Olmesartan Medoxomil-Loaded Niosomal Gel for Buccal Delivery: Formulation, Optimization, and Ex Vivo Studies.

Objectives: Olmesartan medoxomil (OLM) is a low bioavailability antihypertensive drug. This study aimed to prepare and optimize an OLM niosomal gel and investigate drug permeation via a chicken buccal pouch. Materials and Methods: OLM-loaded niosome were prepared using a film hydration technique. The vesicle size, zeta potential, entrapment efficiency, and percentage cumulative drug release of niosome were evaluated. The niosomes were incorporated into a Carbopol 974P (1.5% w/v) gel, and the drug permeability of the niosomal gel was evaluated. The formulations of the niosomal gel were optimized using the Box-Behnken design. The optimized formulation was further characterized by transmission electron microscopy (TEM) and Fourier transform infrared radiation analysis. Results: The particle size and zeta potential of the optimized niosomal formulations were 296.4 nm and -38.4 mV, respectively. Based on TEM analysis, the niosomes were found to be spherical in shape. The permeability, flux, and permeability coefficient of the optimized niosomal gel were 0.507 mg/cm2, 0.083 mg/cm2 × hour, and 041 cm/hour, respectively. Histopathological evaluation revealed that the niosomal gel had better permeability than the OLM gel. Conclusion: Based on the results of the OLM niosomal gel, it can be concluded that the formulation can be beneficial in increasing bioavailability, resulting in better therapeutic efficacy.

Host-Guest Interaction Study of Olmesartan Medoxomil with ß-Cyclodextrin Derivatives.

Olmesartan medoxomil (OLM) is a selective angiotensin II receptor antagonist used in the treatment of hypertension. Its therapeutic potential is limited by its poor water solubility, leading to poor bioavailability. Encapsulation of the drug substance by two methylated cyclodextrins, namely randomly methylated ß-cyclodextrin (RM-ß-CD) and heptakis(2,3,6-tri-O-methyl)-ß-cyclodextrin (TM-ß-CD), was carried out to overcome the limitation related to OLM solubility, which, in turn, is expected to result in an improved biopharmaceutical profile. Supramolecular entities were evaluated by means of thermoanalytical techniques (TG-thermogravimetry; DTG-derivative thermogravimetry), spectroscopic methods including powder X-ray diffractometry (PXRD), universal-attenuated total reflectance Fourier-transform infrared (UATR-FTIR) and UV spectroscopy, saturation solubility studies, and by a theoretical approach using molecular modeling. The phase solubility method reveals an AL-type diagram for both inclusion complexes, indicating a stoichiometry ratio of 1:1. The values of the apparent stability constant indicate the higher stability of the host-guest system OLM/RM-ß-CD. The physicochemical properties of the binary systems are different from those of the parent compounds, emphasizing the formation of inclusion complexes between the drug and CDs when the kneading method was used. The molecular encapsulation of OLM in RM-ß-CD led to an increase in drug solubility, thus the supramolecular adduct can be the subject of further research to design a new pharmaceutical formulation containing OLM, with improved bioavailability.

Efficacy and safety of olmesartan medoxomil­amlodipine besylate tablets (Sevikar®) in older patients with essential hypertension: Subgroup analysis from the Sevikar study.

Essential hypertension is a notable threat for the older (age, ≥65 years) population. However, to the best of our knowledge, a real-world study assessing olmesartan medoxomil-amlodipine besylate (OM-AML) tablets in older Chinese patients with essential hypertension has not been performed. Therefore, the present study aimed to evaluate the efficacy and safety of OM-AML tablets in these patients. A total of 463 older Chinese patients with essential hypertension treated with OM-AML (20/5 mg) tablets (Sevikar®) were analyzed in a prospective, single-arm, multi-center, real-world study. Seated systolic blood pressure (SeSBP) and seated diastolic blood pressure (SeDBP) at baseline, and at week (W)4 and W8 after OM-AML tablet administration were measured. The mean ± standard error change of SeSBP/SeDBP was -10.3±0.8/-4.6±0.5 and -12.5±0.8/-5.6±0.5 mmHg at W4 and W8, respectively. At W4, 74.1 and 26.8% of patients achieved BP target according to the China and American Heart Association (AHA) criteria, while at W8, 78.0 and 38.7% of patients reached these BP targets accordingly. Finally, 76.5 and 80.5% of patients achieved BP response at W4 and W8, respectively. Furthermore, home-measured SeSBP and SeDBP were significantly decreased from W1 to W8 (both P<0.001). Additionally, the satisfaction of both patients and physicians was elevated at W8 compared with at W0 (both P<0.001). The medication possession rate from baseline to W4 and W8 was 95.5 and 92.5%. The most common drug-associated adverse events by system organ classes were nervous system disorder (4.5%), vascular disorder (2.8%), and general disorder and administration site conditions (2.6%), which were generally mild. In conclusion, OM-AML tablets may be considered effective and safe in lowering BP, enabling the achievement of guideline-recommended BP targets in older Chinese patients with essential hypertension.

Efficacy and safety of olmesartan medoxomil-amlodipine besylate tablet in Chinese patients with essential hypertension: A prospective, single-arm, multi-center, real-world study.

There lacks real-world study with a large sample size assessing olmesartan medoxomil-amlodipine besylate (OM-AML) tablet. Therefore, this study aimed to evaluate the efficacy and safety of OM-AML tablet in patients with essential hypertension. Totally, 1341 patients from 36 medical centers with essential hypertension who took OM-AML (20/5 mg) tablet were analyzed in the current prospective, single-arm, multi-center, real-world study (SVK study). Seated systolic blood pressure (SeSBP) and seated diastolic blood pressure (SeDBP) at baseline, week (W)4 and W8 were measured. The mean (±SE) change of SeSBP/SeDBP was -10.8 ± 0.4/-6.6 ± 0.3 mmHg at W4 and -12.7 ± 0.5/-7.6 ± 0.3 mmHg at W8, respectively. At W4, 78.8% and 29.0% patients achieved BP target by China and American Heart Association (AHA) criteria; at W8, 84.7% and 36.5% patients reached blood pressure (BP) target by China and AHA criteria, accordingly. Meanwhile, 80.2% and 86.4% patients achieved BP response at W4 and W8, respectively. Home-measured SeSBP and SeDBP decreased from W1 to W8 (both p < .001). Besides, patients' and physicians' satisfaction were elevated at W8 compared with W0 (both p < .001). The medication possession rate was 94.8% from baseline to W4 and 91.3% from baseline to W8. The most common drug-related adverse events were nervous system disorders (4.6%), vascular disorders (2.6%), and general disorders and administration site conditions (2.3%) by system organ class, which were generally mild and manageable. In conclusion, OM-AML tablet is one of the best antihypertensive agents in patients with essential hypertension.

A Rare Case of Olmesartan-Associated Enteropathy Successfully Managed With Steroid Taper.

Olmesartan is a commonly used antihypertensive medication belonging to the class of angiotensin II receptor blockers. Though generally well-tolerated, olmesartan can rarely cause olmesartan-associated enteropathy (OAE) with non-bloody diarrhea, weight loss, abdominal pain, and vomiting. Patients may develop enteropathy months to years after drug initiation. In severe cases, patients may develop complications that require hospitalization. Diagnosis is often delayed due to unfamiliarity of OAE, nonspecific presenting symptoms, and normal-appearing gross endoscopic findings. Esophagogastroduodenoscopy (EGD) with biopsy is essential to the diagnosis, showing sprue-like enteropathy with intestinal villous atrophy and mucosal inflammation. This report describes a case of a 70-year-old man who presented with three months of profuse watery diarrhea and 40-pound unintentional weight loss. After an extensive workup, including EGD with duodenal biopsies, the patient was diagnosed with OAE. The biopsies showed findings consistent with acute and chronic duodenitis, mucosal desquamation and ulceration, blunting of villi, and a sprue-like pattern with neutrophils. Celiac serologies and anti-enterocyte antibodies were negative, further supporting the diagnosis of OAE. Complete resolution of symptoms was achieved by discontinuing olmesartan and administering a steroid taper. Considering the frequent use of olmesartan, the increasing occurrence of OAE, and the wide range of associated symptoms, it is crucial for providers to recognize OAE and consider early discontinuation of olmesartan. This approach can help prevent further intestinal damage, protracted symptoms, unnecessary diagnostic tests, and financial burdens on both patients and the healthcare system.

Area under the curve and ratio difference spectrophotometric methods with evaluation of the greenness for simultaneous determination of olmesartan medoxomil and metoprolol succinate.

The aim of this study is to develop and validate two simple spectrophotometric methods for simultaneous determination of metoprolol succinate (MET) and olmesartan medoxomil (OLM) in tablet form. Method (I) was area under the curve (AUC) method. This approach involved the measuring of the area over a variety of wavelengths. Two wavelength ranges; 213-230 nm and 244-266 nm were chosen for determination of MET and OLM, respectively. Method (II) was ratio difference spectrophotometricmethod. For determination of MET, the ratio spectra were generated using 15 µg/mL OLM as a divisor then the peak to trough amplitudes between 221 nm and 245 nm were displayed versus the corresponding concentrations of MET. For determination of OLM, the peak-to-peak amplitudes between 247 and 293 nm were chosen and found to be directly proportional to OLM concentrations using 15 µg/mL MET as a divisor. The linearity ranges were 2-30 µg/mL and 2-25 µg/mL for MET and OLM, respectively. The assay results showed good mean %recovery ± SD as well as good agreement with that of the reported method. The developed methods were validated according to ICH guidelines. The developed methods are accurate, precise, eco-friendly and could be applied successfully to estimate OLM and MET in their combined dosage form.

Development of Transdermal Oleogel Containing Olmesartan Medoxomil: Statistical Optimization and Pharmacological Evaluation.

Olmesartan medoxomil (OLM) is a first-line antihypertensive drug with low oral bioavailability (28.6%). This study aimed to develop oleogel formulations to decrease OLM side effects and boost its therapeutic efficacy and bioavailability. OLM oleogel formulations were composed of Tween 20, Aerosil 200, and lavender oil. A central composite response surface design chose the optimized formulation, containing Oil/Surfactant (SAA) ratio of 1:1 and Aerosil % of 10.55%, after showing the lowest firmness and compressibility, and the highest viscosity, adhesiveness, and bioadhesive properties (Fmax and Wad). The optimized oleogel increased OLM release by 4.21 and 4.97 folds than the drug suspension and gel, respectively. The optimized oleogel formulation increased OLM permeation by 5.62 and 7.23 folds than the drug suspension and gel, respectively. The pharmacodynamic study revealed the superiority of the optimized formulation in maintaining normal blood pressure and heart rate for 24 h. The biochemical analysis revealed that the optimized oleogel achieved the best serum electrolyte balance profile, preventing OLM-induced tachycardia. The pharmacokinetic study showed that the optimized oleogel increased OLM's bioavailability by more than 4.5- and 2.5-folds compared to the standard gel and the oral market tablet, respectively. These results confirmed the success of oleogel formulations in the transdermal delivery of OLM.

Coupling of synchronous fluorescence spectroscopy with derivative amplitude outcomes for simultaneous determination of metoprolol succinate and olmesartan medoxomil in combined pharmaceutical preparation: Application in spiked human plasma.

For the first time a spectrofluorimetric method had been achieved for the concurrent analysis of metoprolol succinate (MET) and olmesartan medoxomil (OLM). The approach depended on assessing the first order derivative (1D) of the synchronous fluorescence intensity of the two drugs in aqueous solution at Δλ of 100 nm. The amplitudes of 1D at 300 nm and 347 nm were measured for MET and OLM, respectively. The linearity ranges were 100-1000 ng/mL and 100-5000 ng/mL for OLM and MET, respectively. This approach is uncomplicated, repetitive, quick, and affordable. The results of analysis had been statistically verified. The validation assessments were carried out following the recommendations of The International Council for Harmonization (ICH). This technique could be employed to assess marketed formulation. The method was sensitive with limits of detection (LOD) of 32 ng/ml and 14 ng/mL for MET and OLM, respectively. Limits of quantitation (LOQ) were 99 ng/ml for MET and 44 ng/mL for OLM. So it can be applied to determine both drugs in spiked human plasma within the linearity ranges of 100-1000 ng/mL for OLM and 100-1500 ng/mL for MET.

Determination of Olmesartan in Bulk and Pharmaceutical Dosage Forms through the Development and Validation of Stability-indicating RP-HPLC Method.

BACKGROUND: Angiotensin II type 1 (AT 1) receptor antagonist (angiotensin receptor blocker [ARB]) called Olmesartan medoxomil (OLM) prevents angiotensin II from acting on the renin-angiotensin-aldosterone pathway, which is a crucial factor in the development of hypertension. OLM is reported to rapidly hydrolyze into its active metabolite, Olmesartan, in plasma after oral treatment. OBJECTIVE: The objective of the ongoing study was to develop an easy-to-use, precise, and reliable RP-HPLC method for the determination of Olmesartan in bulk as well as pharmaceutical dosage forms. METHODS: The stability indicating HPLC method for assay includes the use of Kromasil 100-5-C8 (100 mm × 4.6 mm) column, UV detector 265 nm, and mobile phase composition was a mixture of Acetonitrile: water (70:30) and flow rate of 1.0 mL/min. ICH guidelines were followed in the method's validation. To assess the method's specificity and stability in showing characteristics, stress degradation studies were carried out. The working standard solution of Olmesartan was exposed to 0.1 N HCl at room temperature, 0.1 N NaOH at room temperature, 30 percent hydrogen peroxide by volume, and UV radiation in order to conduct a degradation study. RESULTS: The retention periods of the drug were found to be 1.36 and 1.47 min for standard and sample solutions, respectively. The degradation behaviour of drug under different conditions was studied. The drug was found susceptible to acidic, alkaline and oxidative conditions while it was found stable in photolytic condition. The developed stability-indicating RP-HPLC method for assay was validated as per ICH Q2 guidelines and the validation parameters such as accuracy, precision and specificity were obtained within the accepted criteria. CONCLUSION: It may be concluded that this method is stability-indicating and specific and can successfully be applied to analyze tablet dosage form containing Olmesartan.

A novel nano-formulation of olmesartan medoxomil with improved delivery and efficacy in the treatment of indomethacin-induced duodenitis in rats

There are few studies addressing duodenal inflammation. This study was designed to investigate the effects of a recently developed biotechnological product, a nano-formulation of olmesartan medoxomil (OM) - olmesartan medoxomil zeinmersomes (OMZ) - for the treatment of indomethacin-induced duodenitis in rats. Adult male Wistar rats were given indomethacin (10 mg/kg/day) for four weeks. They were divided into a positive control group (PC, untreated) and two groups treated orally with 3 mg/kg per day of OM or OMZ for the last two weeks of the 4-week indomethacin-treatment. At end of the four weeks, blood and duodenum were collected. Duodenal homogenate was used for measurement of levels of myeloperoxidase, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), malondialdehyde, reduced glutathione (GSH), and cleaved caspase-3. Duodenal sections were stained with H&E. Gene expressions of nuclear factor kappa B (NF-κB p65), Bcl-2-associated X protein (Bax), and B-cell lymphoma 2 (Bcl-2) by RT-PCR, and protein expression of survivin by western blot were assessed. Plasma and duodenal olmesartan concentrations were measured by high performance liquid chromatography mass spectrometry. The duodenitis rats showed significantly higher duodenal levels of myeloperoxidase, TNF-α, IL-6, malondialdehyde, and cleaved caspase-3, a significantly lower GSH level, and histopathological alterations. Moreover, they showed upregulated gene expressions of NF-κB p65 and Bax, downregulated gene expression of Bcl-2, decreased Bcl-2/Bax ratio, and lower protein expression of survivin. OMZ was more effective in protecting the duodenum from indomethacin-induced injuries compared to OM due to improved delivery, higher bioavailability, and better anti-inflammatory, antioxidant, and antiapoptotic effects. OMZ could be a better choice for hypertensive patients with non-steroidal anti-inflammatory drugs-induced duodenitis.

Chitosan nanoparticles for intranasal delivery of olmesartan medoxomil: Pharmacokinetic and pharmacodynamic perspectives.

Nasal drug delivery has the potential to improve the systemic bioavailability of drugs with low oral bioavailability. Olmesartan medoxomil (OLM) is one of the most popular drugs for the treatment of hypertension with poor oral bioavailability of approximately 26 %. In this context, the goal of this work was to synthesize chitosan nanoparticles (CS NPs) loaded with OLM using the ionotropic gelation method to enhance the bioavailability and decrease oral side effects through nasal route. The particle size (PS), zeta potential (ZP), entrapment efficiency (%EE), and ex-vivo transmucosal permeation study of CS NPs were all evaluated. The pharmacokinetic and pharmacodynamic studies of selected formula compared to oral and nasal OLM suspensions were conducted. Successful formation of spherically shaped OLM CS NPS in the nano-range (240.02-344.45 nm) favorable for the intranasal absorption with high %EE (75.2-83.51 %) was achieved. The ability of OLM CS NPs to permeate efficiently across the nasal mucosa was proven in an ex vivo permeation experiment. Pharmacokinetic study demonstrated that the intranasal administration of OLM CS NPs exhibited improved bioavailability by 11.3-folds relative to oral OLM suspension as indicated by higher AUC value. The superior effect of intranasal OLM CS NPs was also accentuated in l-NAME induced hypertensive rats compared to intranasal and oral OLM suspension by reducing the high blood pressure (BP) and improving the heart rate (HR) of the induced group. Histological examinations revealed no damage occurred to nasal mucosa. In conclusion, OLM CS NPs had the ability to significantly improve the bioavailability of OLM and decrease BP and HR, suggesting the potential application of CS NPs as a promising carrier for the systemic delivery of OLM via intranasal route.

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.

Olmesartan medoxomil self-microemulsifying drug delivery system reverses apoptosis and improves cell adhesion in trinitrobenzene sulfonic acid-induced colitis in rats.

Olmesartan medoxomil (OM) is an angiotensin receptor blocker. This study aimed to investigate the effects of OM self-microemulsifying drug delivery system (OMS) in trinitrobenzene sulfonic acid (TNBS)-induced acute colitis in rats. Besides two control groups, five TNBS-colitic-treated groups (n = 8) were given orally sulfasalazine (100 mg/kg/day), low and high doses of OM (3.0 and 10.0 mg/kg/day) (OML and OMH) and of OMS (OMSL and OMSH) for seven days. A colitis activity score was calculated. The colon was examined macroscopically. Colonic levels of myeloperoxidase, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), malondialdehyde, and reduced glutathione were measured. Plasma and colonic olmesartan levels were measured. Colonic sections were subjected to hematoxylin and eosin staining and immunohistochemical staining for E-cadherin, caspase-3, and matrix metalloproteinase-9 (MMP-9). Protein expression of E-cadherin, Bcl-2 associated X protein (Bax), and B-cell lymphoma 2 (Bcl-2), and cleaved caspase-3 by Western blot was done. TNBS-colitic rats showed increased colonic myeloperoxidase, TNF-α, IL-6, and malondialdehyde, decreased colonic glutathione, histopathological, immunohistochemical, and protein expression alterations. OMS, compared with OM, dose-dependently achieved higher colonic free olmesartan concentration, showed better anti-inflammatory, antioxidant, and anti-apoptotic effects, improved intestinal barrier, and decreased mucolytic activity. OMS more effectively up-regulated the reduced Bcl-2, Bcl-2/Bax ratio, and E-cadherin expression, and down-regulated the overexpressed Bax, cleaved caspase-3, and MMP-9. OMSL exerted effects comparable to OMH. Sulfasalazine exerted maximal colonic protective effects and almost completely reversed colonic damage, and OMSH showed nearly similar effects with non-significant differences in-between or compared with the normal control group. In conclusion, OMS could be a potential additive treatment for Crohn's disease colitis.

"Ghost peaks" of olmesartan medoxomil: Two solution degradation products of olmesartan medoxomil via oxidation mediated by metal ions.

Two unknown solution degradants were found during the dissolution testing in 0.1-M HCl for olmesartan medoxomil (OLM) tablets. The structure of the degradants was identified and characterized by liquid chromatography-ultraviolet (LC-UV), liquid chromatography with tandem mass spectrometry (LC-MS/MS), and nuclear magnetic resonance (NMR) and demonstrated to be cyclization of tetrazole and benzene in the olmesartan (OL) and OLM structures. A series of studies including stress studies, simulation studies, and mechanism-based studies were performed to reveal the potential mechanisms that lead to the formation of the unknown degradants. The study results demonstrated that the degradation was catalyzed with radicals that originated from the metal ions leached from the inner surface of high-performance liquid chromatography (HPLC) glass vials with dissolved oxygen under acidic condition. Prerinsing the glass vials with acidic solution dissolved with EDTA can effectively avoid the generation of such oxidative impurities. The present work provides new insights into the understanding of degradation pathways of OLM, which might support the development of OLM tablets.

Interaction and Compatibility Studies in the Development of Olmesartan Medoxomil and Hydrochlorothiazide Formulations under a Real Manufacturing Process.

A drug-drug and drug-excipient interactions and compatibilities study was conducted for two fixed-dose combination (FDC) products containing olmesartan medoxomil (OLM)/hydrochlorothiazide (HCT) 20/12.5 mg and OLM/HCT 40/12.5 mg during their development including storage. The study consisted of the evaluation of samples retrieved during all stages of a real manufacturing process. Powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetry (TGA), Fourier transform infrared spectroscopy (FT-IR), and contact angle techniques were applied to the samples to determine interactions and incompatibilities. Dissolution tests and long-term stability studies were conducted to evaluate dosage form performance. Results showed weak solid-state interactions able to obtain a eutectic mixture of OLM and HCT while microcrystalline cellulose (MC) impacted the thermal stability of both drugs. Reliable dissolution and long-term stability tests confirmed that the interactions observed were not considered incompatibilities because they were not influenced by the performance of the final products.

Preparation of olmesartan medoxomil solid dispersion with sustained release performance by mechanochemical technology.

Hypertension is a common disease for human with high morbidity and mortality, and olmesartan medoxomil (OM) is widely used in the therapy of hypertension. However, poor water solubility and low bioavailability limit its widespread use. To improve the effect of OM, a ternary OM solid dispersion consisting of hydroxypropyl-ß-cyclodextrin (HP-ß-CD) and hydroxypropyl methylcellulose (HPMC) was prepared by mechanochemical method. The best preparation parameters were OM/HP-ß-CD/HPMC-E5 with mass ratio of 1:2.6:1 and milling time of 4 h. Under the optimal preparation conditions, the solubility of the ternary solid dispersion could be increased by 12 times as compared with pure OM. Due to the addition of HPMC-E5, the solid dispersion had sustained release performance with prolonged release time of 12 h. Furthermore, in vivo study demonstrated that the prepared solid dispersion could afford significantly improved bioavailability of ~ 3-fold in comparison with pure drug. Hence, the prepared ternary solid dispersion of OM may be a promise delivery system for clinical application.

Four chemometric spectrophotometric methods for simultaneous estimation of amlodipine besylate and olmesartan medoxomil in their combined dosage form.

For determination of amlodipine besylate (AML) and olmesartan medoxomil (OLM) at the same time, four UV chemometric spectrophotometric techniques were created and tested in accordance with ICH standards. Method (I) was absorption subtraction method (ASM) using two wavelengths, one of which was of AML at 365 nm and the other was the isoabsorptive point of both drugs at 237 nm. Method (II) was ratio subtraction method (RSM) for determination of OLM at λmax = 254 nm by taking the ratio spectrum and subtracting the constant values using 10 µg/mL of AML as a divisor in combination with extended ratio subtraction method (ERSM) to determine AML at λmax = 239 nm using 10 µg/mL OLM as a divisor. Method (III) was dual wavelength method; the wavelengths used to determine OLM were 221 nm and 235 nm, while those used to determine AML were 246 nm and 259 nm. Method (IV) was the second order derivative (2D) spectrophotometric method at 219 nm for OLM and 227 nm for AML. The proposed approaches were used to achieve linearity in the concentration range of 2-25 µg/mL for both drugs. The approaches were found to be uncomplicated, reproducible, efficient, and cost-effective as well as they were successfully used to determine the cited drugs in both laboratory samples and commercial pharmaceutical formulations.

Comparison of Pharmacodynamics and Celiac Effects of Olmesartan Medoxomil Formulations by using Olmesartan-induced Celiac-rat-model.

INTRODUCTION: Olmesartan Medoxomil (OM) is an angiotensin receptor blocker and has the adverse effect of celiac like enteropathy which was accepted by the FDA in 2013. This disease is characterized by severe diarrhea, weight loss and enteropathy. Although there are many case reports associated with olmesartan-related enteropathy in humans, it has not been described in a long-term animal model study so far. AIM: We developed a self-microemulsifying drug delivery system (OM-SMEDDS) in our previous study to reduce this side effect of the drug and to enhance bioavailability. METHODS: In this study, an artificial hypertension model was established with a dose of 185 µmol /kg L-NAME (N ω-nitro-L-arginine methyl ester) twice in a day intraperitoneally in Wistar albino rats. To determine and compare side effects, the OM-Suspension and OM-SMEDDS were administered at 1.3 mg/kg therapeutic dose during one-month period to the rats. RESULTS: Tension of rats was recorded by measuring from their tails with non invasive blood pressure system. We observed celiac like enteropathy findings like villous atrophy and intraepithelial lymphocytosis and clinical changes like weight loss and severe diarrhea after the treatment with OM-Suspension during one-month experiment. It was also observed that the antihypertensive efficacy of the OM-SMEDDS formulation was higher than the suspension during the experiment, which did not cause enteropathy, diarrhea and weight loss by reducing intestinal exposure. CONCLUSION: Hereby, we evaluated the side effects of two different pharmaceutical forms by designing a sustainable and reproducible celiac rat model that can be induced with olmesartan medoxomil.

Development and validation of a stability-indicating UPLC method for the determination of olmesartan medoxomil, amlodipine and hydrochlorothiazide degradation impurities in their triple-combination dosage form using factorial design of experiments.

The current work describes the development and validation of a stability-indicating UPLC method for the determination of olmesaratan medoxomil (OLM), amlodipine besylate (AMB), hydrochlorothiazide (HCT) and their degradation products in the triple-combination tablet dosage form. The separation was achieved using a Zorbax Eclipse plus C8 RRHD (100 mm × 3.0 mm), 1.8 µm column with gradient elution of mobile phase A containing 0.02 m of sodium phosphate buffer (pH 3.35) and mobile phase B as acetonitrile and water (90:10, v/v). The detector signal was monitored at UV 250 nm. Analytical performance of the optimized UPLC method was validated as per International Conference on Harmonization guidelines. The linearity ranges for OLM, AMB and HCT were 0.59-240, 0.30-60 and 0.37-150 µg/ml, respectively, with correlation coefficients >0.999. The dosage form was subjected to forced-degradation conditions of neutral, acidic and alkaline hydrolysis, oxidation and thermal and photodegradation. The method was proved to be stability indicating by demonstrating the specificity of the drugs from degradation products. The robustness of the method was evaluated through a two-level, three-factorial design with a multivariate approach. Statistical data analysis with best model fit P-value < 0.05 from an ANOVA test indicated that the influence of individual factors is relatively higher than the interaction effects. The method is useful for the analysis of drug products.

ARB-Based Combination Therapy for the Clinical Management of Hypertension and Hypertension-Related Comorbidities: A Spotlight on Their Use in COVID-19 Patients.

Essential hypertension is the most common cardiovascular (CV) risk factor, being primarily involved in the pathogenesis of CV disease and mortality worldwide. Given the high prevalence and growing incidence of this clinical condition in the general population in both high and low-income countries, antihypertensive drug therapies are frequently prescribed in different hypertension-related CV diseases and comorbidities. Among these conditions, evidence are available demonstrating the clinical benefits of lowering blood pressure (BP) levels, particularly in those hypertensive patients at high or very high CV risk profile. Preliminary studies, performed during the Sars-COVID-19 epidemic, raised some concerns on the potential implication of hypertension and antihypertensive medications in the susceptibility of having severe pneumonia, particularly with regard to the use of drugs inhibiting the renin-angiotensin system (RAS), including angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). These hypotheses were not confirmed by subsequent studies, which independently and systematically demonstrated no clinical harm of these drugs also in patients with Sars-COVID-19 infection. The aim of this narrative review is to critically discuss the available evidence supporting the use of antihypertensive therapies based RAS blocking agents in hypertensive patients with different CV risk profile and with additional clinical conditions or comorbidities, including Sars-COVID-19 infection, with a particular focus on single-pill combination therapies based on olmesartan medoxomil.