Tetrahydropalmatine — THP (Isoquinoline Alkaloid · Analgesic · Anxiolytic)

Compound	Tetrahydropalmatine (THP / L-THP)
Chemical class	Alkaloid — Isoquinoline (Tetrahydroprotoberberine)
CAS	2934-97-6
Primary source	Corydalis yanhusuo (Yan Hu Suo / Chinese corydalis)
Key applications	Analgesic, anxiolytic, sedative, dopaminergic modulation
Claim strength	Moderate
Typical form	Corydalis yanhusuo extract standardised to THP; isolated l-THP
Buy from Herbuno	Request availability and bulk pricing →

Commercial source: Tetrahydropalmatine (THP) is commercially available as a constituent of Corydalis yanhusuo rhizome extract from specialist botanical suppliers. Isolated l-THP is available from specialist suppliers. Contact Herbuno for sourcing availability. Traditional use: Corydalis yanhusuo (Yan Hu Suo, “delay the pain”) is one of the most important TCM analgesic herbs, used for over 1,000 years for pain management — dysmenorrhoea, abdominal pain, headache, chest pain, and traumatic injury. It is classified as a “blood-moving” and analgesic herb in TCM. THP is identified as the primary alkaloid responsible for Corydalis’ analgesic and sedative properties. Research trajectory: THP (specifically l-THP, the naturally occurring enantiomer) has a well-characterised pharmacology as a dopamine receptor antagonist (D1, D2), combined with GABA-A modulation. It has documented analgesic efficacy in animal models and small human clinical studies, and is used clinically in China as an analgesic pharmaceutical. See sourcing options below.

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Evidence for THP Applications

Analgesic activity: l-THP inhibits dopamine D1 and D2 receptors and modulates mu-opioid receptor activity (without direct opioid binding), producing analgesia in both acute and chronic pain animal models. In Chinese clinical use, l-THP (as the pharmaceutical Rotundine) is approved for pain management and dysmenorrhoea. The analgesic mechanism is distinct from NSAIDs (no COX inhibition) and opioids (no direct opioid receptor agonism), providing a pharmacologically differentiated pain relief mechanism. Claim strength: Moderate (pharmaceutical-approved in China; supplement context evidence limited).

Anxiolytic and sedative: THP’s GABA-A potentiation and dopamine antagonism produce anxiolytic and mild sedative effects in rodent behavioural models. Corydalis extract human studies show reduced anxiety and improved sleep quality. Relevant for sleep and stress management formulations. Claim strength: Moderate.

Cardiovascular: THP has antiarrhythmic activity (calcium channel antagonism) and mild blood pressure-lowering effects in animal models. Traditional Corydalis use for chest pain (angina) is mechanistically supported by these cardiovascular actions. Claim strength: Moderate.

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Dosage & Formulator Specification

Pharmaceutical Rotundine (l-THP) dosing in China: 30–100 mg three times daily for pain management. For Corydalis yanhusuo extract in supplement contexts: 200–600 mg/day standardised extract (typically 5–20% dehydrocorydaline or total alkaloids by HPLC). THP content varies by extract; request specific THP quantification by HPLC.

THP is light-sensitive and oxidises on exposure to air — nitrogen-flushed amber packaging is required. The l-enantiomer (naturally occurring) is the pharmacologically active form; racemic THP has reduced activity. Source botanical extracts from Corydalis yanhusuo rather than other Corydalis species for authentic THP content.

Safety note: THP’s dopamine antagonism at higher doses can produce EPS (extrapyramidal symptoms) — akathisia, tremor — similar to antipsychotic medications, though at far higher doses than therapeutic supplement use. At typical supplement doses from Corydalis extract (THP content well below pharmaceutical dosing), EPS risk is not a practical concern. Include standard advisory language for individuals on dopaminergic medications.

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Frequently Asked Questions — Tetrahydropalmatine

Is THP an opioid?
No. THP does not bind to opioid receptors as a primary mechanism. Its analgesic activity operates primarily via dopamine receptor antagonism (D1/D2) and GABA-A potentiation — pharmacologically distinct from opioid analgesia. However, some studies suggest indirect modulation of the opioidergic system through dopaminergic cross-talk, which has attracted research interest in the context of opioid addiction (THP has shown anti-addiction properties in preclinical models). THP is not a controlled substance in most jurisdictions despite its pharmacological activity.

Can THP help with opioid withdrawal?
Preclinical evidence shows THP reduces morphine conditioned place preference and withdrawal symptoms in animal models of opioid dependence, potentially via dopamine D2 receptor normalisation. This has attracted translational research interest, though no human RCTs for opioid withdrawal management have been published. Position cautiously and do not make drug substitution or addiction treatment claims in supplement contexts.

Is Corydalis yanhusuo appropriate for dysmenorrhoea formulations?
Yes — this is one of its most evidence-supported TCM applications, combining THP’s analgesic and smooth muscle-relaxing mechanisms. Co-formulation with Dong Quai (ligustilide, vasodilatory + smooth muscle modulation) and magnesium for a multi-mechanism dysmenorrhoea support product is rationally supported by both traditional use and pharmacological evidence. Position as “may support healthy menstrual comfort” consistent with the evidence level.

Is THP regulated as a controlled substance?
THP (l-THP/Rotundine) is not a scheduled controlled substance in most markets including the US, EU, UK, and India. In China, it is a registered pharmaceutical ingredient. Some online supplement marketplaces have restricted Corydalis products containing THP based on misclassification concerns, but it does not meet the pharmacological criteria for opioid scheduling. Formulators should verify current regulatory status in their specific markets before commercial distribution.

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Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.

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