SGLT-2-inhibition with dapagliflozin reduces tissue sodium content: a randomised controlled trial

Background and aims

Sodium tissue content by ²³Na magnetic resonance imaging (Na-MRI) has been validated in experimental and human studies. SGLT-2 inhibition blocks the reabsorption of glucose and of sodium in the proximal tubular cells in a 1:1 fashion. We hypothesized that SGLT-2 inhibition in patients with type 2 diabetes characterized by sodium retention leads to decreased tissue sodium content due to its pharmacological action.

Materials and methods

In a prospective double blind, placebo controlled, cross-over trial 59 patients (61 ± 7.6 years) with type 2 diabetes were randomized to either dapagliflozin 10 mg or placebo once daily for 6 weeks each. In addition to metabolic parameters and ambulatory blood pressure (BP) we analysed the sodium content in the skin and muscles of the lower leg by Na-MRI.

Results

Compared to baseline 6 weeks treatment with the SGLT-2 inhibitor dapagliflozin decreased fasting (132 ± 28 vs. 114 ± 19 mg/dl, p < 0.001), postprandial blood glucose (178 ± 66 mg/dl vs. 153 ± 46 mg/dl, p < 0.001), body weight (87.6 vs. 86.6 kg, p < 0.001) and systolic (129 ± 12 vs. 126 ± 11 mmHg, p = 0.010), and diastolic (77.4 ± 9 vs. 75.6 ± 8 mmHg, p = 0.024), 24-h ambulatory BP. Tissue sodium content in the skin was reduced after 6 weeks treatment with dapagliflozin compared to baseline [24.1 ± 6.6 vs. 22.7 ± 6.4 A.U.(arbitrary unit) p = 0.013]. No significant reduction of tissue sodium content was observed in the muscle (M. triceps surae: 20.5 ± 3.5 vs. 20.4 ± 3.7 A.U. p = 0.801). No clear significant difference in tissue water content of muscle and skin was observed after 6 weeks of treatment with dapagliflozin, compared to baseline.

Conclusion

SGLT-2 inhibition with dapagliflozin resulted in a significant decrease in tissue sodium content of the skin after 6 weeks. This observation point to a decrease of total sodium content in patients with type 2 diabetes prone to cardiovascular complications, that might be mitigated by SGLT-2 inhibition.

Trial registration The study was registered at http://www.clinicaltrials.gov (NCT02383238) retrospectively registered

Sodium glucose cotransporter (SGLT)-2 inhibitors: Do we need them for glucose-lowering, for cardiorenal protection or both?

Sodium glucose cotransporter (SGLT)-2 inhibitors are the newest addition to our treatment armamentarium for the management of hyperglycemia in type 2 diabetes. Glucose-lowering per se reduces the risk of microvascular complications, but not the risk of cardiovascular disease, including heart failure and cardiovascular mortality. Also, even when embedded in optimal cardiovascular prevention, a large residual risk remains with respect to progression of diabetic kidney disease. SGLT-2 inhibitors lower blood glucose levels by inducing glucosuria. Through various proposed mechanisms, among which diuretic and natriuretic effects, SGLT-2 inhibitors decrease heart failure hospitalization, reduce cardiovascular mortality, and mitigate progression of diabetic kidney disease. In this perspective, we will discuss the glucose-lowering and other protective effects of SGLT-2 inhibitors on the cardiorenal axis, both in primary and secondary prevention. By comparing the glycemic and pleiotropic effects of these agents to other glucose-lowering drugs, we will address questions around whether SGLT-2 inhibitors should be considered primarily as glucose-lowering agents, cardiorenal drugs or both.

Different glucagon effects during DPP-4 inhibition versus SGLT-2 inhibition in metformin-treated type 2 diabetes patients

AIMS

Previous studies have shown that dipeptidyl peptidase (DPP)-4 inhibition lowers glucagon levels whereas sodium-glucose co-transporter 2 (SGLT-2) inhibition increases them. This study evaluated the extent of these opposite effects in a direct comparative head-to-head study.

METHODS

In a single-centre, randomized study with a cross-over design, 28 metformin-treated patients with type 2 diabetes (T2D) (mean age, 63 years; baseline HbA1c, 6.8%) were treated with vildagliptin (50 mg twice daily) or dapagliflozin (10 mg once daily) for 2 weeks, with a 4-week wash-out period between the two separate treatments. After each treatment period, a meal test was undertaken, with measurements of islet and incretin hormones and 4-hour area under the curve (AUC) levels were estimated.

RESULTS

Fasting glucagon (35.6 ± 2.5 vs 39.4 ± 3.4 pmoL/L; P = .032) and postprandial glucagon (4-hour AUC_glucagon , 32.1 ± 2.3 vs 37.5 ± 2.7 nmoL/L min; P = .001) were ~15% lower after vildagliptin compared to dapagliflozin treatment. This was associated with stronger early (15 minute) C-peptide response and higher 4-hour AUC_C-peptide (P < .010), higher 4-hour AUC of the intact form of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) (P < .001) and lower 4-hour AUC of total GIP and GLP-1 (P < .001).

CONCLUSION

Treatment with DPP-4 inhibition with vildagliptin results in 15% lower fasting and postprandial glucagon levels compared to SGLT-2 inhibition with dapagliflozin. DPP-4 inhibition also induces more rapid insulin secretion and higher levels of intact incretin hormones, resulting in stronger feedback inhibition of incretin hormone secretion than SGLT-2 inhibition.

Exposure-response relationships of dapagliflozin on cardiorenal risk markers and adverse events: A pooled analysis of 13 phase II/III trials

AIMS

Dapagliflozin is a sodium-glucose co-transporter 2 inhibitor that has been developed as oral glucose lowering drug. The original dosefinding studies focused on optimal glycaemic effects. However, dapagliflozin also affects various cardiorenal risk markers and provides cardiorenal protection. To evaluate whether the currently registered doses of 5 and 10 mg are optimal for cardiorenal efficacy and safety, we characterized the relationship between dapagliflozin exposure and nonglycaemic cardiorenal risk markers as well as adverse events.

METHODS

Data were obtained from a pooled database of 13 24-week randomized controlled clinical trials of the clinical development programme of dapagliflozin. The exposure-response relationship was quantified using population pharmacodynamic and repeated time-to-event models.

RESULTS

A dose of 10 mg dapagliflozin resulted in an average individual exposure of 638 ng h/mL (95% prediction interval [PI]: 354-1061 ng h/mL), which translated to 71.2% (95% PI: 57.9-80.5%), 61.1% (95% PI: 58.0-64.8%), 91.3% (95% PI: 85.4-94.6%) and 25.7% (95% PI: 23.5-28.3%) of its estimated maximum effect for fasting plasma glucose, haematocrit, serum creatinine and urinary albumin-creatinine ratio, respectively.

CONCLUSION

We demonstrate that doses higher than 10 mg could provide additional beneficial effects in haematocrit, systolic blood pressure, urinary albumin-creatinine ratio and uric acid, without obvious increases in the rate of adverse events. These results raise the question whether future outcome studies assessing the benefits of higher than currently registered dapagliflozin doses are merited.

Combined sodium glucose co-transporter-2 inhibitor and angiotensin-converting enzyme inhibition upregulates the renin-angiotensin system in chronic kidney disease with type 2 diabetes: Results of a randomized, double-blind, placebo-controlled exploratory trial

AIM

Sodium glucose co-transporter-2 inhibitors (SGLT-2i) improve cardiorenal outcomes in patients with chronic kidney disease (CKD), with and without type 2 diabetes. The molecular mechanisms underlying these pleiotropic effects remain unclear, yet it is speculated that SGLT-2i elicit a neurohormonal modulation resulting in renin-angiotensin system (RAS) activation. We hypothesized that combined SGLT-2 and angiotensin-converting enzyme inhibition (ACEi) favours RAS regulation towards the beneficial angiotensin-(1-7)-driven axis.

MATERIALS AND METHODS

This randomized controlled prospective study investigated the effect of 12 weeks treatment with the SGLT-2i empagliflozin on top of ACEi on the molecular RAS dynamics in 24 diabetic and 24 non-diabetic patients with CKD. Systemic RAS peptides were quantified by mass spectrometry.

RESULTS

In patients with type 2 diabetes, combined SGLT-2i and ACEi significantly upregulated plasma renin activity [pre-treatment median and interquartile range 298.0 (43.0-672.0) pmol/L versus post-treatment 577.0 (95.0-1543.0) pmol/L; p = .037] and angiotensin I levels [pre-treatment 289.0 (42.0-668.0) pmol/L versus post-treatment 573.0 (93.0-1522.0) pmol/L; p = .037], together with a significant increase of angiotensin-(1-7) levels [pre-treatment 14.0 (2.1-19.0) pmol/L versus post-treatment 32.0 (5.7-99.0) pmol/L; p = .012]. Empagliflozin treatment resulted in a 1.5 to 2-fold increase in main RAS peptides in patients with diabetes compared with placebo. No significant effect of empagliflozin on top of ACEi on RAS peptides was found in patients with CKD without diabetes.

CONCLUSION

A distinct RAS modulation by SGLT-2i occurs in diabetic kidney disease reflected by enhancement of the beneficial angiotensin-(1-7) providing a molecular background for this renoprotective therapeutic approach.

Empagliflozin Is Not Renoprotective in Non-Diabetic Rat Models of Chronic Kidney Disease

Gliflozins (sodium-glucose transporter-2 inhibitors) exhibited renoprotective effects not only in diabetic but also in non-diabetic patients with chronic kidney disease (CKD). Controversial results were reported in experimental non-diabetic models of CKD. Therefore, we examined empagliflozin effects in three CKD models, namely, in fawn-hooded hypertensive (FHH) rats, uninephrectomized salt-loaded (UNX + HS) rats, and in rats with Goldblatt hypertension (two-kidney, one-clip 2K1C) that were either untreated or treated with empagliflozin (10 mg/kg/day) for eight weeks. Plethysmography blood pressure (BP) was recorded weekly, and renal parameters (proteinuria, plasma urea, creatinine clearance, and sodium excretion) were analyzed three times during the experiment. At the end of the study, blood pressure was also measured directly. Markers of oxidative stress (TBARS) and inflammation (MCP-1) were analyzed in kidney and plasma, respectively. Body weight and visceral adiposity were reduced by empagliflozin in FHH rats, without a significant effect on BP. Experimentally induced CKD (UNX + HS and 2K1C) was associated with a substantial increase in BP and relative heart and kidney weights. Empagliflozin influenced neither visceral adiposity nor BP in these two models. Although empagliflozin increased sodium excretion, suggesting effective SGLT-2 inhibition, it did not affect diuresis in any experimental model. Unexpectedly, empagliflozin did not provide renoprotection because proteinuria, plasma urea, and plasma creatinine were not lowered by empagliflozin treatment in all three CKD models. In line with these results, empagliflozin treatment did not decrease TBARS or MCP-1 levels in either model. In conclusion, empagliflozin did not provide the expected beneficial effects on kidney function in experimental models of CKD.

Sodium-glucose Cotransporter 2 Inhibitors: The Pleiotropic Mechanisms of Actions

BACKGROUND

Sodium-glucose cotransporter 2 (SGLT-2) inhibitors are a new class of oral antidiabetic drugs. So far, there are three agents approved for use in Europe and in the USA, two in Japan and another four agents under testing.

OBJECTIVE

The purpose of this study is to describe the mechanism of action and the favorable and adverse effects of SGLT-2 inhibitors.

METHOD

A thorough review of literature indexed in PubMed, Scopus and Cochrane databases were conducted. Original papers, review papers and their relevant references in English, from 2005 to February 2017, were included.

RESULTS

The main mechanism of action is the glycosuria induced by the inhibition of SGLT-2, located in the early segment of the proximal convoluted tubule. Along with large amounts of glucose, sodium, water and uric acid are also excessively excreted in urine. These actions have various, both desired and adverse, consequent implications in kidneys, blood pressure, cardiovascular system and other systems. Moreover, SGLT-2 inhibitors act directly to organs other than the kidneys, as SGLT-2 can be expressed there.

CONCLUSION

The underlying mechanisms responsible for the SGLT-2 inhibitor actions, are pleiotropic and occur in the kidneys, as well as in other target organs. The comprehension of these mechanisms, not only permits us to understand their actions better, but it could also help us to predict more of their undisclosed favorable actions, as well as their rare adverse effects.

Acute effects of empagliflozin on left atrial and ventricular filling parameters using echocardiography-a subanalysis of the EMPAG-HF trial

BACKGROUND

Sodium-glucose co-transporter 2 (SGLT2) inhibitors improve prognosis in chronic heart failure as part of currently recommended therapeutic strategies. Transthoracic echocardiography (TTE) is frequently used to assess heart function and dimensions in acute heart failure to lead therapy and assess volume status. Immediate changes, especially of left heart haemodynamic parameters, measured by echocardiography in patients with acute heart failure treated with SGLT2 inhibitors, remain unknown.

AIM

The aim of this pre-defined secondary analysis was to assess whether treatment with empagliflozin 25 mg/day in patients with acute heart failure improves echocardiographic parameters of load, left ventricular or right ventricular function.

METHODS AND RESULTS

In the single-centre, prospective, double-blind, placebo-controlled EMPAG-HF trial, patients with acute decompensated heart failure (ADHF) were screened and randomized within 12 h following hospital admission to receive either empagliflozin or placebo in addition to standard medical treatment over 5 days. Sixty patients were enrolled and randomized irrespective of left ventricular ejection fraction or diabetes. All patients received 2D TTE on admission (tB = at baseline) and after completing the study treatment (tC = time after completing study medication) (according to study design). The recorded loops were analysed using dedicated software (Image-Arena™ Version 4.6; TomTec Imaging Systems). After 5 days of treatment, patients in the empagliflozin cohort showed a relevant decrease in left atrial volume [LAV: ∆tB-tC = 30.9 ± 27.4; 95% confidence interval (CI) 20.1-41.7) compared to placebo ∆tB-tC = 10.5 ± 26; 95% CI 0.4-20.5; P = <0.001] and left atrial end-systolic volume index (LAESVI: ∆tB-tC = 15.7 ± 15.1; 95% CI 9.8-21.6 vs. placebo ∆tB-tC = 9.7 ± 10.2; 95% CI 5.7-13.6; P = 0.016) compared to placebo.

CONCLUSION

Immediate addition of empagliflozin to standard therapy improves echocardiographic parameters of LAV in patients following recompensation of ADHF.

Hepatoprotective and cardioprotective effects of empagliflozin in spontaneously hypertensive rats fed a high-fat diet

A combination of liver and heart dysfunction worsens the prognosis of human survival. The aim of this study was to investigate whether empagliflozin (a sodium-glucose transporter-2 inhibitor) has beneficial effects not only on cardiac and renal function but also on hepatic function. Adult (6-month-old) male spontaneously hypertensive rats (SHR) were fed a high-fat diet (60% fat) for four months to induce hepatic steatosis and mild heart failure. For the last two months, the rats were treated with empagliflozin (empa, 10 mg.kg-1.day-1 in the drinking water). Renal function and oral glucose tolerance test were analyzed in control (n=8), high-fat diet (SHR+HF, n=10), and empagliflozin-treated (SHR+HF+empa, n=9) SHR throughout the study. Metabolic parameters and echocardiography were evaluated at the end of the experiment. High-fat diet feeding increased body weight and visceral adiposity, liver triglyceride and cholesterol concentrations, and worsened glucose tolerance. Although the high-fat diet did not affect renal function, it significantly worsened cardiac function in a subset of SHR rats. Empagliflozin reduced body weight gain but not visceral fat deposition. It also improved glucose sensitivity and several metabolic parameters (plasma insulin, uric acid, and HDL cholesterol). In the liver, empagliflozin reduced ectopic lipid accumulation, lipoperoxidation, inflammation and pro-inflammatory HETEs, while increasing anti-inflammatory EETs. In addition, empagliflozin improved cardiac function (systolic, diastolic and pumping) independent of blood pressure. The results of our study suggest that hepatoprotection plays a decisive role in the beneficial effects of empagliflozin in preventing the progression of cardiac dysfunction induced by high-fat diet feeding.