Eprosartan

Palladium-Catalyzed Direct Selanylation of Chalcogenophenes and Arenes Assisted by 2-(Methylthio)amide

The direct and selective conversion of a C-H bond into a C-Se bond remains a significant challenge, which is even more intricate with substrates having an innate regioselectivity under several reaction conditions, such as chalcogenophenes. We overrode their selectivity toward selanylation using palladium, copper, and the 2-(methylthio)amide directing group. This chelation-assisted direct selanylation was also suitable for mono and double ortho functionalization of arenes. The mechanistic studies indicate high-valent Pd(IV) species in the catalytic cycle, a reversible C-H activation step, and Cu(II) as a sequestering agent for organoselenide byproducts.

Angiotensin receptor blockers: Focus on cardiac and renal injury

Angiotensin II, an important component of renin angiotensin system, is a potent vasopressor and its actions are mostly mediated via angiotensin II type 1 receptor (AT1R) and role of AT2R in counterbalancing the actions of AT1R stimulation are under extensive research. In addition to its physiological actions, angiotensin II plays important roles in the pathogenesis of atherosclerosis, hypertension, left ventricular hypertrophy, and heart failure. The effects of angiotensin II can be blocked by either suppressing its production by blocking angiotensin converting enzyme or by antagonizing its actions on AT1R using angiotensin II receptor blockers (ARBs). Instead of the extensive use of ARBs in the treatment of various cardiovascular diseases, proper selection of a particular ARB is crucial as the clinical condition of individual patient is different and also their economic status would play an essential role in medication compliance. Thus a critical review of the proven and promising actions of ARBs against various pathological conditions will be of great importance for the clinicians as well as for the researchers.

Ambulatory monitoring of systolic hypertension in the elderly: Eprosartan/hydrochlorothiazide compared with losartan/hydrochlorothiazide (INSIST trial)

INTRODUCTION

Systolic hypertension is very common in the elderly and is strongly associated with the risk of cardiovascular and cerebrovascular events. The control of systolic hypertension is difficult and most patients require combination antihypertensive therapy. Few data are available regarding the efficacy of angiotensin II receptor antagonists on systolic hypertension of the elderly. The aim of this double-blind, double-dummy, randomized, parallel-group, multicenter study was to assess the efficacy of eprosartan 600 mg in combination with hydrochlorothiazide (HCTZ) 12.5 mg in comparison with losartan 50 mg in combination with HCTZ 12.5 mg, in reducing blood pressure in elderly patients with grade 2 systolic hypertension who did not optimally respond to eprosartan or losartan monotherapy.

METHODS

After a 3-week placebo wash-out, 155 patients with an Office trough sitting systolic blood pressure (Office sitSBP) >or=160 mmHg and <180 mmHg were randomized to eprosartan 600 mg (n=78) or losartan 50 mg (n=77) once daily for 6 weeks. In patients not optimally responding to monotherapy (Office sitSBP>or=130 mmHg) 12.5 mg HCTZ was added as fixed combination once daily for 6 weeks. A 24-hour ambulatory blood pressure monitoring (ABPM) was performed at the end of wash-out and at the end of the fixed-combination period.

RESULTS

No statistically significant difference was found between eprosartan/HCTZ and losartan/HCTZ on the primary endpoint (24-hour ABPM SBP) with an adjusted mean difference between treatments of 3.1 mmHg (95% CI: -0.32-6.59). However, the mean 24-hour ABPM SBP significantly decreased by 16.7 mmHg with eprosartan/HCTZ and 20.3 mmHg with losartan/HCTZ (P<0.001 vs. baseline). The mean Office sitSBP significantly decreased by 28.7 mmHg and 29.6 mmHg respectively, with eprosartan/HCTZ and losartan/HCTZ (P<0.001 vs.baseline and vs. monotherapy).

CONCLUSION

In this study, eprosartan/HCTZ did not demonstrate to be superior to losartan/HCTZ in reducing ABPM systolic hypertension in the elderly.

Eprosartan: a review of its use in hypertension

Eprosartan is an angiotensin II receptor antagonist (angiotensin II receptor blocker [ARB]) used in the treatment of hypertension. In large, randomized trials, eprosartan (with or without hydrochlorothiazide [HCTZ]) demonstrated superior antihypertensive efficacy to that of placebo and, when administered at comparable dosage regimens, had similar blood pressure-lowering effects to enalapril. Eprosartan was generally well tolerated in clinical trials and had a lower incidence of persistent dry cough than enalapril. Eprosartan has a neutral effect on metabolic parameters, such as serum lipid levels and glucose homeostasis, and a low propensity for pharmacokinetic drug interactions. The use of eprosartan or other ARBs in combination with HCTZ tends to reverse the potassium loss associated with thiazide diuretics. Independent of its antihypertensive effects, eprosartan was associated with improved clinical outcomes (primary composite endpoint of all causes of mortality and all cardiovascular and cerebrovascular events, including all recurrent events) compared with nitrendipine in a randomized, secondary prevention trial in hypertensive patients with previous cerebrovascular events (MOSES trial). Eprosartan also reduced blood pressure and was associated with a modest improvement in cognitive function in a large observational study in patients > or =50 years of age with newly diagnosed hypertension (OSCAR study). In both of these trials, additional antihypertensive therapy, such as HCTZ, was permitted. Therefore, eprosartan is a useful treatment option in the management of a broad range of patients with hypertension, and its use with HCTZ provides a rational combination regimen.

Clinical profile of eprosartan: a different angiotensin II receptor blocker

Rationale. The goal of antihypertensive treatment is to reduce risk of cardiovascular morbidity and mortality. Apart from blood pressure lowering per se, also reducing the activities of the renin-angiotensin system and sympathetic nervous system appears to be important. Angiotensin II receptor blocker drugs (ARBs) have provided a useful class of anti-hypertensive drugs. Eprosartan is a relatively new ARB which is chemically distinct (non-biphenyl, non-tetrazole) from all other ARBs (biphenyl tetrazoles). An analysis has been made on available experimental and clinical data on eprosartan which not only is an effective and well tolerated antihypertensive agent, but also lowers the activities of the renin-angiotensin system and sympathetic nervous system. Experimental and pharmacokinetic studies on eprosartan have shown differences with the other ARBs. The distinct properties of this non-biphenyl, non-tetrazole ARB might be relevant in the effort to reduce cardiovascular risk, also beyond its blood pressure lowering capacity.

Validated quantitation of angiotensin II receptor antagonists (ARA-II) in human plasma by liquid-chromatography-tandem mass spectrometry using minimum sample clean-up and investigation of ion suppression

For the quantitation of angiotensin II receptor antagonists (ARA-II) in human plasma, a method using liquid-chromatography (LC)-electrospray ionization tandem mass spectrometry (MS/MS) has been developed with respect to simple sample clean-up and investigation of ion suppression effects. For sample preparation, protein precipitation using zinc sulphate and methanol showed advantages in speed, recovery, and reproducibility over solid-phase extraction. A triple quadrupole mass spectrometer (Sciex API 365) with turbo ionspray source was used for detection of compounds with multireaction monitoring (MRM) of two transitions per compound. Suppression effects caused by endogenous matrix compounds were investigated by post-column infusion of analytes and LC analysis of precipitates of blank plasma samples and could be excluded. A validation was performed for the ARA-II drugs (valsartan, irbesartan, losartan and its active metabolite EXP 3174, eprosartan, candesartan, and telmisartan). The developed method showed good intra- and interday precision (<12% relative standard deviation) and accuracy (<11.5% bias) at different concentrations for all the studied compounds. The calculated lower limits of quantitation were between 7 and 13 ng/mL, and the compounds were stable during the analytical process. These rather expensive drugs against hypertension are prescribed with increasing numbers in Europe and the industrialized nations. Complications might arise from overdosage or metabolic disorders. However, drug monitoring is not usually performed. Because the therapeutic concentrations range from a few nanograms to hundreds of nanograms per milliliter for the different drugs, and they are not amenable to gas chromatography/MS analysis because of their high molecular weight and polarity, the LC-MS/MS method is the golden standard for therapeutic drug monitoring and for clinical and forensic toxicology of ARA-II drugs.

Effects of eprosartan on serum metabolic parameters in patients with essential hypertension

The effect of the anti-hypertensive drug eprosartan on metabolic parameters is currently not extensively documented. We evaluated the effect of eprosartan on parameters involved in atherogenesis, oxidative stress and clotting activity. This open-label unblinded intervention study included 40 adult patients with essential hypertension taking eprosartan. Eprosartan significantly reduced by 8% (p<0.001) the systolic and by 13% (p<.001) the diastolic blood pressure, and in-creased by 24% the time needed to produce oxidative by-products (p=0.001), a marker of oxidative stress. In contrast, ep-rosartan did not alter 8-isoprostane (8-epiPGF2a) levels, another marker of oxidative stress. Additionally, eprosartan re-duced by 14% aspartate aminotransferase and by 21% then alanine aminotransferase activity, while it had a neutral effect on the lipid profile and apolipoprotein levels and did not influence glucose homeostasis, creatinine and uric acid levels. Eprosartan did not affect the clotting/fibrinolytic status (estimated by plasminogen activator inhibitor 1, tissue plasmino-gen activator and a2 antiplasmin levels), or the enzymatic activity of the lipoprotein associated phospholipase A2 (Lp-PLA2) and paraoxonase 1 (PON1). In conclusion, eprosartan should be mainly considered as an anti-hypertensive agent with neutral effects on most of the metabolic parameters in hypertensive patients.

Angiotensin blockade with eprosartan: vascular and functional implications

It is clear that the renin-angiotensin system (RAS) and the sympathetic nervous system (SNS) play key roles in sustaining elevated blood pressure, subsequently resulting in increased risks of cardiovascular (CV), cerebrovascular and kidney disease. Modifying these systems with antihypertensive agents has led to the discovery that their effects may indeed extend beyond controlling blood pressure. Within blood vessels, angiotensin II type 1 receptor blockers (ARBs) inhibit postsynaptic angiotensin II type 1 receptors (AT1). The ARB eprosartan, in contrast to other ARBs, also inhibits prejunctional AT1 receptors, which regulate noradrenaline release. The positive effects of eprosartan on blood pressure have been studied extensively, and are due to modulation of both the RAS and the SNS (through stimulation of the angiotensin II type 2 [AT2] receptor). Of importance to isolated systolic hypertension, trough sitting systolic blood pressure (SBP) is also significantly reduced with eprosartan. In addition, many studies have shown how the benefits of eprosartan go beyond that of blood pressure control alone. Eprosartan has shown positive effects on vascular inflammation and resistance to oxidation and/or modification of low-density lipoprotein. A wealth of other positive actions are associated with eprosartan treatment, including effects on platelet aggregation, kidney function and structure, progressive left ventricular dysfunction and central SBP. Clinical studies have clearly demonstrated the benefits of RAS blockade alongside the additional effects beyond blood pressure control with eprosartan treatment. These data place eprosartan as an effective agent to prevent CV, cerebrovascular and renal complications associated with high blood pressure.

Introduction: The pharmacological profile of eprosartan--implications for cerebrovascular and cardiovascular risk reduction

Moderate elevations in blood pressure translate to significant increases in cardiovascular and cerebro vascular risk. Beneficially, this relationship allows small decreases in blood pressure to be associated with risk reduction. Both the renin-angiotensin system and the sympathetic nervous system are involved in hypertension, hence targeting these systems is likely to be of benefit in the treatment of hypertension. Angiotensin II type 1 receptor blockers (ARBs) are used for controlling blood pressure and treating heart failure in a broad range of patients, including those with diabetes and the elderly. Not only have ARBs shown good efficacy and tolerability, they also appear to have a protective effect that goes beyond that expected from the reduction of blood pressure. The ARB eprosartan is a nonbiphenyl nontetrazole angiotensin II type 1 receptor (AT1) antagonist, which acts to decrease total peripheral resistance. Eprosartan acts at vascular AT1 receptors (postsynaptically) and at presynaptic AT1 receptors, where it inhibits noradrenaline release. In clinical studies, eprosartan has been shown to significantly reduce cardiovascular and cerebrovascular events, whilst avoiding the persistent cough that commonly occurs with the use of angiotensin-converting enzyme inhibitors. Eprosartan can also be differentiated from other ARBs due to its noradrenergic effects, which other ARBs used at therapeutic doses do not possess. Eprosartan, therefore, represents a useful therapeutic option in the management of patients with hypertension, including those with a history of stroke or with co-morbid type 2 diabetes mellitus.

Rationale, design and methods of the OSCAR study: observational study on cognitive function and systolic blood pressure reduction in hypertensive patients

Data from several recent clinical trials have suggested a beneficial effect of antihypertensive medications on preservation of cognitive function. Eprosartan, an angiotensin type-1 receptor antagonist (ARA) with dual action on both pre- and postsynaptic angiotensin type 1 receptors, may be effective in the control of SBP and the prevention of cognitive decline. The OSCAR (Observational Study on Cognitive function And SBP Reduction) study is an international longitudinal observational study with a duration of 6 months intended to examine the impact of the ARA eprosartan on cognitive function (assessed using the Mini-Mental State Examination [MMSE]) and control of systolic blood pressure (SBP) in a large international population of hypertensive patients managed in a standard primary care setting. A total of 100,000 hypertensive patients, aged >or=50 years and with SBP of >140 mmHg will be recruited by more than 20 000 primary care physicians in 27 countries. These patients will receive eprosartan 600 mg once a day for 6 months. The MMSE, a globally validated cognitive screening test, will be performed at baseline, and after 6 months of treatment. After the first month of monotherapy, eprosartan treatment may, at the absolute discretion of individual investigators, be supplemented with other antihypertensive medications for the remainder of the study. The primary outcome indices are the mean relative change in MMSE score and the absolute change from baseline in SBP in the study population as a whole and in subsets of patients according to various factors among them: ethnicity, comorbidities (i.e. target organ damage, diabetes), baseline cognitive level and baseline blood pressure level. The secondary objectives are to identify factors influencing SBP and MMSE changes. The OSCAR trial is the first international observational study focusing on MMSE in a wide international cohort of hypertensive patients. The results are expected in 2007.

Effects of eprosartan on target organ protection

Hypertension is the most important cardiovascular risk factor for stroke. Blood pressure reduction by antihypertensive treatment is clearly efficacious in the prevention of stroke (both primary and secondary), although no clear differences have yet been observed between antihypertensive drug classes. However, a recent study reported the clear superiority of the angiotensin-receptor blocker eprosartan over the calcium channel blocker nitrendipine in cardiovascular protection of hypertensive patients with a previous stroke. Comparative studies using angiotensin-receptor blockers have also suggested the superiority of this class of drugs on primary stroke prevention. This effect may be linked to their beneficial actions on left ventricular hypertrophy, atrial enlargement, and supraventricular arrhythmias, endothelial dysfunction, inflammation, and remodelling, as well as a direct neuroprotective effect mediated through the stimulation of the angiotensin II type-2 receptor. In addition, a sympathoinhibition observed with the renin–angiotensin system blockers and particularly demonstrated with eprosartan, may help to explain the better cardiovascular and cerebrovascular protection in comparison with the calcium antagonist nitrendipine.