Product Information

Registration Status: Active

PARALDEHYDE INJECTION BP is approved to be sold in Singapore with effective from 1988-04-22. It is marketed by PHEBRA (SE ASIA) PTE LTD, with the registration number of SIN00325P.

This product contains Paraldehyde 5ml/ampoule in the form of INJECTION. It is approved for INTRAMUSCULAR use.

This product is manufactured by HOSPIRA AUSTRALIA PTY LTD in AUSTRALIA.

It is a Prescription Only Medicine that can only be obtained from a doctor or a dentist, or a pharmacist with a prescription from a Singapore-registered doctor or dentist.



Paraldehyde is the cyclic trimer of acetaldehyde molecules. It was introduced into clinical practice in the UK by the Italian physician Vincenzo Cervello in 1882. It is a central nervous system 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).


Paraldehyde was used historically as a sedative and hypnotic [A19735]. It has been used in the treatment of seizures as an anticonvulsant [A19736].

Mechanism of Action

Paraldehyde is believed to reduce the release of acetylcholine in response to neuronal depolarization [A19737]. The exact mechanism of this effect is unknown.


93% of orally administered paraldehyde is absorbed from the gastrointestinal tract.
Paraldehyde is believed to undergo depolymerization to acetaldehyde followed by oxidation by aldehyde dehydrogenase [A19378]. It is thought to ultimately be metabolized to carbon dioxide and water.


Paraldehyde overdosage can produce headache, nausea, drowsiness, unconsciousness, coma, severe hypotension, respiratory depression, pulmonary edema and hemorrhages, and right-side heart failure [A19738]. Inhalation of paraldehyde can produce sore throat, headache, dizziness, nausea, drowsiness and unconsciousness but exposure via this route is rare. Chronic use is dependence forming and withdrawal proceeds similarly to ethanol withdrawal producing hallucinations and convulsions. Toxic hepatitis and nephritis have been observed during chronic use. The acute LD50 values determined for various species are as follows [A19738]: Rabbit - 3.3-5 g/kg (oral) Rat - 1.5-1.65 g/kg (oral), 1.3-1.45 g/kg (i.p.) Dog - 3-4 g/kg (oral) Mouse - 2.75 (oral) Cat - 3.3 (oral)

Active Ingredient/Synonyms

Paraldehyde | Paraldehyde |

Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.


  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank