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Methyprylon
Methyprylon is a sedative-hypnotic1 central nervous system depressant of the piperidinedione class2, a subgroup of piperidines. It was previously used for the treatment of insomnia.3 It is structurally related to barbituric acid4 but is classified as a non-barbiturate sedative.4 Its clinical use is now uncommon because newer alternatives have fewer side effects. Methyprylon depresses respiratory, cardiac, and muscle activity.4
Dosage & Duration
Dosage
Doses are population estimates that vary widely between individuals.
Duration
Subjective Effects
Pharmacology
Pharmacodynamics
Methyprylon positively modulates GABA-A receptors at a distinct site associated with their chloride channel, prolonging channel opening and GABA-mediated inhibition in the thalamus. It also has agonist activity at the GABA-A receptor alpha-1 subunit.
Pharmacokinetics
Methyprylon is almost completely metabolized in the liver and is 60% protein bound. Its reported half-life is 6-16 hours. In healthy volunteers given a single oral dose, absorption was best described by a zero-order model, with a mean half-life of 9.2 ± 2.2 hours, apparent clearance of 11.91 ± 4.42 mL/h/kg, and apparent steady-state volume of distribution of 0.97 ± 0.33 L/kg. An overdose case report found that its pharmacokinetics were not concentration dependent, with saturation or inhibition of metabolic pathways proposed as possible explanations. Therapeutic half-life estimates may underestimate how long the drug persists after an overdose.5
Interactions
An unlisted combination is an unknown one, not a safe one. Check a dedicated combination chart before mixing.
Tolerance
Harm Potential
Addiction & Dependence
Psychological
ModerateClassified as habit-forming. As a CNS depressant sedative-hypnotic, it carries potential for psychological dependence with regular use.
Toxicity
CNS depression occurs during use, manifesting as mental depression, confusion, drowsiness, lethargy, clumsiness, lack of coordination, ataxia, dizziness, headache, double vision, and unusual weakness. Overdose may cause paradoxical excitation and convulsions.
Cardiac depression and fast heartbeat have been reported as adverse effects.
Respiratory depression is a documented adverse effect, particularly concerning in overdose or when combined with other CNS depressants.
Muscle tissue depression and swelling of feet or lower legs have been reported.
Unusual bleeding or bruising has been reported as an adverse effect.
Gastrointestinal effects including constipation, diarrhea, nausea, and vomiting have been reported.
Skin rash, fever, and ulcers or sores in mouth or throat have been reported as adverse effects.
Seizure Risk
Convulsions are listed as a symptom of overdose. Excitation and convulsions may occur in overdose situations.
History & Culture
Methyprylon was first developed by Hoffmann-La Roche in the 1940s and was marketed under the trade names Noludar, Noctan, and Dimerin. It was used to treat insomnia6, but its clinical use declined as newer medicines with fewer side effects, including benzodiazepines, replaced it. It was withdrawn from the United States market in June 1975 and the Canadian market in September 1990.
Legality
By Country
United StatesIllegal
CanadaRestrictedReferences
Citations
Article Status
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