A Review of the Structural and Functional Features of Olmesartan Medoxomil, An Angiotensin Receptor Blocker

Safety and cardiovascular effectiveness of olmesartan in combination therapy for advanced hypertension: an electronic health record-based cohort study

OBJECTIVE

Compared with placebo, olmesartan has been linked to numerical imbalances in cardiovascular mortality. There is a paucity of contemporary real-world evidence on this agent for different study populations. This study investigated the clinical outcomes of olmesartan and other antihypertensives in patients with advanced hypertension.

METHODS

This multicenter retrospective study used data from the Korea University Medical Center database, built from electronic health records. Patients prescribed at least two antihypertensive medications as a combined therapy were followed-up for 3 years. The primary outcome was a composite of all-cause mortality, myocardial infarction (MI), stroke, and hospitalization for heart failure. Adjusted outcomes were compared using propensity score (PS) matching.

RESULTS

Among 24 806 patients, 4050 (16.3%) were olmesartan users between January 2017 and December 2018. The average patient age was 64 years, 45% were women, and 41% had diabetes. Olmesartan users were younger and less likely to have diabetes mellitus or chronic kidney disease. In PS-matched cohort, the 3-year cumulative incidences of the primary outcome were similar between the two groups ( P  = 0.91). The cumulative incidence of MI at 3 years was 1.4% in olmesartan users (4.8 per 1000 person-years) and 1.5% in active comparators (5.2 per 1000 person-years; P  = 0.74). Olmesartan also showed similar safety profiles, including acute kidney injury and newly started dialysis.

CONCLUSIONS

In real-world practice, olmesartan use in combination therapy resulted in similar cardiovascular outcomes when compared with those of active comparators, and our findings did not show any conclusive evidence that olmesartan is harmful in patients with hypertension.

Dosing time optimization of antihypertensive medications by including the circadian rhythm in pharmacokinetic-pharmacodynamic models

Blood pressure (BP) follows a circadian variation, increasing during active hours, showing a small postprandial valley and a deeper decrease during sleep. Nighttime reduction of 10–20% relative to daytime BP is defined as a dipper pattern, and a reduction of less than 10%, as a non-dipper pattern. Despite this BP variability, hypertension’s diagnostic criteria and therapeutic objectives are usually based on BP average values. Indeed, studies have shown that chrono-pharmacological optimization significantly reduces long-term cardiovascular risk if a BP dipper pattern is maintained. Changes in the effect of antihypertensive medications can be explained by circadian variations in their pharmacokinetics (PK) and pharmacodynamics (PD). Nevertheless, BP circadian variation has been scarcely included in PK-PD models of antihypertensive medications to date. In this work, we developed PK-PD models that include circadian rhythm to find the optimal dosing time (Ta) of first-line antihypertensive medications for dipper and non-dipper patterns. The parameters of the PK-PD models were estimated using global optimization, and models were selected according to the lowest corrected Akaike information criterion value. Simultaneously, sensitivity and identifiability analysis were performed to determine the relevance of the parameters and establish those that can be estimated. Subsequently, Ta parameters were optimized to maximize the effect on BP average, BP peaks, and sleep-time dip. As a result, all selected models included at least one circadian PK component, and circadian parameters had the highest sensitivity. Furthermore, Ta with which BP>130/80 mmHg and a dip of 10–20% are achieved were proposed when possible. We show that the optimal Ta depends on the therapeutic objective, the medication, and the BP profile. Therefore, our results suggest making chrono-pharmacological recommendations in a personalized way.

Olmesartan Ameliorates Organ Injury and Mortality in Rats With Peritonitis-Induced Sepsis

INTRODUCTION

Sepsis and related complications lead to high morbidity and mortality in humans and animals. Olmesartan medoxomil (OLM), a nonpeptide angiotensin II type 1 receptor blocker, has antiinflammatory and antioxidative effects in various experimental animal models. The present study aimed to investigate whether OLM protects against sepsis in a clinically relevant model of polymicrobial sepsis induced by cecal ligation and puncture (CLP).

METHODS

Sepsis was induced by CLP in anesthetized rats. OLM was administered intraperitoneally 3 h after CLP onset. Hemodynamic, biochemical, and inflammatory parameters were analyzed.

RESULTS

The administration of OLM in CLP rats significantly improved their survival rate. Moreover, OLM mitigated CLP-induced hypotension and organ injury (indicated by biochemical parameters), but not tachycardia. OLM significantly reduced the plasma levels of interleukin-6 and nitric oxide.

CONCLUSIONS

OLM markedly attenuated CLP-induced hypotension and organ injury, and hence improved survival by inhibiting the inflammatory response and nitrosative stress in this clinically relevant model of sepsis.

Stability of Olmesartan Medoxomil Extemporaneous Suspensions

Background: Olmesartan medoxomil (OLM) is only available in the United States as tablets. The United States Pharmacopoeia (USP) has placed OLM on its priority list of preparations that require stability data to support practitioner compounding. Objective: The purpose of the study was to develop a stability-indicating assay and then determine the beyond-use date (BUD) for an extemporaneous OLM suspension. Methods: A reverse-phase high-performance liquid chromatography (HPLC) assay was developed and validated according to guidelines for USP official compounded monographs. OLM 2 mg/mL suspensions were compounded with Ora-Sweet and Ora-Plus and stored at room temperature or in a refrigerator. Suspensions were assayed periodically over 90 days for OLM concentration and observed for physical stability. The pH was measured at the beginning and end of the study. Results: The OLM concentration remained above 97% of the starting concentration for 90 days when stored in the refrigerator and above 94% of the starting concentration for 90 days when stored at room temperature. The suspension pH did not change and indicators of physical stability were unchanged for 90 days. Conclusion: OLM 2 mg/mL suspensions were chemically and physically stable at room temperature and in the refrigerator for 90 days. The BUD may be set at 90 days under either storage condition.

Comparative Efficacy of Angiotensin II Type 1 Receptor Blockers Against Ventilator-Induced Diaphragm Dysfunction in Rats

Mechanical ventilation (MV) is a life‐saving intervention for many critically ill patients. Unfortunately, prolonged MV results in the rapid development of inspiratory muscle weakness due to diaphragmatic atrophy and contractile dysfunction (termed ventilator‐induced diaphragm dysfunction (VIDD)). Although VIDD is a major risk factor for problems in weaning patients from MV, a standard therapy to prevent VIDD does not exist. However, emerging evidence suggests that pharmacological blockade of angiotensin II type 1 receptors (AT1Rs) protects against VIDD. Nonetheless, the essential characteristics of AT1R blockers (ARBs) required to protect against VIDD remain unclear. To determine the traits of ARBs that are vital for protection against VIDD, we compared the efficacy of two clinically relevant ARBs, irbesartan and olmesartan; these ARBs differ in molecular structure and effects on AT1Rs. Specifically, olmesartan blocks both angiotensin II (AngII) binding and mechanical activation of AT1Rs, whereas irbesartan prevents only AngII binding to AT1Rs. Using a well‐established preclinical model of prolonged MV, we tested the hypothesis that compared with irbesartan, olmesartan provides greater protection against VIDD. Our results reveal that irbesartan does not protect against VIDD whereas olmesartan defends against both MV‐induced diaphragmatic atrophy and contractile dysfunction. These findings support the hypothesis that olmesartan is superior to irbesartan in protecting against VIDD and are consistent with the concept that blockade of mechanical activation of AT1Rs is a required property of ARBs to shield against VIDD. These important findings provide a foundation for future clinical trials to evaluate ARBs as a therapy to protect against VIDD.

Development of efficient one-pot three-component assembly of trityl olmesartan medoxomil

We have elaborated a one-pot three-component assembly of trityl olmesartan medoxomil starting from commercially available ethyl 4-(2-hydroxypropan-2-yl)-2-propyl-1H-imidazole-5-carboxylate, 5-(4'-(bromomethyl)-[1,1'-biphenyl]-2-yl)-1-trityl-1H-tetrazole and 4-(chloromethyl)-5-methyl-1,3-dioxol-2-one intermediates. The developed and optimized one-pot process provides 72-75% yield of trityl olmesartan medoxomil over three steps, which represents in average ca. 90% yield per synthetic step, on a 300 g scale. The process is conducted in simple fashion and provides highly pure trityl olmesartan medoxomil (up to 97.5% by HPLC), which can be easily converted to olmesartan medoxomil that fully complies with all ICH requirements. Furthermore, the described process significantly improves the primary process to trityl olmesartan medoxomil by drastic reduction of required unit operations and application of single reaction solvent through the reaction sequence. Moreover, the amount of used organic solvents was notably reduced. The developed process has provided solid bases for industrial production of trityl olmesartan medoxomil.

Monotherapy and Dual Combination Therapies Based on Olmesartan: A Comprehensive Strategy to Improve Blood Pressure Control

Olmesartan medoxomil is an antihypertensive drug of the class of angiotensin II type 1 (AT1) receptor antagonists (or blockers), characterized by tight and prolonged binding to AT1 receptor compared to other molecules within the same class. These characteristics produce effective and sustained blood pressure reductions in hypertensive patients at different cardiovascular risk profile with a good tolerability profile. After a brief description of the pharmacological characteristics of olmesartan, we will provide a thorough overview of the clinical studies that investigated its efficacy and safety in the clinical management of hypertensive patients both in monotherapy and in dual combination therapies with either thiazide diuretics or calcium channel blockers. These studies demonstrated that olmesartan-based antihypertensive strategy may indeed provide sustained BP control over the 24-h period in a wide proportion of hypertensive patients, thus contributing to a substantial progress in hypertension management. Finally, since growing evidence suggest that olmesartan may also exert potential favourable effects at vascular level, thereby antagonizing the vascular inflammatory process involved in the development and progression of atherosclerosis, the main clinical studies addressing this issue will be also discussed.

Olmesartan

Olmesartan is an angiotensin receptor blockers with actions similar to those of losartan; it is used for the treatment of high blood pressure by relaxing blood vessels for this reason blood can flow more easily. It could be used alone or in combination with other antihypertensive drugs. This chapter gives a comprehensive profile of olmesartan, containing detailed nomenclature, formulae, elemental analysis, and appearance of the drug. In addition this chapter also describes several methods of synthesis and usage of the olmesartan. The profile covers the physicochemical properties including pK_a value, solubility, X-ray powder diffraction, melting point, and procedures of analysis (compendial, spectroscopic, electrochemical, and chromatographic techniques of analysis). Comprehensive pharmacology is also presented (pharmacological actions, therapeutic uses and dosing, interactions, and adverse effects and precautions). Eighty references were given as a proof of the above-mentioned studies.

Management of Hypertension Using Olmesartan Alone or in Combination

Hypertension is one of the most significant and consistent risk factors for many cardiovascular diseases. The global prevalence of hypertension has dramatically increased over recent years. Life-style and genetic factors are generally considered to be primarily responsible for the incidence of hypertension. Concerning the high morbidity rate, setting up an updated standard for hypertensive patients becomes indispensable. According to the widely accepted standard treatments for hypertension, these four basic principles should be taken into account: low dosage; medication should provide long term-control; combination therapies are becoming common; personalized treatments are a newer approach. In most patients with hypertension, adequate control of BP can be achieved with combined therapy. Therefore, antihypertensive agents with complementary mechanisms are now recommended. In this review, we focus on the pharmacology, antihypertensive efficacy, and adverse events (AEs) of olmesartan medoxomil, either alone or in combination with other antihypertensive medications. In conclusion, olmesartan medoxomil, is an angiotensin II receptor blocker with an excellent efficacy in the reduction and stabilization of blood pressure. When combined with calcium channel blockers (CCBs) and diuretics, olmesartan medoxomil has a better effect on controlling BP and reducing AEs in patients.

Persistent olmesartan-based blood pressure-lowering effects on morning hypertension in Asians: the HONEST study

Using data from the large-scale HONEST (Home blood pressure measurement with Olmesartan Naive patients to Establish Standard Target blood pressure) study, we investigated the characteristics of the effects of olmesartan-based treatment on morning hypertension in Asian hypertensive patients. Specifically, we investigated the relationship between baseline blood pressure (BP) and BP reduction after 16 weeks by linear regression analyses; determinants of BP reduction were also investigated. For both morning home BP (MHBP) and clinic BP (CBP), reduced systolic BP (SBP) after 16 weeks was associated with baseline SBP (P<0.001). The slope of the regression lines was similar for morning home SBP (MHSBP) (-0.744) and clinic SBP (-0.735). Although sex, concomitant diabetes mellitus and concomitant hepatic disease significantly influence the relationship between BP reduction and baseline BP for MHSBP, none were deemed clinically relevant. In conclusion, olmesartan-based treatment robustly reduced baseline high MHBP, similar to CBP, and the effect was associated with baseline BP but unaffected by patient background factors.

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.

Angiotensin-II blockage, muscle strength, and exercise capacity in physically independent older adults

[Purpose] This study aimed to assess the exercise capacity and muscle strength in elderly people using drugs for angiotensin-II blockage. [Subjects and Methods] Four hundred and seven older adults were recruited for this study. Data about comorbidities and medication use were recorded and the individuals were divided into three groups: control group- elderly people with normal exercise capacity (n=235); angiotensin-converting enzyme inhibitor group - individuals using angiotensin-converting enzyme inhibitors (n=140); and angiotensin-II receptor blocker group- patients using angiotensin-II receptor blockers (n= 32). Exercise capacity was evaluated by a 6-minute walking test and muscle strength was measured using a handgrip dynamometer. [Results] Patients from the angiotensin-converting enzyme inhibitor group (mean: 99 ± 12%) and the angiotensin-II receptor blocker group (mean: 101 ± 14%) showed higher predicted values in the 6-minute walking test than the control group patients (mean: 96 ± 10%). Patients from the angiotensin-converting enzyme inhibitor group (mean: 105 ± 19%) and the angiotensin-II receptor blocker group (mean: 105.1 ± 18.73%) showed higher predicted values of muscle strength than control group patients (mean: 98.15 ± 18.77%). [Conclusion] Older adults using angiotensin-converting enzyme inhibitors or angiotensin-II receptor blockers have better functional exercise capacity and muscle strength.

Synthesis and Physicochemical Characterization of the Process-Related Impurities of Olmesartan Medoxomil. Do 5-(Biphenyl-2-yl)-1-triphenylmethyltetrazole Intermediates in Sartan Syntheses Exist?

During the process development for multigram-scale synthesis of olmesartan medoxomil (OM), two principal regioisomeric process-related impurities were observed along with the final active pharmaceutical ingredient (API). The impurities were identified as N-1- and N-2-(5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl derivatives of OM. Both compounds, of which N-2 isomer of olmesartan dimedoxomil is a novel impurity of OM, were synthesized and fully characterized by differential scanning calorimetry (DSC), infrared spectroscopy (IR), nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectrometry/electrospray ionization (HRMS/ESI). Their ¹H, (13)C and (15)N nuclear magnetic resonance signals were fully assigned. The molecular structures of N-triphenylmethylolmesartan ethyl (N-tritylolmesartan ethyl) and N-tritylolmesartan medoxomil, the key intermediates in OM synthesis, were solved and refined using single-crystal X-ray diffraction (SCXRD). The SCXRD study revealed that N-tritylated intermediates of OM exist exclusively as one of the two possible regioisomers. In molecular structures of these regioisomers, the trityl substituent is attached to the N-2 nitrogen atom of the tetrazole ring, and not to the N-1 nitrogen, as has been widely reported up to the present. This finding indicates that the reported structural formula of N-tritylolmesartan ethyl and N-tritylolmesartan medoxomil, as well as their systematic chemical names, must be revised. The careful analysis of literature spectroscopic data for other sartan intermediates and their analogs with 5-(biphenyl-2-yl)tetrazole moiety showed that they also exist exclusively as N-2-trityl regioisomers.

Drug-induced enteropathy

BACKGROUND/AIMS

Many medications can cause diarrhea by increasing motility, inflammation or enteropathy. Olmesartan and mycophenolic acid (CellCept) are drugs that are capable of increasing inflammation and enteropathy in some individuals and, if not recognized, can lead to chronic diarrhea. It is this type of drug-induced diarrhea that is the focus of this review.

METHODS

A summary of our findings (recent and earlier published) as well as a review of published works from other centers were conducted.

RESULTS

There is increasing evidence that olmesartan use is associated with enteropathy in a small number of individuals who use angiotensin receptor II blockers, and that this enteropathy is characterized by severe diarrhea capable of inducing severe dehydration and, in some instances, failure of organs such as the kidney. Typical patient demographics are Caucasian individuals who are older (>50 years old) and obese or overweight prior to weight loss. Prolonged exposure to olmesartan use for 1-2 years is typical, although case reports of irbesartan and valsartan have been reported as well. Discontinuing olmesartan leads to improvement of symptoms; however, the period for healing is variable, with some patients requiring steroid therapy and even prolonged parental nutrition support. In addition, many histological features of olmesartan-associated enteropathy are also present in celiac disease, including villi shortening and lymphocyte infiltration. Other drug-associated enteropathies have also been reported with mycophenolate mofetil used in transplantation.

CONCLUSIONS

Of the drug-associated enteropathies discussed in this review, olmesartan can generate the most severe symptoms, albeit quite rare. Therefore, with patients who present with severe diarrhea and weight loss, one should consider olmesartan-associated enteropathy. In addition, many of the features associated with olmesartan-associated enteropathy are also found in celiac disease enteropathy; as such, one should review any celiac disease diagnosis for any use of olmesartan at the time of diagnosis.

Pharmacokinetic interaction between rosuvastatin and olmesartan: a randomized, open-label, 3-period, multiple-dose crossover study in healthy Korean male subjects

PURPOSE

Rosuvastatin has been widely used in combination with olmesartan for the treatment of dyslipidemia accompanied by hypertension. With no information currently available on the interaction between the 2 drugs, a pharmacokinetic study was conducted to investigate the influence of rosuvastatin on olmesartan and vice versa when the 2 drugs were coadministered. The purpose of this study was to investigate the pharmacokinetic profile of coadministration of the rosuvastatin 20-mg tablet and the olmesartan 40-mg tablet and the associated drug-drug interaction in healthy Korean male volunteers.

METHODS

This was a randomized, open-label, 3-period, multiple-dose crossover study. Eligible subjects were aged 20 to 50 years and within 20% of their ideal body weight. After being randomly assigned to 6 groups of equal number, subjects received each of the following 3 formulations once a day for 7 consecutive days with an 8-day washout period between the formulations: rosuvastatin 20-mg tablet, olmesartan 40-mg tablet, and coadministration of the rosuvastatin 20-mg tablet and the olmesartan 40-mg tablet. Blood samples were collected up to 72 hours after dosing, and pharmacokinetic parameters were determined for rosuvastatin, its active metabolite (N-desmethyl rosuvastatin), and olmesartan. Adverse events were evaluated based on subject interviews and physical examinations.

FINDINGS

Among the 36 enrolled subjects, 34 completed the study (mean [range] age, 28.6 [23-49] y; mean [range] weight, 66.4 [52.2-78.7] kg). The 90% CIs of the geometric mean ratios for the primary pharmacokinetic parameters for the coadministration of the 2 drugs to the mono-administration of each drug were 85.14% to 96.08% for AUCτ and 81.41% to 97.48% for Css,max for rosuvastatin, and 77.55% to 89.48% for AUCτ and 75.62% to 90.12% for Css,max for N-desmethyl rosuvastatin; those values were 95.61% to 102.57% for AUCτ and 91.73% to 102.98% for Css,max for olmesartan. Dizziness was the most frequently noted adverse drug reaction, occurring in 1 subject receiving mono-administration of rosuvastatin, 1 subject receiving mono-administration of olmesartan, and 4 subjects receiving coadministration of rosuvastatin and olmesartan. All the adverse events were expected, and there was no significant difference in the incidence between the 2 formulations.

IMPLICATIONS

This study suggests that rosuvastatin and olmesartan did not significantly influence each other's pharmacokinetics when coadministered. Although the pharmacokinetics of N-desmethyl rosuvastatin were influenced by olmesartan, such interactions were considered clinically insignificant. All 3 formulations were well tolerated, and no serious adverse events or drug reactions were noted.

The application of solid-state NMR spectroscopy to study candesartan cilexetil (TCV-116) membrane interactions. Comparative study with the AT1R antagonist drug olmesartan

ΑΤ1 receptor (AT1R) antagonists exert their antihypertensive effects by preventing the vasoconstrictive hormone AngII to bind to the AT1 receptor. It has been proposed that these biological effects are mediated through a two-step mechanism reaction. In the first step, they are incorporated in the core of the lipid bilayers and in the second step they reach the active site of the receptor through lateral diffusion. In this model, drug/membrane interactions are key elements for the drugs achieving inhibition at the AT1 receptor. In this work, the interactions of the prodrug candesartan cilexetil (TCV-116) with lipid bilayers are studied at molecular detail. Solid-state (13)C-CP/MAS, 2D (1)H-(1)H NOESY NMR spectroscopy and in silico calculations are used. TCV-116 and olmesartan, another drug which acts as an AT1R antagonist are compared for their dynamic effects in lipid bilayers using solid-state (2)H-NMR. We find a similar localization of TCV-116 compared to other AT1 antagonists in the intermediate polar region. In addition, we can identify specific local interactions. These interactions may be associated in part with the discrete pharmacological profiles observed for different antagonists.

Application of a Stability-Indicating HPTLC Method for Simultaneous Quantitative Determination of Olmesartan Medoxomil and Hydrochlorothiazide in Pharmaceutical Dosage Forms

A rapid, precise, sensitive, economical, and validated high performance thin layer chromatographic method is developed for simultaneous quantification of olmesartan medoxomil and hydrochlorothiazide in combined tablet dosage form. The method used amlodipine as internal standard (IS). Chromatographic separations were achieved on silica gel 60 F254 plates using toluene-methanol-ethyl acetate-acetone (2.5 : 1 : 0.5 : 2, v/v/v/v) as mobile phase. Densitometric analysis was carried out in the reflectance mode at 258 nm. Calibration curves were linear over a range of 80-480 ng/band for olmesartan medoxomil and 25-150 ng/band for hydrochlorothiazide. The detection and quantification limits were found to be 18.12 and 56.35 ng/band for olmesartan medoxomil and 6.31 and 18.56 ng/band for hydrochlorothiazide, respectively. Intra- and interassay precision provided relative standard deviations lower than 2% for both analytes. Recovery from 99.60 to 101.22% for olmesartan medoxomil and 98.30 to 99.32% for hydrochlorothiazide show good accuracy. Both the drugs were also subjected to acid, alkali, oxidation, heat, and photodegradation studies. The degradation products obtained were well resolved from pure drugs with significantly different R f values. As the method could effectively separate the drugs from their degradation products, it can be used for stability-indicating analysis. Validation of the method was carried out as per international conference on harmonization (ICH) guidelines.

Pharmacokinetics of rosuvastatin/olmesartan fixed-dose combination: a single-dose, randomized, open-label, 2-period crossover study in healthy Korean subjects

BACKGROUND

Rosuvastatin, a lipid-lowering agent, has been widely used with olmesartan, a long-acting angiotensin II receptor blocker, indicated for the treatment of dyslipidemia accompanied by hypertension. A fixed-dose combination (FDC) tablet of these 2 drugs was recently developed to enhance the dosing convenience and to increase patient compliance while yielding pharmacokinetic profiles comparable to coadministration of each drug as individual tablets.

OBJECTIVE

The goal of present study was to compare the pharmacokinetic profiles of single-dose administration of an FDC tablet containing rosuvastatin/olmesartan 20/40 mg (test formulation) with coadministration of a rosuvastatin 20-mg tablet and a olmesartan 40-mg tablet (reference formulation) in healthy Korean male volunteers, for the purpose of determining bioequivalence.

METHODS

This single-dose, randomized, open-label, 2-period crossover study enrolled subjects aged 20 to 50 years and within 20% of ideal body weight. Each subject received a single dose of the test and reference formulations orally in a fasted state, with a 7-day washout period between the administrations. Blood samples were collected up to 72 hours after dosing, and pharmacokinetic parameters were determined for rosuvastatin, its active metabolite (N-desmethyl rosuvastatin), and olmesartan. Bioequivalence was concluded if the 90% CIs of the geometric mean ratios for the primary pharmacokinetic parameters were within the predetermined range of 80% to 125%. Adverse events (AEs) were evaluated based on subject interviews and physical examinations.

RESULTS

Among the 58 enrolled subjects, 54 completed the study. The 90% CIs of the geometric mean ratios of the primary pharmacokinetic parameters were as follows: rosuvastatin: AUC(last), 85.60% to 97.40% and C(max), 83.16% to 98.21%; N-desmethyl rosuvastatin: AUC(last), 82.08% to 93.45% and C(max), 79.23% to 93.41%; and olmesartan: AUC(last), 97.69% to 105.69% and C(max), 100.35% to 109.42%. The most frequently noted AE was headache, occurring in 3 and 6 patients with the test and reference formulations, respectively. All of the AEs were expected, and there was no significant difference in the prevalences of AEs between the 2 formulations.

CONCLUSIONS

The pharmacokinetic properties of the newly developed FDC tablet of rosuvastatin/olmesartan 20/40 mg suggest that it is bioequivalent to co-administration of each drug as individual tablets in these healthy Korean male subjects. The two formulations were well tolerated, with no serious AEs observed. ClinicalTrials.gov identifier: NCT01823900.

Synthesis and pharmacological properties of a new hydrophilic and orally bioavailable 5-HT4 antagonist

5-HT4 receptor antagonists have been suggested to have clinical potential in treatment of atrial fibrillation, diarrhea-prone irritable bowel syndrome and urinary incontinence. Recently, the use of 5-HT4 antagonists has been suggested to have a therapeutic benefit in heart failure. Affinity for the hERG potassium ion channel and increased risk for prolonged QT intervals and arrhythmias has been observed for several 5-HT4 ligands. Serotonin may also have beneficial effects in the central nervous system (CNS) through stimulation of the 5-HT4 receptor, and reduced distribution of 5-HT4 antagonists to the CNS may therefore be an advantage. Replacing the amide and N-butyl side chain of the 5-HT4 receptor antagonist SB207266 with an ester and a benzyl dimethyl acetic acid group led to compound 9; a hydrophilic 5-HT4 antagonist with excellent receptor binding and low affinity for the hERG potassium ion channel. To increase oral bioavailability of carboxylic acid 9, two different prodrug approaches were applied. The tert-butyl prodrug 11 did not improve bioavailability, and LC-MS analysis revealed unmetabolized prodrug in the systemic circulation. The medoxomil ester prodrug 10 showed complete conversion and sufficient bioavailability of 9 to advance into further preclinical testing for treatment of heart failure.

Anti-atherogenic effects of the combination therapy with olmesartan and azelnidipine in diabetic apolipoprotein E-deficient mice

Many studies have aimed to identify anti-atherogenic agents in cardiovascular medicine. We have recently demonstrated that the combination therapy with olmesartan (OLM), an angiotensin II receptor blocker, and azelnidipine (AZL), a dihydroprydine calcium-channel blocker, improves endothelial function in diabetic Apolipoprotein-deficient (ApoE(-/-)) mice. In the present study, we examined whether this combination therapy also inhibits atherosclerosis in mice. We used male control and streptozocin-induced diabetic ApoE(-/-) mice. Diabetic ApoE(-/-) mice were orally treated for 5 weeks with vehicle (Untreated), OLM (30 mg/kg/day), AZL (10 mg/kg/day), their combination (OLM+AZL), or hydralazine (HYD, 5 mg/kg/day) as an antihypertensive control. At 5 weeks, systolic blood pressure was significantly elevated in Untreated but was normalized in OLM+AZL and HYD. The atherosclerosis area in the thoracic aorta, perivascular fibrosis and medial thickness of the coronary arteries were increased in Untreated and were ameliorated in OLM+AZL but not in HYD. Staining with a fluorescent probe dihydroethidium showed that production of reactive oxygen species was increased in Untreated, and ameliorated in OLM+AZL. Consistent with these findings, macrophage infiltration in the kidney and the expression of receptor for advanced glycation end-products in the heart, kidney and liver were increased in Untreated and were all ameliorated in OLM+AZL, associated with up-regulation of endothelial NO syntheses (eNOS). In conclusion, the combination therapy with OLM and AZL exerts anti-atherogenic effect in diabetic ApoE(-/-) mice through suppression of oxidative stress and activation of eNOS, independent of its blood pressure-lowering effects. Clinically, this combination therapy may be useful for patients with hypertension, hyperlipidemia and diabetes.

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.

Olmesartan medoxomil is associated with decreased plasma AGEs, pentosidine, and N-(epsilon)-carboxymethyl-lysine levels in hemodialysis patients

BACKGROUND

Advanced glycation end products (AGEs) are associated with comorbidity and death among patients on hemodialysis (HD). Angiotensin II type 1 receptor blockers (ARBs) can decrease the formation of AGEs in vitro. This study examines the ability of various ARBs to decrease plasma AGE levels in hypertensive patients on HD.

METHODS

This preliminary randomized prospective study included 24 hypertensive patients on HD who were treated with candesartan (8 mg/day). The patients were randomly assigned to an olmesartan (20 mg/day, n = 12) or a telmisartan (40 mg/day, n = 12) group and followed up 24 weeks. Blood pressure was monitored before each HD session, and plasma pentosidine, N-(epsilon)-carboxymethyl-lysine (CML), serum malondialdehyde-low-density lipoprotein (LDL), high-sensitive CRP, and serum total free radical (TFR) were measured at baseline, and at 4, 12, and 24 weeks.

RESULTS

Olmesartan was significantly associated with decreased systolic blood pressure compared with telmisartan. After 24 weeks of treatment, plasma pentosidine and CML levels were significantly decreased and serum TFR levels tended to be decreased in the olmesartan group, but remained unchanged in the telmisartan group.

CONCLUSIONS

These results suggest that olmesartan can help to decrease plasma AGE levels in patients on HD.

Thermal, dynamic and structural properties of drug AT1 antagonist olmesartan in lipid bilayers

It is proposed that AT1 antagonists (ARBs) exert their biological action by inserting into the lipid membrane and then diffuse to the active site of AT1 receptor. Thus, lipid bilayers are expected to be actively involved and play a critical role in drug action. For this reason, the thermal, dynamic and structural effects of olmesartan alone and together with cholesterol were studied using differential scanning calorimetry (DSC), 13C magic-angle spinning (MAS) nuclear magnetic resonance (NMR), cross-polarization (CP) MAS NMR, and Raman spectroscopy as well as small- and wide angle X-ray scattering (SAXS and WAXS) on dipalmitoyl-phosphatidylcholine (DPPC) multilamellar vesicles. 13C CP/MAS spectra provided direct evidence for the incorporation of olmesartan and cholesterol in lipid bilayers. Raman and X-ray data revealed how both molecules modify the bilayer's properties. Olmesartan locates itself at the head-group region and upper segment of the lipid bilayers as 13C CP/MAS spectra show that its presence causes significant chemical shift changes mainly in the A ring of the steroidal part of cholesterol. The influence of olmesartan on DPPC/cholesterol bilayers is less pronounced. Although, olmesartan and cholesterol are residing at the same region of the lipid bilayers, due to their different sizes, display distinct impacts on the bilayer's properties. Cholesterol broadens significantly the main transition, abolishes the pre-transition, and decreases the membrane fluidity above the main transition. Olmesartan is the only so far studied ARB that increases the gauche:trans ratio in the liquid crystalline phase. These significant differences of olmesartan may in part explain its distinct pharmacological profile.

Inhibitory effects of olmesartan on catecholamine secretion from the perfused rat adrenal medulla

The present sutdy aimed to determine whether olmesartan, an angiotensin II (Ang II) type 1 (AT(1)) receptor blocker, can influence the CA release from the isolated perfused model of the rat adrenal medulla. Olmesartan (5~50 µM) perfused into an adrenal vein for 90 min produced dose- and time-dependent inhibition of the CA secretory responses evoked by ACh (5.32 mM), high K(+) (56 mM, a direct membrane-depolarizer), DMPP (100 µM) and McN-A-343 (100 µM). Olmesartan did not affect basal CA secretion. Also, in adrenal glands loaded with olmesartan (15 µM), the CA secretory responses evoked by Bay-K-8644 (10 µM, an activator of voltage-dependent L-type Ca(2+) channels), cyclopiazonic acid (10 µM, an inhibitor of cytoplasmic Ca(2+) -ATPase), veratridine (100 µM, an activator of voltage-dependent Na(+) channels), and Ang II (100 nM) were markedly inhibited. However, at high concentrations (150~300 µM), olmesartan rather enhanced the ACh-evoked CA secretion. Taken together, these results show that olmesartan at low concentrations inhibits the CA secretion evoked by cholinergic stimulation (both nicotininc and muscarinic receptors) as well as by direct membrane depolarization from the rat adrenal medulla, but at high concentrations it rather potentiates the ACh-evoked CA secretion. It seems that olmesartan has a dual action, acting as both agonist and antagonist at nicotinic receptors of the isolated perfused rat adrenal medulla, which might be dependent on the concentration. It is also thought that this inhibitory effect of olmesartan may be mediated by blocking the influx of both Na(+) and Ca(2+) into the rat adrenomedullary chromaffin cells as well as by inhibiting the Ca(2+) release from the cytoplasmic calcium store, which is thought to be relevant to the AT(1) receptor blockade, in addition to its enhancement on the CA secreton.

An evaluation of the efficacy of olmesartan medoxomil in Black patients with hypertension

Blacks appear to have a more modest blood pressure (BP) response to angiotensin receptor blocker (ARB) monotherapy than non-Blacks. This post-hoc analysis compared the BP-lowering efficacy of olmesartan medoxomil (OM), losartan potassium (LOS), and valsartan (VAL) in Black versus non-Black participants in a randomized, forced-titration study. Patients were randomized to OM 20, LOS 50, and VAL 80mg/day or placebo for 4 weeks and uptitrated to 40, 100, and 320mg/day doses, respectively, by study end. The primary end point was the mean change from baseline in diastolic BP (DBP) at week 8. All treatments produced significant reductions in mean DBP and systolic BP (SBP) in Blacks (n=150; P < .001). BP <140/90mm Hg was achieved in 35.0%, 15.6%, 29.7%, and 5.0% of Blacks receiving OM, LOS, VAL, and placebo, respectively, and in 41.0%, 21.1%, 28.8%, and 14.5% of non-Blacks receiving OM, LOS, VAL, and placebo, respectively, after 8 weeks. BP-lowering efficacy of the three agents was similar at 3 months. OM had the greatest early efficacy, with numerically greater mean reductions in DBP and SBP, and a higher proportion of Black and non-Black patients achieving goal BP of 140/90mm Hg at week 8.

RP-HPLC-DAD method for determination of olmesartan medoxomil in bulk and tablets exposed to forced conditions

A simple, sensitive and precise RP-HPLC-DAD method was developed and validated for the determination of olmesartan medoxomil (AT-II receptor blocker) in the presence of its degradation products. Olmesartan medoxomil and all the degradation products were resolved on a C(18) column with the mobile phase composed of methanol, acetonitrile and water (60:15:25, V/V/V, pH 3.5 by orthophosphoric acid) at 260 nm using a photodiode array detector. The method was linear over the concentration range of 1-18 microg mL(-1) and precise with RSD < 1 % in intra- and inter-day study. Excellent recoveries of 99.3 +/- 0.9 to 100.8 +/- 1.2% proved the accuracy of the method. Developed method was specific, as indicated by chromatographic resolution > 2.0 for each peak and sensitive with LOD 0.03 microg mL(-1) and LOQ 0.1 microg mL(-1). The method was used to study the drug degradation behavior under forced conditions. Four degradation products (DP-I, II, III, IV) were formed during the degradation study in 0.1 mol L(-1) HCl whereas only DP-I, II and III were formed in water, 0.01 mol L(-1) NaOH and 3% H(2)O(2). No significant thermal or photolytic degradation was observed in solid drug. The method was applied successfully for the assay of olmesartan medoxomil in the tablet dosage form.

Critical appraisal of amlodipine and olmesartan medoxomil fixed-dose combination in achieving blood pressure goals

Hypertension remains a significant health burden in the United States, with almost one in three adults affected, and is an independent risk factor for cardiovascular and renal disease. The goal of antihypertensive treatment is to reduce cardiovascular and renal morbidity and mortality by reducing blood pressure (BP). Guidelines recommend a target BP of <140/90 mmHg, with a more stringent goal of <130/80 mmHg for patients with diabetes and chronic renal disease. However, BP goal attainment rates remain low and most patients require therapy with two or more antihypertensive agents. Combination antihypertensive therapy usually employs agents from different classes, thus benefitting from complementary mechanisms of action to achieve greater BP control with fewer side effects. Patient adherence to therapy is enhanced by formulating treatments as fixed-dose (single-pill) combinations. One example is the combination of amlodipine, a dihydropyridine calcium channel blocker (CCB), with olmesartan medoxomil, an angiotensin receptor blocker (ARB). Here, the rationale for the use of CCB/ARB combination therapy is discussed, as well as the pharmacology and tolerability of the amlodipine/olmesartan medoxomil combination and its efficacy in terms of achieving BP goal in patients with hypertension. Advantages of its use from the patient's perspective are also discussed.

Olmesartan for the treatment of arterial hypertension

Angiotensin-receptor blockers (ARBs) are an important class of agents used for the treatment of arterial hypertension. Olmesartan medoxomil, the seventh latest ARB approved by the US FDA, is an oral, once-daily, AT(1)-receptor selective ARB with high receptor affinity. Pharmacologically, it acts as a competitive and insurmountable Ang II antagonist with linear pharmacokinetics and without cytochrome P450 interaction. The drug is licensed for the treatment of arterial hypertension alone or in combination with other antihypertensive agents. Olmesartan has demonstrated its dose-dependent inhibitory effect on Ang I-induced blood pressure responses between 10 and 80 mg in Phase II studies. These results, confirmed in an international clinical trial programme covering over 3000 hypertensive patients in numerous studies, demonstrated rapid blood pressure-lowering effects within 1 week. A daily oral dose of 20 mg olmesartan is considered to be the optimal dose. In clinical trials and postmarketing studies, olmesartan has been shown to be safe and well tolerated with an adverse event profile similar to the placebo. Active comparative studies demonstrated either similar or superior efficacy of olmesartan compared with other ARBs, angiotensin-converting enzymes inhibitors, beta-blockers or calcium-channel blockers. Besides its antihypertensive efficacy, olmesartan was shown in clinical trials to reduce vascular microinflammation, decrease intrarenal vascular resistance, significantly reduce vascular remodeling of small resistance arteries and exert antiatherosclerotic effects by significantly reducing the volume of large atherosclerotic plaques.

RP-LC and HPTLC Methods for the Determination of Olmesartan Medoxomil and Hydrochlorothiazide in Combined Tablet Dosage Forms

Two new, rapid, precise, accurate and specific chromatographic methods were described for the simultaneous determination of olmesartan medoxomil and hydrochlorothiazide in combined tablet dosage forms. The first method was based on reversed phase liquid chromatography using an Eurosphere 100 RP C18 column (250 x 4.6 mm ID, 5 mum). The mobile phase was methanol-0.05% o-phosphoric acid (60:40 v/v) at a flow rate of 1.0 mL min(-1). Commercially available tablets and laboratory mixtures containing both drugs were assayed and detected using a UV detector at 270 nm. The second method involved silica gel 60 F(254) high performance thin layer chromatography and densitometric detection at 254 nm using acetonitrile-ethyl acetate-glacial acid (7:3:0.4 v/v/v) as the mobile phase. Calibration curves ranged between 200-600 and 125-375 ng spot(-1) for olmesartan and hydrochlorothiazide, respectively.

Complementary mechanisms of angiotensin receptor blockers and calcium channel blockers in managing hypertension

Hypertension affects approximately 73 million individuals in the United States. Clinical studies have shown that antihypertensive therapy can reduce blood pressure (BP) and the risk of cardiovascular events. However, the majority of patients with hypertension do not achieve the recommended BP goal of < 140/90 mm Hg (or < 130/80 mm Hg for patients with diabetes) with antihypertensive monotherapy, and require therapy with 2 or more antihypertensive agents. Combination therapy utilizes antihypertensive agents from different drug classes, which act via distinct pharmacologic mechanisms to improve overall efficacy and tolerability. Although combination therapy is superior to monotherapy in achieving BP goals across the entire spectrum of hypertension, the proportion of patients achieving the recommended BP goal can be further improved by the use of new antihypertensive drug combinations. The beneficial antihypertensive characteristics of both angiotensin receptor blockers and calcium channel blockers suggest that combining these classes may result in a highly efficacious antihypertensive therapy with regard to both activity and safety when used as a fixed-dose combination. In particular, a fixed-dose combination of olmesartan medoxomil plus amlodipine besylate has been demonstrated to be an efficacious antihypertensive combination due in part to the benefits associated with each of these agents within their respective drug classes.

Olmesartan medoxomil: a review of its use in the management of hypertension

Olmesartan medoxomil (Olmetec, Benicar) is an angiotensin II type 1 (AT(1)) receptor antagonist (angiotensin receptor blocker [ARB]) that inhibits the actions of angiotensin II on the renin-angiotensin-aldosterone system, which plays a key role in the pathogenesis of hypertension. Oral olmesartan medoxomil 10-40 mg once daily is recommended for the treatment of adult patients with hypertension. In those with inadequate BP control using monotherapy, fixed-dose olmesartan medoxomil/hydrochlorothiazide (HCTZ) [Olmetec plus, Benicar-HCT] combination therapy may be initiated. Extensive clinical evidence from several large well designed trials and the clinical practice setting has confirmed the antihypertensive efficacy and good tolerability profile of oral olmesartan medoxomil, as monotherapy or in combination with HCTZ, in patients with hypertension, including elderly patients with isolated systolic hypertension (ISH). Notably, BP control is sustained throughout the 24-hour dosage interval, including during the last 4 hours of this period. In clinical trials, olmesartan medoxomil monotherapy provided better antihypertensive efficacy than losartan, candesartan cilexetil or irbesartan monotherapy, and was at least as effective as valsartan treatment, with a faster onset of action than other ARBs in terms of reductions from baseline in diastolic BP (DBP) and, in most instances, systolic BP (SBP). Combination therapy with olmesartan medoxomil plus HCTZ was superior to that with benazepril plus amlodipine, as effective as that with losartan plus HCTZ, noninferior to that with atenolol plus HCTZ, but less effective than that with telmisartan plus HCTZ, in individual trials. Data from ongoing clinical outcome trials are required to more fully determine the relative position of olmesartan medoxomil therapy in the management of hypertension. In the meantime, the consistent antihypertensive efficacy during the entire 24-hour dosage interval and good tolerability profile of olmesartan medoxomil, with or without HCTZ, make it a valuable option for the treatment of adult patients with hypertension, including the elderly.

Comparison of angiotensin II type 1 receptor antagonists in the treatment of essential hypertension

Hypertension is a major health problem worldwide, yet remains under-diagnosed and under-treated. Angiotensin II type 1 receptor antagonists (angiotensin receptor blockers [ARBs]) are highly effective at reducing blood pressure (BP), exhibit renoprotective properties and have placebo-like tolerability. However, it is unclear whether there are clinical differences in efficacy and tolerability between the available ARBs. A review of published, randomized, comparative clinical trials suggests that differences in BP-lowering efficacy and 24-hour BP control may exist between ARBs, although it appears that there is no evidence for important differences in tolerability between ARBs. Few studies have assessed attainment rates for important combined systolic BP (SBP)/diastolic BP (DBP) goals recommended in treatment guidelines. Likewise, few studies have directly compared more than two agents or ARB/hydrochlorothiazide fixed-dose combinations, and most ARBs have not been compared across their full recommended dosage ranges. Overall, there is insufficient weight of evidence to allow definitive conclusions to be drawn regarding the comparative efficacy of the available ARBs. However, newer ARBs (e.g. olmesartan medoxomil and telmisartan) appear to be more effective than older ARBs (e.g. losartan and valsartan) in reducing DBP and/or SBP in some trials. In addition, olmesartan medoxomil treatment regimens resulted in high BP control rates in several trials, but head-to-head trials with other ARBs are required to put these control rates into perspective, especially for SBP control with various agents. The purpose of this review is to present published data from ARB efficacy trials for a comparison of various efficacy parameters among the agents within this drug class.