In vitro and in vivo characterization of the activity of telmisartan: an insurmountable angiotensin II receptor antagonist

Telmisartan loading thermosensitive hydrogel repairs gut epithelial barrier for alleviating inflammatory bowel disease

Inflammatory bowel disease (IBD) remains a global health concern with a complex and incompletely understood pathogenesis. In the course of IBD development, damage to intestinal epithelial cells and a reduction in the expression of tight junction (TJ) proteins compromise the integrity of the intestinal barrier, exacerbating inflammation. Notably, the renin-angiotensin system and angiotensin II receptor type 1 (AT1R) play a crucial role in regulating the pathological progression including vascular permeability, and immune microenvironment. Thus, Telmisartan (Tel), an AT1R inhibitor, loading thermosensitive hydrogel was constructed to investigate the potential of alleviating inflammatory bowel disease through rectal administration. The constructed hydrogel exhibits an advantageous property of rapid transformation from a solution to a gel state at 37°C, facilitating prolonged drug retention within the gut while mitigating irritation associated with rectal administration. Results indicate that Tel also exhibits a beneficial effect in ameliorating colon shortening, colon wall thickening, cup cell lacking, crypt disappearance, and inflammatory cell infiltration into the mucosa in colitis mice. Moreover, it significantly upregulates the expression of TJ proteins in colonic tissues thereby repairing the intestinal barrier damage and alleviating the ulcerative colitis (UC) disease process. In conclusion, Tel-loaded hydrogel demonstrates substantial promise as a potential treatment modality for IBD.

Effect of parathyroid hormone-related protein on intracellular calcium ion and cyclic adenosine monophosphate concentrations in cardiac fibroblasts

Objective

This study aimed to determine the effect of parathyroid hormone-related protein (PTHrP) on proliferation of cardiac fibroblasts (CFs) in primary cultures of neonatal Wistar rats.

Methods

Different PTHrP concentrations were added to CFs of neonatal Wistar rats and the cells were grouped according to the concentrations added. A verapamil (VPL) group and a calcitriol (CAL) group were also established. Changes in cell proliferation and in cyclic adenosine monophosphate and calcium ion levels were identified and recorded.

Results

We found that as the concentration of PTHrP increased, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT, a tetrazolium salt) colorimetric absorbance values (A values) decreased. These values in the PTHrP groups were significantly lower than those in the control group. MTT colorimetric A values and ³H-thymidine deoxyribose intake were lower in the VPL group, low-dose CAL group, and the PTHrP 10⁻⁷ mol/L group compared with the control group. However, MTT colorimetric A values and ³H-thymidine deoxyribose intake were higher in the high-dose CAL group than in the PTHrP 10⁻⁷ mol/L group. As PTHrP concentrations increased, intracellular cyclic adenosine monophosphate concentrations also increased.

Conclusion

PTHrp, VPL, and low-dose CAL inhibit proliferation of CFs, while high-dose CAL promotes proliferation of CFs.

Angiotensin receptor subtypes regulate adipose tissue renewal and remodelling

Obesity is often associated with high systemic and local renin-angiotensin system (RAS) activity in adipose tissue. Adipose-derived mesenchymal stem/stromal cells (ADSCs), responsible for adipose tissue growth upon high-fat diet, express multiple angiotensin II receptor isoforms, including angiotensin II type 1 receptor (AT₁ R), angiotensin II type 2 receptor (AT₂ R), Mas and Mas-related G protein-coupled receptor D. Although AT₁ R is expressed on most ADSCs, other angiotensin receptors are co-expressed on a small subpopulation of the cells, a phenomenon that results in a complex response pattern. Following AT₁ R activation, the effects are transient due to rapid receptor internalisation. This short-lived effect can be prevented by heteromerisation with AT₂ R, a particularly important strategy for the regulation of ADSC differentiation and secretory activity. Heteromeric AT₂ R might be especially important for the generation of thermogenic beige adipocytes. This review summarises current data regarding the regulation of adipose tissue renewal and particularly ADSC adipogenic differentiation and secretory activity by RAS, with an emphasis on AT₂ R and its effects. We reveal a new scheme that implicates AT₂ R into the regulation of ADSC hormonal sensitivity.

A Meta-analysis of antihypertensive effect of telmisartan versus candesartan in patients with essential hypertension

OBJECTIVE

The comparison of antihypertensive effects between telmisartan and candesartan in patients with essential hypertension has been investigated in several small studies. The results were not consistent. We performed this meta-analysis determining the antihypertensive effect of telmisartan versus candesartan in these patients.

METHODS

We searched Pubmed, Web of Science, and Cochrane Central for all published studies comparing the antihypertensive effects between telmisartan and candesartan in patients with essential hypertension.

RESULTS

The antihypertensive effects were assessed in 302 patients included in 4 trials with a mean follow-up of 10 ± 4 weeks. There were no significant differences between telmisartan and candesartan in reduction of systolic blood pressure (SBP) and diastolic BP (DBP) in patients with essential hypertension (weighted mean differences (WMD) for SBP 1.98 mm Hg (95% confidence interval (CI), -0.53, 4.49), p > 0.05; WMD for DBP 0.26 mm Hg (95% CI, -1.65, 2.16), p > 0.05), respectively. In a sub-analysis including 2 randomized studies, there was not a significant difference for the reduction of SBP (WMD 0.90 (95% CI, -2.88, 4.68) mm Hg, p > 0.05) or DBP (WMD -0.80 (95% CI, -3.40, 1.81) mm Hg, p > 0.05) treated with telmisartan or candesartan.

CONCLUSIONS

This meta-analysis provides the evidence that the antihypertensive effects of telmisartan and candesartan are similar on SBP and DBP reduction in patients with essential hypertension, suggesting that strict designed randomized controlled trial would be helpful to compare antihypertensive effects of angiotensin II receptor blockers (ARBs) and improve the choice of ARBs in antihypertensive therapy.

Crosstalk between angiotensin and the nonamyloidogenic pathway of Alzheimer's amyloid precursor protein

The association between hypertension and an increased risk for Alzheimer's disease (AD) and dementia is well established. Many data suggest that modulation of the renin-angiotensin system may be meaningful for the prevention and therapy of neurodegenerative disorders, in particular AD. Proteolytic cleavage of the amyloid precursor protein (APP) by α-secretase precludes formation of neurotoxic Aβ peptides and is expected to counteract the development of AD. An established approach for the up-regulation of α-secretase cleavage is the activation of G protein-coupled receptors (GPCRs). Therefore, our study aimed to analyze whether stimulation of angiotensin AT₁ or AT₂ receptors stably expressed in HEK cells influence the nonamyloidogenic pathway of APP processing. Treatment of both receptors with angiotensin II clearly showed that only activation of the AT₁ receptor increased several fold the α-secretase-mediated shedding of APP. This effect was completely abolished by treatment with the AT₁ receptor-specific antagonist telmisartan. Using the BIM-46187 inhibitor, we demonstrate that the Gαq protein-mediated pathway is involved in this stimulation process. Stimulation of AT₁ receptors with the β-arrestin-biased agonist SII was ineffective regarding α-secretase-mediated APP shedding. This result discloses that only the G protein-dependent pathway is involved in the Ang II-induced APP shedding. Blocking of Gβγ subunits by the inhibitor gallein completely prevented constitutive and Ang II-induced APP shedding. Our findings provide evidence that induction of APP shedding via Ang II/AT₁ receptor stimulation is effected by G protein activation with Gβγ subunits playing important roles.

Angiotensin II type 1 receptor antagonists in animal models of vascular, cardiac, metabolic and renal disease

We have reviewed the effects of angiotensin II type 1 receptor antagonists (ARBs) in various animal models of hypertension, atherosclerosis, cardiac function, hypertrophy and fibrosis, glucose and lipid metabolism, and renal function and morphology. Those of azilsartan and telmisartan have been included comprehensively whereas those of other ARBs have been included systematically but without intention of completeness. ARBs as a class lower blood pressure in established hypertension and prevent hypertension development in all applicable animal models except those with a markedly suppressed renin-angiotensin system; blood pressure lowering even persists for a considerable time after discontinuation of treatment. This translates into a reduced mortality, particularly in models exhibiting marked hypertension. The retrieved data on vascular, cardiac and renal function and morphology as well as on glucose and lipid metabolism are discussed to address three main questions: 1. Can ARB effects on blood vessels, heart, kidney and metabolic function be explained by blood pressure lowering alone or are they additionally directly related to blockade of the renin-angiotensin system? 2. Are they shared by other inhibitors of the renin-angiotensin system, e.g. angiotensin converting enzyme inhibitors? 3. Are some effects specific for one or more compounds within the ARB class? Taken together these data profile ARBs as a drug class with unique properties that have beneficial effects far beyond those on blood pressure reduction and, in some cases distinct from those of angiotensin converting enzyme inhibitors. The clinical relevance of angiotensin receptor-independent effects of some ARBs remains to be determined.

Therapeutic interventions using a combination of Telmisartan and omega 3-fatty acids in sodium arsenite-induced vascular endothelial dysfunction in rats: modulation through ATP-sensitive K+ channels and eNOS

BACKGROUND

Effective diet/drug combinations may show additive or synergistic effects in reducing endothelial risk factors vis-à-vis monotherapies. The study evaluated the effect of combined therapy of Telmisartan and omega 3-fatty acids in sodium arsenite-induced vascular endothelial dysfunction (VED) in rats.

METHODS

Forty-eight male Wistar rats (180-220 g) were randomized into eight groups; control, sodium arsenite (1.5 mg/kg/day) exposed, sodium arsenite exposure followed by treatment with Telmisartan, omega 3-fatty acids, the combination and/or endothelial modulators for 2 weeks depending on the allocated group. VED was assessed by estimating vascular reactivity. Serum thiobarbituric acid-reactive substances (TBARS), nitrite/nitrate levels, reduced glutathione (GSH) levels, superoxide dismutase (SOD) activity, serum cholesterol and triglyceride levels were also determined.

RESULTS

Sodium arsenite produced VED by attenuating acetylcholine-induced endothelial relaxation (% Rmax= 45.36), decreasing levels of serum nitrite/nitrate (9.28 μM/mg protein), GSH (16.06 μg/mg of protein), SOD activity (30.69 units/mg protein) and increasing TBARS (0.19 µM/mg protein) compared with control group. The combined therapy with Telmisartan (10 mg/kg/day) and omega 3-fatty acids (180 mg/kg/day) (% Rmax = 80.93, 13.09 µM/mg protein, 25.93 μg/mg of protein, 57.84 units/mg protein and 0.08 µM/mg protein, respectively) significantly abolished the respective derangements induced by sodium arsenite. Further, this combination significantly prevented rise in serum cholesterol and triglyceride levels that was induced by sodium arsenite. However, the ameliorative effects of this combination were abated by N-omega-nitro-L-arginine methyl ester (L-NAME) and glibenclamide.

CONCLUSIONS

Combined therapy of Telmisartan and omega 3-fatty acids attenuated VED, by activating enzyme nitric oxide synthase (eNOS) through opening of ATP-sensitive K(+) channels.

Characterization of 12 GnRH peptide agonists - a kinetic perspective

BACKGROUND AND PURPOSE

Drug-target residence time is an important, yet often overlooked, parameter in drug discovery. Multiple studies have proposed an increased residence time to be beneficial for improved drug efficacy and/or longer duration of action. Currently, there are many drugs on the market targeting the gonadotropin-releasing hormone (GnRH) receptor for the treatment of hormone-dependent diseases. Surprisingly, the kinetic receptor-binding parameters of these analogues have not yet been reported. Therefore, this project focused on determining the receptor-binding kinetics of 12 GnRH peptide agonists, including many marketed drugs.

EXPERIMENTAL APPROACH

A novel radioligand-binding competition association assay was developed and optimized for the human GnRH receptor with the use of a radiolabelled peptide agonist, [(125) I]-triptorelin. In addition to radioligand-binding studies, a homogeneous time-resolved FRET Tag-lite™ method was developed as an alternative assay for the same purpose.

KEY RESULTS

Two novel competition association assays were successfully developed and applied to determine the kinetic receptor-binding characteristics of 12 high-affinity GnRH peptide agonists. Results obtained from both methods were highly correlated. Interestingly, the binding kinetics of the peptide agonists were more divergent than their affinities with residence times ranging from 5.6 min (goserelin) to 125 min (deslorelin).

CONCLUSIONS AND IMPLICATIONS

Our research provides new insights by incorporating kinetic, next to equilibrium, binding parameters in current research and development that can potentially improve future drug discovery targeting the GnRH receptor.

Protective effect of telmisartan on neurovascular unit and inflammasome in stroke-resistant spontaneously hypertensive rats

OBJECTIVES

Hypertension is a crucial risk factor for both stroke and dementia, including Alzheimer's disease (AD). We inspected the effect of telmisartan on the neurovascular unit (NVU) and related inflammatory responses in spontaneously hypertensive rat stroke resistant (SHR-SR) by observing the components of NVU such as N-acetyl glucosamine oligomer (NAGO), collagen IV, astrocytes, and matrix metalloproteinase-9 (MMP-9), as well as inflammasome NOD-like receptors family protein 3 (NLRP3).

METHODS

In the present study, we examined the effect of a highly selective angiotensin type 1 (AT-1) antagonist of angiotensin 2 receptor with high lipid solubility, telmisartan, on NVU and related inflammatory responses in SHR-SR with a low dose (0.3 mg/kg/day) only for improving metabolic syndrome, and a high dose (3 mg/kg/day) for improving both metabolic syndrome and SHR-SR hypertension.

RESULTS

Compared to normotensive Wistar rats, long-lasting hypertension in SHR-SR disrupted NVU by changing immunohistological components such as NAGO, collagen IV, astrocytes, and MMP-9. SHR-SR also strongly induced AD-related inflammasome NLRP3 in neuronal cells with age. However, such NVU disruption and inflammasome activation were greatly improved with dose-dependent telmisartan treatments.

DISCUSSION

These results suggest that telmisartan comprehensively protected the NVU components by reducing inflammatory reactions relative to AD in hypertensive rats, which could also preclude the risk of AD under hypertension.

Neurovascular protection by telmisartan via reducing neuroinflammation in stroke-resistant spontaneously hypertensive rat brain after ischemic stroke

Telmisartan is a highly lipid-soluble angiotensin receptor blocker (ARB), which improves insulin sensitivity and reduces triglyceride levels and, thus, is called metabo-sartan. We examined the effects of telmisartan on neurovascular unit (N-acetylglucosamine oligomer [NAGO], collagen IV, and glial fibrillary acidic protein [GFAP]) and neuroinflammation (matrix metalloproteinase-9 [MMP-9] and inflammasome) in brain of stroke-resistant spontaneously hypertensive rat (SHR-SR). At 12 weeks of age, SHR-SR received transient middle cerebral artery occlusion (tMCAO) for 90 minutes and were divided into the following 3 groups, that is, vehicle group, low-dose telmisartan group (.3 mg/kg/d), and high-dose telmisartan group (3 mg/kg/d, postoral). Immunohistologic analysis at ages 6, 12, and 18 months showed progressive decreases of NAGO-positive endothelium and collagen IV-positive basement membrane and progressive increases of MMP-9-positive neurons, GFAP-positive astrocytes, and NLRP3-positive inflammasome in the cerebral cortex of vehicle group. Low-dose telmisartan reduced such changes without lowering blood pressure (BP), and high-dose telmisartan further improved such changes with lowering BP. The present findings suggest that a persistent hypertension caused a long-lasting inflammation after tMCAO in SHR-SR, which accelerated neurovascular disruption and emergent inflammasome, and that telmisartan greatly reduced such inflammation and protected the neurovascular unit via its pleiotropic effects in living hypertensive rat brain after ischemic stroke.

Telmisartan ameliorates inflammatory responses in SHR-SR after tMCAO

Telmisartan, an angiotensin receptor blocker with high lipid solubility, also called metabo-sartan, not only reduces blood pressure (BP), but also ameliorates inflammation in the cerebral cortex and in adipose tissue. We examined the effects of telmisartan on inflammatory responses of monocyte chemotactic protein-1, tumor necrosis factor-α, and ionized calcium-binding adapter molecule 1 in the brain of spontaneously hypertensive rat stroke-resistant (SHR-SR) after transient middle cerebral artery occlusion (tMCAO). At 12 weeks of age, SHR-SR received tMCAO for 90 minutes and were divided into 3 groups, that is, the vehicle group, a low-dose telmisartan group (.3 mg/kg/day), and a high-dose telmisartan group (3 mg/kg/day). Immunohistological analysis was performed when rats became 6, 12 and 18 months old. Monocyte chemotactic protein-1, tumor necrosis factor-α, and ionized calcium-binding adapter molecule 1 cells (/mm(2)) immunoreactivities increased with age in the cerebral cortex and hippocampus of the vehicle group, suggesting strong and persistent inflammatory changes in SHR-SR after tMCAO up to 18 months of age. On the other hand, a low dose of telmisartan significantly reduced such inflammatory changes without lowering BP, whereas a high dose of telmisartan showed a few additional improvements, including the lowering of BP throughout 6-18 months of age. The present study suggests that persistent hypertension after tMCAO caused a long-lasting inflammatory response in the SHR-SR brain, and that even a low dose of telmisartan reduced continuous inflammation without lowering BP via its pleiotropic effects in the SHR-SR brain. A high dose of telmisartan had a few additional benefits, including lowering BP.

Comparative review of the blood pressure-lowering and cardiovascular benefits of telmisartan and perindopril

Hypertension is a major cardiovascular (CV) risk factor, and blood pressure (BP)-lowering treatment substantially reduces the risk. This review compares the available clinical evidence from the BP-lowering and CV-outcome studies of telmisartan and perindopril, which are among the most intensively studied members of their respective classes. The PubMed database was searched for telmisartan and perindopril publications meeting the following criteria: 1) head-to-head comparison trials for BP lowering; and 2) CV-outcome studies (ie, ones with a CV event, mortality, or hospitalization outcome) in patients with CV risk factors but without heart failure. In comparative trials, telmisartan treatment resulted in significantly higher reduction in trough BP and mean ambulatory diastolic BP for the last 8 hours of the dosing interval compared with perindopril. In mainly placebo-controlled CV-outcome studies in patients with hypertension, CV benefits with perindopril were associated with large reductions in BP. There were no CV outcome studies with telmisartan in patients with hypertension. The beyond-BP-lowering CV-protective benefits of telmisartan were demonstrated in the active-controlled ONTARGET (ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial) trial, which included patients with controlled BP at baseline. In general, the trials discussed in this review reinforce the fact that perindopril and telmisartan are two long-acting antihypertensive drugs that reduce BP over 24 hours, and are the best-evidenced drugs in their class with proven CV protection. It is also clear that the benefits are not a “class effect”, and vary between the different drugs within each class. Hence, the best approach for treatments tailored to individual patient needs should be evidence-based specific drugs, rather than a drug-class recommendation for achieving therapeutic targets.

Protective effect of telmisartan against progressive oxidative brain damage and synuclein phosphorylation in stroke-resistant spontaneously hypertensive rats

Previously, we reported that reactive oxygen species and signaling molecules of angiotensin II produced lipid peroxides, degenerated proteins, and injured DNA after cerebral ischemia in normotensive Wistar rats. Here, we investigated the long-term effect of the angiotensin II type I receptor blocker telmisartan on oxidative stress and hyperphosphorylated α-synuclein accumulation in stroke-resistant spontaneously hypertensive rats (SHR-SR). At the age of 3 months, SHR-SR were divided into 3 treatment groups: SHR-SR vehicle (SHR/Ve), SHR-SR low-dose telmisartan (.3 mg/kg/day) (SHR/low), and SHR-SR high-dose telmisartan (3 mg/kg/day) (SHR/high). Immunohistologic analyses were conducted in these groups and Wistar rats at the age of 6, 12, and 18 months. The SHR/Ve group demonstrated more progressive increase in advanced glycation end product (AGE)-, 4-hydroxy-2-nonenal (4-HNE)-, and phosphorylated α-synuclein (pSyn)-positive cells in the cerebral cortex and hippocampus compared with the Wistar group at 18 months. These expressions were reduced in the SHR/low group even without lowering blood pressure (BP), and expressions were dramatically suppressed in the SHR/high group with lowering of BP. These data suggest that persistent hypertension in SHR-SR strongly potentiate the markers of oxidative damage (AGEs and 4-HNE) and abnormal accumulation of pSyn, which were greatly suppressed by telmisartan in a dose-dependent manner without and with lowering of BP.

Pharmacokinetic-pharmacodynamic model of the antihypertensive interaction between telmisartan and hydrochlorothiazide in spontaneously hypertensive rats

OBJECTIVES

The goal of this study was to establish an integrated indirect response pharmacokinetic-pharmacodynamic model between telmisartan and hydrochlorothiazide to describe the antihypertensive interaction of these two drugs in spontaneously hypertensive rats.

METHODS

The blood pressure and plasma concentrations were measured by the tail-cuff test and high performance liquid chromatography-mass spectrometry, respectively, in spontaneously hypertensive rats. The current pharmacokinetic-pharmacodynamic model was based on the non-competitive pharmacodynamic interaction of two drugs acting on different physiological processes.

KEY FINDINGS

This model was able to acquire the temporal changes in drug concentration and blood pressure after administration of telmisartan or hydrochlorothiazide. The noncompetitive pharmacodynamic interaction assumed that the decreased blood pressure was attributed to the inhibitory function of telmisartan and stimulatory function of hydrochlorothiazide after administration of these two drugs. There was no significant pharmacokinetic change of telmisartan and hydrochlorothiazide in the different groups tested. The model predicted a synergistic pharmacodynamic interaction when telmisartan was administered in combination with hydrochlorothiazide, which was notably stronger than if the effects were additive.

CONCLUSION

The results showed that the presented pharmacokinetic-pharmacodynamic model was suitable for describing the antihypertensive interaction between telmisartan and hydrochlorothiazide.

Telmisartan/hydrochlorothiazide: a new fixed dose combination

Many patients with hypertension require two or more antihypertensive drugs with complementary mechanisms of action to lower their blood pressure and attain the therapeutic goals specified in internationally accepted guidelines. Yet, these latter guidelines offer the choice of fixed dose combinations as possible first-step therapies. The angiotensin II type 1-receptor antagonist telmisartan and the diuretic hydrochlorothiazide are two antihypertensive agents that have a well-recognized clinical efficacy. Their combination was shown in randomized, controlled trials to be more effective than each agent alone in lowering blood pressure, due to a dual and synergistic mechanism. Indeed, combining telmisartan with hydrochlorothiazide enhances the antihypertensive efficacy of telmisartan in almost two-thirds of hypertensive patients with mild-to-moderate hypertension. The pharmacokinetics and -dynamics of the combination are similar to monotherapy, and the addition of hydrochlorothiazide to telmisartan does not modify the excellent tolerability profile of the drug.

A systematic comparison of the properties of clinically used angiotensin II type 1 receptor antagonists

Angiotensin II type 1 receptor antagonists (ARBs) have become an important drug class in the treatment of hypertension and heart failure and the protection from diabetic nephropathy. Eight ARBs are clinically available [azilsartan, candesartan, eprosartan, irbesartan, losartan, olmesartan, telmisartan, valsartan]. Azilsartan (in some countries), candesartan, and olmesartan are orally administered as prodrugs, whereas the blocking action of some is mediated through active metabolites. On the basis of their chemical structures, ARBs use different binding pockets in the receptor, which are associated with differences in dissociation times and, in most cases, apparently insurmountable antagonism. The physicochemical differences between ARBs also manifest in different tissue penetration, including passage through the blood-brain barrier. Differences in binding mode and tissue penetration are also associated with differences in pharmacokinetic profile, particularly duration of action. Although generally highly specific for angiotensin II type 1 receptors, some ARBs, particularly telmisartan, are partial agonists at peroxisome proliferator-activated receptor-γ. All of these properties are comprehensively reviewed in this article. Although there is general consensus that a continuous receptor blockade over a 24-hour period is desirable, the clinical relevance of other pharmacological differences between individual ARBs remains to be assessed.

Telmisartan modulates mitochondrial function in vascular smooth muscle cells

The development of atherosclerosis is associated with disturbances in mitochondrial function that impair effective adenosine triphosphate (ATP) production, increase generation of superoxide and induce subsequent apoptosis in vascular smooth muscle cells (VSMCs). As peroxisome proliferator-activated receptor gamma (PPARγ) has a potentially important role in the regulation of mitochondrial metabolism, we studied effects of the partial PPARγ agonist and angiotensin receptor blocker telmisartan, on mitochondria-related cellular responses in VSMC. In human VSMC, telmisartan increased ATP levels and activation of mitochondrial complex II, succinate dehydrogenase, reduced the release of H2O2 and attenuated H2O2-induced increases in caspase 3/7 activity, a marker of cellular apoptosis. Eprosartan, an angiotensin II receptor blocker that lacks the ability to activate PPARγ, had no effect on these mitochondria-related cellular responses in VSMC. Studies in PPARγ-deficient VSMC revealed that the effects of telmisartan on mitochondrial function were largely independent of PPARγ although the presence of PPARγ modulated effects of telmisartan on H2O2 levels. These findings demonstrate that telmisartan can have significant effects on mitochondrial metabolism in VSMC that are potentially relevant to the pathogenesis of cardiovascular disease and that involve more than just angiotensin receptor blockade and activation of PPARγ.

Telmisartan: from lowering blood pressure to end-organ protection

The principal aim in the treatment of patients with high blood pressure is to ensure a maximum reduction in the total risk of cardiovascular morbidity and mortality. The renin-angiotensin system plays an important role in volume homeostasis and blood pressure regulation. The angiotensin receptor blockers control high blood pressure by preventing the binding of angiotensin II to the subtype 1 receptor, which is believed to mediate most of the physiologic actions of angiotensin II relevant to the regulation of blood pressure. Telmisartan is a widely used angiotensin receptor blocker with distinct pharmacokinetic and pharmacodynamic properties. Due to its long duration of action, it compares favorably with other angiotensin receptor blockers. Latest data from clinical trials and newest research regarding telmisartan will be reviewed in this article.

Telmisartan for the reduction of cardiovascular morbidity and mortality

Cardiovascular disease (CVD) poses a significant healthcare and economic burden on societies and individuals. Angiotensin II is a key component of the renin-angiotensin system that plays a central role in atherosclerotic mechanisms that contribute to CVD. Renin-angiotensin system blockers are widely used to reduce cardiovascular (CV) risk owing to their potential both to lower blood pressure, a CV risk factor, and to attenuate the atherosclerotic disease process directly. Telmisartan has a number of pharmacological properties that distinguish it from other angiotensin II receptor blockers (ARBs) - the longest plasma half-life, highest lipophilicity and strongest receptor binding affinity in class. The ONTARGET(®) trial showed that telmisartan is as effective as ramipril in reducing CV morbidity (including myocardial infarction and stroke) and mortality in a broad range of patients at increased CV risk. Evidence from other ARBs remains largely restricted to patients with heart failure, diabetic nephropathy or specific subsets of hypertensive patients. Telmisartan is, therefore, the only ARB with a broad indication for CV risk reduction in patients with atherothrombotic disease or diabetes with end-organ damage.

Telmisartan protects against cognitive decline via up-regulation of brain-derived neurotrophic factor/tropomyosin-related kinase B in hippocampus of hypertensive rats

BACKGROUND AND PURPOSE

Cognitive decline may occur as a result of hypertension, and is dependent on the function of hippocampus. Brain-derived neurotrophic factor (BDNF) mediated by angiotensin II-induced oxidative stress protects against cell death in hippocampus. Angiotensin II receptor blocker (ARB), candesartan, activates BDNF in the hippocampus. Furthermore, peroxisome proliferator-activated receptor (PPAR)-gamma activation in the brain prevents brain damage. Telmisartan, a unique ARB with PPAR-gamma stimulating activity, protects against cognitive decline partly because of PPAR-gamma activation. The aim of the present study was to determine whether telmisartan protects against cognitive decline via up-regulation of BDNF and its receptor tropomyosin-related kinase B (TrkB) in the hippocampus of hypertensive rats, partly because of PPAR-gamma activation.

METHODS AND RESULTS

We divided stroke-prone spontaneously hypertensive rats (SHRSPs), as hypertensive and vascular dementia model rats, into five groups, telmisartan-treated (TLM), TLM+GW9662, a PPAR-gamma inhibitor, -treated (T+G), GW9662-treated (GW), TLM+ANA-12, a TrkB antagonist, -treated (T+A), and vehicle-treated SHRSPs (VEH). After the treatment for 28 days, systolic blood pressure did not change in all groups. However, BDNF expression in the hippocampus was significantly higher in TLM than in VEH to a greater extent than in T+G. Cognitive performance was significantly higher in TLM than in VEH to a greater extent than in T+G, and was not different between T+A, GW, and VEH.

CONCLUSION

Telmisartan protects against cognitive decline via up-regulation of BDNF/TrkB in the hippocampus of SHRSPs, partly because of PPAR-gamma activation independent of blood pressure-lowering effect.

Telmisartan or valsartan alone or in combination with hydrochlorothiazide: a review

The aim of this review was to compare telmisartan and valsartan in the treatment of hypertension. PubMed searches were conducted to identify randomized trials (n = 14) comparing the two agents, alone or combined with hydrochlorothiazide. With one exception, all studies with blood pressure reduction as primary endpoint showed significantly greater reductions with telmisartan than with valsartan. Other studies showed that telmisartan was associated with greater improvements in metabolic measures and inflammatory markers than valsartan. These findings suggest that pharmacologic differences between telmisartan and valsartan may translate into clinically relevant differences between the two drugs in the management of hypertension.

Efficacy of renin-angiotensin system (RAS) blockers on cardiovascular and renal outcomes in patients with type 2 diabetes

Cardiovascular disease is the predominant cause of morbidity in people with type 2 diabetes. Hypertension frequently coexists with diabetes and substantially increases the risk of developing end-organ damage. Controlling hypertension in patients with diabetes is therefore critical to reducing microvascular and macrovascular complications. Agents that block the renin-angiotensin system are increasingly used in patients with diabetes based on their cardiovascular and renoprotective effects, in addition to their direct effects on reducing blood pressure. Telmisartan, an angiotensin II receptor blocker (ARB), has a number of distinguishing pharmacological properties such as having the longest half-life and highest lipophilicity in its class. The ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET(®)) trial showed that telmisartan reduces cardiovascular morbidity (including myocardial infarction and stroke) in subjects with a broad spectrum of cardiovascular risk factors, including type 2 diabetes. Telmisartan is the only ARB indicated for the reduction of cardiovascular morbidity in patients with diabetes and end-organ damage, as well as in patients without diabetes but with a history of coronary artery disease, peripheral artery disease, or previous stroke. Trials of telmisartan in patients with diabetes and varying degrees of nephropathy also suggest that this drug can slow the progression of renal disease, an effect that appears to be at least partly independent of reduction in blood pressure. Telmisartan is therefore an important therapeutic option for optimizing cardiovascular and renal protection in the type 2 diabetic population.

Activation of AMPK-Sirt1 pathway by telmisartan in white adipose tissue: A possible link to anti-metabolic effects

Telmisartan exerts anti-metabolic effects beyond its angiotensin receptor blockade activities, but the mechanisms have hitherto remained elusive. We sought to elucidate the peroxisome proliferator-activated receptor-γ (PPAR-γ)-dependent and PPAR-γ-independent mechanisms underlying the anti-metabolic effects of telmisartan in white adipose tissue. Nine-week-old male C57BL/6 mice were fed with a 60% high-fat diet for 6 weeks, with 1mg/kg telmisartan or vehicle administrated orally during the last 3 weeks. 3T3-L1 adipocytes were cultured with telmisartan either with 2-chloro-5-nitro-N-phenylbenzamide (GW9662), a selective irreversible antagonist of PPAR-γ, or compound C, an ATP-competitive inhibitor of AMPK. Western blotting and semiquantitative RT-PCR analysis were used to assess adiponectin, Sirt1, and AMPK levels. Lipid accumulation was assessed by Oil red O staining. The activation of transcription factor PPAR-γ2 was evaluated by using a luciferase reporter assay for mPPAR-γ2 expression plasmid vector. Treatment with telmisartan increased serum adiponectin levels in high-fat diet-fed mice concomitantly with an upregulation of adiponectin mRNA in visceral adipose tissue. In vitro telmisartan treatment dose-dependently increased adiponectin mRNA in 3T3-L1 cells; the increase was inhibited by compound C, but not by GW9662. Telmisartan increased expression of Sirt1 mRNA and Sirt1 protein as well as the phosphorylation of AMPK in 3T3-L1 cells. Telmisartan can increase adiponectin production in white adipose tissue partly via a PPAR-γ2-independent mechanism. Precise understanding of this molecular mechanism will require further investigation.

Telmisartan for the management of patients at high cardiovascular risk

BACKGROUND

Cardiovascular disease (CVD) places a significant burden on healthcare providers. High blood pressure (BP) is the single most prevalent risk factor for CVD worldwide and is responsible for more deaths than any other risk factor. 'Cardiovascular (CV) high-risk patients' make up the broad cross-section of patients in the middle of the risk spectrum for CVD progression that is referred to as the CV continuum and includes those with atherothrombotic disease, those with target organ damage associated with type 2 diabetes and those with multiple risk factors. Angiotensin II is involved in CVD progression at every stage of the CV continuum, making the renin-angiotensin system a rational target for pharmacologic intervention. Angiotensin II receptor blockers (ARBs) offer a better tolerated alternative to angiotensin converting enzyme inhibitors, with greater long-term adherence. The ARB telmisartan recently received an indication for CV prevention.

SCOPE

A PubMed literature search was conducted to identify evidence on the use of telmisartan for preventing CV events.

FINDINGS

Telmisartan has a favourable safety and tolerability profile, and has demonstrated efficacious and long-lasting 24-hour BP reductions, whether as monotherapy or in combination with hydrochlorothiazide or amlodipine. In the largest CV prevention trial program undertaken with an ARB (the ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial; ONTARGET), telmisartan 80 mg/day alone was as effective as ramipril in reducing the composite primary endpoint of CV mortality, non-fatal myocardial infarction, non-fatal stroke and hospitalization for heart failure in CV high-risk patients. However, patients were significantly more likely to adhere to treatment with telmisartan than ramipril due to its better tolerability.

CONCLUSION

To date, telmisartan is the only ARB indicated to reduce CV morbidity in a broad CV high-risk population.

GSK1562590, a slowly dissociating urotensin-II receptor antagonist, exhibits prolonged pharmacodynamic activity ex vivo

BACKGROUND AND PURPOSE

Recently identified antagonists of the urotensin-II (U-II) receptor (UT) are of limited utility for investigating the (patho)physiological role of U-II due to poor potency and limited selectivity and/or intrinsic activity.

EXPERIMENTAL APPROACH

The pharmacological properties of two novel UT antagonists, GSK1440115 and GSK1562590, were compared using multiple bioassays.

KEY RESULTS

GSK1440115 (pK(i)= 7.34-8.64 across species) and GSK1562590 (pK(i)= 9.14-9.66 across species) are high affinity ligands of mammalian recombinant (mouse, rat, cat, monkey, human) and native (SJRH30 cells) UT. Both compounds exhibited >100-fold selectivity for UT versus 87 distinct mammalian GPCR, enzyme, ion channel and neurotransmitter uptake targets. GSK1440115 showed competitive antagonism at UT in arteries from all species tested (pA(2)= 5.59-7.71). In contrast, GSK1562590 was an insurmountable UT antagonist in rat, cat and hUT transgenic mouse arteries (pK(b)= 8.93-10.12 across species), but a competitive antagonist in monkey arteries (pK(b)= 8.87-8.93). Likewise, GSK1562590 inhibited the hU-II-induced systemic pressor response in anaesthetized cats at a dose 10-fold lower than that of GSK1440115. The antagonistic effects of GSK1440115, but not GSK1562590, could be reversed by washout in rat isolated aorta. In ex vivo studies, GSK1562590 inhibited hU-II-induced contraction of rat aorta for at least 24 h following dosing. Dissociation of GSK1562590 binding was considerably slower at rat than monkey UT.

CONCLUSIONS AND IMPLICATIONS

Whereas both GSK1440115 and GSK1562590 represent high-affinity/selective UT antagonists suitable for assessing the (patho)physiological role of U-II, only GSK1562590 exhibited sustained UT residence time and improved preclinical efficacy in vivo.

Telmisartan: a different angiotensin II receptor blocker protecting a different population?

The ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET()) showed that the angiotensin II receptor blocker (ARB) telmisartan was as protective as the reference-standard ramipril in a broad cross-section of patients at increased cardiovascular risk, but was better tolerated. Telmisartan has a unique profile among ARBs, with a high affinity for the angiotensin II type 1 receptor, a long duration of receptor binding, a high lipophilicity and a long plasma half life. This leads to sustained and powerful blood pressure lowering when compared with the first marketed ARBs, such as losartan and valsartan. Some pharmacological properties of telmisartan clearly distinguish it from other members of the ARB class and may contribute to the clinical effects seen with telmisartan. A class effect for ARBs cannot be assumed. To date, telmisartan is the only ARB that has been shown to reduce cardiovascular risk in at-risk cardiovascular patients.

Neuroendocrine characterization and anorexigenic effects of telmisartan in diet- and glitazone-induced weight gain

Telmisartan is an angiotensin II receptor blocker with peroxisome proliferator-activated receptor-gamma agonistic properties. Telmisartan prevents weight gain and decreases food intake in models of obesity and in glitazone-treated rodents. This study further investigates the influence of telmisartan and pioglitazone and their association on weight gain and body composition by examining their influence on neuroendocrine mediators involved in food intake. Male C57/Black 6 mice were fed a high-fat diet, weight matched, and randomized in 4 treatment groups: vehicle, pioglitazone, telmisartan, and pioglitazone-telmisartan. Weight gain, food and water intake, body composition, plasma leptin levels, and the hypothalamic expression of neuroendocrine mediators were analyzed. Additional studies were performed with irbesartan and in angiotensin II 1(A) receptor-knockout mice. Telmisartan abolished weight and fat gain in vehicle- and pioglitazone-treated mice while decreasing food intake, the hypothalamic expression of the agouti-related protein, and plasma leptin levels. Modifications in neuropeptide Y and proopiomelanocortin were not consistent with changes in food intake. The effects on weight gain and expression of the agouti-related protein were intermediate with irbesartan. The effects of telmisartan on weight gain were even more pronounced in angiotensin II 1(A) receptor-knockout mice. This study confirms the anorexigenic effects of telmisartan in mice fed a high-fat diet and suggests for the first time a functional role of telmisartan on hypothalamic orexigenic agouti-related protein regulation. These anorexigenic properties abolish both weight gain and body composition modifications in fat-fed and glitazone-treated mice. The anorexigenic properties are independent from the angiotensin II 1(A) receptor.

AT(1) receptor blockers increase insulin-like growth factor-I production by stimulating sensory neurons in spontaneously hypertensive rats

Insulin-like growth factor-I (IGF-I) is an important cardioprotective substance. We previously reported that sensory neuron stimulation increases IGF-I production by releasing calcitonin gene-related peptide (CGRP) in spontaneously hypertensive rats (SHRs). Because angiotensin II (Ang II) inhibits sensory neuron activation by interacting with Ang II type 1 (AT(1)) receptors, it is possible that AT(1) receptor blockers (ARBs) increase IGF-I production in SHRs. We examined this possibility in the current study, using the ARBs olmesartan, valsartan, losartan, and telmisartan. Plasma, renal, and cardiac levels of CGRP and IGF-I in SHRs were significantly lower than those in normotensive Wistar Kyoto rats (WKYs) (P < 0.01), which increased to levels found in WKYs after the administration of ARBs. These ARB-induced increases in SHRs were completely reversed by pretreatment with capsazepine (CPZ), which is a specific vanilloid receptor-1 (VR-1) antagonist. The mean arterial blood pressure (MABP) was decreased after administration of ARBs in SHRs, and those decreases were reversed by pretreatment with CPZ. The administration of nifedipine decreased MABP but did not increase CGRP or IGF-I levels in SHRs. Baseline CGRP release and cellular cyclic adenosine 3',5'-monophosphate (cAMP) levels in dorsal root ganglion neurons (DRG) isolated from SHRs were significantly lower than those in DRG isolated from WKYs (P < 0.01). Although ARBs reversed decreases in CGRP release and cAMP levels in the presence of Ang II in DRG isolated from WKYs, they increased CGRP release and cAMP levels in the absence of Ang II in DRG isolated from SHRs. Cellular levels of Ang II were not detected in DRG isolated from WKYs or SHRs, but messenger RNA (mRNA) levels for angiotensin-converting enzyme in DRG were significantly higher in SHRs than in WKYs (P < 0.01). The expression of AT(1) receptors in DRG was not different between WKYs and SHRs. Thus, it is likely that decreases in CGRP release and cAMP levels in DRG isolated from SHRs are mainly caused by AT(1) receptor activation by Ang II through an autocrine mechanism. These observations suggest that ARBs might increase CGRP release from sensory neurons by sensitizing VR-1 activation through increases in cAMP levels, which thereby increased the production of IGF-I in SHRs. These activities of ARBs might at least partly explain their therapeutic effects in areas such as improving insulin resistance in patients with diabetes and hypertension.

Relative Effects of Telmisartan, Candesartan and Losartan on Alleviating Arterial Stiffness in Patients with Hypertension Complicated by Diabetes Mellitus: An Evaluation Using the Cardio-Ankle Vascular Index (CAVI)

Using the cardio-ankle vascular index (CAVI) as an indicator, we assessed improvement of arterial stiffness in 95 outpatients with hypertension complicated by type 2 diabetes mellitus who were treated orally for ≤ 12 months with telmisartan 40 mg/day, losartan 50 mg/day or candesartan 8 mg/day. At 1 year, in the telmisartan and losartan groups CAVI did not change whereas in the candesartan group CAVI showed a statistically significant decrease of 2.70%. Although telmisartan is believed to enhance the activity of peroxisome proliferator-activated receptor (PPAR-γ) in vitro, it did not ameliorate arterial stiffness in our patients. Candesartan, however, improved arterial stiffness independently of blood pressure lowering and without PPAR-γ agonist action, possibly by direct action resulting from its potent affinity and binding capacity for the angiotensin II type 1 receptor. We conclude that candesartan is a potentially useful therapy against arterial stiffness in hypertensive patients with type 2 diabetes mellitus.

Residence time of receptor-ligand complexes and its effect on biological function

The formation and duration of binary receptor-ligand complexes are fundamental to many physiologic processes. Most often, the effectiveness of interaction between a receptor and its ligand is quantified in terms of closed system, equilibrium affinity measurements, such as IC50 and Kd. In the context of in vivo biology, however, the extent and duration of responses to receptor-ligand interactions depend greatly on the time period over which the ligand is in residence on its receptor. Here we define receptor-ligand complex residence time in quantitative terms and describe its significance to biological function. Examples of the importance of residence time are presented for natural ligands of different receptor types. The impact of residence time on the optimization of potential ligands as drugs for human medicine is also described.

Cardiovascular reactivity after blockade of angiotensin AT1 receptors in the experimental model of tilting test in conscious rats

BACKGROUND AND PURPOSE

Studies have shown that the angiotensin II AT(1) receptor antagonist, losartan, accentuates the hypotensive response in the orthostatic stress test (tilt) performed in anaesthetized rats. The same effect was not reported with other AT(1) antagonists. The aim of this study was to re-evaluate the effects of AT(1) receptor blockade on the cardiovascular response to tilt in a model developed for conscious rats.

EXPERIMENTAL APPROACH

Rats (n=5-7 per group) were instrumented for infusion of drugs and recording of cardiovascular parameters and, after recovery, placed in a plastic tube positioned over the tilt board. The tilt test was conducted by raising the head side of the tilt board from horizontal position to 75 degrees head up position for 15 min.

KEY RESULTS

Compared with control group (NaCl 0.9%, 1 ml kg(-1)), oral treatment with 1 mg kg(-1) per day of losartan or telmisartan did not alter the blood pressure response during tilt. With the 10 mg kg(-1) dose, both antagonists altered the blood pressure response during tilt (mean maximum changes -11+/-3 mm Hg; P<0.01). A post-tilt hypotension was observed with both doses in losartan and telmisartan groups (-13+/-1 and -9+/-2 mm Hg, respectively; P<0.01).

CONCLUSIONS AND IMPLICATIONS

The present results indicate that the effect of losartan on the cardiovascular reactivity to tilt shares a similar profile to that of other AT(1) antagonists. Evidence discussed addresses the importance of using a conscious model for testing the influence of antihypertensive drugs on the cardiovascular reactivity to orthostatic challenges.

Rationale for combination angiotensin receptor blocker and angiotensin-converting enzyme inhibitor treatment and end-organ protection in patients with chronic kidney disease

Chronic kidney disease (CKD) is a major public health problem that has received increasing attention because of the high rate of associated cardiovascular morbidity and mortality. Mounting evidence indicates that angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), drugs that inhibit the renin-angiotensin-aldosterone system (RAAS) safely slow down progression of CKD. There is also growing evidence supporting combination treatment of nephropathies with an ACE inhibitor plus an ARB to more completely block the RAAS and provide greater renoprotection than either an ACE inhibitor-based or ARB-based regimen. The National Kidney Foundation suggests that ACE inhibitors and ARBs may be used in combination to reduce proteinuria in patients with kidney disease; however, larger outcomes trials are needed.

Pharmacoeconomics and quality of life analysis of telmisartan in hypertension treatment

Hypertension is a major public health problem, being one of the leading causes of death and disability worldwide and a major risk factor for cardiovascular disease. The renin-angiotensin-aldosterone system plays an important role in volume homeostasis and blood pressure regulation, and is a target for several groups of pharmaceutical agents. Telmisartan, a highly selective AT1 receptor antagonist, fulfills all new criteria for antihypertensive agents: high effectiveness, high specificity, high compliance and fewer adverse effects. Several clinical trials and the clinical practice setting indicate substantial evidence that telmisartan, either as monotherapy or in combination with other antihypertensive drugs, provides long-term antihypertensive efficacy. In fact, telmisartan has the property to sustain blood pressure control throughout the 24-h dosage interval. Furthermore, telmisartan can play an important role in improving compliance, because of its documented good tolerability profile, which limits the adverse effects. This article provides the most recent data of the pharmacoeconomic position of telmisartan and its treatment effects on quality of life.

Telmisartan prevents the glitazone-induced weight gain without interfering with its insulin-sensitizing properties

Glitazones are peroxisome proliferator-activated receptor (PPAR)-gamma agonists with powerful insulin-sensitizing properties. They promote the development of metabolically active adipocytes that can lead to a substantial gain in fat mass. Telmisartan is an ANG II type 1 receptor antagonist with partial PPAR-gamma agonistic properties. Recently, telmisartan has been reported to prevent weight gain and improve insulin sensitivity in diet-induced obese rodents. The goal of this study was to examine the influence of telmisartan on pioglitazone-induced weight gain and insulin-sensitizing properties in the following two models of insulin resistance: a nongenetic model (high-fat-fed Sprague Dawley rats) and the genetically obese fa/fa Zucker rat. After a 4-wk treatment, the pioglitazone-induced increase in fat mass was modest in the Sprague Dawley rats and severe in the Zucker rats. In both models, these effects were substantially decreased by concomitant treatment with telmisartan. The effects of telmisartan on body weight and fat mass in the Zucker rats were abolished by pair feeding, suggesting that it is the result of a decrease in food intake. Telmisartan did not interfere with the insulin-sensitizing properties of pioglitazone. This study demonstrates that telmisartan attenuates the glitazone-induced increase in fat mass without interfering with its insulin-sensitizing properties.

Molecular characterisation of the interactions between olmesartan and telmisartan and the human angiotensin II AT1 receptor

BACKGROUND AND PURPOSE

Whereas some angiotensin II (Ang II) type 1 receptor blockers (ARBs) produce surmountable antagonism of AT(1) receptors, others such as olmesartan and telmisartan display varying degrees of insurmountability. This study compared the molecular interactions of olmesartan and telmisartan with the human AT(1) receptor, using well characterised in vitro methods and model systems.

EXPERIMENTAL APPROACH

CHO-K1 cells that stably express human AT(1) receptors (CHO-hAT(1) cells) were used in several pharmacological studies of olmesartan and telmisartan, including direct radioligand binding and inhibition of Ang II-induced inositol phosphate (IP) accumulation.

KEY RESULTS

Both ARBs were found to be competitive antagonists that displayed high affinity, slow dissociation, and a high degree of insurmountability for the AT(1) receptor (the latter greater with olmesartan). Their receptor interactions could be described by a two-step process with the initial formation of a loose complex (IR) and subsequent transformation into a tight binding complex (IR*). In washout experiments, [(3)H] telmisartan dissociated from the receptor with a half-life of 29 min and the Ang II-mediated IP accumulation response was 50% maximally restored within 24 min, whereas values for [(3)H] olmesartan were 72 min and 76 min, respectively.

CONCLUSIONS AND IMPLICATIONS

The high degree of insurmountability, slow dissociation, and high affinity of olmesartan for its receptor may relate to its ability to stabilise IR* via the carboxyl group of its imidazole core. In comparison, telmisartan displays a less potent interaction with the receptor.