Tetrandrine

Pharmacology & Research

Tetrandrine is a bis-benzylisoquinoline alkaloid from Stephania tetrandra (Han Fang Ji) and Abuta — and unusually for a Tier-B constituent, it has genuine pharmacology and real Chinese clinical use. Its defining mechanism is non-selective (L-type) calcium-channel blockade, giving vasodilation and smooth-muscle relaxation, and it has been used in China for hypertension and — for decades — for silicosis as an antifibrotic ^{10,5Reference 102002Cardiovascular pharmacological effects of bisbenzylisoquinoline alkaloid derivativesView study →Reference 52021Thirteen bisbenzylisoquinoline alkaloids in five Chinese medicinal plants: botany, traditional uses, phytochemistry, pharmacokinetics and toxicityView study →}. Two things must frame the page. First, its interesting mechanisms (two-pore-channel blockade, P-glycoprotein inhibition) are largely preclinical, and the anticancer concentrations “far exceed whole-plant content, so results rest on the concentrated isolate, not the decoction” ^{6Reference 62022Tetrandrine overcomes drug resistance mediated by the bone-marrow microenvironment by regulating P-glycoprotein expression in acute leukemiaView study →}. Second, and load-bearing for safety: “Han Fang Ji” (Stephania tetrandra) has historically been confused with or substituted by “Guang Fang Ji” (Aristolochia fangchi) — the source of the notorious aristolochic-acid nephropathy — a sourcing hazard that is not tetrandrine’s own chemistry but is unavoidable context for any Fang-Ji material ^{7Reference 7Nortier JL et al. · 2000Urothelial carcinoma associated with the use of a Chinese herb (Aristolochia fangchi)View study →}.

1. Cardiovascular (Ca-channel)

Tetrandrine is a genuine non-selective L-type calcium-channel blocker producing vasodilation, negative inotropy/chronotropy and pulmonary-artery smooth-muscle relaxation, and it has been used in China as an antihypertensive and antianginal ^{10,11,5Reference 102002Cardiovascular pharmacological effects of bisbenzylisoquinoline alkaloid derivativesView study →Reference 112002Effects of tetrandrine on smooth-muscle contraction induced by mediators in pulmonary hypertensionView study →Reference 52021Thirteen bisbenzylisoquinoline alkaloids in five Chinese medicinal plants: botany, traditional uses, phytochemistry, pharmacokinetics and toxicityView study →}.

Gap: the clinical evidence is old, small, largely Chinese-language and below modern RCT standards, with no Western regulatory approval ^{5Reference 52021Thirteen bisbenzylisoquinoline alkaloids in five Chinese medicinal plants: botany, traditional uses, phytochemistry, pharmacokinetics and toxicityView study →}.

2. Silicosis / pulmonary fibrosis

Tetrandrine has decades of clinical use in China as an antifibrotic for silicosis, and a 2025 retrospective cohort reported slowed HRCT progression and lung-function decline in artificial-stone silicosis ^{4Reference 42025ObservationalTetrandrine slows disease progression on HRCT and lung-function decline in artificial-stone-associated silicosis: a retrospective cohort studyView study →}; it is also studied in connective-tissue-disease-associated interstitial lung disease ^{2Reference 22025The immunoregulatory function and therapeutic potential of tetrandrine in connective-tissue-disease-associated interstitial lung diseaseView study →}.

Gap: the evidence is observational, not randomised, and paradoxical — the same lung accumulation that may help fibrosis also drives pulmonary toxicity (see Safety) ^{4,12Reference 42025ObservationalTetrandrine slows disease progression on HRCT and lung-function decline in artificial-stone-associated silicosis: a retrospective cohort studyView study →Reference 122011AnimalPulmonary toxicity and metabolic activation of tetrandrine in CD-1 miceView study →}.

3. Anti-inflammatory / arthritis

Tetrandrine suppresses articular inflammatory cytokines via NF-κB inactivation in rodent arthritis ^{14Reference 142016Tetrandrine suppresses the articular inflammatory response by inhibiting pro-inflammatory factors via NF-κB inactivationView study →} and downregulates IKK–IκBα–NF-κB signalling in human T cells ^{13Reference 132004The plant alkaloid tetrandrine downregulates the IκB-kinase–IκBα–NF-κB signalling pathway in human peripheral-blood T cellsView study →}.

Gap: there are no arthritis clinical trials of the isolated molecule — the human data are cell-level only ^{13Reference 132004The plant alkaloid tetrandrine downregulates the IκB-kinase–IκBα–NF-κB signalling pathway in human peripheral-blood T cellsView study →}.

4. MDR reversal (cancer)

Tetrandrine inhibits P-glycoprotein (ABCB1), re-sensitising resistant leukemia and tumour cells to chemotherapy, and has been explored as a chemo-sensitiser ^{6Reference 62022Tetrandrine overcomes drug resistance mediated by the bone-marrow microenvironment by regulating P-glycoprotein expression in acute leukemiaView study →}.

Gap: mostly in-vitro and animal, with human oncology use still investigational ^{6Reference 62022Tetrandrine overcomes drug resistance mediated by the bone-marrow microenvironment by regulating P-glycoprotein expression in acute leukemiaView study →}.

5. Antiviral (preclinical)

Landmark work identified the endolysosomal two-pore channel TPC2 as required for Ebola entry and blocked by tetrandrine ^{1Reference 1Sakurai Y et al. · 2015Two-pore channels control Ebola virus host-cell entry and are drug targets for disease treatmentView study →}, and PBPK modelling has been done for SARS-CoV-2 repurposing ^{3Reference 32024Quantitative pulmonary pharmacokinetics of tetrandrine for SARS-CoV-2 repurposing: a physiologically-based pharmacokinetic modelling approachView study →}.

Gap: no antiviral efficacy in humans, and the effective concentrations may exceed a safe systemic window — strictly preclinical ^{1,3Reference 1Sakurai Y et al. · 2015Two-pore channels control Ebola virus host-cell entry and are drug targets for disease treatmentView study →Reference 32024Quantitative pulmonary pharmacokinetics of tetrandrine for SARS-CoV-2 repurposing: a physiologically-based pharmacokinetic modelling approachView study →}.

6. Autophagy / anticancer

Tetrandrine modulates autophagy and induces ROS/ER-stress-mediated cell death — for example in melanoma via SIRT5 ^{15Reference 152024Tetrandrine targeting SIRT5 exerts anti-melanoma properties via inducing ROS, ER stress and blocked autophagyView study →}.

Gap: cell-line pharmacology only, with the direction of the autophagy effect context-dependent ^{15Reference 152024Tetrandrine targeting SIRT5 exerts anti-melanoma properties via inducing ROS, ER stress and blocked autophagyView study →}.

Mechanisms

Target / pathway	Effect	Relevant to
L-type voltage-gated Ca²⁺ channel (block)	vasodilation, negative inotropy, smooth-muscle relaxation	antihypertensive / antiarrhythmic
Two-pore channel TPC2 (endolysosomal Ca²⁺, block)	blocks viral endosomal escape	antiviral (Ebola, preclinical)
P-glycoprotein / ABCB1 (inhibition)	raises intracellular drug/co-drug levels	MDR reversal; drug interactions
IKK–IκBα–NF-κB (inhibition)	↓ pro-inflammatory cytokines	anti-inflammatory, arthritis, antifibrotic

Pharmacokinetics

Load-bearing. Tetrandrine has poor aqueous solubility and low, variable oral bioavailability — enough of a limitation that much recent work is on nanoformulations to improve absorption ^{9Reference 92024Advances in nano-preparations for improving tetrandrine solubility and bioavailabilityView study →}. It undergoes hepatic (CYP-mediated) metabolism, including metabolic activation to reactive intermediates implicated in its organ toxicity ^{12Reference 122011AnimalPulmonary toxicity and metabolic activation of tetrandrine in CD-1 miceView study →}, and it distributes widely with notable accumulation in the lung and liver — a PBPK model built for SARS-CoV-2 repurposing highlighted high pulmonary tissue concentrations ^{3Reference 32024Quantitative pulmonary pharmacokinetics of tetrandrine for SARS-CoV-2 repurposing: a physiologically-based pharmacokinetic modelling approachView study →}. That lung/liver tropism is the pharmacokinetic basis for both its pulmonary/hepatic use and its pulmonary/hepatic toxicity ^{5Reference 52021Thirteen bisbenzylisoquinoline alkaloids in five Chinese medicinal plants: botany, traditional uses, phytochemistry, pharmacokinetics and toxicityView study →}.

Clinical trials

Real Chinese clinical use exists for silicosis (as an antifibrotic) and for hypertension/angina, but most supporting trials are older, Chinese-language, small, non-randomised or of variable quality, with no modern Western RCTs and no Western regulatory approval. The most concrete recent human evidence is a 2025 retrospective cohort in artificial-stone silicosis ^{4Reference 42025ObservationalTetrandrine slows disease progression on HRCT and lung-function decline in artificial-stone-associated silicosis: a retrospective cohort studyView study →}, plus mechanistic/repurposing modelling for lung disease and COVID-19 ^{2,3Reference 22025The immunoregulatory function and therapeutic potential of tetrandrine in connective-tissue-disease-associated interstitial lung diseaseView study →Reference 32024Quantitative pulmonary pharmacokinetics of tetrandrine for SARS-CoV-2 repurposing: a physiologically-based pharmacokinetic modelling approachView study →}. Oncology (MDR reversal) and antiviral uses remain investigational/preclinical.

Last checked: July 2026.

Toxicity & Safety

Tetrandrine carries real, dose-dependent toxicity plus a serious sourcing hazard — hence the moderate flag. It accumulates in lung tissue and is metabolically activated to reactive species, and a controlled mouse study demonstrated dose-related pulmonary toxicity (with phospholipidosis-type concerns on chronic dosing) — the same lung tropism that underlies its silicosis use ^{12Reference 122011AnimalPulmonary toxicity and metabolic activation of tetrandrine in CD-1 miceView study →}. Hepatic accumulation and CYP-mediated bioactivation confer a dose-dependent liver-toxicity risk at high exposure ^{5,12Reference 52021Thirteen bisbenzylisoquinoline alkaloids in five Chinese medicinal plants: botany, traditional uses, phytochemistry, pharmacokinetics and toxicityView study →Reference 122011AnimalPulmonary toxicity and metabolic activation of tetrandrine in CD-1 miceView study →}.

The load-bearing safety-context point is species confusion: “Han Fang Ji” (Stephania tetrandra, the tetrandrine source) has historically been confused with or substituted by “Guang Fang Ji” (Aristolochia fangchi), and the infamous Belgian slimming-clinic nephropathy — aristolochic-acid nephropathy, including urothelial carcinoma — was caused by the Aristolochia substitution, NOT by tetrandrine ^{7,8Reference 7Nortier JL et al. · 2000Urothelial carcinoma associated with the use of a Chinese herb (Aristolochia fangchi)View study →Reference 82015Aristolochic-acid nephropathy (“Chinese herb nephropathy”)View study →}. Tetrandrine is chemically unrelated to aristolochic acid and is not nephrotoxic/carcinogenic in that way, but the botanical-substitution hazard is genuine and unavoidable: real-world Fang-Ji product may carry aristolochic acid. As a P-glycoprotein (and likely CYP) inhibitor, tetrandrine can also raise blood levels of co-administered P-gp/CYP-substrate drugs, and additive hypotension with antihypertensives is plausible ^{6,5Reference 62022Tetrandrine overcomes drug resistance mediated by the bone-marrow microenvironment by regulating P-glycoprotein expression in acute leukemiaView study →Reference 52021Thirteen bisbenzylisoquinoline alkaloids in five Chinese medicinal plants: botany, traditional uses, phytochemistry, pharmacokinetics and toxicityView study →}.

Pregnancy & lactation

Avoid. Bis-benzylisoquinoline alkaloids carry embryotoxicity/reproductive concern, there are no adequate human safety data, and the Fang-Ji adulteration risk compounds it — not for use in pregnancy or lactation.

Dosage

There is no validated supplement dose, and nothing here is a recommendation. In Chinese clinical practice tetrandrine tablets have been used orally in roughly the 60–120 mg/day range (divided doses) for silicosis and cardiovascular indications ^{5Reference 52021Thirteen bisbenzylisoquinoline alkaloids in five Chinese medicinal plants: botany, traditional uses, phytochemistry, pharmacokinetics and toxicityView study →}; the anticancer/MDR and antiviral concentrations studied preclinically are substantially higher and not shown to be safely achievable systemically in humans. Any Fang-Ji-sourced material must be verified free of aristolochic acid.

References