpæm/), first marketed as Valium by Hoffmann-La Roche) is a benzodiazepine derivative drug.
..... Click the link for more information.
The benzodiazepines (pronounced [ˌbɛnzəʊdaɪˈæzəpiːnz], or "benzos" for short) are a class of psychoactive drugs considered minor tranquilizers with varying hypnotic, sedative, anxiolytic,
..... Click the link for more information.
Edith Alice Morrell (1868 – 13 November 1950), was a resident of Eastbourne and patient of the suspected serial killer John Bodkin Adams. He was tried for her murder in 1957 but acquitted. There were indications of interference with the trial.
..... Click the link for more information.
19th century - 20th century - 21st century
1920s  1930s  1940s  - 1950s -  1960s  1970s  1980s
1947 1948 1949 - 1950 - 1951 1952 1953

Year 1950 (MCML
..... Click the link for more information.
John Bodkin Adams (January 21, 1899 – July 4, 1983) was a British general practitioner, more than 160 of whose patients died under suspicious circumstances.[1] He was tried and controversially[1]
..... Click the link for more information.
Peanut oil (arachis oil) is an organic oil derived from peanuts, noted to have the slight aroma and taste of its parent legume. In the UK it is marketed as 'Groundnut Oil'.
..... Click the link for more information.
Olive oil

Olive oil from Italy.

Fat composition

Saturated fats Palmitic acid: 7.5–20.0 %
Stearic acid: 0.5–5.0 %
Arachidic acid: <0.8%
Behenic acid: <0.3%
Myristic acid: <0.1%
Lignoceric acid:
..... Click the link for more information.
Resin or Rosin (Oxford dictionary) is a hydrocarbon secretion of many plants, particularly coniferous trees, valued for its chemical constituents and uses such as varnishes, adhesives, as an important source of raw materials for organic synthesis, or for incense and
..... Click the link for more information.
This article or section is in need of attention from an expert on the subject.
Please help recruit one or [ improve this article] yourself. See the talk page for details.
..... Click the link for more information.
A solvent is a liquid that dissolves a solid, liquid, or gaseous solute, resulting in a solution. The most common solvent in everyday life is water. Most other commonly-used solvents are organic (carbon-containing) chemicals. These are called organic solvents.
..... Click the link for more information.

This article is copied from an article on - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.