Over six months, patients who received either compound alongside their usual nephrology treatment showed declines in serum creatinine and blood urea nitrogen and rises in estimated glomerular filtration rate, while untreated controls moved in the opposite direction. The two interventions also diverged in their biochemical signatures: curcumin lowered the uremic toxin p-cresyl sulfate and the oxidative stress marker malondialdehyde, whereas pentoxifylline reduced the inflammatory marker high-sensitivity C-reactive protein and albuminuria. The study, published in Future Journal of Pharmaceutical Sciences, enrolled adults with stage 3 to 5 chronic kidney disease whose underlying causes were hypertension, diabetes, or both.
The trial randomized 94 patients into three groups: 35 received standard care alone, 33 received standard care plus curcumin at 500 mg twice daily, and 26 received standard care plus pentoxifylline at 400 mg twice daily. Standard care itself was held constant across all arms and included renin-angiotensin system blockade with ACE inhibitors or ARBs, antihypertensive drugs, and antidiabetic medications such as insulin or SGLT-2 inhibitors where indicated. No additional antioxidant or anti-inflammatory agents were permitted during the study, and participants’ baseline medication regimens were kept stable to minimize confounding.
By the end of follow-up, 77 participants remained in the per-protocol analysis: 30 in the control group, 26 in the curcumin group, and 21 in the pentoxifylline group. Dropouts included patients with incomplete follow-up, non-compliance, transplantation, or progression to hemodialysis during the study. The authors report that serum creatinine fell significantly within both intervention groups, from 3.58 to 3.12 mg/dL in the curcumin arm and from 2.75 to 2.34 mg/dL in the pentoxifylline arm, both with p values below 0.001. Blood urea nitrogen declined from 41.03 to 29.96 mg/dL with curcumin and from 35.29 to 28.50 mg/dL with pentoxifylline, again both p < 0.001, while the control group’s values worsened over the same period.
Estimated glomerular filtration rate followed a parallel pattern. The curcumin group rose from a mean of 23.77 to 28.50 mL/min/1.73 m² and the pentoxifylline group from 30.29 to 35.57 mL/min/1.73 m², both changes statistically significant within groups, whereas the control group experienced a significant but clinically unfavorable decline. The authors themselves flag an important nuance here: direct between-group comparisons of creatinine and eGFR at individual time points did not reach significance, and the statistically significant differences emerged only in the analysis of change from baseline. They note this within-group, time-dependent pattern rather than clear between-group separation, and caution that some findings may reflect variability, an honest limitation in a trial of this size.
The biomarker results were more differentiated. Curcumin treatment significantly reduced p-cresyl sulfate, a gut-derived uremic toxin implicated in oxidative injury, endothelial dysfunction, and cardiovascular risk in kidney disease, from 5.79 to 5.02 µg/mL (p = 0.011), and lowered malondialdehyde, a lipid peroxidation product, from 11.26 to 10.43 nmol/mL (p = 0.016). Pentoxifylline, a non-selective phosphodiesterase inhibitor with anti-inflammatory and hemorheological activity, instead produced a significant within-group drop in high-sensitivity C-reactive protein, from 7.13 to 5.52 mg/L (p = 0.019), and a significant reduction in the urinary albumin-to-creatinine ratio (p = 0.034). Curcumin showed only a non-significant trend toward improving albuminuria (p = 0.072), and the change-from-baseline comparison for albuminuria across groups was not significant (p = 0.255). Notably, the discussion acknowledges that despite curcumin’s apparent p-cresyl sulfate reduction, the absence of statistically significant differences versus the control group for some measures means these findings should be interpreted cautiously.
The safety picture was reassuring within the limits of the trial’s duration. Both treatments were described as well tolerated, with only mild gastrointestinal side effects reported across all groups and no serious adverse events observed. In the curcumin arm, diarrhea was the most common complaint at 15.4%, followed by nausea and vomiting and dry mouth at 7.7% each, with constipation and tachycardia each affecting 3.8% of patients; 92.3% reported no adverse events at all. Pentoxifylline produced diarrhea in 9.5% and constipation and nausea or vomiting in 4.8% each. Statistical comparison found no significant differences in adverse event rates between the groups.
Quality-of-life outcomes were largely unremarkable, which the authors attribute to small sample size and high variability. Most domains of the kidney disease quality of life instrument showed no significant within-group or between-group changes. The exceptions were scattered: the curcumin group improved within-group on the burden of kidney disease domain (p = 0.049), scored significantly higher than both other groups on cognitive function at six months (between-group p = 0.002), and exceeded the control group on quality of social interaction (p = 0.002). The pentoxifylline group showed a significant within-group gain in cognitive function (p = 0.038) even though its six-month score remained below the curcumin group’s. Domains covering symptoms, sexual function, sleep, social support, and work status showed no significant differences.
The trial’s context matters for interpretation. Chronic kidney disease is a substantial and growing global burden: according to the Global Burden of Disease 2023 report cited by the authors, nearly 788 million people worldwide were living with the condition in 2023, an age-standardized prevalence of roughly 14.2%, and it contributes to approximately 1.48 million deaths each year. The disease is defined by markers of kidney injury or a glomerular filtration rate below 60 mL/min/1.73 m² persisting for at least three months, and it progresses through sustained inflammation, oxidative stress, endothelial impairment, and retention of uremic toxins. Both study drugs target these pathways mechanistically: curcumin, the active polyphenol in turmeric, neutralizes reactive oxygen species and suppresses NF-κB signaling, while pentoxifylline inhibits tumor necrosis factor-alpha and improves microvascular blood flow.
Several methodological caveats deserve emphasis. The trial was retrospectively registered on ClinicalTrials.gov on June 12, 2024, after enrollment had already begun in October 2023, though before study completion and data analysis. It was open-label with no placebo control and no blinding, which the authors acknowledge could introduce bias in reporting and interpretation. The per-protocol analysis included only completers with full data, a design that can overestimate benefits relative to intention-to-treat analysis. The six-month duration prevents any conclusions about long-term effects, and the authors note that the relatively small sample size and variability in biomarker levels may have limited the statistical power to detect between-group differences, calling for larger randomized studies to confirm the findings on uremic toxin modulation.
Within those constraints, the study’s conclusion is measured rather than triumphant: curcumin and pentoxifylline may provide adjunctive benefits in chronic kidney disease by improving selected secondary outcomes related to oxidative stress, inflammation, and renal function. Curcumin appeared stronger on uremic toxins and oxidative stress markers, pentoxifylline on inflammation and proteinuria, and the authors suggest that future trials should investigate combined use of the two agents, since each demonstrated distinct effects on the evaluated biomarkers. For now, the results position both compounds as plausible candidates for larger, blinded, placebo-controlled trials rather than as established additions to kidney disease therapy.
Subject of Research: A randomized controlled trial of adjunctive curcumin versus pentoxifylline in patients with stage 3–5 chronic kidney disease
Article Title: A randomized controlled trial evaluating the impact of curcumin versus pentoxifylline on patients with chronic kidney disease
Article References: Kamel, N. M., Elkoraie, A., Mostafa, T. M., & Kotkata, F. A. (2026). A randomized controlled trial evaluating the impact of curcumin versus pentoxifylline on patients with chronic kidney disease. Future Journal of Pharmaceutical Sciences, 12(1), Article 83. https://doi.org/10.1186/s43094-026-01012-8
Image Credits: AI Generated
DOI: 10.1186/s43094-026-01012-8
Keywords: chronic kidney disease, curcumin, pentoxifylline, randomized controlled trial, p-cresyl sulfate, oxidative stress, malondialdehyde, hs-CRP, albuminuria, eGFR, quality of life, nephroprotection
News Source: Jerry Hayes. (October 29, 2026). Curcumin and Pentoxifylline Show Modest Kidney Benefits in Six-Month CKD Trial. Scienmag.
