Impact of renin-angiotensin system inhibition on microalbuminuria in type 2 diabetes: a post hoc analysis of the Shiga Microalbuminuria Reduction Trial (SMART)

Switching to an L/N-type calcium channel blocker shows renoprotective effects in patients with chronic kidney disease: the Kyoto Cilnidipine Study

OBJECTIVE

This open-label, randomized controlled trial investigated the effects of cilnidipine, an L/N-type calcium channel blocker (CCB), in patients with chronic kidney disease (CKD).

METHODS

Sixty patients with CKD and well-controlled hypertension being treated with a renin- angiotensin system (RAS) inhibitor and an L-type CCB (L-CCB) were randomly assigned either to switch from the L-CCB to cilnidipine after a 4-week observation period or to continue with L-CCB treatment. Blood pressure, heart rate and renal function were monitored for 12 months. Data were available for analysis from 50 patients: 24 from the cilnidipine group and 26 from the L-CCB group.

RESULTS

Blood pressure was well controlled in both groups. After 12 months, proteinuria and heart rate were significantly decreased in the cilnidipine group, but proteinuria increased and heart rate remained unchanged in the L-CCB group. There was a significant positive correlation between the percentage changes in proteinuria and heart rate.

CONCLUSIONS

Cilnidipine has antihypertensive effects equivalent to those of L-CCBs. In patients with CKD, proteinuria can be decreased by switching from an L-CCB to cilnidipine, thereby improving renal function.

Efficacy and safety of valsartan in reducing blood pressure and albuminuria in Chinese patients with essential hypertension: a multicenter prospective open-label observational study

OBJECTIVE

To evaluate the efficacy and safety of 80 or 160 mg/day valsartan in Chinese adult patients with essential hypertension and albuminuria.

METHODS

A multicenter prospective open-label observational study was conducted. Adult hypertensive patients with albuminuria were treated with 80 or 160 mg/day valsartan. Blood pressure (BP) was recorded at weeks 4, 8 and 12. Albuminuria was selectively measured at week 12.

RESULTS

The intent-to-treat (ITT) population included 1180 patients. Mean sitting systolic BP (MSSBP) and diastolic BP (MSDBP) at baseline was 153.5 [14.41] (mean [SD]) and 88.2 [11.99] (mean [SD]) mmHg. MSSBP and MSDBP at week 4 (mean [SD]: 139.1 [12.02] and 82.2 [8.54] mmHg), week 8 (mean [SD]: 135.3 [10.46] and 80.2 [7.55] mmHg) and week 12 (mean [SD]: 132.1 [9.80] and 78.1 [6.88] mmHg) were significantly lower than baseline (p < 0.001). The BP control rate of ITT patients at week 12 was 17.8%. Diabetic patients exhibited lower BP control rate than non-diabetic patients (14.0 vs. 22.4%, p < 0.001). A total of 904 patients had albuminuria assessed at week 12. UACR and UAER at week 12 were lower compared with baseline (p < 0.05). In all, 171 patients (18.9%) returned to normal albuminuria and albuminuria normalization percentage in diabetic patients exceeded that of non-diabetic patients (26.3 vs. 12.1%, p < 0.001). Albuminuria declined by more than 50% in 340 patients (37.6%) and more diabetic patients exhibited such decline in albuminuria than non-diabetic patients (41.7 vs. 33.8%, p < 0.05). No serious drug-related adverse effects (AEs) were observed.

LIMITATIONS

Prior antihypertensive treatment before valsartan administration may interfere with the efficacy of subsequent treatment. The discrepancy between 80 and 160 mg may affect patient outcomes and occurrence of AEs.

CONCLUSIONS

Valsartan can safely and effectively reduce BP and albuminuria in Chinese adult patients with essential hypertension and albuminuria. Valsartan has the more dramatic effect on albuminuria in diabetic patients than non-diabetic patients.

Modulation of renal superoxide dismutase by telmisartan therapy in C57BL/6-Ins2(Akita) diabetic mice

Renal superoxide excess, which is induced by an imbalance of the superoxide-producing enzyme NAD(P)H oxidase and the superoxide-scavenging enzyme superoxide dismutase (SOD) under hyperglycemia, increases oxidative stress and contributes to the development of diabetic nephropathy. In this study, we treated non-obese and hypoinsulinemic C57BL/6-Ins2^Akita (C57BL/6-Akita) diabetic mice with telmisartan (5 mg kg⁻¹ per day), an angiotensin II type 1 receptor blocker, or amlodipine (5 mg kg⁻¹ per day), a calcium channel blocker, for 4 weeks and compared the effects of these two anti-hypertensive drugs on renal NAD(P)H oxidase, SOD and transcription factor Nrf2 (NF-E2-related factor 2), which is known to upregulate several antioxidant enzymes including SOD. Vehicle-treated C57BL/6-Akita mice exhibited higher renal NAD(P)H oxidase and lower renal SOD activity with increased levels of renal superoxide than the C57BL/6-wild-type non-diabetic mice. Interestingly, telmisartan treatment not only reduced NAD(P)H oxidase activity but also enhanced SOD activity in C57BL/6-Akita mouse kidneys, leading to a reduction of renal superoxide levels. Furthermore, telmisartan-treated C57BL/6-Akita mice increased the renal protein expression of SOD and Nrf2. In parallel with the reduction of renal superoxide levels, a reduction of urinary albumin levels and a normalization of elevated glomerular filtration rate were observed in telmisartan-treated C57BL/6-Akita mice. In contrast, treatment with amlodipine failed to modulate renal NAD(P)H oxidase, SOD and Nrf2. Finally, treatment of C57BL/6-Akita mice with apocynin, an NAD(P)H oxidase inhibitor, also increased the renal protein expression of SOD and Nrf2. Collectively, our data suggest that NAD(P)H oxidase negatively regulates renal SOD, possibly by downregulation of Nrf2, and that telmisartan could upregulate renal SOD by the suppression of NAD(P)H oxidase and subsequent upregulation of Nrf2, leading to the amelioration of renal oxidative stress and diabetic renal changes.

T-type Ca channel blockade as a determinant of kidney protection

Voltage-dependent Ca channels are classified into several subtypes based on the isoform of their α1 subunits. Traditional Ca channels blockers (CCBs), including nifedipine and amlodipine, act predominantly on L-type Ca channels, whereas novel CCBs such as efonidipine, benidipine and azelnidipine inhibit both L-type and T-type Ca channels. Furthermore, cilnidipine blocks L-type and N-type Ca channels. These CCBs exert divergent actions on renal microvessels. L-type CCBs preferentially dilate afferent arterioles, whereas both L-/T-type and L-/N-type CCBs potently dilate afferent and efferent arterioles. The distinct actions of CCBs on the renal microcirculation are reflected by changes in glomerular capillary pressure and subsequent renal injury: L-type CCBs favor an increase in glomerular capillary pressure, whereas L-/T-type and L-/N-type CCBs alleviate glomerular hypertension. The renal protective action of L-/T-type CCBs is also mediated by non-hemodynamic mechanisms, i.e., inhibition of the inflammatory process and inhibition of Rho kinase and aldosterone secretion. Finally, a growing body of evidence indicates that T-type CCBs offer more beneficial action on proteinuria and renal survival rate than L-type CCBs in patients with chronic kidney disease (CKD). Similarly, in CKD patients treated with renin-angiotensin blockers, add-on therapy with N-type CCBs is more potent in reducing proteinuria than that with L-type CCBs, although no difference is found in the subgroup with diabetic nephropathy. Thus, the strategy for hypertension treatment with CCBs has entered a new era: treatment selection depends not only on blood pressure control but also on the subtypes of CCBs.