Metformin and herbal supplements
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Metformin Adulteration in Herbal Supplements
Metformin, a widely used antidiabetic drug, has been found as an undeclared adulterant in various herbal and dietary supplements, especially those marketed for diabetes management. Analytical methods have been developed to detect metformin in these products, revealing its presence in some market samples, which raises concerns about product safety and transparency for consumers using herbal remedies for diabetes 13.
Pharmacokinetic and Pharmacodynamic Interactions: Metformin and Herbal Supplements
Effects of Herbal Supplements on Metformin Pharmacokinetics
Several herbal supplements, including Korean ginseng, Lonicera japonica, Houttuynia cordata, mulberry, banana, Momordica charantia, coconut, and Scutellaria baicalensis, can interact with metformin at the pharmacokinetic level. These interactions may increase metformin uptake in the plasma by inhibiting MATE1 and increasing OCT1 activity, or decrease its uptake in the kidneys by inhibiting hOCT2. Such changes can potentially alter the drug’s effectiveness and safety profile .
Specifically, long-term co-administration of ginseng berry extract with metformin in animal studies increased metformin concentrations in the liver, the main target organ for its glucose-lowering effect, without significantly affecting its levels in the blood or kidneys. This suggests that certain herbal supplements may enhance metformin’s action in the liver while not increasing its systemic toxicity .
Pharmacodynamic Synergy and Additive Effects
Combining metformin with various herbal supplements often results in additive or synergistic effects in lowering blood glucose levels. For example, Swietenine, a compound from Swietenia macrophylla seeds, showed a synergistic effect with metformin in reducing blood glucose and improving antioxidant status in diabetic rats . Similarly, a combination of herbal extracts like cinnamon and fenugreek demonstrated hypoglycemic effects, though metformin alone was more effective in animal studies .
Clinical Efficacy: Herbal Formulations Versus Metformin
Randomized clinical trials have compared the efficacy of proprietary herbal formulations with metformin. For instance, GlycaCare-II, a multi-herb supplement, was found to be as effective as metformin in managing blood sugar levels in both prediabetic and newly diagnosed diabetic patients, with some parameters even showing better improvement with the herbal formulation. No significant adverse events were reported, suggesting a favorable safety profile .
Gut Microbiota Modulation: Combined Metformin and Herbal Therapy
Both metformin and certain Chinese herbal formulas can beneficially alter the gut microbiota in people with type 2 diabetes. Combined therapy has been shown to increase beneficial bacteria such as Bifidobacterium, Lactobacillus, and Blautia, while reducing potentially harmful bacteria. These changes are associated with improved blood glucose control and insulin sensitivity. Some herbal formulas may have a stronger effect on gut microbiota and metabolic parameters than metformin alone 79.
Enhanced Antioxidant and Metabolic Benefits
Combining metformin with specific herbal compounds, such as the SPTC mix (Salvia officinalis, Panax ginseng, Trigonella foenum-graeceum, and Cinnamomum zeylanicum), has been shown in animal studies to more effectively reduce diabetic complications and oxidative stress than either treatment alone. This combination activates the Nrf2 pathway, which is important for cellular antioxidant defense, suggesting a potential for improved management of diabetes-related oxidative damage .
Conclusion
Research indicates that herbal supplements can interact with metformin in both beneficial and potentially risky ways. Some herbal products may enhance metformin’s glucose-lowering effects and improve metabolic health, especially when used in combination. However, the risk of undeclared metformin adulteration in herbal supplements remains a concern. Careful monitoring, quality control, and further clinical studies are needed to ensure the safety and efficacy of combining metformin with herbal supplements for diabetes management 12345678+2 MORE.
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