Therapeutic Usefulness of a Novel Calcium Channel Blocker Azelnidipine in the Treatment of Hypertension: A Narrative Review

The prevalence of hypertension and comorbidities such as metabolic syndrome, diabetes mellitus, and chronic kidney disease in India is alarmingly high. Amlodipine, an older-generation calcium channel blocker (CCB), is currently the gold standard for hypertension management in India. However, it has several disadvantages, including reflex tachycardia and pedal edema. Therefore, an effective antihypertensive agent that does not cause these adverse effects and provides end-organ protection is required for the holistic management of hypertension in the country. Azelnidipine is a new-generation CCB that has recently been approved for the treatment of hypertension in India. This review provides an overview of the utility of azelnidipine for hypertension control, including comparisons with traditional CCBs such as amlodipine. It discusses the key antihypertensive effects of azelnidipine as well as its advantages in the prevention of tachycardia and associated complications. In addition, this review highlights the extensive cardio- and renoprotective activities of azelnidipine, including its effects on systolic and diastolic function and urinary albumin excretion. Overall, this substantial body of evidence supports the use of azelnidipine for the treatment of hypertension, especially in India. It suggests that the adoption of azelnidipine as the new gold standard CCB could help India battle its hypertension epidemic.

Angiotensin II regulates islet microcirculation and insulin secretion in mice

OBJECTIVE

Angiotensin II causes potent increases in systemic and local pressure through its vasoconstrictive effect. Despite the importance of angiotensin II for local blood flow regulation, whether angiotensin II regulates the pancreatic islet microcirculation remains incompletely understood. We hypothesized that angiotensin II directly regulates the pancreatic islet microcirculation and thereby regulates insulin secretion. The aims of this study were to develop a new technique to visualize pancreatic islet hemodynamic changes in vivo and to analyze changes in islet circulation induced by angiotensin II or an angiotensin type 1 receptor blocker.

METHODS

Using an in vivo imaging method, we observed the pancreatic islet microcirculation. Various doses of angiotensin II or an angiotensin type 1 receptor blocker were injected intravenously, and changes in islet microcirculation were observed. Glucose-stimulated insulin secretion from the pancreas was measured from the hepatic portal vein.

RESULTS

We identified islet microcirculation using a fluorescent dye. Angiotensin II significantly induced blood vessel contraction in the islets in a dose-dependent manner. In contrast, the angiotensin type 1 receptor blocker induced vasodilation. Glucose-stimulated insulin secretion was decreased by angiotensin II infusion.

CONCLUSIONS

These results show that angiotensin II is involved in the regulation of pancreatic islet microcirculation and insulin secretion.

Azelnidipine inhibits cultured rat aortic smooth muscle cell death induced by cyclic mechanical stretch

Acute aortic dissection is the most common life-threatening vascular disease, with sudden onset of severe pain and a high fatality rate. Clarifying the detailed mechanism for aortic dissection is of great significance for establishing effective pharmacotherapy for this high mortality disease. In the present study, we evaluated the influence of biomechanical stretch, which mimics an acute rise in blood pressure using an experimental apparatus of stretching loads in vitro, on rat aortic smooth muscle cell (RASMC) death. Then, we examined the effects of azelnidipine and mitogen-activated protein kinase inhibitors on mechanical stretch-induced RASMC death. The major findings of the present study are as follows: (1) cyclic mechanical stretch on RASMC caused cell death in a time-dependent manner up to 4 h; (2) cyclic mechanical stretch on RASMC induced c-Jun N-terminal kinase (JNK) and p38 activation with peaks at 10 min; (3) azelnidipine inhibited RASMC death in a concentration-dependent manner as well as inhibited JNK and p38 activation by mechanical stretch; and (4) SP600125 (a JNK inhibitor) and SB203580 (a p38 inhibitor) protected against stretch-induced RASMC death; (5) Antioxidants, diphenylene iodonium and tempol failed to inhibit stretch-induced RASMC death. On the basis of the above findings, we propose a possible mechanism where an acute rise in blood pressure increases biomechanical stress on the arterial walls, which induces RASMC death, and thus, may lead to aortic dissection. Azelnidipine may be used as a pharmacotherapeutic agent for prevention of aortic dissection independent of its blood pressure lowering effect.

Comparison of effects of azelnidipine and trichlormethiazide in combination with olmesartan on blood pressure and metabolic parameters in hypertensive type 2 diabetic patients

Aims/Introduction:  Angiotensin II type 1 receptor blockers (ARB) are regarded as first-line treatment for type 2 diabetes with hypertension. However, lowering blood pressure to the target level often requires more than one antihypertensive agent as recommended by the guideline. In this open-label, prospective, crossover clinical trial, we compared the effects of combination treatment of ARB with a calcium channel blocker (CCB) or with a low-dose thiazide diuretic on blood pressure (BP) and various metabolic parameters in hypertensive patients with type 2 diabetes.

MATERIALS AND METHODS

  A total of 39 Japanese type 2 diabetics with hypertension treated with olmesartan (20 mg/day) for at least 8 weeks were recruited to this study. At study entry, treatment was switched to either olmesartan (20 mg/day)/azelnidipine (16 mg/day) or olmesartan (20 mg/day)/trichlormethiazide (1 mg/day) and continued for 12 weeks. Then, the drugs were switched and treatment was continued for another 12 weeks. We measured clinical blood pressure and various metabolic parameters before and at the end of each study arm.

RESULTS

  Compared with the olmesartan/trichlormethiazide treatment, treatment with olmesartan/azelnidipine achieved superior clinical blood pressure and pulse rate control. In contrast, the treatment with olmesartan/trichlormethiazide resulted in increased HbA1c, serum uric acid and worsening of estimated glomerular filtration rate, though there were no differences in other metabolic parameters including urine 8-hydroxy-2'-deoxyguanosine, C-reactive protein and adiponectin between the two treatments.

CONCLUSIONS

  Our results show that the combination of ARB with azelnidipine is more beneficial with regard to blood pressure control and metabolic outcome than the combination of olmesartan with low dose trichlormethiazide. This trial was registered with UMIN clinical trial registry (no. UMIN000005064). (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00135.x, 2011).

Determinants of kidney oxygen consumption and their relationship to tissue oxygen tension in diabetes and hypertension

The high renal oxygen (O(2) ) demand is associated primarily with tubular O(2) consumption (Qo(2) ) necessary for solute reabsorption. Increasing O(2) delivery relative to demand via increased blood flow results in augmented tubular electrolyte load following elevated glomerular filtration, which, in turn, increases metabolic demand. Consequently, elevated kidney metabolism results in decreased tissue oxygen tension. The metabolic efficiency for solute transport (Qo(2) /T(Na) ) varies not only between different nephron sites, but also under different conditions of fluid homeostasis and disease. Contributing mechanisms include the presence of different Na(+) transporters, different levels of oxidative stress and segmental tubular dysfunction. Sustained hyperglycaemia results in increased kidney Qo(2) , partly due to mitochondrial dysfunction and reduced electrolyte transport efficiency. This results in intrarenal tissue hypoxia because the increased Qo(2) is not matched by a similar increase in O(2) delivery. Hypertension leads to renal hypoxia, mediated by increased angiotensin receptor tonus and oxidative stress. Reduced uptake in the proximal tubule increases load to the thick ascending limb. There, the increased load is reabsorbed, but at greater O(2) cost. The combination of hypertension, angiotensin II and oxidative stress initiates events leading to renal damage and reduced function. Tissue hypoxia is now recognized as a unifying pathway to chronic kidney disease. We have gained good knowledge about major changes in O(2) metabolism occurring in diabetic and hypertensive kidneys. However, further efforts are needed to elucidate how these alterations can be prevented or reversed before translation into clinical practice.

Azelnidipine attenuates glomerular damage in Dahl salt-sensitive rats by suppressing sympathetic nerve activity

Dihydropyridine-type calcium channel blockers (CCBs) exert potent antihypertensive effects. The CCB azelnidipine decreases heart rate by suppressing sympathetic nerve activity, which affects afferent and efferent arterioles in the glomeruli. We examined whether azelnidipine can improve progressive glomerular injury in comparison with amlodipine by suppressing renal sympathetic nerve activity in Dahl salt-sensitive rats. Glomerular circulation in Dahl salt-sensitive rats was monitored with a charge-coupled device camera before and after administration of amlodipine (0.5 mg kg(-1), bolus injection) or azelnidipine (0.1 mg kg(-1), bolus injection). Systemic sympathetic nerve activity was also compared by analysis of heart rate variability with a telemetry blood pressure monitoring system after crossover administration of amlodipine (1.0 mg kg(-1) per day) and azelnidipine (3.0 mg kg(-1) per day) for 1 week. To investigate renoprotective effects, rats were treated with amlodipine (1.0 mg kg(-1) per day) or azelnidipine (3.0 mg kg(-1) per day) for 3 weeks with or without renal denervation. The efferent arteriole contracted in response to acute amlodipine but not azelnidipine treatment. The low frequency/high frequency ratio, an index of parasympathetic nerve activity, decreased in response to azelnidipine but not amlodipine treatment. In response to chronic treatment, proteinuria and glomerular injury improved to a greater extent with azelnidipine compared with amlodipine. The renoprotective effects of azelnidipine were diminished by renal denervation. Azelnidipine decreased glomerular damage in Dahl salt-sensitive rats to a greater extent than amlodipine. Azelnidipine appeared to decrease intraglomerular pressure by suppressing sympathetic nerve activity.

Silencing of hypoxia-inducible factor-1α gene attenuated angiotensin II-induced renal injury in Sprague-Dawley rats

Although it has been shown that upregulation of hypoxia-inducible factor (HIF)-1α is protective in acute ischemic renal injury, long-term overactivation of HIF-1α is implicated to be injurious in chronic kidney diseases. Angiotensin II (Ang II) is a well-known pathogenic factor producing chronic renal injury and has also been shown to increase HIF-1α. However, the contribution of HIF-1α to Ang II-induced renal injury has not been evidenced. The present study tested the hypothesis that HIF-1α mediates Ang II-induced renal injury in Sprague-Dawley rats. Chronic renal injury was induced by Ang II infusion (200 ng/kg per minute) for 2 weeks in uninephrectomized rats. Transfection of vectors expressing HIF-1α small hairpin RNA into the kidneys knocked down HIF-1α gene expression by 70%, blocked Ang II-induced HIF-1α activation, and significantly attenuated Ang II-induced albuminuria, which was accompanied by inhibition of Ang II-induced vascular endothelial growth factor, a known glomerular permeability factor, in glomeruli. HIF-1α small hairpin RNA also significantly improved the glomerular morphological damage induced by Ang II. Furthermore, HIF-1α small hairpin RNA blocked Ang II-induced upregulation of collagen and α-smooth muscle actin in tubulointerstitial region. There was no difference in creatinine clearance and Ang II-induced increase in blood pressure. HIF-1α small hairpin RNA had no effect on Ang II-induced reduction in renal blood flow and hypoxia in the kidneys. These data suggested that overactivation of HIF-1α-mediated gene regulation in the kidney is a pathogenic pathway mediating Ang II-induced chronic renal injuries, and normalization of overactivated HIF-1α may be used as a treatment strategy for chronic kidney damages associated with excessive Ang II.

Mechanisms of tubulointerstitial fibrosis

The pathologic paradigm for renal progression is advancing tubulointerstitial fibrosis. Whereas mechanisms underlying fibrogenesis have grown in scope and understanding in recent decades, effective human treatment to directly halt or even reverse fibrosis remains elusive. Here, we examine key features mediating the molecular and cellular basis of tubulointerstitial fibrosis and highlight new insights that may lead to novel therapies. How to prevent chronic kidney disease from progressing to renal failure awaits even deeper biochemical understanding.

Effect of cilnidipine on normal to marginally elevated urine albumin-creatinine ratio in asymptomatic non-diabetic hypertensive patients: an exponential decay curve analysis

BACKGROUND

High-normal urinary albumin excretion has been reported to have clinical significance with respect to progression of proteinuria and hypertension.

OBJECTIVE

We analysed the effect of cilnidipine (10 mg/day) on morning systolic blood pressure (SBP) and urine albumin-creatinine ratio (UACR) in 16 non-diabetic hypertensive patients with a normal to marginally elevated UACR (mean +/- SD 29.4 +/- 21.7; range 7.5-72.9 mg/g creatinine).

METHODS

Sequential home BP and UACR data were fitted to a simple exponential function as follows: where y is SBP (mmHg) or UACR (mg/g creatinine); alpha is the extent of the SBP (mmHg)- or UACR (mg/g creatinine)-lowering effect; beta (days) is the time-constant for SBP or UACR decrease; t is the number of days after the start of cilnidipine administration; and gamma is the finally stabilized SBP (mmHg) or UACR (mg/g creatinine).

RESULTS

Mean +/- SD morning SBP and UACR decreased by 20.4 +/- 11.4 mmHg and 15.2 +/- 13.1 mg/g creatinine, respectively, as determined by coefficient alpha. The mean +/- SD time-constant for UACR decrease was significantly longer than that for BP decrease (43.5 +/- 22.9 vs 15.4 +/- 7.1 days). UACR reduction correlated with pre-treatment UACR values (correlation coefficient [R] = 0.88, p < 0.01) but not with BP decrease.

CONCLUSIONS

The present study demonstrated that cilnidipine reduced UACR in hypertensive patients with normal to marginally elevated UACR independent of its BP-lowering effect.