Source of information: Drugbank (External Link). Last updated on: 3rd July 18
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Active Ingredient / Synonyms
Paraldehyde | Paraldehyde |
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.
Paraldehyde blocks neuromuscular transmission [A19737].
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.
70-80% is metabolized to carbon dioxide and subsequently exhaled [A19738]. 11-28% is exhaled as the parent compound. 0.1-2.5% is excreted in the urine as the parent compound.
The mean half life is 7.5 hours in a range if 3.5-9.5 hours [A19738].
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)
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