Tetrandrine in rheumatoid arthritis: Revisiting an old molecule with emerging clinical relevance

Dear Editor, Rheumatoid arthritis (RA) remains a chronic, disabling autoimmune condition that continues to challenge clinicians despite major therapeutic advances. The introduction of biologic agents and targeted synthetic drugs has undoubtedly transformed disease outcomes; however, real-world experience still reflects persistent gaps. A proportion of patients do not achieve sustained remission, others develop intolerance or adverse effects, and the economic burden of long-term therapy remains substantial. These limitations have prompted renewed attention toward alternative or adjunctive agents, particularly those with multi-target effects. In this regard, tetrandrine, a plant-derived alkaloid long used in traditional medicine, deserves closer clinical consideration.1 Tetrandrine is extracted from Stephaniatetrandra and has historically been used for inflammatory and fibrotic conditions. What makes it particularly interesting in RA is not merely its anti-inflammatory activity, but the breadth of its pharmacological effects. Unlike therapies designed to block a single cytokine or pathway, tetrandrine appears to act on several key components of RA pathogenesis simultaneously. This broader mechanism may be especially valuable in a disease characterized by complex immune dysregulation.2 From a mechanistic standpoint, tetrandrine has been shown to suppress the activity of macrophages, which are central drivers of synovial inflammation. Experimental work consistently demonstrates reduced production of pro-inflammatory cytokines such as tumor necrosis factor alpha, interleukin (IL)-1β, and IL-6 following exposure to tetrandrine. These cytokines are not only markers of disease activity but also direct contributors to joint damage. Their downregulation aligns with the clinical improvements observed in both animal models and early human studies.1 Equally noteworthy is its effect on adaptive immunity. The imbalance between Th17 cells and regulatory T cells (Treg) is now well recognized as a hallmark of RA. Tetrandrine appears to correct this imbalance by reducing Th17-mediated inflammation while enhancing Treg-associated immune regulation. This dual action is particularly relevant, as it suggests a shift not just toward symptom control but also toward restoration of immune homeostasis.3 In addition to immune modulation, tetrandrine directly affects fibroblast-like synoviocytes (FLS), which are increasingly understood to play an active role in joint destruction. These cells exhibit aggressive, tumor-like behavior in RA, contributing to cartilage degradation and bone erosion. Studies indicate that tetrandrine inhibits FLS proliferation, migration, and the expression of matrix metalloproteinases, thereby potentially limiting structural joint damage. Such findings reinforce the idea that its therapeutic effects are not confined to inflammation alone.1 While these mechanistic insights are compelling, the question of clinical relevance naturally arises. Although large-scale international trials are still lacking, several clinical studies – primarily conducted in China – provide useful preliminary data. A recent meta-analysis pooling randomized controlled trials involving tetrandrine in RA patients reported a statistically significant improvement in overall clinical effectiveness compared with control treatments. Patients receiving tetrandrine, either alone or in combination with conventional disease-modifying antirheumatic drugs (DMARDs), demonstrated reductions in erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), both of which are widely used markers of systemic inflammation.4 In addition to laboratory parameters, patient-centered outcomes also showed improvement. Measures such as joint tenderness, swelling counts, and duration of morning stiffness were consistently reduced. Pain scores, often assessed using visual analogue scales, also showed a meaningful decline. These findings suggest that tetrandrine’s biological effects translate into tangible symptomatic relief.5 However, it is important to interpret these results with some caution. While improvements in ESR and CRP were robust, changes in rheumatoid factor levels and composite disease activity indices such as DAS28 were less consistent across studies. This variability may reflect differences in study design, patient populations, or treatment duration. It also highlights the need for standardized outcome measures in future trials.4,5 Combination therapy is another area where tetrandrine shows promise. Several studies have evaluated its use alongside methotrexate or other conventional DMARDs. In these settings, tetrandrine appears to enhance therapeutic response without significantly increasing toxicity. Some reports even suggest that it may allow for dose reduction of conventional drugs, which could be beneficial in minimizing long-term adverse effects. While these findings are preliminary, they raise the possibility that tetrandrine could serve as a useful adjunct rather than a standalone therapy.1,2 Safety data, although limited, are generally reassuring. Across clinical studies, the incidence of adverse events has been relatively low, typically around 15%–20%. Most reported side effects are mild and transient, including gastrointestinal discomfort, nausea, and occasional elevations in liver enzymes. Serious adverse events appear to be rare. Nevertheless, long-term safety data are still insufficient, and careful monitoring would be essential if the drug were to be used more widely.4,6 Despite these encouraging observations, several challenges remain. One of the main limitations is the lack of large, multicenter randomized controlled trials conducted across diverse populations. Much of the current evidence is derived from relatively small studies, often with methodological heterogeneity. Differences in dosing regimens, treatment duration, and patient selection make it difficult to draw firm conclusions about optimal use.4,5 Another important consideration is pharmacokinetics. Tetrandrine has moderate oral bioavailability, which may limit its effectiveness in some patients. Advances in drug delivery systems, including nanoparticle-based formulations or liposomal carriers, could potentially address this issue by improving absorption and tissue targeting. Such approaches may enhance both efficacy and safety, but they remain largely experimental at this stage.5,6 Looking ahead, the role of tetrandrine in RA management will likely depend on the outcomes of more rigorous clinical investigations. There is a clear need for well-designed, large-scale trials that evaluate not only clinical efficacy but also long-term safety and quality-of-life outcomes. In addition, exploring its use in combination with newer targeted therapies, such as JAK inhibitors, could provide valuable insights into synergistic treatment strategies.1,3 In conclusion, tetrandrine represents an intriguing example of how traditional medicine can inform modern therapeutic development. Its multi-target mechanism, combined with emerging clinical data, suggests that it may offer benefits beyond those achieved with single-pathway interventions. While it is too early to consider tetrandrine a standard treatment for RA, the existing evidence supports further investigation. With more robust clinical validation, it may eventually find a place as part of a more integrated and individualized approach to RA management. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.