Long-term comparison of losartan and enalapril on kidney function in hypertensive type 2 diabetics with early nephropathy

Aldosterone breakthrough during therapy with angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers in proteinuric patients with immunoglobulin A nephropathy

BACKGROUND

We are investigating whether aldosterone breakthrough negatively impacts on the antiproteinuric effects of angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin II receptor blockers (ARB).

METHODS

We examine the role of aldosterone breakthrough in 43 normotensive, proteinuric (0.7 +/- 0.3 g/day) outpatients (aged 41.5 +/- 10.9 years) with immunoglobulin A nephropathy (IgAN) accompanied by stable renal function (creatinine clearance >50 mL/min). The patients were treated with temocapril (1 mg; n = 14), losartan (12.5 mg; n = 16), or a combination therapy (n = 13) for 12 months. We prospectively evaluated blood pressure (BP), urinary protein excretion (UPE), biochemical parameters and the renin-angiotensin-aldosterone system before and after 12 months of treatment.

RESULTS

Although the overall plasma aldosterone concentrations values did not change after any of the treatments administered for 12 months, they eventually increased in 23 (temocapril, seven patients; losartan, eight patients; combination, seven patients) of the 43 patients (53.4%; aldosterone breakthrough), and fell in the remainder (46.6%). Blood pressure and renal function did not differ among the three groups at 12 months. In contrast, UPE was significantly higher in patients with, than without aldosterone breakthrough during temocapril and losartan administration. However, combination therapy induced a more remarkable reduction in UPE regardless of aldosterone breakthrough.

CONCLUSIONS

A combination of ACE inhibitors and ARB in normotensive patients with IgAN produces a more profound decrease in proteinuria than either monotherapy. This additive antiproteinuric effect is not dependent on aldosterone breakthrough. Additional larger, prospective, randomized studies will be needed for general acceptance of this strategy.

Preventing renal complications in type 2 diabetes: results of the diabetics exposed to telmisartan and enalapril trial

Patients with type 2 diabetes are prone to hypertension and persistent protein leakage from the kidney (microalbuminuria or macroalbuminuria). A progressive decline in renal function can lead to overt diabetic nephropathy and ESRD. The likelihood of cardiovascular disease also is increased. Control of hypertension is paramount to prevent these life-threatening complications. Agents that target the renin-angiotensin system--angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers--have been shown to be renoprotective. The groundbreaking Diabetics Exposed to Telmisartan And enalaprIL (DETAIL) trial was designed to address the absence of comparative data on the long-term effects of an angiotensin II receptor blocker versus an angiotensin-converting enzyme inhibitor on renoprotection and survival in 250 patients with hypertension and early type 2 diabetic nephropathy. The primary purpose of the 5-yr double-blind, double-dummy, randomized study was to establish whether 40 to 80 mg of telmisartan conferred similar (i.e., noninferior) renoprotection to 10 to 20 mg of enalapril as determined by the change from baseline in GFR, measured by the plasma clearance of iohexol. Secondary end points included the emergence of ESRD and all-cause mortality. Telmisartan was not inferior to enalapril in reducing the decline in GFR: Mean annual declines in GFR were 3.7 and 3.3 ml/min per 1.73 m(2) with telmisartan and enalapril, respectively. During the 5-yr study period, no patient developed a serum creatinine >200 micromol/L, and none required dialysis. There were only six deaths in each treatment group during the study, with half being due to cardiovascular events.

Taking the pressure off type 2 diabetes mellitus: implementing hypertension guidelines

Successful treatment of hypertension in patients with type 2 diabetes mellitus increases life expectancy and reduces the risk of many of the complications associated with diabetes, such as heart disease, stroke, and retinopathy. Controlling blood pressure also protects against advancing renal disease, with several recent studies having clearly shown the advantage of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in slowing the progression of renal disease. Here, the authors review current guidelines for the management of hypertension in patients with type 2 diabetes mellitus and explore ways in which nurse practitioners can improve care for these patients.

Angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists for preventing the progression of diabetic kidney disease

BACKGROUND

Angiotensin converting enzyme inhibitors (ACEi) and angiotensin II receptor antagonists (AIIRA) are considered to be equally effective for patients with diabetic kidney disease (DKD), but renal and not mortality outcomes have usually been considered.

OBJECTIVES

To evaluate the benefits and harms ACEi and AIIRA in patients with DKD.

SEARCH STRATEGY

We searched MEDLINE (1966 to December 2005), EMBASE (1980 to December 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library issue 4 2005) and contacted known investigators.

SELECTION CRITERIA

Studies comparing ACEi or AIIRA with placebo or each other in patients with DKD were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and results expressed as relative risk (RR) with 95% confidence intervals (CI). Heterogeneity among studies was explored using the Cochran Q statistic and the I(2) test, subgroup analyses and random effects metaregression.

MAIN RESULTS

Fifty studies (13,215 patients) were identified. Thirty eight compared ACEi with placebo, five compared AIIRA with placebo and seven compared ACEi and AIIRA directly. There was no significant difference in the risk of all-cause mortality for ACEi versus placebo (RR 0.91, 95% CI 0.71 to 1.17) and AIIRA versus placebo (RR 0.99, 95% CI 0.85 to 1.17). A subgroup analysis of studies using full-dose ACEi versus studies using half or less than half the maximum tolerable dose of ACEi showed a significant reduction in the risk of all-cause mortality with the use of full-dose ACEi (RR 0.78, 95% CI 0.61 to 0.98). Baseline mortality rates were similar in the ACEi and AIIRA studies. The effects of ACEi and AIIRA on renal outcomes (ESKD, doubling of creatinine, prevention of progression of micro- to macroalbuminuria, remission of micro- to normoalbuminuria) were similarly beneficial. Reliable estimates of effect of ACEi versus AIIRA could not be obtained from the three studies in which they were compared directly because of their small sample size.

AUTHORS' CONCLUSIONS

Although the survival benefits of ACEi are known for patients with DKD, the relative effects on survival of ACEi with AIIRA are unknown due to the lack of adequate direct comparison studies. In placebo controlled studies, only ACEi (at the maximum tolerable dose, but not lower so-called renal doses) were found to significantly reduce the risk of all-cause mortality. Renal and toxicity profiles of these two classes of agents were not significantly different.

Managing diabetic nephropathy: recent studies

PURPOSE OF REVIEW

This review summarizes recent studies designed to identify improved treatments for diabetic nephropathy.

RECENT FINDINGS

Recent data support the concept that angiotensin converting enzyme inhibitors and angiotensin II receptor blockers have similar renoprotective effects. Aggressive blockade of the renin-angiotensin system appears to have benefits beyond those achieved with conventional doses of single agents. Dual blockade using angiotensin converting enzyme inhibitors and angiotensin II receptor blockers is effective. Aldosterone receptor antagonists may potentiate the effect of these two classes of compounds. It remains unclear, however, whether maximum benefit can be obtained by the combination of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers or aldosterone receptor antagonists as compared to larger doses of single agents. Not enough data are available currently to recommend thiazolidinedione hypoglycemic agents for renal protection. Trials are being conducted with several new classes of agents.

SUMMARY

Evidence from short-term studies favors aggressive blockade of the renin-angiotensin system. Long-term studies, however, remain to be performed. A multifactorial approach that incorporates established interventions affords our best means to retard the progression of diabetic nephropathy.

Prevention of loss of renal function over time in patients with diabetic nephropathy

Management of hypertension is the mainstay of prevention and treatment of diabetic renal disease; evidence suggests that tight blood pressure control slows renal disease progression in established diabetic nephropathy. Inhibition of the renin-angiotensin-aldosterone system (RAAS) has renoprotective effects over and above those achieved by lowering systemic blood pressure. To date, however, no long-term study using hard end points has directly compared current mechanisms for RAAS inhibition, angiotensin II receptor blockade (ARB) and angiotensin-converting enzyme (ACE) inhibition. This issue was addressed in the recently published Diabetics Exposed to Telmisartan and Enalapril (DETAIL) study, a head-to-head comparison of telmisartan and enalapril in 250 patients with hypertension and type 2 diabetes mellitus and early-stage nephropathy. After 5 years' treatment, change in glomerular filtration rate (GFR), the primary efficacy end point, was equivalent in the 2 treatment groups, as were all secondary end points. The expected steep decline in GFR in the first year was followed by a lesser decrease in the second year and then almost complete stabilization of renal function at > or =3 years. Over 5 years, no patient went into end-stage renal disease or required dialysis. There were also no increases in albumin excretion rate, nor was there an increase in creatinine beyond 200 mumol/L. Incidence of cardiovascular morbidity and mortality was extremely low in both treatment groups, a remarkable outcome given that almost 50% of patients had evidence of cardiovascular disease at randomization. Inhibition of the RAAS should play a major part in management of patients with type 2 diabetes with nephropathy, for which both telmisartan and enalapril provide long-term renoprotection.

Emerging drugs for diabetic nephropathy

There is an increasing number of patients with diabetes mellitus in many countries. Diabetic kidney disease, one of its microvascular complications, is also increasing markedly and has become a major cause of end stage renal disease worldwide. Intervention for preventing and delaying the development and progression of diabetic kidney disease is not only a medical concern, but also a social issue. Despite extensive efforts, however, medical interventions thus far are not effective enough to prevent the progression of the disease and the development of end stage renal disease. This justifies attempts to develop novel therapeutic approaches for diabetic nephropathy. Recent insights on its pathogenesis and progression have suggested new targets for the specific treatment of this disease. They include aldosterone, aldose reductase, arachidonic acid metabolites, growth factors, advanced glycosylation end-products, peroxisome proliferator-activated receptors and endothelin. Several other biochemical mediators have been targeted in experimental animal models with the goal to prevent diabetic nephropathy progression, but translation to clinics of these experimental achievements are still limited or lacking.

A meta-analytical approach to the efficacy of antihypertensive drugs in reducing blood pressure

INTRODUCTION

Hypertension constitutes a veritable public health issue. Several classes of drugs are available for the treatment of hypertension. The objective of this meta-analytical approach was to assess the efficacy of antihypertensive drugs most commonly used in France in reducing clinical SBP and DBP.

METHODS

The antihypertensive drugs selected were hydrochlorothiazide, indapamide sustained release (SR), furosemide and spironolactone for diuretics; amlodipine and lercanidipine for calcium channel antagonists; atenolol for beta-adrenoceptor antagonists (beta-blockers); enalapril and ramipril for ACE inhibitors; and candesartan cilexetil, irbesartan, losartan, and valsartan for angiotensin II receptor antagonists. The trials selected were published between 1973 and 2004, evaluated monotherapy with trial drugs as fixed-dosage or with dosage increase, and assessed blood pressure reduction between 2 and 3 months. The analysis method used was based on the calculation of the sum weighted for the trial size.

RESULTS

A total of 72 trials (comprising 9094 patients) were selected and analyzed. No trial evaluating furosemide or spironolactone satisfied the inclusion criteria for this analysis. For SBP, the reduction was more marked with diuretics, calcium channel antagonists, and ACE inhibitors. Of all the drugs studied, indapamide SR gave the greatest SBP reduction (-22.2 mm Hg). Evaluated therapeutic classes had a similar magnitude of effect on DBP, i.e. reduction between -11.4 mm Hg with beta-adrenoceptor antagonists and -10.3 mm Hg with angiotensin II type 1 receptor antagonists.

CONCLUSION

Indapamide SR 1.5 mg appeared to be the most effective drug for a significant reduction in SBP within 2-3 months, which is an essential element in optimizing cardiovascular prevention among hypertensive patients. The clinical application of these results should take into consideration all the limitations discussed in this analysis.

Preventing end-stage renal disease in diabetic patients - dual blockade of the renin-angiotensin system (Part II)

Diabetic nephropathy is a major cause of diabetes related morbidity and mortality. The first part of the current review was published in the last issue of this journal and discussed the important role of the renin-angiotensin system (RAS) in diabetic nephropathy and the genetic influence on development of endstage renal disease (ESRD) in diabetic patients. This second part of the review focus on the potential improvement of the current treatment strategy to slow down the loss of kidney function using dual blockade of the RAS with both ACE-inhibitors (ACE-I) and angiotensin II receptor blockers (ARBs). Substantial evidence from short-term studies using surrogate endpoints indicates a beneficial impact of dual blockade of the RAS, not obtainable with single agent blockade alone, both in diabetic and non-diabetic renal disease. This conclusion has been confirmed and extended in a longterm trial with regard to prevention of ESRD in non-diabetic renal disease. Results indicate that dual blockade of the RAS may further slow down, but not arrest progressive loss of renal function. However, studies defining the optimal dose of ACE-I / ARBs without additional adverse effects are essential to ensure relevant comparison with dual blockade therapy. Trials using primary renal endpoints in diabetic nephropathy are still needed, and will finally establish the role of dual blockade of the RAS in a clinical setting.

Blockade of the renin-angiotensin-aldosterone system: a key therapeutic strategy to reduce renal and cardiovascular events in patients with diabetes

Diabetes (particularly type 2 diabetes) represents a global health problem of epidemic proportions. Individuals with diabetes are not only more likely to develop hypertension, dyslipidemia, and obesity, but are also at a significantly higher risk for coronary heart disease, peripheral vascular disease, and stroke. Angiotensin II plays a key pathophysiological role in the progression of diabetic renal disease, and blockade of the renin-angiotensin system with angiotensin-converting enzyme inhibitors (ACEi) or angiotensin II antagonists has therefore become an important therapeutic strategy to reduce renal and cardiovascular events in patients with diabetes. Several studies have demonstrated the effects of angiotensin II antagonists on the reduction of albuminuria and the progression of renal disease from microalbuminuria to macroalbuminuria. More importantly, several endpoint trials have shown that the antiproteinuric effects of losartan and irbesartan translate into cardiovascular and renoprotective benefits beyond blood pressure lowering, thereby delaying the need for dialysis or kidney transplantation by several years. These and other studies indicate that angiotensin II antagonists not only improve survival and quality of life of patients with diabetic nephropathy, but also have the potential to reduce the substantial healthcare burden associated with managing these patients. ACEi also appear to exert similar beneficial effects in diabetic patients, but whether clinically significant differences in renoprotection or mortality exist between angiotensin II antagonists and ACEi in patients with type 2 diabetes remains to be fully investigated in appropriate head-to-head studies.

Angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers for prevention and treatment of nephropathy associated with type 2 diabetes mellitus

Renal complications resulting from type 2 diabetes mellitus are costly and common. Finding optimal therapy is important for the prevention and management of diabetic nephropathy. Research has focused on antihypertensive agents that modify the renin-angiotensin-aldosterone system. Because of their effects on the glomerulus, angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) have been studied as interventions at various stages of diabetic nephropathy. The ACE inhibitors may delay the progression to microalbuminuria and then clinical albuminuria. The ARBs decrease albuminuria in patients with microalbuminuria and decrease adverse renal events, specifically the progression to end-stage renal disease in patients with clinical albuminuria and hypertension. Limited data suggest that combination therapy with ACE inhibitors and ARBs may slow the progression of microalbuminuria to clinical albuminuria. Because of the variability in degree of albuminuria evaluated and in study designs (numbers of patients, study duration, drug dosages, and outcomes measured), a detailed review of the available literature about ACE inhibitors and ARBs in the prevention or treatment of diabetic nephropathy may provide insight to clinicians.

Isolated home hypertension in the morning is associated with target organ damage in patients with type 2 diabetes

To investigate the relationship between the blood pressure control level and cardiovascular risk in type 2 diabetic patients, we evaluated home blood pressure, office blood pressure, biochemical data, and carotid echographic and echocardiographic findings in 148 patients with type 2 diabetes. According to the criteria for hypertension in the guidelines of the Japanese Society of Hypertension, we classified patients into a normotensive group with home systolic blood pressure in the morning (morning HSBP)<135 mmHg and office systolic blood pressure (OSBP)<140 mmHg, an office hypertension group with a morning HSBP<135 mmHg and OSBP>or=140 mmHg, an isolated home hypertension in the morning group with morning HSBP>or=135 mmHg and OSBP<140 mmHg, and a sustained hypertension group with morning HSBP>or=135 mmHg and OSBP>or=140 mmHg. In the isolated home hypertension in the morning group, the fasting insulin level, urinary albumin excretion, maximum carotid artery intima-media complex thickness, and left ventricular posterior wall thickness were significantly higher and the coefficient of variation for RR intervals was significantly lower than in the normotensive group. These results suggest that isolated home hypertension in the morning is a risk factor for target organ damage in type 2 diabetic patients.

The Role of Angiotensin II Type 1 Receptor Antagonists in Elderly Patients with Hypertension

Hypertension is a major risk factor for stroke and coronary events in elderly people and clinical trials have shown that treatment of hypertension with various drugs can result in a substantial reduction in cerebrovascular and cardiovascular events. The angiotensin II type 1 (AT1) receptor antagonists are the newest class of antihypertensive agents to be used widely in clinical practice. AT1 receptor antagonists can generally be given once-daily. They are also extremely well tolerated with minimal first-dose hypotension and an incidence of adverse effects similar to that seen with placebo. Adverse event rates are significantly lower than with other classes of antihypertensive drugs including ACE inhibitors. These factors result in improved compliance and increased rates of continuance on therapy. AT1 receptor antagonists show similar efficacy in lowering blood pressure to other classes of antihypertensive agents and their antihypertensive effect is potentiated when they are given concomitantly with low-dose thiazide diuretics. AT1 receptor antagonists are eliminated predominantly by the hepatic route but most are not subject to extensive metabolism and interactions with other drugs are uncommon. This is an advantage in the elderly, who are often receiving multiple medications which increases the risk for adverse drug interactions. Dose adjustments are not usually required in the elderly unless there is plasma volume depletion. Although plasma AT1 receptor antagonist concentrations are generally higher in the elderly than in younger subjects, this pharmacokinetic difference may be balanced by decreased activation of the circulating renin-angiotensin-aldosterone system in the elderly. Recent clinical studies in high-risk hypertensive patients with left ventricular hypertrophy or in patients with diabetic nephropathy or heart failure have demonstrated that AT1 receptor antagonists can improve clinical outcomes to a similar or sometimes greater extent than other antihypertensive agents. Many of these studies have included large numbers of older patients and have confirmed the excellent tolerability profile of these drugs. Thus, AT1 receptor antagonists should be considered as a possible first-line treatment or as a component of combination therapy in patients with type 2 diabetes mellitus and microalbuminuria or nephropathy and as an alternative or additional treatment to ACE inhibitors in patients with heart failure or left ventricular dysfunction. AT1 receptor antagonists also appear to reduce the onset of new diabetes compared with some other antihypertensive drugs. The benefits in terms of organ protection have mainly been seen in studies using higher doses of particular AT1 receptor antagonists and it is not certain at present whether these results can be extrapolated to other members of the class. As the elderly are more likely to have developed organ damage related to hypertension or to have heart failure or diabetes as concomitant conditions, AT1 receptor antagonists represent an appropriate option for many elderly patients. The main disadvantage of these drugs is the cost of the medication but this may be offset by their improved tolerability with fewer adverse reactions and thus increased compliance, resulting in better blood pressure control and fewer clinical events. Overall, AT1 receptor antagonists are well tolerated and efficacious for blood pressure-lowering when given as a single daily dose in elderly patients and have many potential benefits in high-risk hypertensive subjects.

Angiotensin II antagonists--therapeutic benefits spanning the cardiovascular disease continuum from hypertension to heart failure and diabetic nephropathy

BACKGROUND

The cardiovascular benefits of angiotensin II antagonists (AIIAs) have been evaluated not only in terms of their ability to lower blood pressure but also on their ability to prevent strokes, cardiac events, and target organ damage. This review summarizes the body of evidence-based data demonstrating the efficacy of AIIAs across the spectrum of cardiovascular disease.

METHODS

A PubMed/MEDLINE search of English-language articles (1990 to September 2005) was used to identify articles describing clinical studies, particularly outcome trials, or mechanisms of therapeutic action pertinent to the therapy of cardiovascular disease or nephropathy.

FINDINGS

The antihypertensive efficacy of AIIAs is apparent across a wide spectrum of hypertensive patients, including black and Asian patients and patients with isolated systolic hypertension. More importantly, large outcome-based studies have demonstrated the efficacy of AIIAs across the continuum of cardiovascular disease, including hypertension, heart failure, post-myocardial infarction, and diabetic nephropathy. The Losartan Intervention For Endpoint reduction in hypertension study (LIFE), Reduction of Endpoints in Non-insulin-dependent Diabetes Mellitus with the AII Antagonist Losartan (RENAAL), and the Irbesartan Type 2 Diabetic Nephropathy Trial (IDNT) indicate that AIIAs confer cardiovascular and renal protective effects beyond their ability to lower blood pressure. These bloodpressure independent protective benefits of AIIAs may arise not only by blocking the deleterious effects of AII mediated via the AT1-receptor but may also be due to beneficial molecule-specific effects. As a class, AIIAs are well tolerated with an overall adverse event profile generally comparable to placebo and superior to that typically seen with calcium channel blockers, ACE inhibitors, diuretics, and beta-blockers.

CONCLUSIONS

By utilizing the body of clinical trial evidence as a guide to rational prescribing of AIIAs, practitioners can expect to deliver clinical benefits to their patients in terms of survival, prognosis, and quality of life.

New concepts in blood pressure-lowering management in diabetic patients: the case for early ACE inhibitor combination therapy with diuretics

Type II diabetes and the dysmetabolic syndrome are becoming more and more prevalent, not only in the Western world, but also in many developing countries. The key issue is early prevention and treatment, not only antihyperglycaemic and antihyperlipidaemic treatment, but also, and maybe in particular, antihypertensive treatment. The first issue is first of all screening patients for elevated blood pressure and for microalbuminuria, especially if blood pressure elevation or diabetes is present. Especially, diabetic patients are at risk. The key feature in the therapeutic approach is blocking the renin-angiotensin system, which has proven effective in many original studies. Also the combination with diuretics is a key issue, since these patients have sodium retention. It has been discussed whether ACEi, ARBs or diuretics should be initial treatment, but usually a combination treatment is recommended to reduce blood pressure early and efficiently. The PREMIER study emphasized combination therapy, since the study had very efficient outcomes with combination therapy compared to an ACEi alone as far as blood pressure lowering is concerned, but also with reduction in microalbuminuria and, indeed, end point-reduction. Cardiovascular events showed a decreased incidence with the combination therapy with Preterax (perindopril/indapamide) compared with the enalapril group.

A public health action plan is needed for chronic kidney disease

In 2005, chronic kidney disease (CKD) meets all criteria for classification as a public health problem in the United States. It imposes a large burden on society that is increasing despite ongoing efforts to control the disease. The burden is unevenly distributed by race and economic status, whereas evidence suggests that preventive strategies could substantially reduce the burden. Finally, there are indications that such strategies are not yet in place. A broad and coordinated public health approach to the burgeoning health, economic, and societal challenges of CKD is needed to complement present clinical approaches, increase awareness, promote early detection, and facilitate prevention and treatment.

Meprin-α in chronic diabetic nephropathy: interaction with the renin-angiotensin axis

Meprin (MEP) A is a metalloendopeptidase that is present in the renal proximal tubule brush-border membrane (BBM) and that colocalizes with angiotensin-converting enzyme (ACE). The MEP β-chain gene locus on chromosome 18 has been linked to a heightened risk of diabetic nephropathy (DN) in patients with type 2 diabetes. This study evaluated 1) whether MEP-α and MEP-β gene and protein expression are altered in db/db mice before the onset of DN and 2) the role of MEP-α in the pathogenesis of DN and the impact of the renin-angiotensin system on this interaction in two experimental models of diabetes. MEP-α and MEP-β gene and protein expression were evaluated in db/db mice, 13–14 wk of age, compared with lean C57BLKS/J littermate animals. A treatment study was then performed in which db/db mice and controls were assigned to one of three groups: control (C) water, no therapy; ACE inhibitor therapy, enalapril (EN)-treated water, 50 mg/l; ANG II receptor type 1 blocker (ARB) therapy, losartan (LOS)-treated water, 500 mg/l. Treatment was started at 8 wk of age and continued for 52 wk. Male Sprague-Dawley rats with diabetes for 52 wk following a single dose of streptozocin (STZ; 60 mg/kg) were also studied. At 13.5 wk of age, MEP-α and MEP-β kidney mRNA abundance and protein expression were significantly lower in db/db mice compared with lean controls, with greater changes in MEP-β ( P < 0.05). In the treatment study, EN ameliorated and LOS exacerbated DN in db/db mice. BBM MEP A enzymatic activity and MEP-α protein content were lower in db/db mice vs. control nonobese mice at 52 wk ( P < 0.02). EN-treated db/db mice showed increased MEP A activity, MEP-α content in BBM, decreased urinary MEP-α excretion, and enhanced BBM staining for MEP-α protein vs. C and LOS-treated db/db mice. In nonobese mice, EN and LOS treatment had no effect on MEP-α expression. In rats with STZ-induced diabetes for 52 wk, urinary MEP-α excretion was increased and MEP A activity and MEP-α protein content per milligram of BBM protein were decreased compared with age-matched control animals ( P < 0.05). These results indicate that db/db mice manifest decreased MEP-α and MEP-β gene and protein expression, before the development of overt kidney disease. Moreover, in db/db mice with DN and rats with STZ-diabetes, there was an inverse relationship between renal MEP-α content and the severity of the renal injury. Treatment with an ACE inhibitor was more effective than ARB in ameliorating DN in db/db mice, a change that correlated with alterations in urinary excretion and BBM content of MEP-α. MEP-α may play a role in the pathogenesis of DN and the benefits of ACE inhibitor therapy on the progression of diabetic kidney disease may be related, in part, to its impact on renal MEP-α expression.

Inhibition of the renin-angiotensin system and cardio-renal protection: focus on losartan and angiotensin receptor blockade

Angiotensin II plays a central role in the pathogenesis and progression of proteinuric nephropathies and related cardiovascular complications. Losartan is a selective non-peptide angiotensin Type 1-receptor blocker (ARB) with unique uricosuric effect, not shared by other ARBs. Losartan has demonstrated renoprotective effects in animals and humans with diabetic and non-diabetic renal diseases similar to those of angiotensin-converting enzyme inhibitors, with a lower incidence of dry cough and angioneurotic oedema. A reduced incidence of cerebrovascular events and diabetes has been reported in hypertensive patients with left ventricular hypertrophy on losartan therapy compared with patients treated with atenolol. Whether ARBs have superior cardioprotective effects, compared with other blood pressure medications, is still unknown. Combined angiotensin-converting enzyme inhibitor and ARB therapy improves renal outcomes in non-diabetic nephropathies more than single drug renin-angiotensin system inhibition. Whether this also applies to diabetic nephropathy and related cardiovascular outcomes is still unknown.

Molecular-specific effects of angiotensin II antagonists: clinical relevance to treating hypertension?

Angiotensin II receptor blockers (ARBs) may produce a number of molecule-specific effects that appear to be independent of interaction with the angiotensin II type 1 (AT1)-receptor. These include antagonism of the thromboxane A2 receptor, inhibition of platelet aggregation, induction of peroxisome proliferator- activated receptor gamma (PPARgamma) activity, and reduction of serum uric acid levels. However, definitive evidence is lacking that these molecule-specific effects give rise to a therapeutic advantage of one ARB over another. Currently, the possibility of a link between a molecule-specific effect of an ARB and an improvement in clinical outcomes is best illustrated by a reduction in serum uric acid levels with losartan. Data from Losartan Intervention For Endpoint reduction in hypertension (LIFE) study suggest a treatment-induced decrease in serum uric acid may contribute to the treatment benefit of a losartan-based versus atenolol-based therapy on the composite endpoint (death, myocardial infarction, or stroke). This finding should prompt further studies to investigate the long-term cardioprotective benefits issue of reducing hyperuricaemia in hypertensive patients.

Effects of losartan and amlodipine on urinary albumin excretion and ambulatory blood pressure in hypertensive type 2 diabetic patients with overt nephropathy

OBJECTIVE

Few studies have assessed whether 24-h blood pressure control induced by antihypertensive agents improves macroalbuminuria in hypertensive type 2 diabetic patients with overt nephropathy. We evaluated the effects of losartan and amlodipine on 24-h blood pressure, autonomic nervous activity, and albuminuria in these patients.

RESEARCH DESIGN AND METHODS

In this open-label, parallel-prospective, randomized study, 44 patients were treated with losartan and 43 with amlodipine for a 12-week titration phase and a maintenance phase for a maximum of 12 weeks. Twenty-four-hour blood pressure and urinary albumin excretion were measured before and during treatment. Simultaneously, power spectral analysis of heart rate was performed to evaluate low frequency (LF) and high frequency (HF) components and LF-to-HF ratios as an index of sympathovagal balance.

RESULTS

Losartan decreased (P < 0.001) mean blood pressure from 162/91 to 150/82 mmHg during daytime and from 146/82 to 137/74 mmHg during nighttime (systolic/diastolic). Amlodipine also decreased (P < 0.001) blood pressure from 159/90 to 147/82 mmHg during daytime and from 143/81 to 131/72 mmHg during nighttime. LF and HF components and nighttime-to-daytime ratios for the LF-to-HF ratios did not differ during treatment in two groups, showing no changes in the diurnal autonomic nervous rhythm. Losartan decreased (P < 0.001) 24-h urinary albumin excretion from 810 mg/day (95% CI 780-1,140) to 570 (510-910). Amlodipine, however, did not decrease (P = 0.893) albuminuria (790 mg/day [780-1,170] vs.790 [710-1,260]).

CONCLUSIONS

These results suggest that in type 2 diabetes with overt nephropathy, 24-h blood pressure regulation alone is inadequate to reduce macroalbuminuria and additional effects of losartan are crucial for antiproteinuric action.

Cardiovascular protection in patients with type 2 diabetes mellitus: Considerations about the tightness of blood pressure control and the choice of treatment

Diabetes mellitus is rapidly evolving as the epidemic of the 21st century. The presently estimated number of 190 million is predicted to grow to over 300 million by the year 2025. Cardiovascular (CVD) morbidity and mortality is two to five times higher in diabetics, while the microvascular complications considerably compromise the quality of life. The main risk factors for CVD, as well as for microangiopathy, are hypertension, dyslipidemia, insulin resistance, hyperglycemia, endothelial dysfunction, and an inflammatory vascular reaction. This review will focus on hypertension, which develops in most patients within the first 10-15 years of their diabetes. The discussion will encompass the criteria for treatment, the target values of blood pressure, and the choice of antihypertensive drugs as primary agents and in various combinations. The special role of angiotensin-receptor blockers will be highlighted, with an emphasis on cardioprotection, risk reduction of stroke, and attenuation of the course of nephropathy.

Diabetes and hypertension, the deadly duet: importance, therapeutic strategy, and selection of drug therapy

Large, placebo-controlled RCTs that involve only diabetic patients who have hypertension have not been performed. Subgroup analyses of hyper-tension control from several recent RCTs un-equivocally demonstrated greater benefit in diabetic populations (see Table 3) with ACE inhibitors, TDs, and CCBs. Treatment with fBs(atenolol) also was beneficial in diabetic patients who had hypertension in the actively-controlled UKPDS. The results of three RCTs support intensive BP control in diabetic patients (see Table 4). In these trials, diabetic patients gained more benefit than nondiabetic patients. Such an effect is consistent with the fact that diabetics are at higher risk for CV events. Although there are limited data from RCTs with head-to-head comparison of newer agents (eg,ACE inhibitors, ARBs, CCBs) to show that these drugs are better than diuretics and betaBs in reducing CV events by treating hypertension in the diabetic population, the available data support ACE inhibitors (and ARBs if ACE inhibitors are not tolerated) as an initial drug of choice in diabetic,hypertensive patients (see Table 5). Most diabetic patients require three or four drugs to control their BP to target range; as such, it is not necessary to justify the choice of any single class of drug. Tight BP control is cost-effective and is more rewarding than hyperglycemic control in diabetic,hypertensive patients. The optimal goal in diabetics should be to achieve BP that is less than 130/80 mm Hg. Appropriate action should be taken if BP is greater than 140/85 mm Hg. In subjects who have diabetes and renal insufficiency,the BP should be decreased to less than 125/75 mm Hg to delay the progression of renal failure. Limited data suggest that an ACE inhibitor or an ARB is the agent of choice, especially in patients who have proteinuria or renal insufficiency. betaBs can be the first-line agent in diabetics who have CAD. TDs and CCBs are the second line drugs.AAAs should be avoided. Most hypertensive patients require more than one agent to adequately control their BP. There is no evidence to support one combination regimen over the others, nevertheless, the combination of an ACE inhibitor with a TD or a fPB may be more beneficial and cost effective than other combinations in the diabetic population. Large outcome studies that compare different combination therapies in hypertensive,diabetic patients are needed.

Recent advances in diabetic nephropathy

Diabetic nephropathy is the leading cause of end stage renal disease worldwide and is associated with increased cardiovascular risk. The earliest clinical manifestation is of microalbuminuria. Tight blood glucose and blood pressure control reduce the risk of microalbuminuria. Once microalbuminuria is present, the rate of progression to end stage renal disease and of cardiovascular disease can be delayed by aggressive management of blood pressure, glucose, and lipids. Inhibition of the renin-angiotensin system is important to reduce intraglomerular pressure but other classes of antihypertensive agent may also be needed to gain adequate control of systemic blood pressure. Such measures can at least half the rate of progression of nephropathy and cardiovascular disease.

Stabilization and regression of albuminuria in Chinese patients with type 2 diabetes: a one-year randomized study of valsartan versus enalapril

This study was designed to compare the short-term (1-y) tolerability and antiproteinuric efficacy of enalapril and valsartan in patients with type 2 diabetes. Forty-two patients with normal renal function or early-stage nephropathy were recruited in Hong Kong and randomized to valsartan 80 mg/day or enalapril 5 mg/day; the doses were increased to 160 mg and 10 mg daily, respectively, as tolerated. Early-morning urine was analyzed for albumin and creatinine and 24-hour urinary albumin excretion at baseline and 1 year after therapy began. Twenty-two patients were randomized to valsartan and 20 to enalapril. The 2 treatment groups were similar in terms of age, sex distribution, and duration of diabetes or hypertension. Blood pressure decreased to a similar extent (-2.5% to -5.0%) with each drug. Similarly, the 24-hour urinary albumin excretion decreased by 5% to 6% with each drug. The albumin-creatinine ratio in early-morning urine samples and plasma creatinine levels decreased in the valsartan group and increased in the enalapril group, but the difference was not significant. Plasma potassium levels were stable in both groups at the end of study. Cough was reported by 7 (35%) patients receiving enalapril and none of those receiving valsartan (P=.003). In conclusion, enalapril and valsartan both reduced blood pressure and albuminuria to a similar extent with 1 year of therapy in Chinese patients with type 2 diabetes and normal renal function or early-stage nephropathy. Fewer adverse events were reported with valsartan, but both drugs appear to be relatively safe.

Do angiotensin II antagonists provide benefits beyond blood pressure reduction?

Hypertension is a powerful risk factor for cardiovascular (CV) morbidity and mortality; therefore, blood pressure (BP) lowering plays a central role in reducing the cardiovascular complications of hypertension, including stroke. Recent outcomes studies--Losartan Intervention For Endpoint reduction in hypertension, Reduction of Endpoints in Non-insulin-dependent Diabetes Mellitus with the Angiotensin II Antagonist Losartan, and the Irbesartan Type 2 Diabetic Nephropathy Trial--suggest that some angiotensin II antagonists are associated with CV and renal effects beyond their ability to lower BP in patients with hypertension or diabetic nephropathy and may play a role in the prevention of new-onset type 2 diabetes. Angiotensin II antagonists are associated with a wide variety of vascular, cardiac, and renal effects, as well as molecule-specific effects independent of those induced by the angiotensin-I receptor. These actions may offer a mechanistic explanation for the outcome benefits observed in patients with hypertension or diabetic nephropathy. Angiotensin-converting enzyme inhibitors and calcium-channel blockers may also have effects that are not completely explained by differences in the antihypertensive response to these agents, but the evidence is less robust. Collectively, these findings suggest that management of patients with hypertension, with or without diabetes or renal disease, should no longer be viewed as simply a matter of correcting elevated BP. Antihypertensive agents that possess CV benefits beyond their BP-reducing effects should be used to prevent the development of end-organ damage.

Diabetic nephropathy: diagnosis, prevention, and treatment

Diabetic nephropathy is the leading cause of kidney disease in patients starting renal replacement therapy and affects approximately 40% of type 1 and type 2 diabetic patients. It increases the risk of death, mainly from cardiovascular causes, and is defined by increased urinary albumin excretion (UAE) in the absence of other renal diseases. Diabetic nephropathy is categorized into stages: microalbuminuria (UAE >20 microg/min and < or =199 microg/min) and macroalbuminuria (UAE > or =200 microg/min). Hyperglycemia, increased blood pressure levels, and genetic predisposition are the main risk factors for the development of diabetic nephropathy. Elevated serum lipids, smoking habits, and the amount and origin of dietary protein also seem to play a role as risk factors. Screening for microalbuminuria should be performed yearly, starting 5 years after diagnosis in type 1 diabetes or earlier in the presence of puberty or poor metabolic control. In patients with type 2 diabetes, screening should be performed at diagnosis and yearly thereafter. Patients with micro- and macroalbuminuria should undergo an evaluation regarding the presence of comorbid associations, especially retinopathy and macrovascular disease. Achieving the best metabolic control (A1c <7%), treating hypertension (<130/80 mmHg or <125/75 mmHg if proteinuria >1.0 g/24 h and increased serum creatinine), using drugs with blockade effect on the renin-angiotensin-aldosterone system, and treating dyslipidemia (LDL cholesterol <100 mg/dl) are effective strategies for preventing the development of microalbuminuria, in delaying the progression to more advanced stages of nephropathy and in reducing cardiovascular mortality in patients with type 1 and type 2 diabetes.

[Vascular impact of anti-hypertensive treatment and renal protection]

Hypertension contributes to the progression of renal disease by accelerating structural changes in the kidney, leading to a progressive decline in glomerular filtration rate. Hypertension and microvascular changes can create a vicious circle, leading to further renal damage and increases in blood pressure. Prevention of renal damage is a priority, especially in the growing number of patients with diabetic hypertension. Angiotensin receptor blocking drugs and ACE inhibitors have been shown to display renoprotective effects, and ACE inhibitors reduce the risk of microalbuminuria, the initial step in renal disease in diabetes. Impressive results have been obtained with a low-dose combination of the ACE-inhibitor perindopril and the diuretic indapamide, which not only gave superior reductions in blood pressure to enalapril, but also a 24% greater reduction in albumin excretion. Perindopril/indapamide also showed a trend towards reducing cardiovascular events. There is evidence from animal studies that this combination protects both renal structure and function.

Proteinuria and microalbuminuria in adults: significance, evaluation, and treatment

This paper reviews current concepts regarding the pathophysiology, diagnostic evaluation, and treatment of microalbuminuria and proteinuria in adults. Microalbuminuria (in diabetics) and proteinuria are early markers for potentially serious renal disease, and are associated with increased risk of atherosclerotic cardiovascular disease. Proteinuria also contributes to renal scarring, and accelerates the progression of chronic kidney disease to end-stage renal failure. Screening of diabetics for microalbuminuria, and the initial workup of proteinuria, should occur in the primary care setting. Reduction of microalbuminuria in diabetics may retard its progression to overt diabetic nephropathy. Therapy of renal diseases should aim for optimal blood pressure control and the maximum possible reduction in urinary protein excretion. Angiotensin-converting enzyme inhibitor (ACE-I) and/or angiotensin-receptor blocker (ARB) therapy is the most effective measure to achieve this. These drugs also provide protection against the cardiovascular problems that are highly prevalent in this patient population.

From secondary to primary prevention of progressive renal disease: The case for screening for albuminuria

Many subjects nowadays present with end-stage renal failure and its attendant cardiovascular complications without known prior renal damage. In this report we review the evidence available to strongly suggest that the present practice of secondary prevention in those with known prior renal disease should be extended to primary prevention for those subjects in the general population who are at risk for progressive renal failure, but who had never suffered from a primary renal disease. We show that such subjects can be detected by screening for albuminuria. Elevated urinary albumin loss is an indicator not only of poor renal, but also of poor cardiovascular prognosis. In addition to diabetic subjects who are at risk for albuminuria, we also show that hypertensive, obese, and smoking subjects are more susceptible. We suggest that therapies that have been shown to lower albumin excretion, such as ACE inhibitors, angiotensin II receptor antagonists, and statins be started early in such patients to prevent them from developing clinical renal disease and its attendant cardiovascular complications.

Comparison of the effects of angiotensin receptor antagonist, angiotensin converting enzyme inhibitor, and their combination on regression of left ventricular hypertrophy of diabetes type 2 patients on recent onset hemodialysis therapy

Left ventricular hypertrophy (LVH) is frequently found at the initiation of dialysis therapy of diabetic and hypertensive patients, and is highly predictive of future cardiac morbidity and mortality. In patients with hypertension and LVH, both an angiotensin converting enzyme (ACE) inhibitor and an angiotensin type 1 receptor (AT1) antagonist regress LVH. However, it remains controversial whether dual blockade of the renin-angiotensin system will regress LVH in these patients using a combination of ACE inhibitor and AT1 antagonist. Thirty-three type II diabetic patients with end-stage renal disease who had just entered into hemodialysis therapy and were diagnosed as having LVH evaluated by echocardiography were selected from three dialysis units staffed by the faculty of Saitama Medical School, Saitama, Japan between 1999 and 2001. The study was carried out for 1 year. All patients were assigned randomly to three groups with equal number: group I, an ACE inhibitor, enalapril 10 mg daily; group II, an AT1 antagonist, losartan 100 mg daily; group III, combination of enalapril 10 mg and losartan 100 mg daily. All antihypertensive drugs were given 30 min after the cessation of dialysis therapy. LVH was evaluated by echocardiography before the start of administration of drugs, at 6 months and 12 months after the start of drug therapy. Systolic blood pressure levels less than 140 mmHg were the target for the three groups. Using repeated measures analysis of variance, applied to those with four echocardiograms, there were progressive decreases over time in left ventricular mass index, posterior wall thickness and interventricular septum thickness. There were no significant differences in regression of LVH as well as blood pressure control between enalapril and losartan groups; however, dual blockade induced an additional 28% reduction in left ventricular mass index compared with any type of monotherapy. Both ACE inhibitors and AT1 antagonists benefit the regression of LVH in diabetic patients who start dialysis therapy. Moreover, combination therapy with ACE inhibitors and AT1 antagonists would provide more beneficial effects on LVH in these patients than monotherapy.

Angiotensin-receptor blockade versus converting-enzyme inhibition in type 2 diabetes and nephropathy

BACKGROUND

Few studies have directly compared the renoprotective effects of angiotensin II-receptor blockers and angiotensin-converting-enzyme (ACE) inhibitors in persons with type 2 diabetes.

METHODS

In this prospective, multicenter, double-blind, five-year study, we randomly assigned 250 subjects with type 2 diabetes and early nephropathy to receive either the angiotensin II-receptor blocker telmisartan (80 mg daily, in 120 subjects) or the ACE inhibitor enalapril (20 mg daily, in 130 subjects). The primary end point was the change in the glomerular filtration rate (determined by measuring the plasma clearance of iohexol) between the baseline value and the last available value during the five-year treatment period. Secondary end points included the annual changes in the glomerular filtration rate, serum creatinine level, urinary albumin excretion, and blood pressure; the rates of end-stage renal disease and cardiovascular events; and the rate of death from all causes.

RESULTS

After five years, the change in the glomerular filtration rate was -17.5 ml per minute per 1.73 m2 (where the minus sign denotes a decrement) in the telmisartan-treated subjects, as compared with -15.0 ml per minute per 1.73 m2 in the enalapril-treated subjects; the treatment difference was thus -2.6 ml per minute per 1.73 m2 (95 percent confidence interval, -7.1 to 2.0 ml per minute per 1.73 m2)[corrected] The lower boundary of the confidence interval, in favor of enalapril, was greater than the predefined margin of -10.0 ml per minute per 1.73 m2, indicating that telmisartan was not inferior to enalapril. The effects of the two agents on the secondary end points were not significantly different after five years.

CONCLUSIONS

Telmisartan is not inferior to enalapril in providing long-term renoprotection in persons with type 2 diabetes. These findings do not necessarily apply to persons with more advanced nephropathy, but they support the clinical equivalence of angiotensin II-receptor blockers and ACE inhibitors in persons with conditions that place them at high risk for cardiovascular events.

Hypertensive renal damage: insights from animal models and clinical relevance

Investigations using chronic blood pressure (BP) radiotelemetry in conscious animals have provided substantial insights into the pathophysiology of hypertensive renal damage. Normal renal autoregulation protects the renal microvasculature from significant injury in most patients with primary hypertension, unless BP exceeds a certain threshold, when malignant nephrosclerosis develops. However, if autoregulation is impaired, as in chronic renal disease and/or diabetes models, the threshold for renal damage is lowered and glomerulosclerosis (GS) increases linearly with increasing BP. Modest BP reductions are predicted to prevent malignant nephrosclerosis, but prevention of GS in patients with diabetes and chronic renal disease requires that BP be lowered well into the normotensive range, as recognized in the currently recommended BP goals. When BP load is accurately assessed in these experimental models, renal protection is proportional to the achieved BP reductions, and there is little evidence of BP-independent protection, even with agents that block the renin-angiotensin system (RAS). Recent clinical data also suggest that achieving lower BP targets might be vastly more important than the choice of therapeutic regimens. Nevertheless, because aggressive diuretic use is usually necessary to achieve such BP goals, RAS blockade should be included as initial therapy both for antihypertensive synergy and to minimize the potassium and magnesium depletion associated with diuretics.

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers for IgA nephropathy

The lengthy course of IgA nephropathy and the possibility of good outcomes without therapy suggest nontoxic therapies such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs.) Among patients with IgA nephropathy, both ACE inhibitors and ARBs reduce the transglomerular passage of large, but not small, molecules, reducing proteinuria. The antiproteinuric effects of ACE inhibitors and ARBs are probably equivalent. Dual ACE inhibitor-ARB therapy reduces proteinuria by 54% to 73% and is more effective than either agent alone. To determine whether ACE inhibitors or ARBs preserve renal function long-term, one must rely on trials studying nondiabetic, proteinuric renal diseases rather than on trials specific to IgA nephropathy. Among this group of patients, several randomized, controlled trials, including the AIPRI trial, the REIN trial, and a metaanalysis of 11 randomized, controlled trials, have established clearly that the ACE inhibitors preserve renal function. There is no reason to believe that this information is not applicable to IgA nephropathy. The COOPERATE trial, in which 50% of the subjects had IgA nephropathy, established that ACE inhibitors and ARBs preserve renal function equally, and that dual ACE inhibitor-ARB therapy preserves renal function more effectively than either therapy alone. These data suggest that most individuals with proteinuric renal diseases, including IgA nephropathy, should be treated with ACE inhibitors and ARBs, ideally in combination. Polymorphisms of the angiotensinogen gene, the ACE gene, and the angiotensin II type I receptor gene have, so far, failed to predict either susceptibility to or progression of IgA nephropathy. However, the D allele of the ID polymorphism, particularly the DD genotype, could predict a favorable response to renin-angiotensin blockade.

Antiproteinuric effect of RAS blockade: New mechanisms

Experimental and clinical studies have shown that blockade of the renin-angiotensin system (RAS) is effective in reducing proteinuria in conditions such as diabetes by reducing systemic and intraglomerular hydrostatic pressure. However, increasing evidence suggests that nonhemodynamic effects, such as preservation of the podocyte slit diaphragm structure and function, may also mediate the antiproteinuric effects of RAS blockade. In this review, we analyze in detail the evidence for known and novel mechanisms considered to play important roles in mediating the antiproteinuric effect of RAS blockers, with a particular focus on diabetic nephropathy.

Irbesartan: a review of its use in hypertension and in the management of diabetic nephropathy

Irbesartan (Avapro, Aprovel) is a potent and selective angiotensin II subtype 1 receptor antagonist indicated for use in patients with hypertension, including those with type 2 diabetes mellitus and nephropathy. Once-daily administration of irbesartan provided 24-hour control of blood pressure (BP). In patients with mild-to-moderate hypertension irbesartan was as effective as enalapril, atenolol and amlodipine, and more effective than valsartan in terms of absolute reduction in BP and response rates. Irbesartan produced a greater reduction in diastolic BP at trough than once-daily losartan, but had a smaller effect than olmesartan; the reduction in systolic BP achieved with irbesartan was similar or greater than that with losartan and similar to that seen with olmesartan. The combination of irbesartan with hydrochlorothiazide produced additive effects on BP reduction. Irbesartan also induced regression of left ventricular mass in patients with hypertension and left ventricular hypertrophy. In two large studies (IRbesartan MicroAlbuminuria type 2 diabetes mellitus in hypertensive patients [IRMA 2] and the Irbesartan Diabetic Nephropathy Trial [IDNT]) irbesartan exerted a renoprotective effect in hypertensive patients with type 2 diabetes at both the early and later stages of diabetic nephropathy. The renoprotective effect was at least partly independent of the BP-lowering effect. In the IRMA 2 trial, the proportion of patients progressing to overt nephropathy was significantly lower for recipients of irbesartan 300mg once daily than placebo. In patients with overt nephropathy in the IDNT, irbesartan 300mg once daily provided significantly greater renoprotection than amlodipine 10mg once daily or placebo. The relative risk of doubling of serum creatinine was significantly lower with irbesartan than amlodipine or placebo. Irbesartan is well tolerated in hypertensive patients, including those with type 2 diabetes and incipient or overt nephropathy. The overall incidence of adverse events with irbesartan was similar to that with placebo. Irbesartan was associated with a lower incidence of cough than enalapril and was not associated with ankle oedema or with any clinically significant drug interactions. In conclusion, irbesartan is a well tolerated and effective antihypertensive agent. It also slows the progression of renal disease in hypertensive patients with type 2 diabetes at both the early and later stages of diabetic nephropathy. Thus, irbesartan is a valuable agent in the management of patients with these indications.

Anti-proteinuric effects of combination therapy with enalapril and losartan in patients with nephropathy due to type 2 diabetes

The benefits of angiotensin-converting enzyme inhibitors and angiotensin II (ATII) receptor antagonist therapy of diabetic nephropathy (DNP) are thought to be largely the result of attenuation of ATII effects on proteinuria. The aim of the study was to ascertain whether there is the additive anti-proteinuric effect of enalapril plus losartan in DNP. Twenty-two patients with DNP were studied. Patients were randomly assigned to enalapril 10 mg/day (11 patients) or losartan 50 mg/day (11 patients) administered in a single oral dose in the morning for 12 weeks. and then, in 10 patients (five patients from enalapril group and five patients from losartan group), combination therapy (10 mg/day enalapril and 50 mg/day losartan) was started and continued for 12 weeks. In 12 patients, initial drugs dosages were doubled (six patients 20 mg/day enalapril and six patients 100 mg/day losartan), and monotherapy was continued for 12 weeks. Blood pressure and proteinuria were measured before and after therapy. Adverse effects were recorded at every visit. Proteinuria decreased by 33% with enalapril and losartan administered alone (p < 0.05). Co-administration of enalapril and losartan decreased proteinuria by a greater extent compared with enalapril and losartan administered alone (51%, p<0.05). This proteinuria level was significantly lower than the proteinuria level of 12 weeks therapy with enalapril and losartan alone. The decrease of proteinuria was 37% in double-dose monotherapy group (p < 0.05). Reduction of mean arterial blood pressure (MAP) in co-administration of enalapril and losartan was higher than enalapril and losartan administered alone (p < 0.05). Combination of enalapril and losartan decreased proteinuria and MAP by a greater extent compared with enalapril and losartan administered alone. We have found that proteinuria reduction induced by combined therapy is maintained throughout short-term follow-up; a greater anti-proteinuric response was observed in the patients with DNP.

Angiotensin receptor blockers in diabetic nephropathy: renal and cardiovascular end points

The activity of the renin-angiotensin-aldosterone system (RAAS) is elevated both in the circulation and in the renal tissue of diabetic and nondiabetic nephropathies. The increased RAAS activity plays an important role in the hemodynamic and nonhemodynamic pathogenetic mechanisms involved in kidney disease. Previous studies have demonstrated that albuminuria is not only a marker of glomerular lesions, but also a progression promoter, and finally a powerful predictor of the long-term beneficial effect of blood pressure-lowering therapy. Randomized crossover and parallel blind studies in patients with diabetic nephropathy have demonstrated that angiotensin II receptor blockers (ARB) induce favorable changes in systemic blood pressure, renal hemodynamics, and proteinuria similar to those induced by angiotensin-converting enzyme (ACE) inhibition. Studies have revealed the optimal renoprotective dose for some ARBs; however, additional dose titration studies are urgently needed to obtain the maximum benefit of this valuable new class of compounds. The combination of ARB and ACE inhibition is well tolerated and even more effective than monotherapy in reducing systemic blood pressure and albuminuria in diabetic nephropathy. In addition, dual RAAS blockade is safe and well tolerated. Impaired autoregulation of glomerular filtration rate (GFR); demonstrated with some blood pressure-lowering agents implies disturbances in the downstream transmission of the systemic blood pressure into the glomerulus, leading to capillary hypertension or hypotension depending of the level of blood pressure. ARB does not interfere with GFR autoregulation in hypertensive diabetic patients. In contrast to previous observational studies with ACE inhibition, long-term treatment with ARB has similar beneficial renoprotective effect on progression of diabetic kidney disease in hypertensive diabetic patients with ACE II and DD genotypes. ARB can prevent/delay development of diabetic nephropathy independently of its beneficial blood pressure-lowering effect in patients with type 2 diabetes and microalbuminuria. Recently, two landmark studies led to the following conclusion: "Losartan and Irbesartan conferred significant renal benefit in patients with type 2 diabetes and nephropathy. This protection is independent of the reduction in blood pressure it causes. The ARB is generally safe and well tolerated." A recent metaanalysis indicates that ARBs reduce cardiovascular events mainly because of reduction in first hospitalization for congestive heart failure in hypertensive type 2 diabetic patients with albuminuria. The studies mentioned here suggest that ARB represents a beneficial treatment of hypertension and proteinuria in incipient and overt diabetic nephropathy.

Advances in the treatment of diabetic renal disease: focus on losartan

Diabetic nephropathy is the leading cause of end stage renal disease (ESRD), and given that treating this condition is a considerable economic burden, the prevention of ESRD is a major public health goal. The renin-angiotensin system (RAS) is aberrantly activated in patients with diabetes. Angiotensin II (AII), a downstream effector of the RAS, has haemodynamic and non-haemodynamic effects that contribute to the development and progression of nephropathy. For patients with type 2 diabetes mellitus (T2DM) and hypertension, an AII receptor blocker (AIIRB) is recommended as the first drug that should be used. This review will focus on the rationale for the use of losartan as a treatment for nephropathy associated with T2DM. In animal models of diabetes, losartan reduced proteinuria and conferred renal protection. In RENAAL (Reduction in Endpoints in Non-Insulin-Dependent Diabetes Mellitus with the Angiotensin II Antagonist Losartan), the first major randomised trial that investigated the benefit of losartan in patients with T2DM and nephropathy, losartan significantly reduced the risk of a doubling of serum creatinine and progression to ESRD, significantly lowered the levels of proteinuria and slowed the rate of decline in glomerular filtration rate. This review also discusses other clinical trials of losartan and other AIIRBs in T2DM, and considers alternative mechanisms by which losartan may be exerting its effects. The collective experience in treatment trials highlighted in this review indicate that losartan and other AIIRBs can reduce blood pressure and the progression of proteinuria in diabetic renal disease. However, losartan is thus far the only AIIRB that has been shown to reduce significantly the risk of ESRD and cardiovascular events in patients with T2DM. Its use in hypertensive patients with T2DM and nephropathy may play an important role in reducing the burden of ERSD.

Angiotensin receptor blockers as anti-hypertensive treatment for patients with diabetes mellitus: meta-analysis of controlled double-blind randomized trials

AIMS

To assess the evidence for possible reduction of all-cause mortality, cardiovascular morbidity and mortality, and end-stage renal disease in diabetic patients treated with angiotensin II type 1 receptor blockers (ARBs) as an anti-hypertensive treatment.

METHODS

Systematic review and meta-analysis of randomized, double-blind controlled trials of at least 1 year's duration. ARBs were used in the intervention group vs. placebo or standard anti-hypertensive treatment in the control group. The main outcome measures were all-cause mortality, cardiovascular morbidity and mortality, and end-stage renal disease.

RESULTS

Three studies fulfilled the inclusion criteria. Separate analyses were conducted for comparisons of ARBs with groups given placebo and those given standard anti-hypertensive treatment. There was no significant difference in mortality between the ARBs and placebo groups, with an estimated odds ratio (OR) of 0.99 [95% confidence interval (CI) 0.81, 1.20]. There was a non-significant difference in patients treated with ARBs compared with standard anti-hypertensive treatment, with an OR of 0.78 (95% CI 0.45, 1.36). No statistically significant difference in cardiovascular morbidity and mortality between the intervention and placebo groups was found, with an OR of 0.91 (95% CI 0.77, 1.08). When ARBs were compared with standard treatment, the OR was estimated at 0.85 (0.54, 1.33). Data on end-stage renal disease were available for two studies comparing ARBs vs. placebo and showed a statistically significant advantage of ARBs, with an OR of 0.73 (95% CI 0.6, 0.89). As only one study compared end-stage renal disease outcome for ARBs vs. standard treatment, a meta-analysis was not possible. This study reported a considerable benefit of ARBs [OR = 0.73 (0.54, 1.01)] compared with the calcium channel blocker amlodipine.

CONCLUSIONS

ARBs failed to show significant reduction in total mortality and cardiovascular morbidity and mortality in diabetic patients. The only statistical benefit was the reduction of end-stage renal disease compared with placebo. Therefore, at this time ARBs have not proved to be superior to standard anti-hypertensive treatment in diabetic patients.

Dual blockade of the renin-angiotensin system in diabetic nephropathy

The presence of inadequately controlled hypertension in a diabetic patient with clinical signs of renal involvement portends a poor prognosis. Initial assessment should include ruling out factors which may exacerbate the hypertension and careful assessment of the stage of hypertension, renal function and amount of proteinuria. Intensive treatment requires finding a combination of medications which will reduce not only blood pressure but also proteinuria. It is suggested that treatment should be started with an ACE inhibitor or an AT1 receptor blocker often in a fixed combination with a low-dose thiazide diuretic. Calcium channel blockers and beta-blockers may be added if required as second or third-line agents. In patients not responding to this combination, the dosages of the ACE inhibitor or AT1 blocker should be titrated upwards in order to obtain the maximal therapeutic effect. However, if this is still insufficient, dual blockade of the RAS should be considered and even an aldosterone receptor blocker may need to be added to the therapeutic regimen. It should be remembered that such a patient requires close monitoring in order to be sure that he is compliant with respect to the prescribed treatment and that there are no side-effects such as hyperkalaemia.

Losartan and other angiotensin II antagonists for nephropathy in type 2 diabetes mellitus: A review of the clinical trial evidence

BACKGROUND

End-stage renal disease (ESRD) in patients with type 2 diabetes mellitus (DM) is associated with a bleak prognosis. The life span of patients with DM who have undergone renal transplantation or who are undergoing dialysis is up to 30% shorter than that of individuals in the general population. Preventing or delaying the progression of renal disease from microalbuminuria to nephropathy, and ultimately, to ESRD is thus a crucial goal of DM management.

OBJECTIVE

This article reviews the growing worldwide problem of type 2 DM and ESRD, the renoprotective benefits of angiotensin II (AII) antagonists (AIIAs) such as losartan in patients with or without type 1 or 2 DM, potential mechanisms of renoprotection of AIIAs beyond blood pressure (BP) control, and the clinical-practice implications of available megatrials.

METHODS

Articles included in this review were identified using a MEDLINE search for English-language studies published between 1990 and 2003 and included the search terms diabetic nephropathy, type 2 diabetes mellitus, microalbuminuria, proteinuria, angiotensin II antagonists, angiotensin-converting enzyme inhibitors, and cardiovascular disease. Articles describing major clinical trials, new data, or new mechanisms pertinent to the management of type 2 DM were selected for review.

RESULTS

Currently, AIIAs such as losartan represent the only evidence-based treatment strategy for patients with type 2 DM and proteinuria. The Irbesartan in Patients with Type 2 Diabetes and Microalbuminuria (IRMA-2) study, the Reduction of End Points in Non-Insulin Dependent Diabetes Mellitus with the Angiotensin II Antagonist Losartan (RENAAL) study, and the Irbesartan Type 2 Diabetic Nephropathy Trial (IDNT) indicate that AIIAs postpone the progression of type 2 diabetic renal disease at all stages, ranging from microproteinuria to overt nephropathy and ESRD, RENAAL showed that losartan improves renal outcomes in patients with type 2 DM and nephropathy over and above that attributable to BP control alone. The renoprotective effect of losartan corresponded to an average delay of 2 years in the need for dialysis or kidney transplantation.

CONCLUSIONS

AIIAs such as losartan should perhaps be considered mandatory therapy in patients with diabetic nephropathy and should complement existing management strategies, such as reduced dietary protein intake, strict blood glucose control, and standard antihypertensive therapy. Collectively, these measures should improve survival and quality of life and reduce the health care burden of managing patients with diabetic nephropathy.

Prevention and treatment of diabetic nephropathy in older patients

Renal disease in older diabetic patients is costly in terms of morbidity, mortality and expenditure. Therefore, prevention and treatment of diabetic nephropathy has become a prominent goal in the treatment of patients with diabetes mellitus. Preventive treatment should begin no later than at the stage of microalbuminuria, and regular screening for microalbuminuria is recommended for all patients with diabetes, irrespective of age. Improved metabolic control has been demonstrated to lower urinary albumin excretion. Target glycosylated haemoglobin levels should be below 7%, or 1% above the upper limit of normal of non-diabetic subjects. The use of an intensified treatment regimen is recommended. Insulin therapy has no adverse effects on renal indexes. To preserve renal function in older diabetic patients, blood pressure should be kept at or below 130/80 mm Hg. Treatment with ACE inhibitors or angiotensin II receptor antagonists (angiotensin II receptor blockers; ARBs) is superior to other pharmacological therapy, and should be initiated as first-line treatment. Most of the calcium channel antagonists have been found to increase or to have no effect on microalbuminuria despite blood pressure reduction. Moreover, there is substantial controversy as to whether they may be associated with increased cardiovascular morbidity. Non-dihydropyridine derivatives and calcium channel antagonists, such as nitrendipine, may be nephroprotective and have favourable effects on patients outcomes. A renoprotective action of diuretics may be confined to indapamide. Although beta-adrenoreceptor blockers are effective antihypertensive agents, they may not adequately preserve kidney function in older diabetic patients. However, as add-on treatment to ACE inhibitors or ARBs, they are particularly beneficial in nephropathic patients at risk of cardiovascular disease or with arrhythmias, in whom they may prove life-saving.

Pharmacoeconomic aspects of losartan treatment to delay progression of renal disease in patients with Type 2 diabetes

There is growing evidence from clinical trials that losartan (Cozaar, Merck & Co., Inc.) and other angiotensin (A)-II-receptor antagonists have beneficial effects on the progression of renal disease among Type 2 diabetic patients beyond the benefits derived from the effect of blood-pressure lowering alone [corrected]. Comparators used is the studies were not angiotensin-converting enzyme-inhibitors but typically conventional hypertensive therapy plus placebo, placebo alone and in one case, amlodipine. These trials have reported reductions in progression to end stage renal disease (ESRD) (losartan and irbesartan) and to nephropathy (irbesartan). An important pharmacoeconomic question is whether potential cost-savings on reduced progression to ESRD and nephropathy outweigh the extra costs of A-II-antagonist treatment. This paper will review the published economic studies for A-II-receptor antagonists and their pharmacoeconomic implications. In particular, potential pharmacoeconomic implications and related methodological aspects of the recent RENAAL trial for losartan are considered.

The renin-angiotensin system and the long-term complications of diabetes: pathophysiological and therapeutic considerations

The relationship between the renin-angiotensin system (RAS) and the progression of diabetic renal disease has been a major focus of investigation over the past 20 years. More recently, experimental and clinical studies have also suggested that the RAS may have a pathogenetic role at other sites of micro- and macrovascular injury in diabetes. Complementing major advances into the understanding of the local, as distinct from the systemic RAS, a number of large clinical trials have examined whether blockade of the RAS might provide protection from the long-term complications of diabetes, beyond that due to blood pressure reduction alone. While some controversy remains, these studies have, in general, suggested that angiotensin converting enzyme (ACE) inhibition and more recently, angiotensin receptor blockade reduce the development and progression of diabetic nephropathy, cardiovascular disease and possibly retinopathy. This review will focus on recent developments in our understanding of the tissue-based RAS and its role in end-organ injury in diabetes, the results of recent clinical trials and newer strategies for the pharmacological manipulation of the RAS.