L-THP is the left-handed form of tetrahydropalmatine, an alkaloid from Corydalis and Stephania plants whose preparations have long been used for sedation and pain relief.
Amounts reported for L-THP are listed under Reported protocols, each with its source and study kind. No amount ladder is inferred from them. This is educational source context, not a protocol or recommendation.
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Human study rows are described per source under Reported protocols; they belong to their trial populations and are not a general amount.
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What published studies and recent community write-ups report about amounts, timing and course length. 5 clinical, 1 preclinical and 1 community-reported rows, each linked to its source. These are descriptions of what others report, not instructions, and nothing here is medical advice.
| Context | Dose | Frequency | Route | Course | Source |
|---|---|---|---|---|---|
| Clinical5 rows | |||||
| Safety and pharmacokinetics with a cocaine challenge24 adult men who use cocaine, randomised double-blind; 20 completed and 19 gave full pharmacokinetic data | 30 mg twice daily (60 mg per day) | Twice daily | Oral capsules | A 3.5 day course, with an intranasal cocaine challenge of 40 mg on day 4Not applicable | Journal of Clinical Pharmacology (PubMed Central)2017 |
| The short course was safe and well tolerated, did not change cocaine's pharmacokinetics and did not change its acute cardiovascular effects, with no difference in side-effect counts against placebo. The authors chose 30 mg twice daily specifically to stay below the amounts where sedation appears, and the study was designed to test safety rather than whether the drug reduces cocaine use. | |||||
| Randomised trial in heroin dependence120 heroin-dependent inpatients, randomised double-blind against placebo | Two 30 mg tablets twice daily (120 mg per day) | Twice daily | Oral tablets | 4 weeks of treatment, 4 weeks of observation, then 3 months of follow-up after dischargeNone described | Acta Pharmacologica Sinica (PubMed Central)2008 |
| Four weeks of treatment reduced the severity of protracted withdrawal, including physical symptoms, mood, insomnia and craving, and among those who stayed in the programme past the first two weeks the abstinence rate at three months was 47.8 percent against 15.2 percent on placebo. The paper calls itself a pilot study, the dose was deliberately kept low to limit liver risk and the figures come from one site. | |||||
| Long-standing approved use in China, reviewedPatients treated under the Chinese drug name Rotundine | Sedation is described as appearing above roughly 100 mg per 70 kg of body weight, which is why trial doses sit below that | Not stated | Oral | In use as an approved medicine for more than 40 yearsNot described | Future Medicinal Chemistry (PubMed Central)2012 |
| This review sets out the case for developing L-THP as an addiction medicine and notes it is already approved and marketed in China as Rotundine or Rotundin for analgesia and sedation. It is candid about the problem that the sedative and reward-blunting effects of a dopamine antagonist can interfere with the very behaviours being measured, and about the regulatory work a United States approval would need. | |||||
| Trial in schizophrenia63 participants randomised to L-THP or placebo | 30 mg twice daily | Twice daily | Oral | The registered study ran from September 2014Not described | ClinicalTrials.gov2014 |
| Registered at the Maryland Psychiatric Research Center on the reasoning that L-THP is a dopamine antagonist with anti-inflammatory and antiprotozoal activity, with positive and negative symptom improvement as the primary outcome. The record is marked completed with no results posted, so the dose and design are public but the findings are not. | |||||
| Multi-ingredient pain formula trial27 healthy adults aged 22 to 63 with unresolved non-pathological aches, in a crossover design | 2 capsules daily of a 10-ingredient formula containing L-THP; the paper does not state the L-THP amount | Daily | Oral capsules | Three 7-day periods separated by 7-day washouts7-day washout between periods | Nutrients (PubMed Central)2020 |
| The formula scored better than 325 mg of acetaminophen on worst-pain scores and reduced musculoskeletal discomfort totals after a week. L-THP is only one of ten ingredients alongside B vitamins, white willow bark, Angelica root, acetyl L-carnitine, caffeine, L-theanine and benfotiamine, so nothing in this result can be attributed to L-THP on its own, and an employee of the product's maker was an author. | |||||
| Preclinical1 row | |||||
| Reinstatement of cocaine seeking in ratsMale Sprague-Dawley rats trained to self-administer cocaine, then extinguished | 3.0 or 10.0 mg/kg | Single dose, one hour before each test | Oral gavage | Single-dose test sessionsNot applicable | Drug and Alcohol Dependence (PubMed Central)2011 |
| Both doses blocked the return of drug-seeking triggered by a cocaine challenge, by footshock stress and by drug-associated cues. At 10 mg/kg the animals also responded less for food, which suggests general sedation, while at 3 mg/kg they did not, so the lower dose is the cleaner result. These are rat amounts given by gavage and they do not convert to a human dose. | |||||
| Community-reported1 row | |||||
| Vendor capsule product | 50 mg per capsule, 60 capsules per bottle | Not stated | Oral capsule | Not stated | Community resource2026 |
| A vendor claim about what ships, not a protocol. The 50 mg capsule strength sits above the 30 mg used in both human studies and close to the roughly 100 mg per 70 kg point where the reviews place the onset of sedation. The listing states the material is not for human use. | |||||
Plus 2 community resources (dosing guides, forum threads and vendor write-ups), reported above but not linked.
L-THP is the left-handed form of tetrahydropalmatine, an alkaloid from Corydalis and Stephania plants whose preparations have long been used for sedation and pain relief. Purified or synthetic L-THP has been sold in China as Rotundine for more than forty years as an analgesic and sedative, and its pharmacology is unusual for a plant compound: it blocks dopamine D1 and D2 receptors and also acts at D3, alpha-adrenergic and serotonin receptors. That profile drew interest in addiction medicine, and human studies have given 30 mg twice daily to cocaine users and four weeks of treatment to heroin users, alongside rat work showing it blocks cocaine-seeking triggered by drug, stress or cues.
These themes describe recurring questions in published research. They are not claims of effectiveness or recommendations for use.
Neuroplasticity, cognition, stress and sleep models.
The short course was safe and well tolerated, did not change cocaine's pharmacokinetics and did not change its acute cardiovascular effects, with no difference in side-effect counts against placebo. The authors chose.
Four weeks of treatment reduced the severity of protracted withdrawal, including physical symptoms, mood, insomnia and craving, and among those who stayed in the programme past the first two weeks the abstinence rate.
This review sets out the case for developing L-THP as an addiction medicine and notes it is already approved and marketed in China as Rotundine or Rotundin for analgesia and sedation. It is candid about the problem.
Registered at the Maryland Psychiatric Research Center on the reasoning that L-THP is a dopamine antagonist with anti-inflammatory and antiprotozoal activity, with positive and negative symptom improvement as the.
The formula scored better than 325 mg of acetaminophen on worst-pain scores and reduced musculoskeletal discomfort totals after a week. L-THP is only one of ten ingredients alongside B vitamins, white willow bark.
Study models remain visible so laboratory and animal findings are not mistaken for established human outcomes.
5 protocol rows on this page come from human trials, trial registrations, regulator labels or reviews of human data. Approval status and populations are stated per row.
1 protocol row describe animal, cell or toxicology work. Amounts from these rows do not translate to people.
1 row record what blogs, vendor write-ups or forums describe for L-THP. None has been verified against primary literature.
Sequence, synonyms and registry identifiers as recorded in PubChem, the National Library of Medicine's open chemistry database. Formula, mass and CAS number are summarized at the top of the page.
levo-Tetrahydropalmatine, (-)-Tetrahydropalmatine, Rotundine, (-)-rotundine, Gindarine, Hyndarine, (-)-Corydalis B, UNII 3X69CO5I79
AEQDJSLRWYMAQI-KRWDZBQOSA-N
(13aS)-2,3,9,10-tetramethoxy-6,8,13,13a-tetrahydro-5H-isoquinolino[2,1-b]isoquinoline
7 curated references, each with its journal, year and study model, plus 2 community resources reported but not linked.