Losartan: a review of its use in stroke risk reduction in patients with hypertension and left ventricular hypertrophy

Losartan (Cozaar) is an angiotensin AT1 receptor antagonist. It is approved in numerous countries for the treatment of hypertension and has been approved in the UK, the US and several European countries for stroke risk reduction in patients with hypertension and left ventricular hypertrophy (LVH). Losartan is recommended for use alone or with hydrochlorothiazide, but it can also be administered with other antihypertensive medications. In patients with hypertension, losartan effectively lowers blood pressure and also leads to regression of LVH. In the large, well designed LIFE (Losartan Intervention For Endpoint reduction in hypertension) study in patients with hypertension and LVH, losartan was more effective than atenolol in reducing the composite primary endpoint of cardiovascular (CV) mortality, stroke or myocardial infarction (MI). This was mainly due to a significant 25% reduction in the risk of stroke in the losartan group. Losartan recipients also had a significantly lower incidence of new-onset diabetes mellitus compared with atenolol recipients. Similar benefits were observed in several patient subgroups from the LIFE study, but not in the subgroup of Black patients. Losartan is well tolerated and is a cost effective alternative to atenolol in the setting of stroke reduction. Comparative data on clinical outcomes in hypertensive patients for losartan versus other antihypertensive agents would be of interest. Nonetheless, in addition to its established antihypertensive and end organ effects, the LIFE study indicates that, with the possible exception of Black patients, losartan can reduce the risk of stroke in patients with hypertension and LVH.     

Losartan for LIFE in hypertension with left ventricular hypertrophy?

When ACE inhibitors are used to lower blood pressure to the same degree as beta-adrenoceptor antagonists or calcium channel blockers, ACE inhibitors do not seem to have additional benefits to these agents. In the Losartan Intervention for End Point Reduction in Hypertension study (LIFE), losartan was compared to atenolol in hypertensives with the additional risk factor of left ventricular hypertrophy (LVH). For similar effects on blood pressure, losartan had a greater benefit on the primary composite end point (cardiovascular mortality, stroke and myocardial infarction) than atenolol in the hypertensives with LVH, including a prespecified subgroup of patients with additional diabetes mellitus. Losartan also had a greater ability to reverse LVH than atenolol. Thus, losartan should become the standard treatment for hypertension when LVH is present.     

Use of losartan in diabetic patients in the primary care setting: review of the results in LIFE and RENAAL

SUMMARY

Objective: To review outcomes of diabetic patients treated with losartan in two recent randomized, double-blind, clinical trials and compare outcomes to similar studies in diabetics.

Methods: The Reduction in ENdpoints with the Angiotensin II Antagonist Losartan (RENAAL) study recruited 1513 patients with type 2 diabetes and nephropathy. The Losartan Intervention For Endpoint reduction (LIFE) study recruited 9193 hypertensive patients with left ventricular hypertrophy (LVH) including 1195 with diabetes mellitus. The maximum losartan dose in both studies was 100?mg daily. All study patients could receive additional antihypertensive medications, excluding angiotensin converting enzyme inhibitors (ACEIs) and other angiotensin receptor blockers (ARBs), if blood pressures (BP) < 140/90?mmHg were not achieved. In RENAAL, the control group received placebo whereas in LIFE, controls received atenolol. BP reductions were comparable in the treatment and control groups of both studies. In RENAAL, the primary outcome was the composite of doubling of serum creatinine, end-stage renal disease, or death. In LIFE, the primary composite outcome was cardiovascular death and non-fatal myocardial infarction or stroke.

Results: In RENAAL, losartan reduced the primary composite end-point 16% (?p = 0.02) and the incidence of end-stage renal disease (ESRD) 28% (?p = 0.002). In LIFE, the primary composite endpoint among diabetics was reduced 24% (?p = 0.03), cardiovascular mortality was reduced 37% (?p = 0.03) and total mortality was reduced 39% (?p = 0.002).

Discussion: In diabetic patients with nephropathy, losartan reduces progression to end-stage renal disease. In hypertensive diabetic patients with LVH, losartan reduces cardiovascular morbidity and mortality and total mortality. Angiotensin receptor blockade with losartan appears to confer benefits beyond BP reduction in diabetic patients at high-risk for cardiovascular and renal events.     

Use of losartan in diabetic patients in the primary care setting: review of the results in LIFE and RENAAL

OBJECTIVE: To review outcomes of diabetic patients treated with losartan in two recent randomized, double-blind, clinical trials and compare outcomes to similar studies in diabetics. METHODS: The Reduction in ENdpoints with the Angiotensin II Antagonist Losartan (RENAAL) study recruited 1513 patients with type 2 diabetes and nephropathy. The Losartan Intervention For Endpoint reduction (LIFE) study recruited 9193 hypertensive patients with left ventricular hypertrophy (LVH) including 1195 with diabetes mellitus. The maximum losartan dose in both studies was 100 mg daily. All study patients could receive additional antihypertensive medications, excluding angiotensin converting enzyme inhibitors (ACEIs) and other angiotensin receptor blockers (ARBs), if blood pressures (BP) < 140/90 mmHg were not achieved. In RENAAL, the control group received placebo whereas in LIFE, controls received atenolol. BP reductions were comparable in the treatment and control groups of both studies. In RENAAL, the primary outcome was the composite of doubling of serum creatinine, end-stage renal disease, or death. In LIFE, the primary composite outcome was cardiovascular death and non-fatal myocardial infarction or stroke. RESULTS: In RENAAL, losartan reduced the primary composite end-point 16% (p = 0.02) and the incidence of end-stage renal disease (ESRD) 28% (p = 0.002). In LIFE, the primary composite endpoint among diabetics was reduced 24% (p = 0.03), cardiovascular mortality was reduced 37% (p = 0.03) and total mortality was reduced 39% (p = 0.002). DISCUSSION: In diabetic patients with nephropathy, losartan reduces progression to endstage renal disease. In hypertensive diabetic patients with LVH, losartan reduces cardiovascular morbidity and mortality and total mortality. Angiotensin receptor blockade with losartan appears to confer benefits beyond BP reduction in diabetic patients at high-risk for cardiovascular and renal events.     

A cost-utility analysis of losartan versus atenolol in the treatment of hypertension with left ventricular hypertrophy

INTRODUCTION: The LIFE (Losartan Intervention For Endpoint reduction in hypertension) study demonstrated a 13% relative risk reduction in the primary composite endpoint (myocardial infarction, stroke or death) for patients with hypertension and electrocardiographically diagnosed left ventricular hypertrophy (LVH) treated with losartan compared with atenolol. Losartan recipients also had a 25% relative risk reduction for stroke compared with atenolol recipients. Incorporating the results found in the LIFE study into an economic model, an incremental cost-effectiveness analysis was performed comparing losartan with atenolol in the treatment of 67-year old patients with hypertension and LVH. METHODS: A Markov state transition model, based on published results of the LIFE trial (mean follow-up of 4.8 years), was utilised to extrapolate the outcomes observed in this trial to the patients' lifetime. Utility estimates for the associated health states were obtained from various published sources. Lifetime treatment costs were calculated adopting a societal perspective. Both costs and benefits were discounted and incremental cost-effectiveness ratios (ICERs) were estimated. One-way and probabilistic sensitivity analyses were performed. RESULTS: The estimated ICER for losartan versus atenolol was 1337 Canadian dollars per QALY gained (1 Canadian dollar =0.75 US dollars, 2002 values). This ICER was robust to extensive sensitivity analysis, demonstrating a 95% probability that the ICER would be <20,000 Canadian dollars per QALY gained. CONCLUSION: From a Canadian societal perspective, losartan appears to be a cost-effective alternative to atenolol in patients with hypertension and LVH. The estimated ICERs, including the sensitivity analyses, were within the range of cost-effectiveness ratios for various currently funded interventions and drugs in developed countries.     

Potential mechanisms of stroke benefit favoring losartan in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study

ABSTRACT

Introduction: The Losartan Intervention For Endpoint reduction in hypertension (LIFE) study is the first, and, so far, the only endpoint trial in patients with hypertension and left ventricular hypertrophy (LVH) to show a divergent therapeutic outcome of one treatment modality over another with equivalent blood pressure control. The purpose of this article is to review post hoc sub-analyses of LIFE study data and other clinical studies that offer some insight into possible treatment-related differences contributing to the superior stroke outcome of losartan versus atenolol beyond blood pressure reduction.

Methods: Relevant randomized clinical trials and review articles were identified through a MEDLINE search of English-language articles published between 1990 and 2006 using the search terms losartan, atenolol, LIFE, hypertension, and LVH. Articles describing major clinical studies, new data, or mechanisms pertinent to the LIFE study were selected for review.

Results: Differences in blood pressure or in the distribution of add-on medications were not evident between study groups in the LIFE study. Thus, the observed outcomes benefits favoring losartan may involve other possible mechanisms, including differential effects of losartan and atenolol on LVH regression, left atrial diameter, atrial fibrillation, brain natriuretic peptide, vascular structure, thrombus formation/platelet aggregation, serum uric acid, albuminuria, new-onset diabetes, and lipid metabolism. Alternative explanations for the LIFE study findings have also been put forward, including the choice of atenolol as an appropriate active comparator and differential effects between treatment groups on central pulse pressure. Additional clinical trials are needed to determine if the beneficial effects of losartan seen in LIFE are shared by other inhibitors of the renin–angiotensin system.

Conclusion: Sub-analyses of the LIFE study data suggest that losartan's stroke benefit may arise from a mosaic of mechanisms rather than a single action. Further studies are expected to continue to delineate the mechanisms of differential responses to treatments in LIFE.     

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.     

Fixed-Dose Combinations in the Management of Hypertension

We discuss combination therapy with angiotensin receptor antagonists (angiotensin receptor blockers; ARBs) and thiazide diuretics in light of the independent actions of both types of agents, and the adverse effects of both agents independently and in the context of the physiologic synergy achieved in using these agents together. ARBs counteract many of the adverse events associated with the use of thiazide diuretics and have been shown to reduce the occurrence of new-onset diabetes mellitus. We also review outcome trials in patients with hypertension (such as LIFE [Losartan Intervention For Endpoint reduction in hypertension], VALUE [Valsartan Antihypertensive Long-term Use Evaluation], and SCOPE [Study on COgnition and Prognosis in the Elderly]), in which losartan, valsartan, and candesartan cilexetil were used in combination with hydrochlorothiazide. Fixed combination ARB/hydrochlorothiazide agents make sense as initial therapy for patients in whom BP is >20/10 mm Hg above goal.     

Implications of the LIFE trial

The recent Losartan Intervention For Endpoint Reduction in Hypertension (LIFE) study was conducted in patients with essential hypertension with electrocardiogram evidence of left ventricular hypertrophy. This showed that losartan compared to atenolol resulted in a significant reduction in the primary endpoint of cardiovascular morbidity and mortality, as well as a greater reduction in electrocardiographically-defined left ventricular hypertrophy. Importantly, this was despite a mean blood pressure reduction which was similar in both groups. Furthermore, the atenolol arm was associated with higher incidence of newly diagnosed diabetics. The LIFE study has firmly confirmed a place for losartan (and other angiotensin receptor blockers) in the management of hypertension. Losartan has also been shown to be effective in diabetics and in patients with atrial fibrillation, as well as in left ventricular hypertrophy regression. This trial also raises the possibility that β-blockers should perhaps not be used as first-line monotherapy.     

Implications of the LIFE trial

The recent Losartan Intervention For Endpoint Reduction in Hypertension (LIFE) study was conducted in patients with essential hypertension with electrocardiogram evidence of left ventricular hypertrophy. This showed that losartan compared to atenolol resulted in a significant reduction in the primary endpoint of cardiovascular morbidity and mortality, as well as a greater reduction in electrocardiographically-defined left ventricular hypertrophy. Importantly, this was despite a mean blood pressure reduction which was similar in both groups. Furthermore, the atenolol arm was associated with higher incidence of newly diagnosed diabetics. The LIFE study has firmly confirmed a place for losartan (and other angiotensin receptor blockers) in the management of hypertension. Losartan has also been shown to be effective in diabetics and in patients with atrial fibrillation, as well as in left ventricular hypertrophy regression. This trial also raises the possibility that beta-blockers should perhaps not be used as first-line monotherapy.     

Do losartan and atenolol have differential effects on BNP and central haemodynamic parameters?

INTRODUCTION: It has been suggested that angiotensin-converting enzyme inhibitors (ACE-Is) and angiotensin II receptor blockers (ARBs) have a differential effect on brachial and aortic haemodynamics. This is why they seem to have beneficial effects that are beyond brachial blood pressure (BP) lowering. We aimed to investigate if this was the case with losartan when compared to atenolol. We also investigated the differential effect of losartan and atenolol on the prognostic marker, brain type natriuretic peptide (BNP). METHODS: We studied 17 patients who were similar to those in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study. Patients were randomised to receive four months of losartan and atenolol in a crossover fashion. Main outcome measures were BNP and Augmentation index (AIx), which gives an indication of central haemodynamics. Brachial pulse wave velocity (PWV) and time to reflected wave (Tr) were measured as an indication of vascular stiffness. RESULTS: BNP was significantly lower on losartan than atenolol (p=0.007). AIx was lower on losartan than atenolol (p=0.03), however, this result was not significant when heart rate was considered as a covariate (p=0.09). Heart rate was significantly lower on atenolol than losartan (p=0.03). There was no difference between treatments for both brachial PWV and Tr (p=0.2 and p=0.99, respectively). CONCLUSION: The benefits seen when losartan was compared to atenolol in the LIFE trial may be due to a reduction in BNP. We failed to detect a differential effect in central compared to peripheral haemodynamics when losartan was compared to atenolol.     

Losartan in diabetic nephropathy

Losartan is an orally active, selective, nonpeptide, angiotensin II AT(1) receptor antagonist. Losartan 50 or 100 mg/day was significantly more effective than placebo in reducing the incidence of a doubling of serum creatinine, end-stage renal disease (ESRD) or death (43.5% vs 47.1%, p = 0.02) in a pivotal, well designed trial (Reduction of Endpoints in Non insulin dependent diabetes mellitus with the Angiotensin II Antagonist Losartan [RENAAL] study) in 1513 patients with type 2 diabetes mellitus and proteinuria. Losartan also significantly reduced the incidence of doubling of serum creatinine level (p = 0.006), ESRD (p = 0.002), ESRD or death (p = 0.01) and doubling of serum creatinine and ESRD (p = 0.01) compared with placebo in the RENAAL trial. There were similar incidences of overall mortality and morbidity and mortality from cardiovascular causes between treatment groups. In addition, data from several nonblind and double-blind studies indicates that losartan effectively reduces the mean albumin excretion rate. Two double-blind studies show that losartan has similar effects to enalapril on kidney function. Data from 4058 patients (3300 with essential hypertension) who have received losartan (10-150 mg/day) in clinical trials indicate it is well tolerated. In the RENAAL study 17.2% and 21.7% of losartan and placebo recipients discontinued treatment because of adverse events, but causality was not determined.     

Losartan for the treatment of hypertension and left ventricular hypertrophy: the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study

Losartan is an orally active, selective, nonpeptide, angiotensin-II Type I-receptor antagonist, and was the first drug marketed in this class. It has been approved for the treatment of hypertension, and may be used alone or in combination with other antihypertensive agents. Based on the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study, losartan has been approved for the reduction of cardiovascular events in patients with hypertension and left ventricular hypertrophy, but there is evidence that this benefit does not apply to black patients. Based on the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study, losartan is also indicated for the treatment of diabetic nephropathy with an elevated serum creatinine and proteinuria, in patients with Type 2 diabetes. The focus of this review is the LIFE study.     

Losartan for the treatment of hypertension and left ventricular hypertrophy: the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study

Losartan is an orally active, selective, nonpeptide, angiotensin-II Type I-receptor antagonist, and was the first drug marketed in this class. It has been approved for the treatment of hypertension, and may be used alone or in combination with other antihypertensive agents. Based on the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study, losartan has been approved for the reduction of cardiovascular events in patients with hypertension and left ventricular hypertrophy, but there is evidence that this benefit does not apply to black patients. Based on the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study, losartan is also indicated for the treatment of diabetic nephropathy with an elevated serum creatinine and proteinuria, in patients with Type 2 diabetes. The focus of this review is the LIFE study.     

The role of angiotensin antagonism in stroke prevention in patients with hypertension: focus on losartan

Summary

Optimal management of hypertension has been shown to reduce the risk of stroke. In recent years, newer classes of antihypertensive such as the angiotensin II (Ang II) antagonists have become available. Results from the Losartan Intervention for Endpoint reduction in hypertension (LIFE) study suggest the utility of this particular Ang II antagonist in stroke prevention. Treatment with a losartan-based regimen or an atenolol-based regimen produced similar reductions in blood pressure during almost 5 years of follow up. Losartan, however, reduced the risk of stroke by 25% compared with atenolol (p = 0.001). For a subgroup of patients with isolated systolic hypertension, losartan reduced the risk of stroke by 40% (p = 0.02). As well as blocking the Ang II type 1 receptor, losartan also acts as an antagonist at the thromboxane A₂ receptor and has uricosuric effects, which may provide additional mechanisms by which losartan provides protective benefits beyond its antihypertensive action. The relevance of these molecular properties of losartan over other Ang II antagonists is further supported by comparison of the outcomes obtained in clinical trials employing two other Ang II antagonists, valsartan and candesartan.     

The role of angiotensin antagonism in stroke prevention in patients with hypertension: focus on losartan

Optimal management of hypertension has been shown to reduce the risk of stroke. In recent years, newer classes of antihypertensive such as the angiotensin II (Ang II) antagonists have become available. Results from the Losartan Intervention for Endpoint reduction in hypertension (LIFE) study suggest the utility of this particular Ang II antagonist in stroke prevention. Treatment with a losartan-based regimen or an atenolol-based regimen produced similar reductions in blood pressure during almost 5 years of follow up. Losartan, however, reduced the risk of stroke by 25% compared with atenolol (p = 0.001). For a subgroup of patients with isolated systolic hypertension, losartan reduced the risk of stroke by 40% (p = 0.02). As well as blocking the Ang II type 1 receptor, losartan also acts as an antagonist at the thromboxane A2 receptor and has uricosuric effects, which may provide additional mechanisms by which losartan provides protective benefits beyond its antihypertensive action. The relevance of these molecular properties of losartan over other Ang II antagonists is further supported by comparison of the outcomes obtained in clinical trials employing two other Ang II antagonists, valsartan and candesartan.     

Reversal of Left Ventricular Hypertrophy

Regression of left ventricular hypertrophy (LVH) is an important intermediate target for antihypertensive therapy. Thus, several trials and meta-analyses have attempted to compare the effects of different antihypertensive agents on LVH, but flawed study designs and methodologic problems have limited the utility of these studies. PRESERVE (Prospective Randomized Enalapril Study Evaluating Regression of Ventricular Enlargement), LIVE (LVH: Indapamide Sustained Release Versus Enalapril) and LIFE (Losartan Intervention For Endpoint reduction in hypertension) represent a new generation of large well designed trials with the power to compare different antihypertensive drugs. These studies have shown that treatment regimens based on enalapril and a nifedipine gastrointestinal therapeutic system are of similar efficacy (PRESERVE), that indapamide sustained release (SR) is superior to enalapril (LIVE), and that a regimen based on losartan is superior to a regimen based on atenolol (LIFE) in reversing hypertensive LVH. LIVE incorporated on-treatment echocardiographic quality control, with centralized readers blinded for both treatment and sequence of recording. The findings of these rigorous studies, to some extent in disagreement with results of previous meta-analyses, support the notion that antihypertensive drugs need to be judged on their individual effects on important intermediate endpoints such as LVH in well designed and adequately sized studies. However, extrapolation of the results of these studies in terms of class effects could be misleading and should be made with caution.     

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.     

Telmisartan/hydrochlorothiazide: in the treatment of essential hypertension

Oral telmisartan/hydrochlorothiazide (HCTZ) combines two antihypertensive agents, a selective angiotensin II receptor antagonist with a long half-life and once-daily administration, and a thiazide diuretic. In two large, 8-week, double-blind trials, patients with hypertension unresponsive to monotherapy who received combined telmisartan/HCTZ 80/12.5 or 40/12.5 mg/day, achieved significantly larger reductions in diastolic and systolic blood pressure (BP), than recipients of continued telmisartan monotherapy (p < 0.05 for all). Compliance with telmisartan/HCTZ 80/12.5 mg/day was 98.9%. In patients with hypertension, telmisartan/HCTZ resulted in similar BP reductions to oral enalapril/HCTZ and atenolol/HCTZ in 26-week double-blind trials and greater reductions than oral losartan/HCTZ 50/12.5 mg/day in a 6-week randomised open-label trial (p < 0.001). Up to one-third of patients with hypertension initially responsive to telmisartan 40 or 80 mg/day in a 4-year study required the eventual addition of HCTZ 12.5 or 25 mg/day and/or another agent to maintain BP control. BP was controlled in about 75% of these by adding only HCTZ. In clinical trials of up to 4 years, including elderly patients, telmisartan/HCTZ had similar tolerability to placebo, with few reports of hypokalaemia. Most adverse events were mild to moderate.     

Candesartan cilexetil: an update of its use in essential hypertension

Candesartan cilexetil is converted to the angiotensin II receptor antagonist candesartan during absorption from the gastrointestinal tract. The selective and competitive binding of candesartan to the angiotensin II type 1 (AT(1)) receptor prevents binding of angiotensin II, a key mediator in the renin-angiotensin system. Significant reductions in systolic BP and diastolic BP are achieved with a once-daily dosage of candesartan cilexetil 2 to 32 mg/day in patients with mild to moderate hypertension. In randomised studies, candesartan cilexetil 8 to 16 mg/day was at least as effective as therapeutic dosages of losartan or other angiotensin II receptor antagonists. At a dosage of up to 32 mg/day candesartan cilexetil demonstrated greater antihypertensive efficacy than losartan 50 or 100 mg/day. In comparative trials, candesartan cilexetil demonstrated similar or greater antihypertensive efficacy compared with enalapril or hydrochlorothiazide and equivalent efficacy compared with amlodipine. The efficacy of candesartan cilexetil is not affected by age, and the drug provided significant BP reductions in Black patients and in those with severe hypertension. Long-term clinical studies to assess the effects of treatment with candesartan cilexetil on cardiovascular morbidity and mortality are ongoing. Regression of left ventricular hypertrophy has been seen with candesartan cilexetil treatment in patients with hypertension. Furthermore, the drug has favourable effects on renal function in patients with hypertension with or without coexisting diabetes mellitus. Renal vascular resistance and albumin excretion were reduced following treatment with candesartan cilexetil. Glucose homeostasis and lipid metabolism were not affected by treatment in patients with type 2 diabetes mellitus. Candesartan cilexetil is well tolerated and is not associated with cough, a common adverse effect of angiotensin converting enzyme inhibitor treatment. A pooled analysis of clinical trials found that the tolerability profile of candesartan cilexetil is not significantly different from that of placebo. Adverse events are not dose-related and are generally of mild to moderate severity. Conclusions: Candesartan cilexetil is an effective antihypertensive agent with a tolerability profile similar to that of placebo. Comparative data indicate that candesartan cilexetil has antihypertensive efficacy equivalent to that of other major classes of antihypertensive agents and has a long duration of action. Therefore, candesartan cilexetil is a useful therapeutic option in the management of patients with hypertension.