Pentoxifylline, total urinary protein excretion rate and arterial blood pressure in long-term insulin-dependent diabetic patients with overt nephropathy

Efficacy of AST-120 for Patients With Chronic Kidney Disease: A Network Meta-Analysis of Randomized Controlled Trials

AST-120, an oral spherical activated carbon, may delay the need for kidney dialysis and improve uremia symptoms because it can adsorb acidic and basic organic compounds, especially small-molecule uremic toxins. However, previous studies produced no conclusive evidence regarding the benefits of AST-120 in delaying the progression of chronic kidney disease (CKD). Therefore, this systematic review and network meta-analysis evaluated the effects of AST-120 in patients with CKD. Related keywords of CKD and AST-120 were used to search four databases to obtain potential evidence on this topic, and two authors individually completed evidence selection, data extraction, and quality assessment. Network meta-analysis was performed for mortality, end-stage renal disease, composite renal outcomes, and laboratory outcomes based on a frequentist approach. In total, 15 randomized controlled trials (n = 3,763) were included in the present synthesis, and the pooled results revealed non-significant differences in mortality among the treatment strategies. Low- and high-dose AST-120 were not superior to no AST-120 treatment regarding renal outcomes. However, the event rates of end-stage renal disease (risk ratio [RR] = 0.78, 95% confidence interval [CI] = 0.62–0.99) and composite renal outcomes (RR = 0.78, 95% CI: 0.63–0.97) were significantly lower in the tailored-dose AST-120 group than in no AST-120 group. The results did not reveal a small-study effect on the outcomes. Tailored dosing of AST-120 appeared to represent an optimal treatment strategy because it resulted in lower rates of composite renal outcomes and end-stage renal disease.

Targeting Inflammation in Diabetic Kidney Disease: Is There a Role for Pentoxifylline?

Diabetic kidney disease (DKD) is the most common cause of ESKD in the United States and worldwide. Current treatment for DKD includes strict glycemic control and normalization of BP with renin-angiotensin-aldosterone system (RAAS) blockade. Although RAAS blockers slow progression of disease, they do not generally prevent ESKD and none of the studies with these agents in DKD included patients who were nonproteinuric, which make up an increasingly large percentage of patients with diabetes now seen in clinical practice. Recent studies with glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter-2 (SGLT2) inhibitors have shown beneficial renal effects, and the benefits of SGLT2 inhibitors likely extend to patients who are nonproteinuric. However, there remains a need to develop new therapies for DKD, particularly in those patients with advanced disease. A role of chronic low-grade inflammation in microvascular complications in patients with diabetes has now been widely accepted. Large clinical trials are being carried out with experimental agents such as bardoxolone and selonsertib that target inflammation and oxidative stress. The Food and Drug Administration–approved, nonspecific phosphodiesterase inhibitor pentoxifylline (PTX) has been shown to have anti-inflammatory effects in both animal and human studies by inhibiting the production of proinflammatory cytokines. Small randomized clinical trials and meta-analyses indicate that PTX may have therapeutic benefits in DKD, raising the possibility that a clinically available drug may be able to be repurposed to treat this disease. A large, multicenter, randomized clinical trial to determine whether this agent can decrease time to ESKD or death is currently being conducted, but results will not be available for several years. At this time, the combination of RAAS blockade plus SGLT2 inhibition is considered standard of care for DKD, but it may be reasonable for clinicians to consider addition of PTX in patients whose disease continues to progress despite optimization of current standard-of-care therapies.

Effect of pentoxifylline in proteinuric chronic kidney disease: a systematic review and meta-analysis

AIM

The aim of this study was to assess the effect of pentoxifylline on proteinuria and renal function in chronic kidney disease (CKD) treatment.

METHODS

We systematically searched PubMed, EMBASE, the Cochrane Library and ClinicalTrials.gov for randomized and non-randomized controlled trials comparing pentoxifylline to placebo, no treatment or renin-angiotensin system blockade in proteinuric CKD patients. The outcomes concerning proteinuria, renal function, blood pressure and adverse events were extracted.

RESULTS

Twelve trials with 613 participants were identified. Pentoxifylline significantly decreased proteinuria [weighted mean difference (WMD) -0.60 g/day (95 % CI -0.84 to -0.36); p < 0.001] compared to placebo or no-treatment groups, but the decrease was not significant [WMD: 0.10 g/day (-0.34 to 0.54); p = 0.66] compared to captopril treatment. The decrease of glomerular filtration rate was significantly less [WMD: 3.67 ml/min (2.71-4.62); p < 0.001] in the pentoxifylline group than in the controls. There was no significant difference in serum creatinine [WMD: -0.03 mg/dl (-0.10 to 0.03); p = 0.28], diastolic blood pressure [WMD: 0.94 mmHg (-0.74 to 2.61); p = 0.27] and adverse events [RR: 0.89 (0.60 to 1.32); p = 0.56].

CONCLUSIONS

Pentoxifylline may decrease proteinuria and protect renal function in patients with CKD. Further studies are needed to confirm this result.

Novel effective drugs for diabetic kidney disease? or not?

INTRODUCTION

Diabetes mellitus is increasingly common worldwide and is expected to affect 592 million people by 2035. The kidney is often involved. A key goal in treating diabetes is to reduce the risk of development of kidney disease and, if kidney disease is already present, to delay the progression to end-stage renal disease (ESRD). This represents a social and ethical issue, as a significant proportion of patients reaching ESRD in developing countries do not have access to renal replacement therapy.

AREAS COVERED

The present review focuses on novel therapeutic approaches for diabetic nephropathy (DN), implemented on the basis of recent insights on its pathophysiology, which might complement the effects of single inhibition of the renin-angiotensin-aldosterone system (RAAS), the cornerstone of renoprotective interventions in diabetes, along with glycemic and blood pressure control.

EXPERT OPINION

Although a plethora of new treatment options has arisen from experimental studies, the number of novel renoprotective molecules successfully implemented in clinical practice over the last two decades is disappointingly low. Thus, new investigational strategies and diagnostic tools - including the appropriate choice of relevant renal end points and the study of urinary proteome of patients - will be as important as new therapeutic interventions to fight DN. Finally, in spite of huge financial interests in replacing the less expensive ACE inhibitors and angiotensin II receptor blockers with newer drugs, any future therapeutic approach has to be tested on top of - rather than instead of - optimal RAAS blockade.

Pentoxifylline for diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD) is associated with increased morbidity and mortality, mostly relating to cardiovascular complications. The relevance of inflammation in the pathogenesis of DKD has been investigated in recent years, and it has been shown that inflammatory markers are higher in people with DKD compared with the wider population. Pentoxifylline is a methylxanthine phosphodiesterase inhibitor with favourable anti-inflammatory effects and immunoregulatory properties. The anti-inflammatory effects conferred by pentoxifylline may be beneficial in the management of DKD.

OBJECTIVES

To assess the benefits and harms of pentoxifylline for treating people with DKD.

SEARCH METHODS

We searched the Cochrane Renal Group's specialised register (January 2012), CENTRAL (Issue 12, 2011), MEDLINE, EMBASE and four Chinese biomedical literature databases (CBM-disc, 1979 to July 2009), Chinese Science and Technique Journals Database (VIP, until July 2009), China National Knowledge Infrastructure (CNKI, until July 2009) and WanFang database (until July 2009).

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs studying the benefits and harms of pentoxifylline for DKD.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two authors. Meta-analyses were performed when more than one study provided data on a comparable outcome in sufficiently similar patients. Results of dichotomous outcomes were expressed as risk ratios (RR) with 95% confidence intervals (CI). Mean differences (MD) were calculated to assess the effects of treatment where outcomes were expressed on continuous scales, and standardised mean differences (SMD) calculated where different scales were used. Data was pooled using the random effects model. Adverse effects were assessed using descriptive techniques and where possible, risk differences (RD) with 95% CI.

MAIN RESULTS

We identified 17 studies that included a total of 991 participants with DKD which met our inclusion criteria. Overall, the methodological quality of included studies was low: 4/17 reported the method of randomisation, 13/17 did not; no study described the method of random allocation; 4/17 studies were considered to be at high risk of bias and 13/17 were considered to have unclear risk for incomplete outcome data reporting; 9/17 studies were at low risk bias and in 8/17 the risk of bias was unclear for selective outcome reporting.Compared with placebo, pentoxifylline significantly reduced serum creatinine (SCr) (MD -0.10 mg/dL, 95% CI -0.17 to -0.03), albuminuria (SMD -2.28, 95% CI -3.85 to -0.70) and overt proteinuria (MD -428.58 µg/min, 95% CI -661.65 to -195.50), but there was no difference in creatinine clearance (CrCl) (MD -5.18 mL/min, 95% CI -15.55 to 5.19). When compared with routine treatment alone, pentoxifylline did not significantly reduce SCr (MD 0.00 mg/dL, 95% CI -0.06 to 0.07) or blood pressure (systolic (SBP): MD -0.28 mm Hg, 95% CI -2.20 to 1.63; diastolic (DBP): MD -0.15 mm Hg, 95% CI -1.44 to 1.14), but did significantly reduce albuminuria (SMD 0.62, 95% CI 0.18 to 1.07) and proteinuria (MD 0.46 g/24 h, 95% CI 0.17 to 0.74). There was no significant difference in SCr (MD 0.00 mg/dL, 95% CI -0.08 to 0.07), albuminuria (MD -8.79 µg/min, 95% CI -27.18 to 9.59), proteinuria (MD -0.01 g/24 h, 95% CI -0.03 to 0.01) or blood pressure (SBP: MD 1.46 mm Hg, 95% CI -0.57 to 3.50; DBP: MD 1.37 mm Hg, 95% CI -0.23 to 2.98) between pentoxifylline and the active comparator (captopril or clonidine/methyldopa) for patients with type 1 and type 2 DKD. CrCl was significantly increased when pentoxifylline was compared to clonidine/methyldopa (MD 10.90 mL/min, 95% CI -1.40 to 20.40) but not with captopril (MD 3.26 mL/min, 95% CI -1.05 to 7.59). No data were available on the incidence of end-stage kidney disease (ESKD), time to ESKD, quality of life, or all-cause mortality. The adverse events of pentoxifylline were mild; no serious adverse events were reported in any of the included studies.

AUTHORS' CONCLUSIONS

From the available evidence, pentoxifylline seems to offer some beneficial effects in renal function improvement and reduction in albuminuria and proteinuria, with no obvious serious adverse effects for patients with DKD. However, most studies were poorly reported, small, and methodologically flawed. Evidence to support the use of pentoxifylline for DKD was insufficient to develop recommendations for its use in this patient population. Rigorously designed, randomised, multicentre, large scale studies of pentoxifylline for DKD are needed to further assess its therapeutic effects.

Captopril and combination therapy of captopril and pentoxifylline in reducing proteinuria in diabetic nephropathy

Chronic kidney disease is a worldwide health problem. Type II diabetes mellitus is now a major cause of end stage renal disease. The effect of diabetes mellitus through the dysregulation of the innate immunity results in increased tumor necrosis factor-alpha. This can lead to an increasing protein trafficking through the glomerular capillary, which can have an intrinsic renal toxicity. Seventy-four patients with type II diabetes mellitus with overt proteinuria were included in the study. They were randomly assigned to two groups of 37 patients (group 1: captopril 25 mg three times a day, group 2: captopril 25 mg and pentoxifylline 400 mg each three times per day). In the course of the study, two patients were excluded from each group. Daily urinary protein excretion was assessed at baseline and at two and six months. The reduction of urinary protein to creatinine clearance ratio in group 2 was 15.16 points more than in group 1 from baseline to the end of the study (p = 0.001). The difference in reduction only started after two months of pentoxifylline use. The differences in HbA1c and duration of diabetes mellitus at baseline in the two groups had not adversely affected the outcome of the study. There was a modest decrease in systolic blood pressure in group 2 as well (p = 0.041). Combining an angiotensin-converting enzyme inhibitor and pentoxifylline can lead to a greater reduction in proteinuria.

The effect of pentoxifylline on proteinuria in diabetic kidney disease: a meta-analysis

BACKGROUND

Pentoxifylline is a potential therapeutic agent for diabetic kidney disease because it has anti-inflammatory, antifibrotic, and hemorheological properties.

STUDY DESIGN

Systematic review and meta-analysis of randomized controlled trials.

SETTING, POPULATION, & INTERVENTION

Adult patients with diabetic kidney disease who received oral pentoxifylline.

SELECTION CRITERIA FOR STUDIES

We searched bibliographic databases for trials involving pentoxifylline that reported proteinuria, glomerular filtration rate, or blood pressure.

OUTCOMES

The primary outcome measure was the effect of pentoxifylline on proteinuria stratified by whether pentoxifylline was compared with renin-angiotensin system blockade.

RESULTS

10 studies including a total of 476 participants with a median duration of 6 months were identified. Pentoxifylline significantly decreased proteinuria (weighted mean difference, -278 mg/d of protein; 95% confidence interval [CI], -398 to -159; P < 0.001) compared with placebo or usual care. Compared with captopril, the decrease in proteinuria with pentoxifylline was similar (weighted mean difference, 0 mg/d of protein; 95% CI, -17 to 18; P = 0.9). Secondary analysis showed that patients with microalbuminuria had a nonsignificant decrease in protein excretion (weighted mean difference, -87 mg/d; 95% CI, -201 to 27; P = 0.1), whereas those with overt proteinuria (protein > 300 mg/d) had a significant decrease (weighted mean difference, -502 mg/d; 95% CI, -805 to -198; P = 0.001). No significant changes in systolic or diastolic blood pressure or glomerular filtration rate were found.

LIMITATIONS

Quality scores of studies were low, and there was significant heterogeneity.

CONCLUSIONS

Available evidence suggests that pentoxifylline may decrease proteinuria in patients with diabetic nephropathy. To confirm these findings, large high-quality studies are required.

The effects of pentoxifylline on diabetic renal changes in streptozotocin-induced diabetes mellitus

The aim of the study was to investigate the effects of pentoxifylline on the renal growth, the epidermal growth factor receptor expression, and renal total nitric oxide content in streptozotocin-induced diabetic rats. Adult male Wistar albino rats were randomly divided into three groups: normal control (the N group), diabetic nephropathy (the DN group), and diabetic nephropathy treated with pentoxifylline at the dosage of 20 mg x kg(-1) x d(-1), intraperitoneally (the group DNP). Diabetes was induced by injection of streptozotocin intraperitoneally. The kidney wet weight (KWW) and dry weight (KDW), fractional kidney weight (FKW), glomerular volume (VG), renal tissue protein (RTP) contents, and renal tissue total nitric oxide (NO) production were determined after the rats were sacrificed on 10th day. There was a significant increase in KWW and KWD in the DNP and DN groups when compared to the N group (p=0.000 for the DNP group, p = 0.000 and p < 0.01 for the DN group). In the DN group, FKW was increased for both wet and dry kidney weight (p<0.05 and p=0.001, respectively) while in the DNP group there was increase in FKW only for dry kidney weight. VG was increased in both two diabetic groups (p<0.05), but this increase was less prominent in the rats treated with pentoxifylline. RTP was significantly decreased in the DNP group when compared with the values in the DN group (p < 0.05). Immunohistochemically epidermal growth factor receptor expression was increased in diabetic rats, and it was not affected by pentoxifylline treatment. In diabetic rats renal content of total NO was decreased (p<0.05 for the DNP group, p<0.01 for the DN group). In conclusion, the results provide that pentoxifylline may have some beneficial effects on renal changes in streptozotocin-induced diabetic rats.

Comparison of the Effect of Pentoxifylline and Captopril on Proteinuria in Patients with Type 2 Diabetes mellitus

OBJECTIVES

To compare the relative efficacy of pentoxifylline (PTX) and angiotensin-converting enzyme (ACE) inhibitor, captopril in the treatment of proteinuria of type 2 diabetic patients.

DESIGN

A randomized open, crossover, clinical trial conducted from October 2000 to March 2001.

SETTING AND PARTICIPANTS

39 patients with type 2 diabetes age 34-75 years were randomly allocated to the two treatment groups. The first group received PTX (400 mg three times a day) orally for a total of 2 months. The second group received captopril (25 mg three times a day) for 2 months. Response to treatment was assessed at 1, 2, 4, and 8 weeks after start of therapy.

RESULTS

Captopril appeared to be equivalent in efficacy and safety to PTX. A significant decrease in proteinuria occurred in both groups. Of the 20 patients treated with PTX, the mean (SD) of 24 h urinary protein decreased from 1.4 (0.7) to 1.0 (0.7) g/24 h (p < 0.05). Correspondingly, in the 19 patients treated with captopril, the mean (SD) of 24 h urinary protein decreased from 1.3 (0.7) to 0.8 (0.7) g/24 h (p < 0.01).

CONCLUSION

This study demonstrates that treatment with PTX and captopril both significantly reduce overt proteinuria in patients with type 2 diabetes. This effect of ACE inhibition has previously been shown to slow progression to renal failure and we postulate that treatment with PTX may have a similar benefit.

Urinary protein excretion and serum tumor necrosis factor in diabetic patients with advanced renal failure: effects of pentoxifylline administration

In 24 diabetic patients with advanced renal failure (creatinine clearance [C(Cr)] < 35 mL/min), we prospectively studied serum tumor necrosis factor-alpha (TNF-alpha) levels, the possible relationship with urinary protein excretion, and the effects of pentoxifylline (PTF) administration. PTF (400 mg daily) was administered for 6 months to 14 patients, and the results were compared with data from a control group (n = 10). Baseline parameters were similar in both groups. At the end of the study, urinary protein excretion and serum TNF-alpha decreased in the active group from 2.7 (1.2 to 5.8) g/d and 569 +/- 285 pg/mL to 1.1 (0.3 to 4.0) g/d and 329 +/- 232 pg/mL, respectively (P < 0.001). By contrast, proteinuria and TNF-alpha did not change in the control group. Regression analysis showed a significant correlation between proteinuria and serum TNF-alpha both at basal (r = 0.55) and at the sixth month (r = 0.57). Furthermore, the reduction of urinary protein excretion was strongly correlated with the decrease of TNF-alpha (r = 0.72, P < 0.01). Serum Cr and C(Cr) remained stable in both groups during the study. Our findings suggest that cytokines might play a role in renal damage in diabetic nephropathy. PTF is effective in reducing proteinuria in diabetic patients with advanced renal failure. The anticytokine activity of PTF may be a further explanation for this antiproteinuric effect.

Renal syndromes in diabetes

Renal disorders attributed to diabetes mellitus are increasingly recognized as the dominant feature of long-term management. Renal failure in diabetic patients is the most commonly recognized cause of irreversible uremia in the United States, Europe, and Japan. Treating hypertension and normalizing hyperglycemia slows the previously thought inexorable progress of renal insufficiency in diabetes. Once end-stage renal disease has developed, either dialytic therapy or a renal transplant affords life extension, often with excellent rehabilitation.

Nephroprotective effects of nitrendipine in hypertensive type I and type II diabetic patients

Hypertension is significantly involved in the progression of diabetic nephropathy and in the development of end stage renal disease in both type I and type II diabetes mellitus. We have investigated whether long-term monotherapy with a calcium antagonist, nitrendipine, prevents the development of overt diabetic nephropathy in type I and type II diabetic patients with mild to moderate hypertension and persistent microalbuminuria (ie, incipient nephropathy). After a 4-week run-in and washout period, respectively, 25 patients met the inclusion criteria. Twenty-two patients (six with type I and 16 with type II diabetes) completed the 12-month study. Twelve months of treatment with nitrendipine resulted in a significant reduction in systolic blood pressure in patients with type I (157.5 +/- 8.1 mm Hg v 135.8 +/- 4.2 mm Hg, P < 0.05) and type II (163.1 +/- 4.3 mm Hg v 135.9 +/- 3.6 mm Hg, P < 0.001) diabetes. A significant reduction also was seen in diastolic blood pressure (91.7 +/- 1.7 mm Hg v 79.2 +/- 3.5 mm Hg in type I diabetic patients, P < 0.01; 94.7 +/- 1.4 mm Hg v 78.1 +/- 1.5 mm Hg in type II diabetic patients, P < 0.001). A significant reduction in albuminuria was associated with the blood pressure reduction in both type I (57.8 +/- 11.9 mg/24 hr v 24.9 +/- 5.9 mg/24 hr, -57%) and type II (134.6 +/- 20.7 mg/24 hr v 70.3 +/- 16.8 mg/24 hr, -48%) diabetic patients. The mean glomerular filtration rate increased by 21% (112 +/- 12 mL/min v 135 +/- 14 mL/min) and by 23% (106 +/- 12 mL/min v 130 +/- 14 mL/min) in type I and type II diabetic patients, respectively. No significant changes were found in renal plasma flow rates or in serum concentrations of beta 2-microglobulin. With the exception of a significant (P < 0.05) reduction in hemoglobin A1 concentration in type II diabetic patients after 3 months of treatment with nitrendipine, fasting blood glucose, hemoglobin A1, residual beta-cell function (C-peptide levels), total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and body mass index remained essentially unchanged during follow-up. These findings suggest that 12 months of monotherapy with the dihydropyridine-type calcium antagonist nitrendipine reduced albuminuria and increased the lowered glomerular filtration rate without adverse effects on glucose and lipid control.(ABSTRACT TRUNCATED AT 400 WORDS)