Ethnopharmacological Evidence and Scientific Validation of Costus spicatus (Cana-do-Brejo) for Renal Pain Management in Elderly Populations: A Comprehensive Review of Traditional Use, Phytochemistry, and Experimental Dat

Background: Costus spicatus (Jacq.) Sw., vernacularly known as “cana-do-brejo” (swamp cane) in Brazil, represents one of the most culturally significant and widely used medicinal plants for kidney-related disorders, particularly among elderly populations experiencing renal pain. Despite centuries of traditional use, systematic scientific validation has emerged only in the past two decades through rigorous preclinical studies. Objective: This comprehensive review synthesizes ethnopharmacological documentation with contemporary experimental evidence to critically evaluate the scientific rationale for C. spicatus use in managing kidney pain, with specific consideration of elderly patient populations (age ≥65 years) and their unique physiological vulnerabilities. Methods: A systematic literature review was conducted, encompassing ethnobotanical surveys, phytochemical characterizations, and preclinical pharmacological studies published between 1990 and 2026. Databases searched included PubMed, Scopus, Web of Science, LILACS, SciELO, and Google Scholar. Search terms: “Costus spicatus,” “cana-do-brejo,” “nephroprotective,” “kidney pain,” “elderly,” “diuretic,” “antilithiatic,” “anti-inflammatory,” “antioxidant,” and “polyphenols.” Results: Ethnobotanical surveys across Brazil consistently identify C. spicatus among the top three medicinal plants used for kidney diseases. Phytochemical analyses reveal the presence of polyphenolic compounds (caffeic acid, quercetin, ferulic acid, kaempferide, tamarixetin), steroidal saponins, bioactive polysaccharides, and flavonol glycosides. Preclinical studies demonstrate: Nephroprotection: Significant improvement in acute kidney injury (AKI) models with reduced serum creatinine (42–58%), blood urea nitrogen (38–52%), and histological damage. Anti-inflammatory activity: Dose-dependent reduction of TNF-α (48–62%), IL-6 (51–67%), and IL-1β (44–59%). Antioxidant capacity: Increased SOD (38–54%), catalase (42–61%), and GPx (36–49%) activities, with reduced malondialdehyde (MDA) levels (51–68%). Antinociceptive effects: Peripheral pain inhibition (52.8–92.1%) observed in formalin and writhing tests. Diuretic activity: Acute and prolonged urine volume increase. Antilithiatic properties: Inhibition of calcium oxalate crystal growth and aggregation. Acute toxicity studies show an LD₅₀ > 2000 mg/kg, with no mortality or observable adverse effects, indicating a favorable safety profile. Conclusions: Substantial preclinical evidence validates the traditional use of C. spicatus for kidney disorders through multiple complementary mechanisms—direct nephroprotection, inflammation reduction, oxidative stress mitigation, pain relief, diuresis, and kidney stone prevention. The convergence of ethnopharmacological wisdom and experimental pharmacology provides a strong mechanistic rationale for symptomatic relief in elderly patients experiencing kidney pain. However, clinical trials in humans are absent, and safety data in elderly populations with polypharmacy and comorbidities remain limited. Urgent research priorities include Phase II/III clinical trials, pharmacokinetic and drug interaction studies in geriatric populations, and standardization of extract preparations for therapeutic use.