Conversion of Olmesartan to Olmesartan Medoxomil, A Prodrug that Improves Intestinal Absorption, Confers Substrate Recognition by OATP2B1.

PURPOSE: Olmesartan medoxomil (olmesartan-MX), an ester-type prodrug of the angiotensin II receptor blocker (ARB) olmesartan, is predominantly anionic at intestinal pH. Human organic anion transporting polypeptide 2B1 (OATP2B1) is expressed in the small intestine and is involved in the absorption of various acidic drugs. This study was designed to test the hypothesis that OATP2B1-mediated uptake contributes to the enhanced intestinal absorption of olmesartan-MX, even though olmesartan itself is not a substrate of OATP2B1. METHODS: Tetracycline-inducible human OATP2B1- and rat Oatp2b1-overexpressing HEK 293 cell lines (hOATP2B1/T-REx-293 and rOatp2b1/T-REx-293, respectively) were established to characterize OATP2B1-mediated uptake. Rat jejunal permeability was measured using Ussing chambers. ARBs were quantified by liquid chromatography-tandem mass spectrometry. RESULTS: Significant olmesartan-MX uptake was observed in hOATP2B1/T-REx-293 and rOatp2b1/T-REx-293 cells, whereas olmesartan uptake was undetectable or much lower than olmesartan-MX uptake, respectively. Furthermore, olmesartan-MX exhibited several-fold higher uptake in Caco-2 cells and greater permeability in rat jejunum compared to olmesartan. Olmesartan-MX uptake in hOATP2B1/T-REx-293 cells and in Caco-2 cells was significantly decreased by OATP2B1 substrates/inhibitors such as 1 mM estrone-3-sulfate, 100 µM rifamycin SV, and 100 µM fluvastatin. Rat Oatp2b1-mediated uptake and rat jejunal permeability of olmesartan-MX were significantly decreased by 50 µM naringin, an OATP2B1 inhibitor. Oral administration of olmesartan-MX with 50 µM naringin to rats significantly reduced the area under the plasma concentration-time curve of olmesartan to 76.9%. CONCLUSION: Olmesartan-MX is a substrate for OATP2B1, and the naringin-sensitive transport system contributes to the improved intestinal absorption of olmesartan-MX compared with its parent drug, olmesartan.

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.

A Review of Olmesartan-based Therapy in Targeting Effective Blood Pressure Control and Achieving Blood Pressure Goals.

For >3 decades now, angiotensin receptor blockers (ARB) have been used in the management of hypertension (HTN) and HTN-related cardiovascular (CV) diseases. Olmesartan medoxomil (OLM) is an angiotensin II type 1 (AT1) receptor antagonist (or blocker) that binds tightly to the AT1 receptor with long-lasting efficacy over the 24-hour period and safety demonstrated in several trials. It is well tolerated and effective in reducing blood pressure (BP) in mono and combination therapy with thiazide diuretics or calcium channel blockers across a wide range of patient subgroups. The effectiveness and safety of OLM-based combination therapies have good and tolerable profiles with high adherence in the fixed single-pill formulation. Consistent antihypertensive efficacy and good tolerability when used as monotherapy or as a combined therapy make OLM a valuable treatment option for adults with HTN. In this review, we discuss the important clinical implications of OLM as an optimal choice as monotherapy and combination therapy in managing patients with HTN.

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.

Development of a Sensitive Screening Method for Simultaneous Determination of Nine Genotoxic Nitrosamines in Active Pharmaceutical Ingredients by GC-MS.

A worldwide crisis with nitrosamine contamination in medical products began in 2018. Therefore, trace-level analysis of nitrosamines is becoming an emerging topic of interest in the field of quality control. A novel GC-MS method with electron ionization and microextraction was developed and validated for simultaneous determination of nine carcinogenic nitrosamines (NDMA, NMEA, NDEA, NDBA, NMOR, NPYR, NPIP, NDPA, and N-methyl-npz) in active pharmaceutical ingredients (APIs): cilostazol, sunitinib malate, and olmesartan medoxomil. The method was validated according to the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines, demonstrating good linearity in the range of LOQ up to 21.6 ng/mL (120% of specification limit). The limits of detection for the nine nitrosamines were determined to be in the range 0.15-1.00 ng/mL. The developed trace level GC-MS method turned out to be specific, accurate, and precise. The accuracy of all the tested APIs ranged from 94.09% to 111.22% and the precision evaluated by repeatability, intermediate precision, and system precision was RSD ≤ 7.65%. Nitrosamines were not detected in cilostazol and sunitinib, whereas in olmesartan medoxomil NDEA was detected at the level of LOQ. The novel protocol was successfully applied for nitrosamines determination in selected APIs and can be used for the routine quality control of APIs under Good Manufacturing Practices rules, ensuring the safety and effectiveness of pharmaceutical products.

Permeability of olmesartan medoxomil from lipid based and suspension formulations using an optimized HDM-PAMPA model.

Hexadecane membrane-parallel artificial membrane permeability assay (HDM-PAMPA) is based on an artificial HDM that separates the two compartments (donor and acceptor compartment). This model is used to predict the permeability of drugs in gastrointestinal tract and to simulate the passive absorption. In vivo behavior of the drugs can be estimated with these systems in drug development studies. In our study, we optimized HDM-PAMPA model to determine permeability of olmesartan medoxomil (OM) lipid based drug delivery system (OM-LBDDS). In order to prove that LBDDS formulation facilitates the weak permeability of OM, permeation rates were compared with the OM suspension formula (containing 0.25% v/w carboxymethylcellulose). The experiment was performed on a 96-well MultiScreen® PAMPA filter plate (MAIPN4510). The permeability of olmesartan formulations from the donor to acceptor compartment separated by a HDM membrane were determined by the previous validated HPLC method. We created positive control series without coating HDM to present the LBDDS and suspension formulation permeability from uncoated plates. The effective permeability constant (Pe) was calculated by the formula and improvement of permeability of OM-LBDDS formulation from HDM was confirmed. On the contrary there was no permeation of OM-Suspension in the hexadecane coated plates. As a result, the intestinal permeability of OM-LBDDS was calculated to be at least 100 times more than the suspension. OM-Suspension permeation was only observed in the hexadecane uncoated positive control plates. This was also manifestation of HDM-PAMPA mimicking permeability of intestines because of its lipidic construction.

Dissolution enhancement of olmesartan medoxomil through polymer-based surface solid dispersion and solidified surfactant techniques.

This study aims to formulate Olmesartan medoxomil (OM) into oral fast-dissolving tablets (FDTs) to improve its solubility and bioavailability via two different techniques; The polymer-based surface solid dispersion (SSD) technique and the solidified surfactant (SS) technique. In the first technique, two polymers were used; polyvinylpyrrolidone (PVP K90) and Poloxamer 407 (Pluronic®F127), while in the second technique the liquid Tween 80 was solidified by adsorption onto Aeroperl®300. The pre-compression and post-compression parameters of the obtained formulations were assessed. The best formulations were subjected to a taste masking evaluation and a short-term stability study. The results demonstrated that, in comparison to the pure drug, the proportion of drug released from each of the prepared FDTs considerably increased. Results of the stability studies showed that the chosen drug formulations remained stable throughout the storage period.

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.

Olmesartan-associated duodenal villous atrophy, an emerging clinical issue.

Duodenal villous atrophy with olmesartan was described in 2012, 10 years following registration of olmesartan. Clinical features are severe watery diarrhoea, usually occurring in association with weight loss. Onset is delayed, with a mean duration of prior exposure to olmesartan of 3 years. Diagnosis may be delayed. Symptoms resolve over weeks following cessation of olmesartan. Epidemiological studies suggest increased risk with olmesartan, rather than a class effect of all angiotensin receptor blockers. Post-marketing surveillance for drug safety remains important.

Influence of pre-treatment blood pressure levels on antihypertensive drug benefits in diabetics: the roadmap experience.

Purpose: Most guidelines for treatment of hypertension in the setting of diabetes recommend a blood pressure (BP) target of <130/80 mmHg. However, uncertainty exists about the extent, effectiveness and safety of lowering BP in diabetics. To expand the evidence on this issue, we analysed data from the Randomised Olmesartan and Diabetes MicroAlbuminuria Prevention (ROADMAP) study population.Material: Substudy with blood pressure readings.Methods: The response after initiation of therapy and adequacy of BP control across patients with different BP levels at baseline were analysed.Results: BP at randomisation was 136.2(15.3)/80.6(9.5) [mean (SD)] mmHg with a range of 87-213/37-123 mmHg. At 1 year, mean BP was 127 (11.9)/75 (8.1) mmHg and the overall control rate (<130/80 mmHg) exceeded 61% in this population. The mean reductions in systolic [-9.4 (15.4) mmHg] and diastolic BP [-5.4 (9.5) mmHg] were highly dependent on the BP stage at Visit 1. At 1 year, treatment decreased the prevalence of patients with baseline BP levels of >160/100 from 9 to 2%[[mean BP change -31 (15.7)/ -14 (9.8) mmHg]] and of 140-159/90-99 mmHg from 32 to 11% [[mean BP change -16(12.7)/ -8.9 (8.7) mmHg]], with corresponding increases in the prevalence of patients with baseline BP levels of 120-139/80-99 from 48 to 65% [[mean BP change -4.1 (10.6)/ -3.1 (7.8) mmHg]]and of <120/80 from 11 to 22% [[mean BP change +5.9 (11.8)/+2.5 (8.6) mmHg]]. These effects did not change significantly thereafter and were maintained throughout follow-up.Conclusion: Blood pressure control is feasible in patients with diabetes without nephropathy, independent of baseline BP values. Asymmetric BP-lowering in the first year after starting therapy represents a true antihypertensive effect with sustainable shifts in BP severity.

Solubility determination and solution thermodynamics of olmesartan medoxomil in (PEG-400 + water) cosolvent mixtures.

The solubility and solution thermodynamic properties of a weakly water-soluble compound olmesartan medoxomil (OLM) in binary 'polyethylene glycol (PEG-400) + water' cosolvent compositions were determined. The 'mole fraction solubility (x e)' of OLM in binary 'PEG-400 + water' cosolvent compositions and pure solvents (PEG-400 and water) was determined at 'T = 295.15-330.15 K' and 'p = 0.1 MPa'. The Hansen solubility parameter (HSP) of OLM, pure PEG-400, pure water, and binary 'PEG-400 + water' cosolvent compositions free of OLM were also predicted. The obtained x e values of OLM were correlated using 'van't Hoff, modified Apelblat, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-van't Hoff' computational models with the error values of <4.0%. The maximum and minimum x e value of OLM was predicted in neat PEG-400 (1.15 × 10-2 at T = 330.15 K) and neat water (1.90 × 10-7 at T = 295.15 K), respectively. The OLM HSP was predicted to be more close with that of neat PEG-400. The x e value of OLM was found increased significantly with increase in temperature and PEG-400 mass fraction in all 'PEG-400 + water' cosolvent compositions including neat PEG-400 and neat water. An 'apparent thermodynamic analysis' studies presented an 'endothermic and entropy-driven dissolution' of OLM in all 'PEG-400 + water' cosolvent compositions including pure PEG-400 and pure water.

Formulation of lyophilized oily-core poly-Ɛ-caprolactone nanocapsules to improve oral bioavailability of Olmesartan Medoxomil.

Objective: This study aims to detect the enhancement in the oral bioavailability of a poorly water-soluble antihypertensive drug Olmesartan Medoxomil (OM) due to the formulation of lyophilized oily-core nanocapsules.Significance: A comparative pharmacokinetic study in rats was conducted for oily-core polymeric nanocapsules (ONC) after formulation and lyophilization against market tablet products to show the significant improvement in oral absorption of OM.Materials and methods: OM loaded ONC were prepared using poly-Ɛ-caprolactone (0.5% w/v) as a polymer and an oily core of Labrafac PG® by applying a well-controlled nanoprecipitation technique in terms of injection rate (80 mL/h) and magnetic stirring rate (300 rpm). The prepared lyophilized ONC were in-vitro characterized after reconstitution and evaluated in-vivo for oral bioavailability after a single OM oral dose (20 mg/kg) of reconstituted lyophilized ONC dispersion was administered to rats.Results: The prepared lyophilized ONC containing 10% w/v mannitol showed an average particle size of 158 nm, polydispersity index of 0.37, negative zeta potential value equals 33.9 and entrapment efficiency of 90%. The dissolution profile for OM from lyophilized ONC powder filled into hard gelatin capsules (HGC) showed a 1.8-fold increase in dissolution rate as compared to the pure drug. In-vivo pharmacokinetic study in rats revealed a significant enhancement in the oral bioavailability of OM with 1.6-fold increase for AUC0-24 and a 1.9-fold increase for Cmax as compared to marketed product.Conclusion: It is concluded that the formulation of lyophilized ONC for OM can significantly enhance its oral bioavailability and consequently, its therapeutic efficacy and patient compliance.

Effectiveness of Olmesartan on Blood Pressure Control in Hypertensive Patients in India: A Real World, Retrospective, Observational Study from Electronic Medical Records.

BACKGROUND: Real-world data on the effectiveness of antihypertensive drugs (AHDs) in India is limited. The present study aims to provide updated evidence regarding the effectiveness of olmesartan as monotherapy or in combination with other AHDs in Indian patients with essential hypertension. METHODS: Electronic medical record data of adult patients who were diagnosed with essential hypertension (≥140/90 mmHg) and were prescribed olmesartan as mono- or add-on therapy were retrospectively analyzed. Patients were classified based on the number of AHD classes prescribed on initiation of olmesartan. Change in systolic and diastolic blood pressure (SBP and DBP) from baseline was the primary endpoint. Secondary endpoint was evaluation of proportion of patients who achieved treatment goals as per 2018 European Society of Cardiology/European Society of Hypertension guidelines. Readings were obtained before initiating olmesartan and after at least a month of therapy with olmesartan. RESULTS: Among the 459 included patients, majority were on olmesartan monotherapy or olmesartan+1AHD (91.7%). Mean (95% confidence interval [CI]) change in olmesartan monotherapy group was: SBP (-13.4 [-15.7, -11.1] mmHg) and DBP (-8.3 [-9.5, -7.1] mmHg) and mean (95% CI) change in olmesartan+1AHD group was: SBP (-11.7 [-15.1, -8.3] mmHg) and DBP (-6.6 [-8.3, -4.9] mmHg) (P<0.001 for all). SBP and DBP goals were achieved by 40.4% and 50.3% of patients on olmesartan monotherapy and by 36.1% and 46.2% of patients on olmesartan+1AHD. Among patients with comorbid diabetes, mean (95% CI) change in olmesartan monotherapy group was: SBP (-15.5 [-18.6, -12.4] mmHg) and DBP (-8.7 [-10.2, -7.2] mmHg) and mean (95% CI) change in olmesartan+1AHD group was: SBP (-13.5 [-18.3, -8.7] mmHg) and DBP (-7.6 [-9.8, -5.4] mmHg) (P<0.001 for all). SBP and DBP goals were achieved by 38.5% and 49.4% of patients on olmesartan monotherapy and by 31.7% and 42.9% of patients on olmesartan+1AHD. CONCLUSION: Olmesartan prescribed as mono- or add-on therapy during routine clinical practice significantly reduced blood pressure in Indian patients with essential hypertension as well as in patients with comorbid diabetes.

Bioavailability Enhancement of Olmesartan Medoxomil Using Hot-Melt Extrusion: In-Silico, In-Vitro, and In-Vivo Evaluation.

Olmesartan medoxomil (OLM) an antihypertensive molecule with poor solubility and poor bioavailability (26% when taken orally) was selected as a model drug. Herein, rationale development of amorphous solid dispersion with hot-melt extrusion of poorly bioavailable OLM was carried out with the aid of quality by design (QbD), in-silico, in-vitro, and in-vivo evaluations. Polymer selection commenced with the selection of thermoplastic water-soluble polymers with the compatible processing temperature window as per the thermal behavior of OLM. Molecular dynamics (MD) simulations as well assisted in the selection of a carrier. Promising dissolution enhancement was observed with the help of Kollidon VA-64 (VA-64) as a carrier. Optimization of the formulation was executed using the QbD approach with design of experiment as a statistical optimization tool. Interactions between VA-64 and OLM on the atomic level were studied with the help of atomistic MD simulations. Characterization of the optimized extrudates were carried out with scanning electron microscopy, atomic force microscopy, differential scanning calorimetry, thermogravimetric analysis, Fourier transforms infrared spectroscopy, powder X-ray diffraction, in-vitro dissolution study, and in-vivo pharmacokinetic studies. Molecular-level mixing of OLM with VA-64 resulted into glass solution formation which rapidly dissolves (28 times in-vitro dissolution enhancement) in GI tract fluids and instantly gets absorbed into blood circulation. In-vivo pharmacokinetic studies performed in Sprague-Dawley rats reflected superior bioavailability (201.60%) with a significant increase in the Cmax with short Tmax through amorphization of OLM. The in-silico results were in agreement with the observed results of in-vitro dissolution studies and in-vivo pharmacokinetic study.

[Effects of Olmesartan Medoxomil on Patients with Thoracic and Thoracoabdominal Aortic Aneurysm;Evaluation of Anti-hypertensive Effect and Possible Suppression of Aneurysmal Dilation( OLM 40 Study)].

We evaluated the blood pressure( BP) lowering effect and possible suppression of aortic enlargement by olmesartan (OLM) in patients with thoracic and thoracoabdominal aortic aneurysm. In this single center prospective, forced titration study, 50 patients were registered between 2008 and 2011. After all patients received any of OLM 10, 20, and 40 mg/day as an initial dose, the dosage of OLM was titrated up to 40 mg as needed during follow-up period. Home BP (HBPs), aortic aneurysm size assessed by computed tomography (CT) scan, indices of renal function were recorded at 3- and 6-months follow-up. Depending on whether 40 mg/day of prescription was continued for more than 4 months or not, the patients were divided into 2 groups:less than 40 mg (<40 mg) and 40 mg groups. Morning HBPs tended to decrease in both groups, and the percent changes in BPs were essentially the same regardless of dosage. The absolute value of aortic diameter tended to slightly enlarge only in <40 mg group. Also in the <40 mg group, the absolute differences in aortic diameter between those at the time of study registration and each follow-up were 0.5±1.8 mm at 3-month and 1.2±2.3 mm at 6-month (p=0.047),whereas the percent changes were 0.9±3.3% and 2.2±4.5% at 3 and 6 months, respectively( p=0.058). As for 40 mg group, the absolute differences and percent changes did not reach statistically significant increase during the follow-up period. No severe renal dysfunction related to OLM 40 mg prescription was observed. Our results imply that OLM 40 mg may suppress aortic aneurysmal dilation independently of blood pressure lowering effect. Further study with larger number of sample size is warranted to assure this observation.

Design and development of a self-microemulsifying drug delivery system of olmesartan medoxomil for enhanced bioavailability.

Olmesartan medoxomil (OM) is a hydrophobic antihypertensive drug with low bioavailability (26%) and is known to have adverse effects such as celiac disease and enteropathy. The purpose of this study was to develop SMEDDS to increase bioavailability and decrease potential side effects of OM. Hydrophilic lipophilic balance was calculated by testing solubility of OM in different oils, surfactants, and cosurfactants to obtain the most suitable combination of SMEDDS. Pseudoternary phase diagram was used to select the better oil/water formulation of SMEDDS. After a test for 3-month stability, dissolution tests and parallel artificial membrane permeability assay (PAMPA) were conducted to investigate drug solubility and permeability. Biodistribution of fluorescent marked SMEDDS was observed by using in vivo imaging system. The pharmacodynamics of the drug were determined by measuring blood pressure from tails of rats. At the end of the experiment, intestines were examined for adverse effects of OM. Compared with tablet formulation according to the dissolution study, SMEDDS formulation showed 1.67 times improvement in solubility of OM. PAMPA studies suggested a much faster permeability rate for OM SMEDDS compared to the suspension form. Labeled SMEDDS gave 3.96 times stronger fluorescent emission than control dye administered mice in in vivo imaging system (IVIS®) studies, indicating an increased bioavailability. Treating effect of SMEDDS was 3.1 times more efficient compared to suspension in hypertensive rats. It caused neither celiac-like enteropathy nor diarrhea, during 21-day noninvasive blood pressure system (NIBP) assay. Our results suggest that SMEEDS formulation improves dissolution and oral bioavailability of OM while reducing its adverse effects.

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.

Protective effect of angiotensin II receptor blocker against oxidative stress and inflammation in an oral mucositis experimental model.

BACKGROUND: The aim of this study was to evaluate the effect of olmesartan medoxomil (Olme), an angiotensin II receptor antagonist, on oral mucositis (OM) experimental model. METHODS: Oral mucositis was induced in hamsters with 5-fluorouracil (5-FU; 60 mg/kg day 1 and 40 mg/kg day 2). Animals (n = 10/group) were pretreated with oral Olme (1, 5, or 10 mg/kg) or vehicle 30 minutes before 5-FU injection and daily, until day 10. Cheek pouch samples were subjected to histopathological and immunostaining analysis of IL-1ß, TNF-α, IL-10, TGF-ß, macrophage migration inhibitory factor (MIF), SOD, MMP-2 and FGF-2. In addition, IL-1ß and TNF-α levels were evaluated by ELISA. Myeloperoxidase activity (MPO), glutathione (GSH) and malondialdehyde (MDA) levels were investigated by spectroscopic UV/VIS analysis. Reverse transcriptase polymerase chain reactions (RT-PCRs) were used to quantify the expression of IL-1ß, TNF-α, NF-κBp65, MKP1 and ACE2. Inducible nitric oxide synthase (iNOS) and extracellular regulated kinase (ERK)1/2 protein levels were analysed by Western blot. RESULTS: Treatment with 10 mg/kg Olme reduced ulceration, inflammatory cell infiltration, MPO activity, MDA levels, iNOS and ERK1/2 proteins levels, MIF expression and TNF-α and IL-1ß of levels and gene expression. These findings were associated with a significant increase in the immunostaining of IL-10, FGF-2 and TGF-ß. In addition, gene expression of IL-1ß, TNF-α, NF-κBp65 MKP1 and ACE2 was decreased. CONCLUSION: Olmesartan at a dose of 10 mg/kg prevented the mucosal damage and inflammation associated with 5-FU-induced OM, increasing granulation and tissue repair.

The Effect of Ethanol on the Hydrolysis of Ester-Type Drugs by Human Serum Albumin.

Human serum albumin (HSA) has two major ligand-binding sites, sites I and II, and hydrolyzes compounds at both sites. Although the hydrolytic interaction of ester-type drugs with other drugs by HSA has been reported, there are only a few studies concerning the effect of pharmaceutical excipients on the hydrolysis of ester-type drugs by HSA. In the present study, we investigated the effect of ethanol (2 vol%; 345 mM) on the hydrolysis of aspirin, p-nitrophenyl acetate, and olmesartan medoxomil, which are ester-type drugs, with 4 different lots of HSA preparations. The hydrolysis activities of HSA toward aspirin, p-nitrophenyl acetate, and olmesartan medoxomil were measured from the pseudo-first-order degradation rate constant (kobs) of salicylic acid, p-nitrophenol, and olmesartan, respectively, which are the HSA-hydrolyzed products. Ethanol inhibited hydrolysis of aspirin by HSA containing low levels of fatty acids, but not by fatty acid-free HSA. Ethanol inhibited hydrolysis of p-nitrophenyl acetate by both fatty acid-free HSA and HSA containing low levels of fatty acids. In contrast, the hydrolysis of olmesartan medoxomil by HSA was insignificantly inhibited by ethanol, but inhibited not only by warfarin and indomethacin but also by naproxen, which are site I binding drugs and a site II binding drug, respectively. These results suggest that the inhibitory action of ethanol on the hydrolysis of ester-type drugs by HSA differs between site I binding drugs and site II binding drugs.

QbD-driven development and evaluation of nanostructured lipid carriers (NLCs) of Olmesartan medoxomil employing multivariate statistical techniques.

PURPOSE: This research work entails quality by design (QbD)-based systematic development of nanostructured lipid carriers (NLCs) of Olmesartan medoxomil (OLM) with improved biopharmaceutical attributes. METHODS: Quality target product profile (QTPP) was defined and critical quality attributes (CQAs) were earmarked. Solubility of drug was performed in various lipids for screening of them. NLCs were prepared by hot-microemulsion method using solid lipids, liquid lipids and surfactants with maximal solubility. Failure mode and effect analysis (FMEA) was carried out for identifying high risk formulation and process parameters. Further, principal component analysis (PCA) was applied on high risk parameters for evaluating the effect of type and concentration of lipids and surfactants on CQAs. Further, systematic optimization of critical material attributes (CMAs) was carried out using face centered cubic design and optimized formulation was identified in the design space. RESULTS: FMEA and PCA suggested suitability of stearic acid, oleic acid and Tween 80 as the CMAs for NLCs. Response surface optimization helped in identifying the optimized NLC formulation with particle size ∼250 nm, zeta potential <25 mV, entrapment efficiency >75%, in vitro drug release >80% within 6 h. Release kinetic modeling indicated drug release through Fickian-diffusion mechanism. CONCLUSIONS: Overall, these studies indicated successful development of NLCs using multivariate statistical approaches for improved product and process understanding.