Effect of manidipine and delapril on insulin sensitivity in type 2 diabetic patients with essential hypertension

Treatments for diabetes mellitus type II: New perspectives regarding the possible role of calcium and cAMP interaction

Diabetes mellitus (DM) is among the top ten causes of death worldwide. It is considered to be one of the major global epidemics of the 21st century, with a significant impact on public health budgets. DM is a metabolic disorder with multiple etiologies. Its pathophysiology is marked by dysfunction of pancreatic β-cells which compromises the synthesis and secretion of insulin along with resistance to insulin action in peripheral tissues (muscle and adipose). Subjects presenting insulin resistance in DM type 2 often also exhibit increased insulin secretion and hyperinsulinemia. Insulin secretion is controlled by several factors such as nutrients, hormones, and neural factors. Exocytosis of insulin granules has, as its main stimulus, increased intracellular calcium ([Ca⁺²]i) and it is further amplified by cyclic AMP (cAMP). In the event of this hyperfunction, it is very common for β-cells to go into exhaustion leading to failure or death. Several animal studies have demonstrated pleiotropic effects of L-type Ca²⁺ channel blockers (CCBs). In animal models of obesity and diabetes, treatment with CCBs promoted restoration of insulin secretion, glycemic control, and reduction of pancreatic β-cell apoptosis. In addition, hypertensive individuals treated with CCBs presented a lower incidence of DM when compared with other antihypertensive agents. In this review, we propose that pharmacological manipulation of the Ca²⁺/cAMP interaction system could lead to important targets for pharmacological improvement of insulin secretion in DM type 2.

Antihypertensive drugs and glucose metabolism

Hypertension plays a major role in the development and progression of micro- and macrovascular disease. Moreover, increased blood pressure often coexists with additional cardiovascular risk factors such as insulin resistance. As a result the need for a comprehensive management of hypertensive patients is critical. However, the various antihypertensive drug categories have different effects on glucose metabolism. Indeed, angiotensin receptor blockers as well as angiotensin converting enzyme inhibitors have been associated with beneficial effects on glucose homeostasis. Calcium channel blockers (CCBs) have an overall neutral effect on glucose metabolism. However, some members of the CCBs class such as azelnidipine and manidipine have been shown to have advantageous effects on glucose homeostasis. On the other hand, diuretics and β-blockers have an overall disadvantageous effect on glucose metabolism. Of note, carvedilol as well as nebivolol seem to differentiate themselves from the rest of the β-blockers class, being more attractive options regarding their effect on glucose homeostasis. The adverse effects of some blood pressure lowering drugs on glucose metabolism may, to an extent, compromise their cardiovascular protective role. As a result the effects on glucose homeostasis of the various blood pressure lowering drugs should be taken into account when selecting an antihypertensive treatment, especially in patients which are at high risk for developing diabetes.

Role of manidipine in the management of patients with hypertension

Manidipine is a third-generation dihydropyridine calcium antagonist, which causes systemic vasodilation by inhibiting the voltage-dependent calcium inward currents in smooth muscle cells. In clinical studies, manidipine has been shown to significantly lower office and 24-h blood pressure compared with placebo in patients with essential hypertension. The resulting reduction in blood pressure is maintained over 24 h, with preservation of the circadian blood pressure pattern; its blood pressure-lowering capacity appears to be similar to that of other calcium antagonists. In elderly patients with mild-to-moderate essential hypertension, manidipine is able to significantly decrease blood pressure compared with placebo for up to 3 years of treatment. The drug also significantly lowers blood pressure in patients with hypertension and concomitant Type 2 diabetes mellitus or renal impairment, and is devoid of adverse metabolic effects. It is well-tolerated with few untoward adverse effects related to vasodilation. In particular, manidipine appears to have less potential for pedal edema than other calcium channel blockers.

Effects of manidipine plus rosuvastatin versus olmesartan plus rosuvastatin on markers of insulin resistance in patients with impaired fasting glucose, hypertension, and mixed dyslipidemia

AIM

To compare the effect of manidipine 20 mg plus rosuvastatin 10 mg versus olmesartan 20 mg plus rosuvastatin 10 mg on markers of insulin resistance in patients with mixed dyslipidemia, hypertension, and impaired fasting glucose (IFG).

METHODS

This study had a prospective, randomized, open-label, blinded endpoint (PROBE) design. A total of 40 patients with IFG, mixed dyslipidemia, and stage 1 hypertension were included. Following dietary intervention, patients were randomly allocated to rosuvastatin (10 mg/d) plus olmesartan (20 mg/d) or manidipine (20 mg/d). The primary end point was the between-group difference in changes in the Homeostasis Model Assessment Insulin Resistance (HOMA-IR) index following 3 months of treatment. Secondary end points included changes in fasting plasma glucose (FPG), fasting insulin levels, and glucosylated hemoglobin.

RESULTS

At the end of the 3-month treatment period, a significant increase in HOMA-IR index by 14% (from 2.4 [0.5-7.9] to 2.7 [0.5-5.2], P = .02 versus baseline) was seen in the olmesartan plus rosuvastatin group. On the contrary, no significant change in HOMA-IR index was observed in the manidipine plus rosuvastatin group (1.7 [0.5-5.2] to 1.7 [0.8-6.0], P = NS versus baseline, P = .04 versus olmesartan plus rosuvastatin group). An increase in fasting insulin levels was observed in the olmesartan plus rosuvastatin group (+8%, from 10.1 [2.0-29.6] to 10.9 [2.0-19.1] μU/mL, P < .05 versus baseline), while no significant change was seen in the manidipine plus rosuvastatin group (+3%, from 7.3 [2.0-17.6] to 7.5 [1.9-15.6] μU/mL, P = NS versus baseline, P = .02 versus olmesartan plus rosuvastatin group). Fasting plasma glucose and glycosylated hemoglobin did not change significantly in any group.

CONCLUSION

Manidipine seems to ameliorate the possible statin-associated increase in insulin resistance as compared with olmesartan in patients with IFG, hypertension, and mixed dyslipidemia.

Metabolic effects of manidipine

The calcium channel antagonists (CCAs) were originally introduced as vasodilators for the treatment of coronary heart disease, but are now also noted for their clinical efficacy in the management of hypertension. Data from large clinical studies have shown that CCAs are not associated with the undesirable metabolic effects (e.g. worsening of dyslipidemia and reduction of insulin sensitivity) seen with older agents such as thiazide diuretics and beta-adrenoceptor antagonists (beta-blockers) that are used to treat hypertension. Indeed, reductions in cardiovascular risk and rates of onset of new cases of diabetes mellitus have been reported in trials in patients with hypertension treated with CCAs. These beneficial effects extend beyond those expected to accompany reductions in BP. Until recently, the biochemical effects underlying these metabolic changes were only poorly understood, but pharmacologic studies have now started to shed more light on these issues. Of particular interest are studies with manidipine, some of which suggest that this agent may be associated with greater improvements in insulin sensitivity and may have better renal protective properties than other CCAs. Confirmation of potential differences among CCAs in terms of the relative magnitude of any beneficial metabolic effects requires further study. Ongoing research is expected to clarify further the action of these agents at the cellular level and to assist with the optimization of antihypertensive therapy, particularly in patients with elevated cardiovascular risk profiles.

Manidipine: A different dihydropyridine

Blood pressure (BP) plays an important role in the development and progression of cardiovascular disease. Moreover, hypertensive patients often have additional cardiovascular risk factors. Despite the abundance of antihypertensive drug categories, satisfactory BP regulation is often difficult to achieve. A major cause of this difficulty to properly manage BP is the less than optimal adherence of subjects to treatment. This is often due to the various adverse effects of the antihypertensive drugs. Calcium channel blockers (CCB) have an established efficacy for reducing BP. However, their side effect of peripheral edema is often a cause for the discontinuation of treatment. Manidipine holds some unique properties differentiating it from the rest of the CCB class. It has a better safety profile with a lower incidence of peripheral edema. Moreover, there are indications that manidipine holds additional beneficial attributes, such as improvement of renal function and decrease of insulin resistance.

Combination delapril/manidipine as antihypertensive therapy in high-risk patients

The majority of patients with hypertension, and in particular high-risk patients or those with diabetes mellitus or renal dysfunction, are likely to require combination therapy with at least two antihypertensive agents (from different classes) to achieve their blood pressure (BP) target. The delapril/manidipine fixed-dose combination consists of two antihypertensive agents with different, yet complementary, mechanisms of action. Delapril/manidipine has demonstrated short- and long-term antihypertensive efficacy in a number of clinical studies in patients with hypertension with an inadequate response to monotherapy. Comparative studies have demonstrated that delapril/manidipine is as effective as enalapril/hydrochlorothiazide (HCTZ) in patients with hypertension with an inadequate response to monotherapy, and as effective as irbesartan/HCTZ, losartan/HCTZ, olmesartan medoxomil/HCTZ, ramipril/HCTZ and valsartan/HCTZ in reducing BP in patients with hypertension and diabetes, or in obese patients with hypertension. Therapy with delapril/manidipine also appears to exert beneficial effects that extend beyond a reduction in BP, including nephroprotective activity and an improvement in fibrinolytic balance, supporting its value as a treatment option in these patient populations at high or very high cardiovascular risk because of the presence of organ damage, diabetes or renal disease.

Manidipine in hypertensive patients with metabolic syndrome: the MARIMBA study

OBJECTIVES

To evaluate the effects of manidipine versus amlodipine on blood pressure, albuminuria, insulin sensitivity, adiponectin, TNF-alpha and C-reactive protein in nondiabetic subjects with metabolic syndrome (ATP-III definition), including impaired fasting glucose (>5.6 mmol/l) and hypertension.

METHODS

In total, 64 patients were recruited and randomly assigned to manidipine 20 mg versus amlodipine 10 mg (for 12 +/- 2 weeks).

RESULTS

Blood pressure was reduced to a similar extent (p < 0.001) by both treatments. Albuminuria was significantly reduced by manidipine (-37.3%; p = 0.003), but not by amlodipine. C-reactive protein was reduced similarly (p < 0.01) by both treatments. Plasma adiponectin was increased (32.9%; p = 0.011) and plasma TNF-alpha was reduced by manidipine (-37.1%; p = 0.019), but neither was significantly changed by amlodipine. The HOMA insulin resistance index was significantly reduced by manidipine (-21.3%; p = 0.007), but not by amlodipine (-8.3%; p = 0.062). Tolerability with manidipine was superior to that with amlodipine (p = 0.04).

CONCLUSION

These data support the added value of manidipine in renal and metabolic protection beyond blood pressure reduction in the treatment of hypertensive patients with metabolic syndrome.

Blocking the renin-angiotensin-aldosterone system to prevent diabetes mellitus

Type 2 diabetes mellitus (DM) is increasing around the world, and the public health impact of DM, driven largely by cardiovascular disease complications, underpins the importance of continued efforts toward primary prevention of DM. Only a few interventions have been shown to prevent DM, with none of them yet proven to improve cardiovascular risk commensurately. Accumulating evidence suggest that drugs that block the renin-angiotensin-aldosterone system (RAAS), many of which have proven cardiovascular disease (CVD) benefit, also have favourable effects on parameters of glucose metabolism and incident diabetes. Here we review the evidence accumulated to date from animal studies, clinical mechanistic studies and clinical trials regarding the effect of RAAS inhibition and incident DM.

Manidipine: a review of its use in the management of hypertension

Manidipine is a lipophilic, third-generation dihydropyridine calcium channel antagonist with a high degree of selectivity for the vasculature, thereby inducing marked peripheral vasodilation with negligible cardiodepression. In addition, manidipine does not significantly affect norepinephrine levels, suggesting a lack of sympathetic activation. It has a gradual onset of action and a long duration of action enabling once daily administration. Furthermore, manidipine dilates both the efferent and the afferent renal arterioles and appears to have beneficial renal effects unrelated to its antihypertensive effect. Once-daily oral manidipine is an effective and generally well tolerated antihypertensive agent for younger and elderly adult patients with mild-to-moderate hypertension. In particular, in a large double-blind trial, the incidence of ankle oedema was significantly lower in manidipine than in amlodipine recipients. Manidipine is also effective in hypertensive patients with comorbidities, such as type 2 diabetes mellitus and/or renal impairment, and appears to improve insulin sensitivity without affecting metabolic function. Thus, manidipine represents a first-line treatment option for patients with essential mild-to-moderate hypertension.

Role of ANG II in coronary capillary angiogenesis at the insulin-resistant stage of a NIDDM rat model

With the use of Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of human non-insulin-dependent diabetes mellitus (NIDDM), we assessed whether ANG II is involved in coronary capillary angiogenesis at the insulin-resistant stage of NIDDM (20 wk of age). In OLETF rats, ANG II labeling and angiotensin type 1 (AT(1)) receptor expression in coronary vessels were increased more than in nondiabetic controls. A marked increase in vascular expression of vascular endothelial growth factor (VEGF) at both mRNA and protein levels was found in OLETF rats. The increased expression level of VEGF was associated with accumulation of hypoxia-inducible factor-1alpha (HIF-1alpha) activated by increased advanced glycation end products (AGEs). Morphometric analysis showed a significantly increased total coronary capillary density, which was a result of arterialization of the venular capillary portion in OLETF rats. Treatment of OLETF rats with candesartan, an AT(1) receptor blocker, inhibited vascular expressions of VEGF, HIF-1alpha, and AGEs, and ameliorated the morphometric changes. These results suggest a key role of ANG II in the pathogenesis of the coronary capillary remodeling in this NIDDM model.

Antiatherosclerotic effects of calcium channel blockers

Over the past 30 years, a considerable body of experimental and clinical evidence has accumulated to support the suggestion that calcium channel blockers (CCBs) have significant antiatherosclerotic effects that are independent of their hypotensive effects. Early research using animal models of atherosclerosis and CCBs in concentrations that exceeded the normal therapeutic dose range showed definite antiatherosclerotic effects, especially in the development of new lesions. Investigations of these effects in humans have used quantitative coronary angiography and B-mode ultrasonography and have demonstrated some antiatherosclerotic effects. This article reviews the currently available evidence of antiatherosclerotic effects of CCBs in animal models and in clinical trials.

Manidipine: a review of its use in hypertension

Manidipine is a dihydropyridine calcium antagonist, which causes systemic vasodilation by inhibiting the voltage-dependent calcium inward currents in smooth muscle cells. The resulting reduction in blood pressure (BP) in patients with hypertension is maintained over 24 hours. Manidipine 10 to 40 mg once daily for 4 weeks significantly lowered office BP from baseline and compared with placebo, and significantly reduced 24-hour BP compared with placebo in patients with essential hypertension in a well controlled trial. The decline in BP was maintained over 24 hours (trough to peak BP ratios were >50%) without disturbing the circadian BP pattern. BP reductions with therapeutic dosages of manidipine were maintained for up to 1 year in noncomparative trials. The BP-lowering capacity of manidipine 5 to 20 mg/day appears to be similar to that of other calcium antagonists with which it has been compared in randomised double-blind and nonblind trial. In a well controlled short term trial, manidipine 10 mg daily significantly decreased trough sitting BP compared with placebo in elderly patients with mild to moderate essential hypertension. Decreases in BP were maintained for up to 3 years of treatment. The drug (10 or 20 mglday) also significantly lowered sitting BP from baseline in patients with hypertension and type 2 diabetes mellitus in randomised, long term comparative trials. In general, the observed reduction in BP with manidipine was similar to that observed with amlodipine, enalapril or delapril. The effects of manidipine on urinary albumin excretion (UAE) have not been clearly demonstrated in clinical trials in this patient group. BP was also reduced with manidipine in patients with impaired glucose tolerance. Manidipine was well tolerated in clinical trials, with most adverse effects related to vasodilation. Commonly reported events included ankle oedema, headache. palpitation. flushing, dizziness, rash and fatigue. Manidipine appears to have less potential for pedal oedema than amlodipine.

CONCLUSIONS

Manidipine has shown antihypertensive efficacy and appears to be well tolerated in adult and elderly patients with mild or moderate essential hypertension. The BP-lowering effects of the drug in patients with hypertension and type 2 diabetes mellitus or impaired glucose tolerance were not associated with any adverse metabolic effects. The effects of manidipine on UAE in this patient group remain unclear. Manidipine provides an additional treatment option for patients for whom dihydropyridine calcium antagonists are appropriate. Manidipine is a dihydropyridine calcium antagonist, which causes systemic vasodilation by inhibiting the voltage-dependent calcium inward currents in smooth muscle cells. The resulting reduction in blood pressure (BP) in patients with hypertension is maintained over 24 hours. Manidipine 10 to 40mg once daily for 4 weeks significantly lowered office BP from baseline and compared with placebo, and significantly reduced 24-hour BP compared with placebo in patients with essential hypertension in a well controlled trial. The decline in BP was maintained over 24 hours (trough to peak BP ratios were >50%) without disturbing the circadian BP pattern. BP reductions with therapeutic dosages of manidipine were maintained for up to 1 year in non-comparative trials. The BP-lowering capacity of manidipine 5 to 20 mg/day appears to be similar to that of other calcium antagonists with which it has been compared in randomised double-blind and nonblind trial. In a well controlled short term trial, manidipine 10 mg daily significantly decreased trough sitting BP compared with placebo in elderly patients with mild to moderate essential hypertension. Decreases in BP were maintained for up to 3 years of treatment. The drug (10 or 20 mg/day) also significantly lowered sitting BP from baseline in patients with hypertension and type 2 diabetes mellitus in randomised, long term comparative trials. In general, the observed reduction in BP with manidipine was similar to that observed with amlodipine, enalapril or delapril. The effects of manidipine on urinary albumin excretion (UAE) have not been clearly demonstrated in clinical trials in this patient group. BP was also reduced with manidipine in patients with impaired glucose tolerance. Manidipine was well tolerated in clinical trials, with most adverse effects related to vasodilation. Commonly reported events included ankle oedema, headache. palpitation. flushing, dizziness, rash and fatigue. Manidipine appears to have less potential for pedal oedema than amlodipine.

CONCLUSIONS

Manidipine has shown antihypertensive efficacy and appears to be well tolerated in adult and elderly patients with mild or mo

Cilostazol, a phosphodiesterase inhibitor, improves insulin sensitivity in the Otsuka Long-Evans Tokushima Fatty Rat, a model of spontaneous NIDDM

AIM

Angiotensin converting enzyme inhibitors and alpha1-adrenergic blockers improve insulin sensitivity, the mechanism of which was considered, at least in part, to be due to the increased blood flow to muscle. The present study aimed to clarify whether cilostazol, a phosphodiesterase inhibitor, improves insulin sensitivity in a model of spontaneous non-insulin dependent diabetes mellitus (NIDDM), Otsuka Long-Evans Tokushima Fatty (OLETF) rat.

METHODS

OLETF rats were divided into the two groups at the age of 16 weeks: the cilostazol-supplemented group (cilostazol 40 mg/kg/day) and the normal-diet group. As a non-diabetic control, we used Long-Evans-Tokushima-Otsuka rats (non-diabetic rats). Oral glucose tolerance test and hyperinsulinemic euglycemic clamp was performed at the ages of 23 and 25 weeks, respectively. Serum levels of lipids and leptin were measured.

RESULTS

Body weight and abdominal fat was increased in OLETF rats but cilostazol supplementation did not alter them. Insulin sensitivity, as measured by the hyperinsulinemic euglycemic clamp technique, was significantly decreased in OLETF rats (glucose infusion rate: 73.5 +/- 10.0 vs. 41.5 +/- 9.8 micromol/min/kg body weight, p < 0.01). Cilostazol supplementation improved insulin sensitivity partially but significantly 51.0 +/- 5.7 micromol/min/kg body weight, p < 0.05) in OLETF rats at 25 weeks of age, although it did not decrease serum levels of glucose, lipids or leptin. However, this effect was not observed in non-diabetic rats.

CONCLUSION

Cilostazol, which is used in diabetic patients for the treatment of obstructive disease of artery, is expected to have a beneficial effect on insulin sensitivity in NIDDM.