Comparative effects of Irbesartan on ambulatory and office blood pressure: a substudy of ambulatory blood pressure from the Irbesartan in Patients with Type 2 Diabetes and Microalbuminuria study

Comparative Efficacy of Angiotensin II Antagonists in Essential Hypertension: Systematic Review and Network Meta-Analysis of Randomised Controlled Trials

BACKGROUND

Evidence on the long-term clinical benefits of individual members of angiotensin II receptor blockers is limited given the lack of head-to-head studies. We conducted a network meta-analysis to determine the comparative efficacy of different members within this drug class with respect to outcomes of (i) blood pressure reduction (at 24 and 52 weeks) and (ii) prevention of cardiovascular disease (>104 weeks).

METHODS

A systematic literature review was conducted - Protocol registration: (PROSPERO - CRD42014007067) - to identify relevant literature from the following databases: Cochrane Library, PubMed, Medline and EMBASE; searched from inception to July 2016. Randomised controlled trials (RCTs) were included if they reported long-term effectiveness relating to blood pressure, mortality, myocardial infarction or stroke. Eligible studies included those with placebo or specific active-treatment comparators (either another angiotensin II receptor blockers or hydrochlorothiazide). A Bayesian random-effects network model was used to combine direct within-trial comparisons between treatment groups with indirect evidence from other trials.

RESULTS

Thirty-six studies were identified, representing 28 unique trials. Blood pressure reduction, based on 12 studies (n=807) with fixed dosing regimen, was found to be similar amongst members of the angiotensin receptor blocker drug class at both 24 and 52 weeks. A network meta-analysis of five studies (n=16,716) with a treat-to-target approach found that prevention of all-cause mortality, stroke and myocardial infarction was similar across the angiotensin-receptor blockers therapies initiated.

CONCLUSIONS

Current evidence is insufficient to show differences in any members within the angiotensin II receptor blocker drug class with respect to blood pressuring lowering effects or a reduction in cardiovascular diseases.

Microalbuminuria: a parameter that has changed diabetes care

Diabetic nephropathy is characterised by persistent albuminuria, elevated blood pressure, relentless decline in GFR and enhanced fatal and nonfatal cardiovascular diseases. Microalbuminuria has been central to the development of clinical practise in prevention and treatment of diabetic nephropathy and cardiovascular disease. Treatment-induced and spontaneous remission of microalbuminuria has been reported both in type 1 and type 2 diabetic patients, underlining the importance of sustained elevation of urinary albumin excretion. Recently many new biomarkers have been evaluated in diabetic patients, and apart from urinary proteomics, none has yet outperformed Harry Keen's discovery of microalbuminuria as the best screening tool for diabetic nephropathy. Remission of microalbuminuria preserves renal function. Microalbuminuria has also stood the test of time as a valid powerful independent predictor for fatal and nonfatal cardiovascular outcome in diabetes. Improved glycaemic control, blood pressure reduction, RAS blockade and multifactorial treatment of cardiovascular risk factors reduce the risk of development of micro-and macroalbuminuria, declining renal function and cardiovascular events.

Indications for and utilization of angiotensin receptor II blockers in patients at high cardiovascular risk

The worldwide burden of cardiovascular disease is growing. In addition to lifestyle changes, pharmacologic agents that can modify cardiovascular disease processes have the potential to reduce cardiovascular events. Antihypertensive agents are widely used to reduce the risk of cardiovascular events partly beyond that of blood pressure-lowering. In particular, the angiotensin II receptor blockers (ARBs), which antagonize the vasoconstrictive and proinflammatory/pro-proliferative effects of angiotensin II, have been shown to be cardio vascularly protective and well tolerated. Although the eight currently available ARBs are all indicated for the treatment of hypertension, they have partly different pharmacology, and their pharmacokinetic and pharmacodynamic properties differ. ARB trials for reduction of cardiovascular risk can be broadly categorized into those in patients with/without hypertension and additional risk factors, in patients with evidence of cardiovascular disease, and in patients with severe cardiovascular disease, such as heart failure. These differences have led to their indications in different populations. For hypertensive patients with left ventricular hypertrophy, losartan was approved to have an indication for stroke prevention, while for most patients at high-risk for cardiovascular events, telmisartan is an appropriate therapy because it has a cardiovascular preventive indication. Other ARBs are indicated for narrowly defined high-risk patients, such as those with hypertension or heart failure. Although in one analysis a possible link between ARBs and increased risks of cancer has surfaced, several meta-analyses, using the most comprehensive data available, have found no link between any ARB, or the class as a whole, and cancer. Most recently, the US Food and Drug Administration completed a review of the potential risk of cancer and concluded that treatment with an ARB medication does not increase the risk of developing cancer. This review discusses the clinical evidence supporting the different indications for each of the ARBs and the outstanding safety of this drug class.

Do we need more than just powerful blood pressure reductions? New paradigms in end-organ protection

Antihypertensive therapy can lower the risk of cardiovascular morbidity and mortality. Yet, partly because of inadequate dosing, wrong pharmacological choices, and poor patient adherence, hypertension control remains suboptimal in the majority of hypertensive patients. Achieving greater blood pressure control requires a multifaceted approach that raises awareness of hypertension, uses effective therapies, and improves adherence. Particular classes of antihypertensive therapy have beneficial actions beyond blood pressure and studies have evaluated differences in cardiovascular protection among classes. The LIFE and HOPE studies showed between-class differences that may be due to effects other than blood pressure-lowering. In the ONTARGET study, telmisartan and ramipril provided similar cardiovascular protection but adherence was higher with telmisartan, which was better tolerated. This difference in compliance is likely to be important for long-term therapy. The selection of an agent for cardiovascular protection should depend on an appreciation of its composite properties, including any beneficial effects on tolerability and increased patient adherence, as these are likely to be advantageous for the long-term management of hypertension. This review examines the evidence that the effects beyond blood pressure provided by some antihypertensive agents can also lower the risk of cardiovascular, cerebrovascular, and renal events in patients with hypertension.

Antihypertensive activity of angiotensin II AT1 receptor antagonists: a systematic review of studies with 24 h ambulatory blood pressure monitoring

OBJECTIVE

To perform a systematic review of the antihypertensive activity of the angiotensin II AT1 receptor antagonists (ARB).

METHODS

Studies in which blood pressure (BP) was measured using ambulatory BP monitoring for at least 24 h were collected from MEDLINE. Data for each treatment group, ARB, placebo or the drug used for its comparison were obtained from the selected studies. Only studies with a minimum of quality criteria were selected. The final study group contained 36 publications, with a total of 47 patient cohorts receiving ARB in monotherapy, 10 with placebo, 10 with amlodipine, and five with enalapril. The reduction in clinical and ambulatory BP during 24 h, day, night and the last 4-h period for each of the drugs analysed were calculated and adjusted by age, sex, number of participants and by the initial BP level.

RESULTS

The global antihypertensive activity of ARB differs from that observed with amlodipine in the sense that the magnitude of the reduction in the BP values does not essentially depend on the initial BP values nor on the dose used. When only ARB were considered, the drug used was a determinant for systolic BP reduction, whereas for diastolic BP the influence was on the BP reduction and the duration of the antihypertensive activity. The dose used had a particular influence on the duration of the antihypertensive activity for both systolic and diastolic BP.

CONCLUSION

Among the ARB, the influence is on duration more than on the magnitude of BP reduction. Dose, therefore, is an important factor in the duration of antihypertensive activity.

Diabetic nephropathy: worldwide epidemic and effects of current treatment on natural history

Diabetic nephropathy has become a worldwide epidemic, accounting for approximately one third of all cases of end-stage renal disease. With increasing prevalence of diabetes particularly in Asia, and a global prevalence of microalbuminuria of 39%, the problem is expected to grow. Improved management of diabetes aimed at improved glycemic control, to avoid initiation of diabetic nephropathy, and antihypertensive treatment blocking the renin-angiotensin system, to avoid its progression, need to be implemented, particularly in high-risk patients.

The renin-angiotensin system and its blockade in diabetic renal and cardiovascular disease

Diabetic nephropathy, the most common cause of end-stage renal disease in the United States, is also associated with increased cardiovascular mortality. The renin-angiotensin-aldosterone system (RAAS) plays a central role in the development and progression of kidney disease and cardiovascular disease. Randomized, controlled trials have demonstrated renoprotection with the use of angiotensin receptor blockers (ARBs) in type 2 and angiotensin-converting enzyme inhibitors (ACEIs) in type 1 diabetes. More recent studies have demonstrated similar cardiovascular benefits with the use of ARBs compared with ACEIs. The combination of the two classes of RAAS blockers has been investigated in large studies of patients with heart failure and after myocardial infarction, and a few small studies of patients with diabetic nephropathy. In this review, we summarized the results of the studies on the benefits of ARBs, ACEIs, and their combination in patients with diabetic nephropathy or cardiovascular diseases.

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.

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.

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.

New insights into the significance of microalbuminuria

PURPOSE OF REVIEW

This review summarizes recent work that has explored the association between microalbuminuria and adverse clinical outcomes in the presence and absence of diabetes.

RECENT FINDINGS

Recent investigations have documented the prevalence of microalbuminuria in the general community and have also highlighted the continuous relationship between the level of urinary albumin excretion and clinical endpoints. Even below traditional microalbuminuria thresholds, urinary albumin levels appear to correlate with clinical outcomes. Microalbuminuria is becoming increasingly recognized as an independent risk factor for cardiovascular morbidity and mortality. At least for subjects with type 2 diabetes and microalbuminuria, intensive, multifactorial interventions can reduce the risk of cardiovascular events by about 50%. Although several studies have found an association between microalbuminuria and surrogate measurements of vascular disease, the exact molecular mechanisms linking an increase in urinary albumin excretion and vascular disease are still unknown. Microalbuminuria also has a well-documented association with progressive diabetic renal disease but recent studies have suggested that the prognostic significance of microalbuminuria in this regard may not be as powerful as originally reported.

SUMMARY

Aggressive, multifactorial interventions, including the use of drugs that interrupt the renin-angiotensin system are strongly recommended for patients with diabetes and micro-albuminuria to ameliorate the progression of renal and vascular complications. This approach should also possibly apply to microalbuminuric subjects without diabetes. The relationship between microalbuminuria and progressive diabetic renal disease requires re-evaluation given temporal trends in the prevention and treatment of diabetic complications.