Glucose and lipid metabolism during long-term treatment with cilazapril in hypertensive patients with or without impaired glucose metabolism

Role of angiotensin-converting enzyme inhibition in glucose metabolism and renal injury in diabetes

The role of angiotensin-converting enzyme (ACE) inhibition in glucose metabolism and renal injury in diabetes has been extensively investigated in diabetic humans, as well as in animal models of diabetes. Accumulated data indicate that ACE inhibitors have either no adverse effect on glucose control or insulin sensitivity or may even improve them. ACE inhibitors also appear to have neutral or positive effects on lipid metabolism. The variability of results between studies may relate to differences in experimental design, the degree of glycemia or insulin resistance, potassium balance, and dose or duration of ACE inhibitor treatment, among others. In contrast, ACE inhibitors have proved effective in limiting proteinuria and retarding renal function loss in insulin-dependent diabetes mellitus (IDDM) or non-insulin-dependent diabetes mellitus (NIDDM) patients. In rats with experimental or spontaneous diabetes, ACE inhibitors also reduce proteinuria and limit glomerular as well as tubulointerstitial damage, independent of their effects on systemic arterial pressure. How ACE inhibitors limit renal injury in diabetes is not entirely clear, but hemodynamic and nonhemodynamic mechanisms may be involved. Increasing evidence suggests that the intrarenal renin-angiotensin system (RAS) may be altered or activated in the diabetic kidney. Such activation may be specifically inhibited by ACE inhibitors and may explain the superiority of this class of agents over other antihypertensive agents in reducing proteinuria and slowing the progression of diabetic nephropathy.

Captopril does not improve insulin action in essential hypertension: a double-blind placebo-controlled study

OBJECTIVE

To compare the effect of captopril with that of placebo on peripheral and hepatic insulin action in essential hypertension, in light of evidence that insulin resistance is associated with cardiovascular risk.

DESIGN

Randomized, double-blind, placebo-controlled, crossover trial, with 8 week treatment periods of captopril and placebo preceded and separated by 6 weeks of placebo.

SETTING

Belfast teaching hospital.

PATIENTS

Eighteen Caucasian nondiabetic patients (10 males), aged under 65 years, with essential hypertension, recruited from general practices in the greater Belfast area.

INTERVENTIONS

Captopril at 50 mg twice a day or placebo twice a day for two 8 week treatment periods.

MAIN OUTCOME MEASURES

Peripheral and hepatic insulin sensitivity assessed by glucose clamps.

RESULTS

Fourteen patients completed the study. Mean (+/- SEM) levels of fasting glucose, fasting insulin and postabsorptive hepatic glucose production were similar after captopril and placebo (5.4+/-0.1 versus 5.4+/-0.1 mmol/l, 10.6+/-2.2 versus 9.5+/-1.1 mU/l, 11.2+/-0.6 versus 11.0+/-0.5 mmol/kg per min, respectively). During hyperinsulinaemia, hepatic glucose production was suppressed to comparable levels after both treatments (4.8+/-0.6 versus 4.3+/-0.6 mmol/kg per min) and exogenous glucose infusion rates required to maintain euglycaemia were also similar (30.0+/-2.6 versus 30.3+/-2.6 mmol/kg per min).

CONCLUSION

Captopril therapy in uncomplicated essential hypertension has no effect on peripheral or hepatic insulin sensitivity.

Long-term effects of perindopril on metabolic parameters and the heart in the spontaneously hypertensive/NIH-corpulent rat with non-insulin-dependent diabetes mellitus and hypertension

The spontaneously hypertensive/NIH-corpulent (SHR/N-cp) rat is a genetic model that exhibits both non-insulin-dependent diabetes mellitus (NIDDM) and hypertension. To determine the impact of long-term treatment with the long-acting angiotensin-converting enzyme (ACE) inhibitor perindopril (PE) on the glucose metabolism, lipid levels, and heart in this model, studies were performed in three groups of SHR/N-cp rats maintained on a diet containing 54% carbohydrate with 18% sucrose and 36% starch. One group of obese rats received PE (0.5 to 1.0 mg/kg body weight/d) for 3 to 4 months, a second group of obese rats received no treatment, and a third group of lean rats were used as controls. The mean systolic blood pressure (SBP) increased gradually in both untreated obese and lean rats, with lean animals showing slightly higher levels compared with untreated obese rats. By contrast, SBP was reduced to normal levels in PE-treated obese rats throughout the treatment period. Compared with lean rats, obese rats showed significantly higher body weight and fasting serum levels of glucose, insulin, total cholesterol (TC), and triglyceride (TG). However, no significant differences were observed in these metabolic parameters between PE-treated and untreated obese rats. Plasma renin activity measured at the end of the treatment period was significantly higher in PE-treated rats compared with untreated obese and untreated lean rats. The mean heart weight and left ventricular weight, expressed in absolute terms or indexed to body weight, were significantly lower in PE-treated versus untreated obese and untreated lean rats. To further determine whether glucose metabolism is directly affected by PE treatment, in vitro glycogen synthesis was evaluated in isolated soleus muscles obtained from three additional groups of animals. The basal rate of muscle glycogen synthesis was significantly lower in obese compared with lean rats (P < .05), but did not differ between PE-treated and untreated obese rats. Maximal insulin-stimulated glycogen synthesis increased threefold in PE-treated obese rats, but this increase did not differ from the increases observed in untreated obese and lean rats. In conclusion, the present study shows that long-term PE treatment in obese SHR/N-cp rats with NIDDM and hypertension effectively controlled systemic arterial pressure and resulted in a significant reduction in left ventricular weight. However, these favorable effects of PE were not associated with significant improvement in glucose tolerance, hyperinsulinemia, and hyperlipidemia in this model. PE also had no direct stimulatory effects on either basal or insulin-mediated glycogen synthesis in the isolated soleus muscle of obese rats, perhaps because of the severe insulin-resistant state of the animals. Our results support the clinical observations that antihypertensive therapy with ACE inhibitors has neutral effects on glucose metabolism and insulin sensitivity in patients with combined hypertension and NIDDM.

Effect of doxazosin therapy on glucose tolerance and lipid metabolism in hypertensive patients with impaired glucose tolerance

The effects of long-term monotherapy with doxazosin, an alpha 1-blocker, or placebo on blood pressure (BP), glucose tolerance, and serum lipid levels were investigated prospectively in 43 hypertensive patients with impaired glucose tolerance. The levels of plasma glucose, serum lipids, fructosamine, and glycated hemoglobin A1c (Hb A1c) were determined before and during long-term (mean treatment period, 6.7 months) therapy with doxazosin (n = 23) or placebo (n = 20). A 75-g oral glucose tolerance test was performed before and during therapy. Significant decreases in both systolic and diastolic BP were maintained during doxazosin therapy; BP did not change in the placebo group. Neither fasting nor post-glucose-load venous plasma glucose levels were altered, and there was no significant change in the insulinogenic index in either group. Glucose intolerance was slightly improved with significant reductions in Hb A1c and fructosamine levels during doxazosin therapy. Serum total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol levels were significantly decreased, and high-density lipoprotein cholesterol levels were significantly increased in patients treated with doxazosin. Moreover, TC, LDL cholesterol, and apolipoprotein B levels were significantly decreased in patients with hypercholesterolemia (TC > or = 5.69 mmol/L). In contrast, there were no significant changes in Hb A1c, fructosamine, and lipid levels in the placebo group. These results suggest that long-term doxazosin therapy may improve glucose and lipid metabolism in hypertensive patients. Doxazosin appears useful as an antihypertensive agent for hypertensive patients with either impaired glucose metabolism or dyslipidemia.

Metabolic manifestations of low-dose diuretics

Hypertension has been defined and treated as a disease of abnormal systolic and diastolic blood pressure. Recent data have, however, demonstrated that effective blood-pressure control has not resulted in the expected decrease in coronary artery disease. These findings are probably a result of hypertension being a complex inherited syndrome of cardiovascular risk factors, all of which are genetically linked and all of which contribute to the development of cardiovascular disease in these patients. Included in the hypertension syndrome are abnormalities of lipid profile, insulin resistance, changes in renal function, left ventricular hypertrophy and reduced arterial compliance. In many patients, high blood pressure is a late manifestation of this disease process. Since all cardiovascular risk factors contribute to heart disease in these patients, they should all be considered in the management of this disease process. Diuretics and beta blockers, when used at high doses, negatively impact lipid metabolism and insulin sensitivity, while angiotensin converting enzyme (ACE) inhibitors and calcium antagonists tend to have a neutral effect on these metabolic risk factors. These findings have resulted in decreased use of diuretics and beta blockers in favor of newer agents such as ACE inhibitors and calcium antagonists. However, recent data have demonstrated that when used at low doses (6.25 or 12.5 mg of hydrochlorothiazide), diuretics lack significant metabolic side effects while bringing about significant reductions in blood pressure. Thus, at these doses, hydrochlorothiazide is a useful drug in the treatment of hypertension, both as monotherapy and in combination therapy.

Metabolic neutrality of perindopril: focus on insulin sensitivity in overweight patients with essential hypertension

To assess the effects of antihypertensive treatment with the angiotensin-converting enzyme (ACE) inhibitor perindopril on insulin sensitivity, plasma insulin, and lipoprotein metabolism in overweight hypertensive patients, we measured the insulin sensitivity index (SI, determined according to the minimal model method of Bergman), fasting plasma insulin and glucose concentrations, serum total triglyceride and lipoprotein cholesterol fractions, and blood pressure (BP) in 30 overweight [mean body mass index (BMI) 30.9 kg/m2], nondiabetic patients with essential hypertension after a 4-week run-in period and after 6 weeks of perindopril (n = 20) or placebo (n = 10) administered in a double-blind fashion. Furthermore, we estimated their state of physical fitness using the Conconi bicycle ergometer test before and after perindopril or placebo administration. SI was low in our study population (3.2 vs. 13.3 10(-4) ml.microU-1.min-1 in normal lean control subjects). It did not differ between the perindopril and placebo group after the placebo run-in period (3.1 vs. 3.3 x 10(-4) ml.microU-1.min-1) and was not influenced by perindopril (3.3 x 10(-4) ml.microU-1.min-1) or placebo (3.6 x 10(-4) ml.microU-1.min-1) treatment. Moreover, no significant changes were apparent in fasting plasma insulin and glucose, the areas under the glucose and insulin curves, the glucose disappearance rates, serum total triglycerides (TG), or cholesterol or lipoprotein cholesterol fractions between run-in and active treatment phases in the perindopril or the placebo group, respectively. Heart rate (HR), body weight, and anaerobic threshold remained stable in both groups. Compliance, assessed by pill counting was > 90% in both groups at all visits. Therefore, the ACE inhibitor perindopril is neutral with regard to insulin sensitivity, plasma insulin and glucose, and lipoprotein metabolism in overweight, nondiabetic patients with essential hypertension.

Effect of cilazapril therapy on glucose and lipid metabolism in patients with hypertension

The effects of long-term monotherapy with cilazapril, an angiotensin-converting enzyme inhibitor, on blood pressure, glucose tolerance, and serum lipid profiles were prospectively investigated in 66 patients with hypertension: 23 with normal glucose tolerance and 43 with glucose intolerance (including 9 patients with non-insulin-dependent diabetes mellitus). The levels of plasma glucose, serum insulin, serum lipids, glycated hemoglobin A(lc) (Hb A(lc)), and fructosamine were determined before and during long-term (mean +/- SD, 26.2 +/- 1.2 weeks) therapy with cilazapril. A 75-g oral glucose tolerance test was performed before and during treatment. Significant reductions in both systolic and diastolic blood pressures in both patient groups were maintained during the study. Neither fasting nor post-glucose load venous plasma glucose levels were altered in either group of patients, and no patient with normal glucose tolerance developed diabetes mellitus during the study. There was no significant change in the insulinogenic index (delta serum insulin/delta venous plasma glucose at 30 minutes post-glucose load) in either group, and glucose intolerance was slightly improved with significant reductions (P < 0.01) in Hb A(lc) and fructosamine in the patient group with impaired glucose tolerance. Serum total cholesterol (TC), low-density lipoprotein cholesterol, and triglyceride levels were significantly (P < 0.01) decreased and high-density lipoprotein cholesterol levels increased in patients with hypercholesterolemia (TC levels > or = 5.69 mmol/L). These results suggest that long-term cilazapril therapy may improve glucose and lipid metabolism in hypertensive patients with impaired glucose tolerance. Cilazapril also appears to be useful as an antihypertensive agent for hypertensive patients with either impaired glucose tolerance or hypercholesterolemia.

Effects of long-term cilazapril treatment on glucose and lipid metabolism in hypertensive patients with non-insulin-dependent diabetes mellitus

The effects of long-term cilazapril treatment on glucose and lipid metabolism were assessed in 25 hypertensive patients with non-insulin-dependent diabetes mellitus (NIDDM). Patients were treated with 0.5 to 1 mg of cilazapril once daily or a combination of cilazapril and other antihypertensive drugs once daily for 48 weeks. Both systolic and diastolic blood pressures were significantly reduced (P < 0.001) throughout the study with no significant changes in heart rate and no adverse effects such as cough. There were no significant changes in body mass index or serum levels of glycated hemoglobin A1c, fructosamine, total cholesterol, triglycerides, lipoproteins (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and very-low-density lipoprotein cholesterol), or apolipoproteins (apo A-I, apo C-II, apo C-III, apo B, and apo E). Cilazapril caused a significant increase (P < 0.05) in levels of apo A-II and a significant decrease (P < 0.05) in the apo B:apo A-I ratio, an index of arteriosclerosis. These results suggest that cilazapril has favorable effects on glucose and lipid metabolism and that it may be useful as the first or second choice of antihypertensive drugs in hypertensive patients with NIDDM.

Felodipine therapy may not alter glucose and lipid metabolism in hypertensives. Felodipine Multicenter Prospective Study Group in Japan

The effects of long-term monotherapy with felodipine, a calcium antagonist, on blood pressure, glucose tolerance, and serum lipid profiles were prospectively investigated in 51 hypertensive patients: 13 with normal glucose tolerance and 38 with glucose intolerance. The levels of plasma glucose, serum lipids, and glycosylated hemoglobin A1c were determined before and during long-term (7.5 +/- 0.5 months; range, 6 to 9 months) therapy with felodipine. A 75-g oral glucose tolerance test was performed before and during long-term felodipine therapy. Significant decreases in both systolic and diastolic blood pressures in both patient groups were maintained during the therapy. Neither fasting nor post-glucose load venous plasma glucose levels were altered in either group of patients, and no patients with normal glucose tolerance developed diabetes mellitus during the study. Serum lipid levels did not change significantly in either group of patients except for significant decreases in high-density lipoprotein cholesterol and apolipoprotein A-I in the group with normal glucose tolerance tests, but those changes remained within the normal range. Furthermore, neither serum lipid nor apolipoprotein levels were altered, even in patients with hypercholesterolemia (total cholesterol levels, > 5.69 mmol/L = 220 mg/dL). These results suggest that long-term therapy with felodipine may not alter glucose and lipid metabolism in hypertensive patients, and felodipine appears to be useful as an antihypertensive agent for hypertensive patients with either dyslipidemia or impaired glucose metabolism.

Cilazapril. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in cardiovascular disease

Cilazapril is an orally active angiotensin converting enzyme (ACE) inhibitor which lowers peripheral vascular resistance without affecting heart rate. Like enalapril and ramipril it is a prodrug, and is hydrolysed after absorption to cilazaprilat, which has a long terminal phase elimination half-life permitting once daily administration. Given once daily at doses between 2.5 and 5 mg, cilazapril reduces arterial blood pressure in patients with mild to moderate essential and renal hypertension. Patients who do not respond adequately to cilazapril monotherapy usually respond with the addition of a diuretic such as hydrochlorothiazide. Preliminary data suggest that cilazapril is of comparable antihypertensive efficacy to usual therapeutic dosages of hydrochlorothiazide, slow release propranolol, nitrendipine, captopril and enalapril. In small studies cilazapril has produced sustained beneficial haemodynamic effects in patients with congestive heart failure. Cilazapril has been well tolerated and exhibits tolerability typical of ACE inhibitors as a class, including their lack of detrimental effect on glucose or lipid metabolism. Cilazapril should provide an effective alternative in the treatment of hypertension and, if preliminary data are confirmed, in congestive heart failure.