Antihypertensive and anti-albuminuric effects of losartan potassium and felodipine in Chinese elderly hypertensive patients with or without non-insulin-dependent diabetes mellitus

Angiotensin-converting-enzyme inhibitors and angiotensin receptor blockers for preventing the progression of diabetic kidney disease

BACKGROUND

Guidelines suggest that adults with diabetes and kidney disease receive treatment with angiotensin-converting-enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB). This is an update of a Cochrane review published in 2006.

OBJECTIVES

We compared the efficacy and safety of ACEi and ARB therapy (either as monotherapy or in combination) on cardiovascular and kidney outcomes in adults with diabetes and kidney disease.

SEARCH METHODS

We searched the Cochrane Kidney and Transplants Register of Studies to 17 March 2024 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included studies evaluating ACEi or ARB alone or in combination, compared to each other, placebo or no treatment in people with diabetes and kidney disease.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

One hundred and nine studies (28,341 randomised participants) were eligible for inclusion. Overall, the risk of bias was high. Compared to placebo or no treatment, ACEi may make little or no difference to all-cause death (24 studies, 7413 participants: RR 0.91, 95% CI 0.73 to 1.15; I2 = 23%; low certainty) and with similar withdrawals from treatment (7 studies, 5306 participants: RR 1.03, 95% CI 0.90 to 1.19; I2 = 0%; low certainty). ACEi may prevent kidney failure (8 studies, 6643 participants: RR 0.61, 95% CI 0.39 to 0.94; I2 = 0%; low certainty). Compared to placebo or no treatment, ARB may make little or no difference to all-cause death (11 studies, 4260 participants: RR 0.99, 95% CI 0.85 to 1.16; I2 = 0%; low certainty). ARB have uncertain effects on withdrawal from treatment (3 studies, 721 participants: RR 0.85, 95% CI 0.58 to 1.26; I2 = 2%; low certainty) and cardiovascular death (6 studies, 878 participants: RR 3.36, 95% CI 0.93 to 12.07; low certainty). ARB may prevent kidney failure (3 studies, 3227 participants: RR 0.82, 95% CI 0.72 to 0.94; I2 = 0%; low certainty), doubling of serum creatinine (SCr) (4 studies, 3280 participants: RR 0.84, 95% CI 0.72 to 0.97; I2 = 32%; low certainty), and the progression from microalbuminuria to macroalbuminuria (5 studies, 815 participants: RR 0.44, 95% CI 0.23 to 0.85; I2 = 74%; low certainty). Compared to ACEi, ARB had uncertain effects on all-cause death (15 studies, 1739 participants: RR 1.13, 95% CI 0.68 to 1.88; I2 = 0%; low certainty), withdrawal from treatment (6 studies, 612 participants: RR 0.91, 95% CI 0.65 to 1.28; I2 = 0%; low certainty), cardiovascular death (13 studies, 1606 participants: RR 1.15, 95% CI 0.45 to 2.98; I2 = 0%; low certainty), kidney failure (3 studies, 837 participants: RR 0.56, 95% CI 0.29 to 1.07; I2 = 0%; low certainty), and doubling of SCr (2 studies, 767 participants: RR 0.88, 95% CI 0.52 to 1.48; I2 = 0%; low certainty). Compared to ACEi plus ARB, ACEi alone has uncertain effects on all-cause death (6 studies, 1166 participants: RR 1.08, 95% CI 0.49 to 2.40; I2 = 20%; low certainty), withdrawal from treatment (2 studies, 172 participants: RR 0.78, 95% CI 0.33 to 1.86; I2 = 0%; low certainty), cardiovascular death (4 studies, 994 participants: RR 3.02, 95% CI 0.61 to 14.85; low certainty), kidney failure (3 studies, 880 participants: RR 1.36, 95% CI 0.79 to 2.32; I2 = 0%; low certainty), and doubling of SCr (2 studies, 813 participants: RR 1.14, 95% CI 0.70 to 1.85; I2 = 0%; low certainty). Compared to ACEi plus ARB, ARB alone has uncertain effects on all-cause death (7 studies, 2607 participants: RR 1.02, 95% CI 0.76 to 1.37; I2 = 0%; low certainty), withdrawn from treatment (3 studies, 1615 participants: RR 0.81, 95% CI 0.53 to 1.24; I2 = 0%; low certainty), cardiovascular death (4 studies, 992 participants: RR 3.03, 95% CI 0.62 to 14.93; low certainty), kidney failure (4 studies, 2321 participants: RR 1.15, 95% CI 0.67 to 1.95; I2 = 29%; low certainty), and doubling of SCr (3 studies, 2252 participants: RR 1.18, 95% CI 0.85 to 1.64; I2 = 0%; low certainty). Comparative effects of different ACEi or ARB and low-dose versus high-dose ARB were rarely evaluated. No study compared different doses of ACEi. Adverse events of ACEi and ARB were rarely reported.

AUTHORS' CONCLUSIONS

ACEi or ARB may make little or no difference to all-cause and cardiovascular death compared to placebo or no treatment in people with diabetes and kidney disease but may prevent kidney failure. ARB may prevent the doubling of SCr and the progression from microalbuminuria to macroalbuminuria compared with a placebo or no treatment. Despite the international guidelines suggesting not combining ACEi and ARB treatment, the effects of ACEi or ARB monotherapy compared to dual therapy have not been adequately assessed. The limited data availability and the low quality of the included studies prevented the assessment of the benefits and harms of ACEi or ARB in people with diabetes and kidney disease. Low and very low certainty evidence indicates that it is possible that further studies might provide different results.

Effect of calcium channels blockers and inhibitors of the renin-angiotensin system on renal outcomes and mortality in patients suffering from chronic kidney disease: systematic review and meta-analysis

BACKGROUND

The renoprotective effect of inhibitors of renin-angiotensin system (RAS) has been identified through placebo-controlled trials. However, the effect of calcium-channel blockers (CCBs) on renal system is still controversial. Our current meta-analysis includes available evidences to compare the effect of dihydropyridine CCBs and ACEIs or ARBs on renal outcomes and mortality. We also further investigate whether CCBs can be used in combination with inhibitors of RAS to improve the prognosis of patients with chronic kidney disease (CKD).

METHODS AND RESULTS

Electronic databases were searched up to July 2012, for clinical randomized controlled trials, assessing the effect of dihydropyridine CCBs on the incidence of end-stage renal disease (ESRD) and all-cause mortality in contrast to ACEIs or ARBs. Eight clinical trials were included containing 25,647 participants. ESRD showed significantly higher frequency with CCBs therapy compared with ACEIs or ARBs therapy, though blood pressure was decreased similarly in both groups in every trial (OR, 1.25; 95% CI, 1.05-1.48; p = 0.01). In contrast, there was no significant difference in the incidence of all-cause mortality between these two groups, though ACEIs or ARBs exhibited better renoprotective effect compared to CCBs (OR, 0.96; 95% CI, 0.89-1.03; p = 0.24).

CONCLUSIONS

CCBs did not increase all-cause mortality incidence in patients with CKD though they displayed weaker renoprotective, compared to ACEIs or ARBs therapy. Our results suggest the combination of a CCB and an ACEI or ARB should be a preferable antihypertensive therapy in patients with CKD, considering their higher effect in decreasing blood pressure and fewer adverse metabolic problems caused.

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

BACKGROUND AND OBJECTIVE

Despite advances in the treatment of hypertension, control rates continue to be suboptimal in both Europe and the US. Strategies that improve hypertension control are therefore urgently needed. This study aimed to assess the relative efficacies of various antihypertensive drugs commonly used in France in reducing systolic and diastolic blood pressure (SBP and DBP) by using a meta-analytical approach. This update of a previously published meta-analytical approach extends the number of drugs evaluated from 13 to 19.

METHODS

A total of 80 randomised, controlled trials published between 1973 and 2007 involving 10 818 patients were selected for inclusion in the meta-analytical approach. Data were examined for 19 drugs, and 16 drugs were included in the analysis: hydrochlorothiazide, indapamide sustained-release (SR), atenolol, amlodipine, lercanidipine, manidipine, enalapril, ramipril, trandolapril, candesartan cilexetil, irbesartan, losartan, olmesartan medoxomil, telmisartan, valsartan and aliskiren. Weighted average reductions in SBP and DBP over a period of 8-12 weeks were calculated for each drug from information on both the mean and the variability in BP reduction. No trials evaluating furosemide, spironolactone or cicletanine satisfied the inclusion criteria for this analysis.

RESULTS

The average weighted reductions in SBP over 8-12 weeks were most marked with diuretics, and in particular indapamide SR 1.5 mg/day (mean change from baseline -22.2mm Hg), which reduced SBP to a greater extent than any of the other drugs evaluated (at any dosage considered). Average weighted reductions in DBP were generally similar with all classes of antihypertensives and ranged from -11.4mm Hg with the beta-adrenoceptor blocker atenolol and calcium channel antagonists to -10.3mm Hg with the angiotensin II type 1 receptor antagonists.

CONCLUSION

This new analysis supports the results of the earlier investigation, in that indapamide SR 1.5 mg/day appeared to be the most effective drug for producing significant reductions in SBP within 8-12 weeks, which is an essential element in optimising cardiovascular prevention among hypertensive patients. The clinical application of these results should take into consideration all the limitations discussed in this analysis.

Urinary albumin excretion and the renin-angiotensin system in cardiovascular risk management

Microalbuminuria has been shown to be a strong predictor of cardiovascular morbidity and mortality in diabetic and hypertensive patients, but also in the general population. Moreover, several reports suggest that reduction of urinary albumin excretion (UAE) is associated with improvement of cardiovascular prognosis. Reduction of UAE can be achieved by lowering arterial blood pressure, but blockers of the renin-angiotensin system (RAS) with their specific renal actions have demonstrated to be able to reduce UAE more than might be expected from reduction of blood pressure alone. Consequently, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may also provide superior cardiovascular protection, especially in subjects with higher levels of albuminuria, but evidence is still scarce. The ability of both angiotensin-converting enzyme inhibitors and angiotensin receptor blockers to reduce UAE and provide cardiovascular protection suggests that the RAS may play a central role. New developments in this area include the use of aldosterone antagonists in albuminuric/proteinuric subjects, and the development of oral renin inhibitors. Combinations of the aforementioned drugs may have the ability to fully block the RAS, potentially avoiding all detrimental effects of this hormonal cascade. However, combination therapy is expected to also increase the incidence of side effects, such as hyperkalaemia and acute renal insufficiency. The current knowledge of microalbuminuria represents the proverbial tip of the iceberg, and future studies should focus on the underlying pathophysiological mechanism of urinary albumin excretion in relation to cardiovascular protection. Only then can a better understanding of the problem be achieved and the optimal pharmacological approach be ascertained.

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.

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.

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.

Comparison of the efficacy and tolerability of telmisartan 40 mg vs. enalapril 10 mg in the treatment of mild-to-moderate hypertension: a multicentre, double-blind study in Taiwanese patients

The purpose of this randomised, double-blind, double-dummy, parallel-group study was to evaluate the efficacy and tolerability of telmisartan 40 mg once daily vs. enalapril 10 mg once daily in 147 Taiwanese patients with mild-to-moderate essential hypertension (diastolic blood pressure [DBP] 90-109 mmHg). After 6 weeks' treatment, telmisartan produced a significantly greater reduction from baseline in the primary endpoint of trough seated DBP compared with enalapril 10 mg (11.7 vs. 8.7 mmHg, respectively; p = 0.02). Numerically greater reductions compared with baseline in seated systolic blood pressure (SBP), standing DBP, and standing SBP were achieved with telmisartan compared with enalapril. Also, numerically greater proportions of patients achieved blood pressure control (DBP/systolic blood pressure [SBP] <90/140 mmHg) and responded to treatment (reduction from baseline in trough seated DBP > or = 10 mmHg and/or post-treatment DBP <90 mmHg; reduction from baseline in trough seated SBP > or = 10 mmHg and/or post-treatment SBP <140 mmHg) with telmisartan 40 mg compared with enalapril 10 mg. Although both treatments were well tolerated, the incidence of cough was markedly lower with telmisartan 40 mg (8.5%) than with enalapril 10 mg (18.4%) in this population of Taiwanese hypertensive patients.

Effects of Losartan and Chlorthalidone on Blood Pressure and Renal Vascular Resistance Index in Non-Diabetic Patients with Essential Hypertension and Normal Renal Function

Antihypertensive drugs can differ in target organ protection despite similar blood pressure (BP) control. We compared the effects of losartan (L) and chlorthalidone (C) on renal vascular resistance index (RVRI) in 194 grade I to II, non-diabetic hypertensive patients with increased RVRI (>0.68 m/s by echo-Doppler) but normal renal function. Patients were randomly allocated to C 25 mg/d or L 50 mg/d according to a single blind, PROBE study design. After 4 weeks of treatment, 92 patients (48 L/44 C) with BP <140/90 mm Hg were enrolled in the long-term phase of the study. After 12 months a normalization of RVRI was observed in 47 of 48 patients treated with L (97.5%) and only in 14 of 44 of those treated with C (25.8%) despite no differences in BP control. Patients whose RVRI remained elevated during C therapy underwent a 2-week washout period and then were treated with L 50 mg/d for 12 additional months. After that period 28 of 30 (95%) of patients who were nonresponders to C showed a normalization of RVRI despite no differences in BP control. In conclusion, our data suggest that treatment with L can improve renal hemodynamic and exert a protective renal effect beyond BP control in patients with hypertension.

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.

Effects of the selective aldosterone blocker eplerenone versus the calcium antagonist amlodipine in systolic hypertension

Eplerenone is a highly selective aldosterone blocker, which is under development for the treatment of hypertension and heart failure. To assess its usefulness in older patients with systolic hypertension and widened pulse pressure, we compared the effects of eplerenone with amlodipine, on clinic blood pressure (BP) and pulse pressure and in a subset of the patients, ambulatory BP, vascular compliance, and urinary albumin excretion. The study involved 269 patients > or =50 years of age who were randomly assigned to either eplerenone (50 to 200 mg daily) or amlodipine (2.5 to 10 mg daily) in a double-blind titration to effect design. After 24 weeks of therapy, reductions in clinic systolic BP were similar for both treatments (eplerenone, -20.5+/-1.1 mm Hg; amlodipine, -20.1+/-1.1 mm Hg). Reductions in clinic diastolic BP were modestly larger on amlodipine (-6.9+/-0.7 mm Hg) compared with eplerenone (-4.5+/-0.7 mm Hg) (P=0.014). Pulse pressure was also reduced similarly from baseline by the 2 treatment groups (eplerenone, -15.9 mm Hg versus amlodipine, -13.4 mm Hg, P=0.07). Changes from baseline in pulse wave velocity after 24 weeks of therapy were statistically similar for eplerenone and amlodipine. In patients with microalbuminuria at baseline (>30 mg albumin/g creatinine), eplerenone reduced the urinary albumin/creatinine ratio by 52% compared with a reduction of 10% by amlodipine (P=0.04). Thus, eplerenone was as effective as amlodipine in lowering systolic BP and pulse pressure as well as pulse wave velocity in older patients with widened pulse pressure hypertension. Furthermore, eplerenone reduced microalbuminuria to a greater extent than amlodipine in this older patient group.

Combination is better than monotherapy with ACE inhibitor or angiotensin receptor antagonist at recommended doses

OBJECTIVE

The combination of an angiotensin-converting enzyme (ACE) inhibitor and an angiotensin II (Ang II) receptor antagonist (ARB) could provide a higher degree of blockade of the renin-angiotensin system(RAS) than either agent alone. The primary aim of this study was to look at the effect of three therapeutic regimens (titrated ACE inhibitor (ACE-I) versus titrated ARB versus the combination of an ACE-I and an ARB) on the attainment of adequate blood pressure (BP) control and antiproteinuric effect. Both ACE-I and ARB were titrated as monotherapy up to the maximal recommended dose.

METHODS

A pilot randomised, parallel group open-label study was conducted in 36 patients with primary renal disease, proteinuria above 1.5 g/day and BP >140/90 mmHg while on therapy with an ACE-I. Patients were randomly assigned to (1) benazepril, n=12; (2) valsartan, n=12; or (3) benazepril plus valsartan, n=12. Other antihypertensive therapies could also be added to attain goal BP (<140/90 mmHg). The primary endpoint was the change in proteinuria during six months of follow-up.

RESULTS

In the presence of similar BP decreases and stable creatinine clearance values, mean proteinuria decreases were 0.5+1.7, 1.2+2.0 and 2.5+1.8 g/day in groups 1, 2 and 3, respectively. When compared with baseline values, only the fall induced by the combination of ARB and ACE-I attained statistical significance (p<0.05).

CONCLUSION

The antiproteinuric capacity of monotherapy at recommended doses with either an ACE-I or an ARB is lower than that obtained with the combination of the two drugs.

Losartan in patients with type 2 diabetes and proteinuria: observations from the RENAAL Study

BACKGROUND

Recently, the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) Study demonstrated the benefit of losartan in reducing renal outcomes in patients with type 2 diabetes and proteinuria. Additional questions concerning the reduction of proteinuria and its relationship to end-stage renal disease (ESRD) as well as cardio-renal outcomes and the safety and tolerability of losartan remain to be addressed.

METHODS

Three analyses were performed: (a) the impact of losartan on the relationship between the reduction of proteinuria and ESRD; (b) a time-to-event analysis of the cardio-renal composite endpoint of ESRD, myocardial infarction, stroke or all-cause death; and (c) additional analyses of adverse events, particularly in patients with serum creatinine >or=2.0 mg/dL.

RESULTS

After adjusting the values for proteinuria over the entire study, the reduction of proteinuria accounted for approximately half of the treatment effect of losartan on the risk reduction for ESRD. In addition, losartan was associated with a 21% risk reduction for the composite cardio-renal outcome (P=0.003). The addition of losartan to a conventional antihypertensive regimen did not increase the overall incidence of adverse events, regardless of severity of renal impairment.

CONCLUSIONS

Losartan significantly reduced the risk of cardiorenal outcomes and was well tolerated by patients, including those with serum creatinine levels >or=2.0 g/dL. In addition, although this study shows that the reduction of proteinuria does not completely explain the impact of intervention on outcomes such as ESRD, reduction of proteinuria must remain an important consideration when treating patients with type 2 diabetes and nephropathy. However, the reduction of outcomes such as ESRD should remain the goal of therapy when evaluating renal protection in this patient population.

The choice of antihypertensive drugs in patients with diabetes: angiotensin II and beyond

Affecting over 16 million individuals, diabetes mellitus is among the leading causes of mortality in the United States. Hypertension is a common finding among diabetic patients and increases their morbidity and mortality. Control of blood pressure in this population has been shown to improve outcomes. Recent randomized trials have proven the benefit of lower blood pressure goals in the treatment of hypertensive patients as compared with nondiabetic patients. Randomized controlled trials have also demonstrated that the selection of the antihypertensive agent used to treat hypertension in diabetic patients is as important as the reduction of blood pressure levels to the recommended levels. In this article, we first focus on the importance of the renin angiotensin system in the development of diabetic complications, and then we review the results of the recent studies that have had a major impact on the treatment of hypertension in diabetes.

Losartan titration versus diuretic combination in type 2 diabetic patients

METHODS

We compared the effects of Losartan dose titration to 100 mg versus the addition of 12.5 mg of hydrochlorothiazide, in 90 type 2 diabetic patients with microalbuminuria and blood pressure > 130/85 mmHg, receiving losartan 50 mg as initial treatment during 4 weeks.

RESULTS

With the first dose of losartan, systolic (SBP) and diastolic blood pressure (DBP) decreased from 154.5 (152.1-157.5) to 144.4 (141.3-147.5) mmHg (P < 0.001) and from 91.1 (89.4-92.8) to 84.6 (82.8-86.4) mmHg (P < 0.001), with 20 patients attaining the expected goal blood pressure (< 130/85 mmHg); albuminuria decreased from 109.8 (90.5-133.3) to 83.5 (63.6-109.5) mg per 24 h (P = 0.006). Patients not attaining the target blood pressure were randomly allocated to titration or to the combination arm. After an additional 4 weeks, patients titrated exhibited a fall in SBP and DBP from 157.1 (152.7-161.5) to 142.1 (136.4-147.8) mmHg (P < 0.001) and from 92.4 (89.5-95.3) to 83.6 (81.1-86.1) mmHg (P < 0.001); albuminuria decreased from 136.3 (97.8-189.9) to 99.7 (69.3-143.4) mg per 24 h (P = 0.002). In the combination arm, there were similar reductions in SBP and DBP from 155.3 (151.5-159.1) to 139.1 (132.1-146.1) mmHg (P < 0.001) and from 92.1 (89.3-94.9) to 80.9 (77.4-84.4) mmHg (P < 0.001); while albuminuria fell from 107.7 (82.2-141.0) to 64.2 (45.9-89.9) mg per 24 h (P = 0.001).

CONCLUSIONS

Losartan 50 mg was effective in reducing blood pressure and albuminuria in type 2 diabetic patients. When the blood pressure target was not reached, the two strategies tested seem to contribute similarly to further reductions in blood pressure and albuminuria.

Effects of antihypertensive therapy on intrarenal angiotensin and bradykinin levels in experimental renal insufficiency

BACKGROUND

Whereas angiotensin converting enzyme inhibitors and angiotensin type 1 receptor antagonists have beneficial effects in the remnant model of renal failure, calcium channel blockers do not consistently improve renal disease in this model. This study examined whether these different means of blood pressure reduction have different effects on renal levels of angiotensin (Ang) and bradykinin peptides.

METHODS

Rats subjected to five-sixths nephrectomy were divided into groups with similar hypertension and proteinuria at 4 to 5 weeks. They then received either no treatment, or enalapril, losartan or nifedipine for 2 weeks. Following repeat measurements of proteinuria and blood pressure, Ang II and bradykinin peptides were measured in the remnant kidney and renin, Ang II, and aldosterone were measured in the plasma.

RESULTS

All three drugs had equivalent blood pressure-lowering effects. Enalapril and losartan reduced proteinuria but nifedipine did not. Reduction of proteinuria in rats treated with enalapril and losartan was associated with a reduction in Ang II levels in both the peri-infarct and intact portions of the remnant kidney. By contrast, nifedipine increased Ang II levels in the intact portion of the remnant kidney. Losartan reduced bradykinin levels in the peri-infarct portion of the remnant kidney while enalapril reduced bradykinin levels in the intact portion of the remnant kidney. Nifedipine had no effect on intrarenal bradykinin levels.

CONCLUSIONS

The differential effects of enalapril, losartan and nifedipine on proteinuria and intrarenal Ang II and bradykinin levels suggest that the ability of an antihypertensive to decrease proteinuria may depend on its ability to decrease kidney Ang II and bradykinin levels.

Angiotensin receptor blockers in diabetic nephropathy

Where shall we place angiotensin receptor blockers in the scheme of the prevention of diabetic nephropathy? Only the results of a large, randomized double-blind trial with a comparable and appropriate alternative would prove therapeutic efficacy. The results of several trials with angiotensin-converting enzyme (ACE) inhibitors have proven them to be the standard of care for diabetics and their kidneys. As reviewed in this article, the results of three large such clinical trials have recently been completed with angiotensin receptor blockers in patients with type 2 diabetes mellitus. Initial results appear favorable. However, whether angiotensin blockers have more to offer than ACE inhibitors is still speculative. The renin-angiotensin system plays an important role in the pathogenesis of diabetic nephropathy. Since alternative pathways to ACE have been uncovered in the formation of angiotensin II, inhibition at the final end point would provide favored blockade. Because angiotensin receptor blockers do provide this specific blockade, they offer far more promise than ACE inhibitors.

Relationships between the taqI polymorphism of the dopamine D2 receptor and blood pressure in hyperglycaemic and normoglycaemic Chinese subjects

BACKGROUND

We have previously reported an association of the A2 allele of the dopamine D2 receptor (DRD2) TaqI polymorphism with increased blood pressure in normoglycaemic Chinese subjects, but conversely possibly with decreased indices of obesity. Hypertension is also a common feature of patients with type 2 diabetes, with up to 50% being hypertensive.

OBJECTIVE

To compare the relationship between the DRD2 TaqI polymorphism, blood pressure and obesity in Chinese patients with and without fasting hyperglycaemia.

METHOD

The DRD2 TaqI polymorphism was determined by PCR-RFLP in 519 normoglycaemic and 471 hyperglycaemic Chinese subjects, of whom 53.2 and 48.8% were hypertensive, respectively.

RESULTS

In the normoglycaemic subjects there was a significant increase in mean arterial pressure (P= 0.041) with increasing proportions of the A2 allele, 95 +/- 16, 96 +/- 17 and 100 +/- 17 mmHg for the A1A1, A1A2 and A2A2 genotypes, respectively. However, the relationship was not observed in the subjects with fasting hyperglycaemia either in the total group or in the subgroup who were not receiving blood pressure-lowering medication (n = 383, 97 +/- 15, 98 +/- 14 and 97 +/- 15 mmHg, respectively). When the whole group was divided into those subjects obese by either body mass index or waist-to-hip ratio (n = 484) and those subjects not obese by both these criteria (n= 506), the A1 allele (49.2 vs. 43.8%, P = 0.02) and A1 allele containing genotypes (P = 0.03) were more frequent in the obese subjects. Similar relationships were seen in the normoglycaemic and hyperglycaemic groups separately, although these did not reach significance.

CONCLUSIONS

In the normoglycaemic subjects, the A2 allele was associated with increased blood pressure and possibly lower indices of obesity, but in the hyperglycaemic subjects only the possible association with obesity was noted.

Comparative pharmacokinetics and pharmacodynamics of amlodipine in hypertensive patients with and without type II diabetes mellitus

Recent clinical trials aimed at attenuating complications in diabetes mellitus have generated interest in the impact of drug formulation and altered pharmacokinetics and pharmacodynamics in diabetes. Specifically, it has been proposed that the diabetic state may alter the pharmacokinetics of several cardiovascular drugs, including some calcium antagonists. The present study investigates the effects of diabetes mellitus on the pharmacokinetics and pharmacodynamics of amlodipine in hypertensive subjects with and without diabetes mellitus to determine whether the diabetic state alters these parameters. This trial consisted of a 2-week placebo washout phase, a 2-week titration phase, and a 2-week maintenance phase. Study patients included 18 hypertensive patients with type II diabetes mellitus and 10 nondiabetic hypertensive patients. Blood samples were collected after administration of amlodipine and AUC, Cmax, and tmax were determined. The acute 24-hour pharmacodynamic response to amlodipine was assessed by blood pressure and telemetric heart rate measurements. There were no significant differences for either amlodipine 5 or 10 mg in AUC (p = 0.40 for 5 mg; p = 0.59 for 10 mg), Cmax (p = 0.41 for 5 mg; p = 0.45 for 10 mg), and tmax (p = 0.79 for 5 mg; p = 0.67 for 10 mg) between diabetic and nondiabetic hypertensive subjects. Similarly, the 24-hour pharmacodynamic effects of amlodipine on systolic blood pressure, diastolic blood pressure, and heart rate did not differ between diabetic and nondiabetic subjects as assessed by repeated-measures analysis of variance. Because of the theoretical basis for anticipating that diabetes mellitus may provoke important pharmacokinetic and pharmacodynamic alterations, our study provides an important database in clearly demonstrating that the diabetic milieu did not alter the pharmacokinetics or pharmacodynamics of amlodipine.

Effects of low-dose losartan treatment on persistent microalbuminuria in normotensive type 1 diabetic subjects

To examine the effect of low-dose losartan, an angiotensin II antagonist, on persistent microalbuminuria in normotensive Type 1 diabetes mellitus, 16 subjects with Type 1 diabetes were randomly assigned to two 2-month treatment periods, with either losartan (25 mg/day) or enalapril (5 mg/day) in a single-blind cross-over design. Urinary albumin excretion (UAE), blood pressures, lipids, glycemia, HbA1C, serum potassium and creatinine clearance were measured before and after each treatment period. The UAEs were similarly reduced after both treatments. The median UAE decreased by 27.8%, from 162 (range 65-250) to 117 (34-190) mg/day (p<0.01) after enalapril, and decreased by 25%, from 160 (60-246) to 120 (36-184) mg/day (p<0.01) after losartan. The systolic and diastolic blood pressures also decreased significantly (p<0.05), whereas serum levels of potassium increased (p<0.01) after both treatments. The levels of serum HbA1c, mean fasting glucose, total cholesterol, triglycerides, LDL cholesterol, HDL cholesterol and creatinine clearances were not significantly (p>0.05 in all) changed by either the enalapril or losartan treatment. No significant differences were found between the effects of enalapril and losartan. In conclusion, losartan treatment reduces microalbuminuria as effectively as enalapril in normotensive Type 1 diabetic patients.

Renin-angiotensin system gene polymorphisms, blood pressure, dyslipidemia, and diabetes in Hong Kong Chinese: a significant association of tne ACE insertion/deletion polymorphism with type 2 diabetes

OBJECTIVE

In Chinese populations, hypertension is common and is a major risk factor for cerebrovascular and coronary heart disease, particularly when associated with diabetes. The clustering of these disorders and dyslipidemia and obesity is termed the metabolic syndrome and is increasing in prevalence in the populations of modernizing Asian nations. The renin-angiotensin system (RAS) helps maintain blood pressure and salt homeostasis and may play a role in the pathogenesis of aspects of the metabolic syndrome. We investigated three RAS gene polymorphisms--the ACE insertion/deletion (I/D), angiotensinogen (AGT) M235T, and angiotensin II type 1 receptor (AT1R) A1166C polymorphisms--for a possible role in modulating these disorders in 853 Chinese subjects with varying components of the metabolic syndrome.

RESEARCH DESIGN AND METHODS

The three gene polymorphisms of this cross-sectional study were detected using polymerase chain reaction-based protocols. The genotype frequencies were compared between the controls (n = 119) and both overlapping and nonoverlapping groups of patients with type 2 diabetes, hypertension, and dyslipidemia using chi2 test. Differences in levels of the biochemical parameters between the genotypes were determined using analysis of variance.

RESULTS

No significant relationship was identified between these polymorphisms and blood pressure in this population. Although the AT1RA1166C polymorphism was not associated with any aspect of the metabolic syndrome examined, there was limited evidence to suggest that the AGT M235T polymorphism may be associated with cholesterol levels. The ACE I allele was significantly more frequent in each group comprising subjects with type 2 diabetes/glucose intolerance (GIT), and the I allele was associated with higher fasting plasma glucose levels.

CONCLUSIONS

These findings suggest that these polymorphisms are unlikely to be involved in the pathogenesis of hypertension. The ACE I/D polymorphism was associated with the metabolic syndrome, having a higher frequency of I allele-containing genotypes in those groups, but this appeared to result predominantly from the relationship with type 2 diabetes/GIT in this population of Chinese subjects.

Treating high-risk diabetic hypertensive patients with comorbid conditions

Diabetes mellitus, a highly prevalent metabolic and vascular disease, affects 155 million people worldwide. Tight blood glucose control can significantly reduce the incidence of diabetic retinopathy, nephropathy, and neuropathy, but does not appear to significantly reduce its macrovascular complications. Several randomized clinical trials indicate that tight blood pressure control can reduce the risk of microvascular and macrovascular complications in patients with diabetes and hypertension. Blockade of the renin-angiotensin system (RAS) with angiotensin-converting enzyme (ACE) inhibitors has proven effective both in lowering blood pressure and in independently slowing the progression of nephropathy. If instituted early, ACE inhibitor therapy potentially may prevent progression to end-stage renal disease in normotensive patients with type 1 or 2 diabetes. Additionally, ACE inhibitors may reduce cardiovascular morbidity and mortality in this patient population. Angiotensin II (Ang II) receptor blockers (ARBs), which attenuate the deleterious effects of the RAS via blockade of the Ang II subtype 1 receptor, may also be beneficial. Clinical trials are under way to evaluate this possibility.

Treatment of hypertension in diabetes mellitus

In this article we emphasize the need for prompt intervention in diabetic patients with high blood pressure in order to protect the heart, brain, kidney, and the vascular tree against arteriosclerotic damage, which is the main cause of mortality in type 1, and particularly type 2 diabetes mellitus. Recent placebo-controlled, randomized trials indicate that compared with the nondiabetic population, a lower blood pressure threshold for intervention and a lower target blood pressure are adequate in terms of target organ protection. Although all major classes of antihypertensive drugs have demonstrated a potential benefit in treating diabetic hypertensive patients, blocking the renin-angiotensin system with angiotensin converting enzyme (ACE) inhibitors is especially useful in patients at high risk for myocardial infarction and/or renal damage. The new class of antihypertensive agents that block the angiotensin II receptor have renal effects very close to those observed with ACE inhibitors. The potential role of this new class in the treatment of hypertension in diabetes will depend on the results of ongoing trials.

Renoprotective benefits of RAS inhibition: from ACEI to angiotensin II antagonists

In landmark clinical trials, pharmacological inhibition of the renin-angiotensin system (RAS) with angiotensin-converting enzyme inhibitors (ACEIs) attenuated the decline in renal function associated with chronic renal disease (CRD). Hemodynamic and nonhemodynamic effects of angiotensin II (Ang II) attest to its central role in the pathogenesis of CRD. Angiotensin II subtype 1 receptor antagonists (AT1RA) differ from ACEI in their effects on the RAS and on bradykinin metabolism. Elevations in bradykinin levels associated with ACEI and stimulation of angiotensin subtype 2 receptors resulting from AT1RA may produce therapeutic effects unique to each class of drug. Nevertheless, in animal models of CRD, ACEI and AT1RA exert equivalent renoprotection, implying that their renoprotective effects result primarily from inhibition of Ang II-mediated stimulation of angiotensin subtype 1 receptors. Clinical data comparing ACEI and AT1RA therapy in renal disease are limited to short-term studies, which indicate that AT1RAs have equivalent effects to ACEI on the major determinants of CRD progression, namely blood pressure and proteinuria. AT1RAs were well tolerated, with side-effect profiles similar to placebo. Taken together, available evidence suggests that AT1RAs will share the renoprotective properties of ACEI in human CRD. Nevertheless, the results of long-term clinical trials are required before AT1RA can be recommended as an alternative to ACEI in renoprotective therapy.

KRH-594, a new angiotensin AT1 receptor antagonist, ameliorates nephropathy and hyperlipidaemia in diabetic spontaneously hypertensive rats

1. We examined whether KRH-594, a new angiotensin AT1 receptor antagonist, ameliorates the progression of diabetic nephropathy and hyperlipidaemia in streptozotocin (STZ)-induced diabetic unilateral nephrectomized spontaneously hypertensive rats (DM-1K-SHR) or not. 2. The oral administration of KRH-594 (3 and 10 mg/kg per day) and candesartan cilexetil (1 mg/kg per day) for 16 weeks significantly reduced systolic blood pressure, urinary albumin and urinary total protein in DM-1K-SHR. 3. In a histological study, KRH-594 (3 and 10mg/kg per day) and candesartan cilexetil (0.3 and 1 mg/kg per day) dose-dependently improved glomerulosclerosis and the hyalin cast of tubules in DM-1K-SHR kidneys. Both KRH-594 (10 mg/kg per day) and candesartan cilexetil (0.3 and 1 mg/kg per day) dose-dependently inhibited cardiac hypertrophy. 4. KRH-594 (3 and 10 mg/kg per day), but not candesartan cilexetil, dose-dependently reduced the levels of triglyceride, total cholesterol and phospholipids in DM-1K-SHR. 5. These results suggest that KRH-594 improves diabetic complications, such as nephropathy and hyperlipidaemia, with hypertension.

Losartan: a review of its use, with special focus on elderly patients

Losartan is an orally active, nonpeptide, selective angiotensin subtype 1 (AT1) receptor antagonist. It provides a more specific and complete blockade of the actions of angiotensin II than renin or ACE inhibitors. Short term (up to 12 weeks' duration) clinical trials have shown losartan to be as effective at lowering blood pressure (BP) [causes a decrease in BP < or = 26/20 mm Hg] in elderly patients with hypertension as recommended dosages of captopril, atenolol, enalapril, felodipine and nifedipine. In patients with isolated systolic hypertension (ISH) the efficacy of losartan was similar to that of atenolol. The addition of hydrochlorothiazide to losartan therapy provides greater antihypertensive efficacy, equivalent to that seen with captopril plus hydrochlorothiazide. Preliminary evidence also indicates that losartan therapy contributes to the regression of left ventricular hypertrophy associated with chronic hypertension. Exercise capacity is increased by losartan in patients with either asymptomatic or symptomatic heart failure. Results from the Losartan Heart Failure Survival or ELITE II (Evaluation of Losartan in the Elderly II) study indicate that there was no statistically significant difference between losartan and captopril in reducing overall deaths or in reducing sudden cardiac death and/or resuscitated cardiac arrest in patients with heart failure. Other than ELITE II, little conclusive long term mortality and morbidity data exist for losartan. Additional long term trials to evaluate the survival benefits of losartan in elderly patients with hypertension, renal disease or after an acute myocardial infarction are currently in progress. In elderly patients with hypertension, the incidence of treatment-related adverse events associated with once daily losartan (alone or in combination with hydrochlorothiazide) [19 to 27%] was similar to felodipine (23%) and nifedipine (21%), however, losartan tended to be better tolerated than captopril (11 vs 16%). Losartan was also better tolerated than atenolol in patients with ISH (10.4 vs 23%). In patients with heart failure the renal tolerability of losartan was similar to that of captopril, but losartan was associated with a lower withdrawal rate because of adverse events. No dosage adjustment is required in elderly or in patients with mild to moderate renal dysfunction, and the risk of first-dose hypotension is low.

CONCLUSIONS

comparative data have shown losartan to be as effective as other antihypertensive agents in the treatment of elderly patients with hypertension. Treatment with losartan is therefore an option for first-line therapy in all patients with hypertension, particularly those who are not well managed with or who are intolerant of their current therapy. Morbidity and mortality data from the Losartan Heart Failure Survival (ELITE II) study show that losartan has potential in the treatment of heart failure.

Evaluation of Losartan Usage in a Regional Hospital in Hong Kong

Objective:

To determine whether losartan usage follows the hospital's guidelines in terms of indications and reasons for use and to assess the accuracy of physicians in completing the losartan usage monitoring forms.

Design:

Drug utilization survey.

Setting:

A major government hospital in Hong Kong.

Participants:

Inpatients or outpatients prescribed losartan for the first time.

Intervention:

Physicians were to complete a monitoring form with both indications and reasons for losartan use.

Main Outcome Measures:

The appropriateness of losartan prescribing was evaluated in terms of indications (for hypertension with impaired left-ventricular function or hypertension in diabetic patients with persistent proteinuria) and reasons for preferred use (previous intolerance to adverse effects of angiotensin-converting enzyme inhibitors). The accuracy of completed monitoring forms was also assessed.

Results:

Forty-eight patients were prescribed losartan since its addition to the hospital formulary through the end of the study period (September 1997-May 1998). A review of medical records (regardless of the information provided by the physicians on the monitoring forms) revealed that 39 patients (81.3%) were prescribed losartan for appropriate indications and that 22 (45.8%) were given losartan rather than angiotensin-converting enzyme inhibitors for appropriate reasons according to the guidelines. Both appropriate indications and reasons were met in only 15 patients (31.3%). Of the 48 monitoring forms that were collected, three (6.3%) were not completed. The concordance rate of information provided by the doctors and information from case notes was 61.5% for indications and 34.8% for reasons of preferred use.

Conclusions:

Adherence to the hospital's usage guidelines and accuracy of the monitoring forms were suboptimal. Considering the high cost of losartan and its potential for long-term use, more educational activities, better dissemination of information, and more frequent evaluation of the acceptability of recommended usage guidelines are warranted.

Blood pressure control, microalbuminuria and cardiovascular risk in Type 2 diabetes mellitus

Type 2 (noninsulin-dependent) diabetes mellitus (DM) affects about 3% of the UK population. Diabetes often coexists with a cluster of other potent cardiovascular risk factors, including hypertension, dyslipidaemia and increased tendency for thrombosis, and increases the risk of early death from cardiovascular causes by about threefold. Microalbuminuria or proteinuria also may be present, further increasing the risk of cardiovascular mortality. Cardiovascular risk factors must be treated aggressively in patients with Type 2 diabetes and control of blood pressure at 140/85 mm Hg or lower is a priority. The management of hypertension in patients from some ethnic groups demands special consideration because they have a high incidence of diabetes and hypertensive complications. Patients must be urged to adopt appropriate lifestyle changes in the first instance but additional drug treatment for hypertension is usually required. All the major classes of antihypertensive agents lower blood pressure in Type 2 diabetic patients but have different effects on metabolic risk factors in different ways. Low-dose thiazide diuretics, beta-blockers, calcium channel blockers and angiotensin converting enzyme (ACE) inhibitors have been shown to reduce cardiovascular risk. Individually, the effects of low-dose thiazide diuretics and beta-blockers on glucose and lipid metabolism is clinically insignificant, though in combination much larger metabolic effects are seen. ACE inhibitors and calcium channel blockers have no, or small, beneficial effects on glucose and lipid metabolism, while the greater beneficial effects of alpha1-blockers on lipid profiles may render them especially useful in the Type 2 diabetic patient. Long-acting calcium-channel blockers and ACE inhibitors protect renal function and are suitable as first line therapy in patients with microalbuminuria or proteinuria. Until results from the current batch of randomized, placebo-controlled trials comparing different classes of antihypertensive agents are available, the choice of antihypertensive agent is difficult. Addressing overall cardiovascular risk factors, rather than hypertension alone, is essential in the management of the hypertensive Type 2 diabetic patient.

AT1 receptor antagonists: a challenge for ACE inhibitors in diabetic nephropathy

Due to its hemodynamic, metabolic and growth promoting effects, angiotensin II (AII) may play an important role in the pathogenesis of diabetic kidney disease. Consequently, decreasing the production or cellular action of AII is a rational target for therapeutic attempts aimed at slowing the progression of diabetic nephropathy. Based on their superior renoprotective performance in recent landmark studies, currently ACE inhibitors are the drugs of choice in diabetic patients with microalbuminuria or overt proteinuria. A new class of antihypertensive medications, the AT1 receptor antagonists may represent an alternative to ACE inhibitors in the treatment of diabetic nephropathy. They provide a more complete blockade of the renal renin-angiotensin system and are generally better tolerated than ACE inhibitors. On the other hand, AT1 receptor antagonists do not increase bradykinin levels, an effect that may contribute to the high level of renoprotection achieved by ACE inhibitors. Although human data are not available at this point, ACE inhibitors and AT1 receptor antagonists have similar beneficial effects on proteinuria, renal hypertrophy and glomerulosclerosis in animal models of diabetic kidney disease. Currently several prospective studies are being conducted to compare the efficacy of ACE inhibitors and AT1 receptor antagonists in the treatment of human diabetic nephropathy.

Therapeutic implications and new perspectives for essential hypertension and renal damage

The kidney can suffer the consequences of a persistently elevated blood pressure. In fact end-stage renal failure caused by essential hypertension appears to be one of the most prevalent etiologies in patients entering a dialysis program. Blood pressure control is needed in order to prevent the progressive loss of renal function. Target blood pressure control has been established at values as low as 125/75 mm Hg for patients with proteinuria above 1 g/day. Attainment of this target level usually requires the combination of two or more drugs. However, the possibility that differences exist among the different classes of antihypertensive drugs beyond their capacity to simply lower blood pressure remains to be clearly elucidated. The fact that the presence of chronic renal failure is also accompanied by an enhanced cardiovascular risk potentiates the need to explore the renoprotective and cardiovascular protective capacity of the different classes of antihypertensive drugs, in patients with essential hypertension and some degree of renal involvement, characterized by the presence of microalbuminuria, proteinuria and/or an elevated serum creatinine.

Angiotensin II receptor antagonists and treatment of hypertension and renal disease

Angiotensin II, the principal effector of the renin-angiotensin cascade, stimulates a variety of physiological responses that support blood pressure and renal function. Abnormal generation of angiotensin II also contributes to the pathogenesis of hypertension, arterial diseases, cardiac hypertrophy, heart failure and proteinuric progressive renal diseases. It is well recognized that angiotensin-converting enzyme inhibitors effectively limit the progression of diabetic and non-diabetic proteinuric renal diseases towards end-stage renal disease, a capacity not necessarily shared by other blood pressure lowering agents. Whether angiotensin II type 1 receptor antagonists have the same renoprotective effect as angiotensin-converting enzyme inhibitors in progressive renal diseases remains ill defined. Angiotensin II type 1 receptor antagonists as antiproteinuric agents have been used originally in animal models of renal disease progression. Results have shown that angiotensin II type 1 receptor blockers are as effective as angiotensin-converting enzyme inhibitors in normalizing proteinuria in models of renal disease. Studies in humans are very few, but those that have been undertaken report consistent antiproteinuric effects of angiotensin II type 1 receptor antagonists that are similar to those with angiotensin-converting enzyme inhibitors. Long-term studies, however, are required to examine whether the antiproteinuric effects of angiotensin II type 1 receptor antagonists can be translated into renoprotection.

Nephroprotective effect of antihypertensive drugs in essential hypertension

BACKGROUND

Effective antihypertensive treatment has prevented target-organ involvement in hypertension, markedly reducing morbidity and mortality from strokes, coronary heart disease, cardiac failure, and hypertensive emergencies. However, the incidence of hypertension-related end-stage renal disease continues to increase, suggesting that therapeutic reduction in arterial pressure by itself is not sufficient to prevent the development of hypertensive renal failure.

OBJECTIVE

To examine experimental and clinical data concerning the protective effect of reduction of arterial pressure on the progression of hypertension-related renal disease, and the evidence indicating that some antihypertensive agents may afford more nephroprotection, over and above that attributable to reduction of arterial pressure.

RESULTS

Results of numerous studies clearly indicate that adequate control of arterial pressure, irrespective of the antihypertensive agent used, slowed the progression of renal disease. Results of some studies suggest that lowering arterial pressure below the level that is usually considered adequate has an additional beneficial effect by slowing the progression of renal injury.

CONCLUSION

Results of a number of studies evaluating nephroprotective effects of various drugs and regimens have indicated that certain agents, most notably angiotensin converting enzyme inhibitors and their combination with calcium antagonists, afford more protection than do others at similar levels of reduction of arterial pressure. Results of still other studies suggest that certain agents that exert greater nephroprotection are more efficient at controlling arterial pressure. Therefore, further data are needed before any final conclusion can be drawn. However, it is clear that, in order to establish nephroprotection in patients with essential hypertension, the problem should not be further complicated by additional comorbid diseases such as diabetes mellitus.

Losartan potassium: a review of its pharmacology, clinical efficacy and tolerability in the management of hypertension

Losartan potassium is an orally active, nonpeptide angiotensin II (AII) receptor antagonist. It is the first of a new class of drugs to be introduced for clinical use in hypertension. This novel agent binds competitively and selectively to the AII subtype 1 (AT(1)) receptor, thereby blocking AII-induced physiological effects. An active metabolite, E3174, contributes substantially to its antihypertensive effect, which persists throughout 24 hours after once-daily administration. In patients with mild to moderate hypertension, losartan potassium 50 to 100mg once daily as monotherapy lowers blood pressure to a similar degree to enalapril, atenolol and felodipine extended release (ER). Losartan potassium combined with hydrochlorothiazide reduces blood pressure further than either drug given separately. About one-third of patients with severe hypertension have responded to the combination product. Losartan potassium appears to be effective in elderly patients. Losartan potassium is very well tolerated. In clinical trials, dizziness was the only drug-related event reported more frequently with losartan potassium monotherapy than with placebo. First-dose hypotension is uncommon. An aspect of the drug's tolerability profile which may prove to be particularly advantageous is that it is associated with a similar incidence of cough to placebo in patients with a history of ACE inhibitor-related cough. Additionally, clinically relevant adverse metabolic effects or laboratory abnormalities have not been documented during losartan potassium therapy and renal function is preserved in patients with or without renal insufficiency. The adverse effect profile of the losartan potassium-hydrochlorothiazide combination resembles those for losartan potassium monotherapy and placebo. Long term tolerability data are limited (<2 years) but support the very good tolerability profile in shorter studies. Elements of the drug's profile yet to be assessed or reported fully in the literature include long term efficacy; potential to favourably influence cardiovascular and renovascular systems (and ultimately mortality) in patients with hypertension and, lastly, cost effectiveness and influence on quality of life. In summary, losartan potassium is the first AT(1)+ receptor antagonist to become available for the management of hypertension and, as such, it is an important new antihypertensive agent. Pending long term data as outlined above, it is likely to find initial use in patients with mild to severe hypertension who are unresponsive to, or intolerant of their current therapy. However, with its novel mechanism of action, good efficacy and favourable tolerability profile, losartan potassium is well placed to claim a prominent position in the management of patients with essential hypertension in the future.