Renal disorders, including nephrolithiasis and acute kidney injury (AKI), pose a substantial and escalating burden on global healthcare systems. These conditions not only cause considerable morbidity and mortality but also significantly impact the quality of life and healthcare expenditures.

Nephrolithiasis affects approximately 10%–15% of the global population, and incidences are increasing due to sedentary lifestyles, dietary habits, and climate-related dehydration. It is associated with high recurrence rates, pain, urinary obstruction, and risk of renal impairment if untreated (Tamborino et al., 2024). In many regions, especially in Asia and the Middle East, the prevalence is even higher, reaching up to 20% in certain populations (Kidney stone pathophysiology, evaluation, and management, 2023). Moreover, stone recurrence rates are high, with approximately 50% of patients experiencing a second episode within 5 years, despite treatment (Balawender et al., 2024).

Acute kidney injury, on the other hand, is characterised by a sudden decline in renal function, leading to electrolyte imbalance, metabolic acidosis, fluid overload, and accumulation of nitrogenous wastes, with mortality rates ranging from 10% to over 50%, depending on the severity and comorbid conditions (Martin, 2010). Survivors of AKI are also at increased risk of developing chronic kidney disease (CKD), which further complicates long-term health outcomes.

Despite the availability of pharmacological and surgical interventions, current treatment options for both nephrolithiasis and AKI have several limitations. In the case of kidney stones, alkalising agents, thiazide diuretics, and extracorporeal shock wave lithotripsy (ESWL) are commonly used. However, these approaches often fail to prevent recurrence, and ESWL can cause tissue damage and renal scarring (Loftus et al., 2016). Similarly, in AKI management, the mainstays of therapy include fluid resuscitation, dialysis, and supportive care, which are non-curative and are aimed only at mitigating complications and stabilising the patient. There are no approved nephroprotective drugs that can effectively reverse or prevent AKI (Rumana et al., 2024).

The increasing burden of CKD and AKI has intensified the search for effective nephroprotective therapies, including those derived from traditional medicine (Tamargo et al., 2024). In addition, the shortcomings of current treatment options have fuelled a growing interest in complementary and alternative medicine (CAM) approaches, especially herbal therapies, which have been traditionally used in various cultures to support renal function and treat urinary ailments. Herbal formulations are recognised for their multifaceted mechanisms of action, including antioxidant, anti-inflammatory, antimicrobial, and diuretic effects, which are particularly relevant in mitigating renal injury and stone formation (Kang et al., 2021; Lu et al., 2024). Moreover, herbal drugs tend to have fewer adverse effects, are often more cost-effective, and can be used chronically without significant toxicity (Butterweck and Khan, 2009; Josa et al., 2024).

Revstone®, a polyherbal formulation available as a capsule and syrup, is designed to promote renal health and prevent kidney impairment. Its composition includes herbs reputed for their renoprotective properties.

The current study was designed to evaluate both the acute oral toxicity and renoprotective efficacy of Revstone® in a preclinical setting using Wistar rats. A well-established experimental model of nephrotoxicity, often induced by chemical agents such as gentamicin, was used to simulate kidney injury. Both capsule and syrup forms of Revstone® were tested to assess any formulation-dependent differences in efficacy or safety. Through this comparative approach, the study aims to provide evidence for the nephroprotective potential of Revstone®.

The acute oral toxicity study was conducted to evaluate the safety profile of Revstone ^® syrup and capsule formulations following a single-dose administration in Wistar rats. This assessment is a critical component of preclinical evaluation, intended to identify potential toxic effects and determine the safe dose range before initiating efficacy or chronic toxicity studies. The study was performed in accordance with OECD guideline 423, which utilises a stepwise dosing procedure uses minimal animal numbers, and allows estimation of the LD₅₀ range.

Throughout the 14-day observation period, no mortality or treatment-related clinical signs of toxicity were observed in any of the test groups at the administered dose levels of both capsule and syrup formulations. Animals maintained normal behaviour, feeding patterns, and physiological activity. There were no significant changes in body weight gain, indicating the absence of systemic toxicity or metabolic disturbances. This is important because body weight loss of more than 10% in toxicity studies is often considered a sign of adverse effects (OECD, 2001).

Post-mortem gross necropsy revealed no visible pathological changes in vital organs such as the liver, kidneys, heart, lungs, or gastrointestinal tract, indicating that the test formulations did not induce any overt organ-specific toxicity. These findings indicate that Revstone ^® formulations, in both syrup and capsule forms, are well-tolerated and non-toxic at the doses tested.

The absence of acute toxicity indicates that the herbal components of Revstone ^® are safe at the therapeutic and possibly higher doses.

We conducted the acute toxicity study because herbal formulations typically contain multiple phytoconstituents with a wide margin of safety, especially when used in traditional medicine systems, but they also contain minerals and metals in minor quantities. However, it is important to validate their safety through controlled studies to support regulatory compliance and rational clinical use (Khajuria and Jude, 2023).

Overall, the results of the acute toxicity study indicate that Revstone ^® formulations do not produce any immediate toxic effects and are safe for further evaluation in subacute and efficacy studies.

The efficacy study was conducted to evaluate the renoprotective potential of Revstone ^® formulations (syrup and capsule) in a rat model of gentamicin-induced nephrotoxicity. Gentamicin, a commonly used aminoglycoside antibiotic, is well-documented for its nephrotoxic effects, particularly when administered in high doses or over prolonged durations (Bencheikh et al., 2021). The nephrotoxicity primarily results from the accumulation of gentamicin in the renal proximal tubules, where it induces oxidative stress, mitochondrial dysfunction, and apoptosis, ultimately leading to acute tubular necrosis (Klementa et al., 2025).

In this study, repeated administration of gentamicin 80 mg/kg i.p. for 7 days produced significant renal injury, as evidenced by elevated serum creatinine, BUN, and uric acid levels. These biochemical alterations reflect compromised glomerular filtration and tubular reabsorption, which are hallmark features of renal dysfunction (Randjelovic et al., 2017). Additionally, histopathological examination revealed prominent morphological changes, including tubular epithelial degeneration, glomerular shrinkage, and interstitial inflammatory infiltration, which are consistent with previous reports on gentamicin-induced kidney damage (Bencheikh et al., 2021). Oxidative stress is one of the major contributing factors to gentamicin-induced nephrotoxicity. Gentamicin enhances the production of reactive oxygen species, which damage cellular lipids, proteins, and DNA, leading to membrane disruption and cell death. In this context, increased MDA levels serve as a marker of lipid peroxidation, while decreased activities of endogenous antioxidants such as SOD and CAT indicate impaired antioxidant defence mechanisms (Balakumar et al., 2010).

Treatment with Revstone ^® formulations resulted in marked improvement in renal function parameters. Both syrup and capsule forms, particularly at higher doses, significantly reduced serum creatinine, BUN, and uric acid levels compared to those in the disease control group (Table 5). These findings indicate the restoration of glomerular filtration and overall renal function. Furthermore, the histopathological evaluation of renal tissue showed a notable reduction in tubular necrosis, cellular degeneration, and inflammation in the treatment groups, indicating structural preservation of the kidney (Figures 2, 3). Revstone ^® reduced the inflammatory markers TNF-α and interleukin-6, demonstrating its anti-inflammatory effects (Figure 4). In addition, its antioxidant potential was evident from its impact on oxidative stress markers (Table 6).

Revstone ^® capsule contains nano curcumin, patharchatta, patherpori, punarnava, ushira, varuna, guggul, gokharu, dhaniya, pashanbheda, cowrie shells, shuddha shilajit, daruharidra, shwet chandan, makoy, ber patthar, shatavari, khadir, salam mishri, and lata karanja.

The combination of these botanicals and mineral preparations offers renoprotection through multiple complementary mechanisms. Nano curcumin (Curcuma longa), daruharidra (Berberis aristata), makoy (Solanum nigrum), shatavari (Asparagus racemosus), and khadir (Acacia catechu) provide potent antioxidant and anti-inflammatory effects, thus reducing oxidative stress, apoptosis, and fibrosis in renal tissues (Ramesh and Radhakrishnan, 2010; Trujillo et al., 2013). Patharchatta (Bryophyllum pinnatum) (Pandhare et al., 2021), patherpori (Didymocarpus pedicellata), varuna (Crataeva nurvala), pashanbheda (Saxifraga granulata), and gokharu (Tribulus terrestris) exhibit anti-urolithiatic activity, thus preventing crystal deposition, dissolving calculi, and protecting renal tubular epithelium (Singh et al., 2025). Punarnava (Boerhavia diffusa) and ushira (Vetiveria zizanioides) act as diuretics and anti-inflammatory agents, thus improving glomerular function and reducing proteinuria (Shivananjappa, 2021). Guggul (Boswellia serrata) and lata karanja (Caesalpinia crista) inhibit pro-inflammatory mediators and protect against renal fibrosis (Zanin et al., 2012; Abdel-Tawab et al., 2011). Mineral-based agents such as shuddha shilajit (asphaltum) and cowrie shells (Cypraea moneta) contribute adaptogenic and alkalinising effects, supporting renal resilience (Senturk et al., 2008). Additional herbs such as dhaniya (Coriandrum sativum), shwet chandan (Santalum album), ber patthar (Aegle marmelos), and salam mishri (Polygonatum cirrhifolium) provide supportive antioxidant, cytoprotective, and rejuvenating properties (Tsai et al., 2024). Collectively, these agents protect the kidneys by reducing oxidative stress, inflammation, and fibrosis; preventing lithiasis; enhancing diuresis; and restoring renal function, thus demonstrating a holistic renoprotective potential.

Capsule formulation rich in classical Ayurvedic renal herbs such as punarnava, varuna, gokhru, and patharchatta, along with shilajit and antioxidants such as curcumin and daruharidra, emphasises chronic kidney protection through antioxidant, anti-fibrotic, diuretic, and nephroprotective actions, making it suitable for CKD, proteinuria, and toxin-induced nephropathy.

Revstone ^® syrup contains betel leaf, cinnamon, clove, cardamom, catechu, black pepper, curcumin, patharchatta, cowrie shells, punarnava, gokhru, varuna, hansraj, key lime, and calcium oxide.

Many of these herbal and mineral agents exhibit synergistic renoprotective effects through antioxidant, anti-inflammatory, and anti-urolithiatic mechanisms. Betel leaf (Piper betle), cinnamon (Cinnamomum verum), clove (Syzygium aromaticum), cardamom (Elettaria cardamomum), and black pepper (Piper nigrum) are rich in polyphenols and essential oils that provide antioxidant, antimicrobial, and anti-inflammatory activity, thus protecting renal tissue from oxidative and infectious insults (Fazal et al., 2014; Tjandrawinata et al., 2026). Catechu (Senegalia catechu) and curcumin (Curcuma longa) exert strong free-radical scavenging and antifibrotic effects, reducing nephrotoxic injury¹⁸ (Trujillo et al., 2013). Patharchatta (Bryophyllum pinnatum), punarnava (Boerhavia diffusa), gokhru (Tribulus terrestris), and varuna (Crataeva nurvala) demonstrate anti-urolithiatic and diuretic activities, thereby preventing stone formation, enhancing urinary excretion, and restoring renal histology (Varalakshmi et al., 1990). Hansraj (Adiantum capillus-veneris) and key lime (Citrus aurantifolia) contribute additional antioxidant and litholytic effects and are useful in nephrolithiasis (Nazim et al., 2018). Cowrie shells (Monetaria moneta) and calcium oxide preparations are traditionally used for urinary alkalinisation and litholysis, thereby reducing crystal aggregation and supporting renal function. Collectively, this formulation offers renal protection by neutralising oxidative stress, reducing inflammation, preventing lithiasis, and improving urinary parameters, thereby preserving kidney function. In the syrup preparation, selected renal herbs and alkalinisers, such as cowrie shells and calcium oxide, are used for urolithiasis prevention, urinary alkalinisation, antimicrobial action, and metabolic support, making it more useful in kidney stone management and early renal protection.

The protective effects observed may be attributed to the phytoconstituents present in Revstone ^® , which likely exert antioxidant, anti-inflammatory, and cytoprotective activities. Herbal formulations often contain flavonoids, polyphenols, terpenoids, and other bioactive compounds that can scavenge free radicals, enhance antioxidant enzyme activities, and modulate inflammatory pathways (Vardi et al., 2005; Ghaznavi et al., 2015). The reduction in MDA levels along with a significant elevation in SOD and CAT activities in the Revstone ^® -treated groups supports this hypothesis (Table 6). These findings are consistent with earlier studies in which phytotherapeutic agents such as curcumin, silymarin, and glycyrrhizin conferred nephroprotection through similar mechanisms (Cuzzocrea et al., 2000).

The efficacy of Revstone ^® formulations was found to be comparable to that of the standard drug valsartan, an angiotensin II receptor blocker known for its nephroprotective effects. Valsartan not only reduces intra-glomerular pressure but also possesses antioxidant properties that protect renal tissues against oxidative stress and inflammation.

Although this study provides promising evidence of Revstone ^® ’s nephroprotective action, further studies are needed to isolate and characterise the active phytoconstituents responsible for these effects. Additionally, evaluation in chronic renal injury models and molecular studies targeting oxidative and inflammatory pathways would offer deeper insights into the mechanisms of action and therapeutic applicability in clinical settings.

The findings of the study indicate that Revstone ^® exhibits significant renoprotective activity, which may be attributed to its anti-inflammatory and antioxidant properties. By reducing pro-inflammatory cytokines such as TNF-α and IL-6 and attenuating oxidative stress, Revstone ^® helps preserve renal function and minimise tissue damage. Revstone ^® syrup preparation was more effective than capsule preparation in this model.