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Prazepam

Prazepam molecule structurePrazepam molecule structure
Prazepam
Centrac, Centrax, Demetrin, Lysanxia, Mono DemetrinOpen in Piru

Prazepam is a depressant1 of the 1,4-benzodiazepine class2 used to treat anxiety disorders.3 It reduces anxiety and has sedative, anticonvulsant,4 and skeletal muscle relaxant effects.5 It was developed by Warner-Lambert in the 1960s. Like other benzodiazepines, prazepam can cause mental or physical dependence,2 particularly when taken for prolonged periods or at high doses.4

Dosage & Duration

Dosage

Doses are population estimates that vary widely between individuals.

Threshold~5 mg
Light5-10 mg
Moderate10-20 mg
Strong20-40 mg
Heavy40+ mg

Duration

Onset45-120 minutes
After Effects8-24 hours
Total8-20 hours

Subjective Effects

Subjective Effects not written up yet

Pharmacology

Pharmacodynamics

Prazepam positively modulates GABA-A receptors through the benzodiazepine binding site, enhancing inhibitory GABA signaling in the brain. This mechanism supports its anxiolytic, sedative, anticonvulsant, and skeletal muscle relaxant activity. Prazepam also modulates the translocator protein.

Pharmacokinetics

Study data suggest that prazepam is a prodrug6 that undergoes hepatic metabolism2 and is a CYP3A4 substrate.7 Its principal active metabolite accounts for most of its therapeutic activity,8 and a separate hydroxylated metabolite undergoes further metabolism.2 Reported elimination half-life ranges for prazepam are 29-224 hours and 36-200 hours; its principal active metabolite has an elimination half-life of 36-200 hours.

Interactions

Dangerous

Highest risk

These combinations are considered extremely harmful and should always be avoided. Reactions to these drugs taken in combination are highly unpredictable and have a potential to cause death.

AlcoholGHB/GBLOpioidsTramadol

Unsafe

Avoid

There is considerable risk of physical harm when taking these combinations, they should be avoided where possible.

Caution

Use caution

These combinations are not usually physically harmful, but may produce undesirable effects, such as physical discomfort or overstimulation. Extreme use may cause physical health issues. Synergistic effects may be unpredictable. Care should be taken when choosing to use this combination.

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Tolerance

Tolerance timelines are rules of thumb, not exact schedules, and vary widely between individuals and use patterns.

Full Tolerance
Tolerance can develop with long-term prazepam use. It may develop more slowly and be less severe than with other benzodiazepines, such as diazepam.

Harm Potential

Addiction & Dependence

Psychological

Prazepam has abuse potential4 and can be habit-forming.10

Physical

High

Dependence is among the most common adverse effects of long-term prazepam use; dose reduction or cessation can cause tremor, dysphoria, psychomotor agitation, tachycardia and sweating. Withdrawal risk and severity increase with higher doses and longer use, and severe withdrawal can include hallucinations, psychosis and seizures. Abrupt or overly rapid discontinuation after long-term use can cause protracted withdrawal even at low doses.

Toxicity

Nervous system

Prazepam overdose can cause somnolence, confusion, agitation, ataxia, diminished reflexes and coma, with hypotonia in severe cases.

Reproductive and developmental

Animal studies found that prazepam exposure during pregnancy caused delayed growth and reproductive abnormalities.

Psychosis Risk

Severe prazepam withdrawal can cause hallucinations and psychosis. Withdrawal-related psychosis is generally unresponsive to antipsychotic medications.

Seizure Risk

Seizures can occur during severe prazepam withdrawal; withdrawal risk and severity increase with higher doses and longer use.

History & Culture

Warner-Lambert developed prazepam during the 1960s.11

Legality

International

Prazepam has approved and illicit regulatory groupings.

By Country

Illegal1
United States flagUnited StatesIllegal

References

Source Pages

  1. DrugBank
  2. DrugBank: Article on Prazepam Metabolism
  3. DrugBank: Benzodiazepine Category
  4. PsychonautWiki: Benzodiazepines
  5. TripSit Wiki: Benzodiazepines
  6. TripSit Wiki: Uncommon Benzodiazepines
  7. Wikipedia

Citations

  1. CENTRAX Tablet Pharmacology. RxReasoner (2020). https://www.rxreasoner.com/monographs/centrax/pharmacology1
  2. PRAZEPAM BIOGARAN 10 mg, comprimé — Résumé des caractéristiques du produit. ANSM — Base de Données Publique des Médicaments (2026). https://base-donnees-publique.medicaments.gouv.fr/medicament/67086191/extrait12345
  3. Prazepam MeSH Descriptor Data 2026. National Library of Medicine (2026). https://meshb.nlm.nih.gov/record/ui?ui=D0112221
  4. Centrax 10mg Tablets—Summary of Product Characteristics. Health Products Regulatory Authority (2023). https://assets.hpra.ie/products/Human/21640/Licence_PA0822-010-001_25052023120251.pdf123
  5. PRAZEPAM. Probes & Drugs (n.d.). https://www.probes-drugs.org/compound/PD009466/1
  6. Comparison of sublingual and oral prazepam in normal subjects. II. Pharmacokinetic and pharmacodynamic data. Neuropsychobiology / PubMed (1988). https://doi.org/10.1159/0001184581
  7. Showing BioInteractions for Prazepam (DB01588). DrugBank (n.d.). https://go.drugbank.com/drugs/DB01588/biointeractions1
  8. Prazepam Pharmacology. RxReasoner — CENTRAX Summary of Product Characteristics (2020). https://www.rxreasoner.com/substances/prazepam/pharmacology1
  9. Prazepam — Some Pharmaceutical Drugs. International Agency for Research on Cancer / NCBI Bookshelf (1996). https://www.ncbi.nlm.nih.gov/books/NBK423852?report=printable1
  10. LYSANXIA 15 mg/ml, solution buvable en gouttes: product information. Base de Données Publique des Médicaments (2026). https://base-donnees-publique.medicaments.gouv.fr/medicament/60534076/extrait1

Further Reading

  1. Drug-Do: Benzos

Article Status

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