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    Pentazocine molecular structure

    Pentazocine Stats & Data

    Depressant Opioid
    Talwin
    NPS DataHub
    MW285.43
    FormulaC19H27NO
    CAS359-83-1
    IUPAC(1~{R},9~{R},13~{R})-1,13-dimethyl-10-(3-methylbut-2-enyl)-10-azatricyclo[7.3.1.0^{2,7}]trideca-2(7),3,5-trien-4-ol
    SMILESCC(C)=CCN1CCC2(C)C(C)C1Cc1ccc(O)cc12
    InChIKeyVOKSWYLNZZRQPF-GDIGMMSISA-N
    Chemical Class Opioid
    Psychoactive Class Depressant

    Pharmacology

    DrugBank
    Half-life 2 to 3 hours State Solid Metabolism Hepatic

    Description

    The first mixed agonist-antagonist analgesic to be marketed. It is an agonist at the kappa and sigma opioid receptors and has a weak antagonist action at the mu receptor. (From AMA Drug Evaluations Annual, 1991, p97)

    Mechanism of Action

    The preponderance of evidence suggests that pentazocine antagonizes the opioid effects by competing for the same receptor sites, especially the opioid mu receptor.

    Pharmacodynamics

    Pentazocine is a potent analgesic which when administered orally in a 50 mg dose appears equivalent in analgesic effect to 60 mg (1 grain) of codeine. Onset of significant analgesia usually occurs between 15 and 30 minutes after oral administration, and duration of action is usually three hours or longer. Onset and duration of action and the degree of pain relief are related both to dose and the severity of pretreatment pain. Pentazocine weakly antagonizes the analgesic effects of morphine and meperidine; in addition, it produces incomplete reversal of cardiovascular, respiratory, and behavioral depression induced by morphine and meperidine. Pentazocine has about 1/50 the antagonistic activity of nalorphine. It also has sedative activity.

    Absorption

    Well absorbed from the gastro-intestinal tract.

    Indication

    For the relief of moderate to severe pain.

    Effect Profile

    Curated + 3 Reports
    Opioid 5.4

    Strong euphoria with mild sedation and itching/nausea

    Euphoria / Warmth×3
    9
    Analgesia×2
    0
    Sedation / Relaxation×1
    5
    Itching / Nausea×1
    4
    Based on reports from:
    Erowid Experience Reports PsychonautWiki Pentazocine

    Tolerance & Pharmacokinetics

    drugs.wiki

    Tolerance Decay

    Full tolerance 1d Half tolerance 21d Baseline ~35d

    Experience Report Analysis

    Erowid
    3 Reports
    2004–2019 Date Range
    1 With Age Data

    Demographics

    Gender Distribution

    Age Distribution

    Reports Over Time

    Form / Preparation

    Most common forms and preparations reported

    Opioid Equivalence (MME)

    NIH HEAL 2024 & CDC 2022
    ⚠ Citation & Disclaimer: Conversion factors sourced from the NIH HEAL Initiative MME Calculator (Adams et al., PAIN 2025), the CDC 2022 Clinical Practice Guideline for Prescribing Opioids for Pain, and the MDCalc MME Calculator. These are approximate equianalgesic ratios for educational reference only. Individual responses vary significantly based on genetics, tolerance, cross-tolerance, and route of administration. This is not medical advice. Do not use these conversions to adjust opioid dosing without professional medical guidance.
    27 mg Pentazocine ≈ 10 mg Morphine (oral)
    MME factor 0.37×

    Pentazocine 27 mg oral ≈ 10 mg Morphine oral

    ⓘ Mixed agonist-antagonist. Evidence level: Low (C).
    Read full reports on Erowid →
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