Determination of plasma concentrations of losartan in patients by HPLC using solid phase extraction and UV detection

Preparation of amine-modified lignin and its applicability toward online micro-solid phase extraction of valsartan and losartan in urine samples

In the present work, with the focus on an environmentally-friendly approach, some gels were prepared by synthesizing amine-modified lignin, extracted from sugarcane bagasse, and further esterification and subsequent freeze-drying. These lignin-based gels were implemented as extractive phases in an online micro-solid phase extraction (μSPE) setup in conjunction with high performance liquid chromatography (HPLC) with UV detector. The developed method was used for analytical determination of valsartan and losartan in urine samples. To study the effect of the functionalization process, the efficiency of the unmodified lignin and the functionalized lignin were compared both in the absence and the presence of graphene oxide (GO), presumably as a suitable doping agent. Surprisingly, higher extraction efficiency for the functionalized lignin, compared to both unmodified lignin and GO was observed. The amination process for the prepared gel was analyzed and proved by CHNS elemental analysis and Fourier transform infrared (FT-IR) spectroscopy. The morphology of sorbet was investigated via scanning electron microscope (SEM) imaging and a nanoscale cauliflower feature was observed. The method was optimized and subsequently applied to the analysis of the urine samples. Limits of detection (LOD) of 8 and 6 µg L ^- 1, limits of quantification (LOQ) of 27 and 20 µg L ^- 1 and linear dynamic range (LDR) of 27-2000 and 20-2000 µg L ^- 1 with intraday relative standard deviations (RSD%) of 4 and 3% were obtained for valsartan and losartan, respectively. The whole online μSPE-HPLC setup was conveniently used for the analysis of a patient urine sample and a quantity of 352 μg L ^- 1 of losartan was found. Acceptable relative recoveries (109-108 and 95-94% for valsartan and losartan) revealed the analytical potential of the method for the determination of drugs in complex urine samples.

New Analytical Method for Simultaneous Analysis of Losartan and E-3174 by HPLC in Human Plasma: Application in Pharmaceutical Science

Background:

Losartan, one of the most frequently used drugs in Heart Failure (HF) treatment, could be modified for its bioavailability (BA) by generic formulations and other factors. Hence, the importance of therapeutic drug monitoring.

Objective:

Development and validation of a simplified analytical method using HPLC for simultaneous quantification of losartan and E-3174 in human plasma samples. The method was tested for determining the pharmacokinetics parameters of HF patients.

Methods:

Analytical conditions were optimized using a C18 column (4.6 X 50 mm, 3 μm. Thermo Scientific) at 25ºC. Conditions of mobile phase: a phosphate buffer (0.01M), adjusted to pH 2.5 with phosphoric acid (1M) and Acetonitrile (60:40 v/v). The flow rate was maintained at 1.2 mL/min, on a running time of 5 min and a sample injection volume of 50 μL. Absorbance for measurement of losartan and E-3174 was 200 nm. Pharmacokinetics profiles were determined with Phoenix Win- Nonlin 8.1 software in a non-compartmental model.

Results:

Analytical method developed and validated in this work is precise and accurate for simultaneous determination of losartan and E-3174 in human plasma samples in a range of 0.02 -10 μg/mL. In HF subjects, lower Tmax and higher Cmax for losartan and E-3174 patent than generic formulation were observed, which can be translated into less biological effect and more time to present it by the generic drug.

Conclusion:

The pharmacokinetic profile is dependent on the type of formulation studied (generic/ patent) hence the importance of conducting evaluations in our patients to ensure that the expected therapeutic effect is achieved with treatment administered.

Screen-printed anion-exchange solid-phase extraction: A new strategy for point-of-care determination of angiotensin receptor blockers

A miniaturized system of anion exchange solid phase extraction (SPE) based on a screen-printed electrode was developed as a point of care (POC) device for extraction and quantitative determination of anionic analytes. Nylon 6/polyaniline nanofibers were fabricated by electrospinning and in-situ oxidative polymerization techniques coated on a screen-printed working electrode and characterized by Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) methods. The effects of essential parameters such as desorption conditions, pH of the sample solution, adsorption voltage, adsorption time, and salt concentration on the performance of the method were investigated. To evaluate the performance of the system, angiotensin ΙΙ receptor antagonists, including valsartan, losartan, and irbesartan, were selected as model compounds and analyzed by HPLC/UV after extraction. The limits of detection and quantification were ranging between 0.4 and 0.9 μg L^-1 and 1.3-3.0 μg L^-1, respectively. The linear dynamic range for Losartan, Irbesartan, and Valsartan was 2-400, 4-1000, and 2-400 μg L^-1, respectively, with R² > 0.991. Finally, the method was applied for the determination of ARA-IIs in human blood plasma samples, and relative recoveries in the range of 89.0-107.8% with relative standard deviation (RSDs (≤8.9% were obtained.

Rapid ultra-performance liquid chromatography assay of losartan potassium in bulk and formulations

Background

Losartan potassium is a non-peptide AT1 receptor drug used in the treatment of hypertension.

Methods

A simple, rapid, sensitive, and validated isocratic reverse-phase ultra-performance liquid chromatographic (RP-UPLC) method was developed and validated for the determination of losartan potassium (LOS) in bulk drug and tablets. The assay was developed using Waters Acquity BEH C18 (100 mm × 2.1 mm), 1.7-μm column with a mobile phase consisting of a mixture of phosphate buffer (pH 3.2) and acetonitrile (50:50 v/v).

Results

An assay with a total run time of only 5 min was developed. The method monitored at 245 nm exhibited linearity over a concentration range of 2.0 to 15.0 μg mL−1 LOS. The limits of detection and quantification (signal-to-noise ratio (S/N) = 10) were found be 0.018 and 0.054 μg mL−1, respectively. The intraday and interday RSDs were less than 1.0%. The method was validated by the determination of LOS levels in tablets where the percentage on the label claim was 100 ± 2. The accuracy of the method was further ascertained by recovery studies via the standard addition procedure, which yielded satisfactory results.

Conclusion

A rapid UPLC assay of LOS in bulk drug and tablets was developed and validated.

A new spectrofluorimetric method for determination of losartan potassium in rabbit plasma and its application to pharmacokinetic study

A new spectrofluorimetric method to determine losartan potassium (LP) in rabbit plasma is described. The method was based on measuring the native fluorescence of LP in acidic medium. Optimum excitation and emission wavelengths were found to be 248 nm and 410 nm, respectively, in methanol that was diluted with a sulfurous acid solution LP was extracted from rabbit plasma by methyl-tertiary-butyl-ether in acidic media and then back extracted with NaOH. The calibration curves were linear between 0.025 and 0.5 µg/mL with a lower limit of detection 0.004 µg/mL. Precision and accuracy values of the method were calculated as lower than 4.97% and ± 5.68, respectively and the recovery of LP from rabbit plasma was higher than 91.1%. In addition, stability studies of LP in rabbit plasma were carried out and demonstrated its good stability at - 20 °C and at room temperature. The developed and validated method was successfully applied for estimating the pharmacokinetic parameters of LP following oral administrations of a single 10 mg LP/kg to rabbits and it could be concluded that the method can be applied to clinical trials.

Analysis of Sartans: a review

The risk of cardiovascular diseases is closely related to hypertension, high cholesterol levels, and diabetes. When these risk factors appear together they are referred to as a metabolic syndrome. In the treatment of cardiovascular diseases, a combination of antihypertensive, hypolipemiant, and antidiabetic drugs is often applied. Diuretics (chlortalidone, hydrochlorothiazide, etc.) and angiotensin II receptors antagonist (sartans) are used to control hypertension, whereas statins (fluvastatin, simvastatin, etc.) are used to reduce cholesterol levels. This review is concerned with methods for the analysis of sartans in various matrices, such as pharmaceutical formulations, environmental and biological samples, and discusses the current status of stability studies of sartans . It also presents analytical methods for the simultaneous determination of sartans, diuretics, and statins.

Influence of compound danshen tablet on the pharmacokinetics of losartan and its metabolite EXP3174 by liquid chromatography coupled with mass spectrometry

Losartan is an effective anti-hypotension drug frequently used in clinic. Compound danshen tablet (CDST) is an important traditional Chinese multiherbal formula composed of Danshen, Sanqi and Bingpian, which is widely used for the treatment of cardiovascular and cerebrovascular diseases in China. More often, losartan and CDST are simultaneously used for the treatment of anti-hypertension in the clinic. The aim of this study was to compare the pharmacokinetics of losartan and EXP3174 after oral administration of single losartan and both losartan and CDST, and to investigate the influence of CDST on the pharmacokinetics of losartan and its metabolite EXP3174. Male Sprague-Dawley rats were randomly assigned to two groups: a losartan-only group and a losartan and CDST group. Plasma concentrations of losartan and EXP3174 were determined by LC-MS at designated points after drug administration, and the main pharmacokinetic parameters were estimated. It was found that there were significant differences (p < 0.05) between the pharmacokinetic parameters of losartan and EXP3174, which showed that CDST influenced the metabolism and excretion of losartan in vivo. The result could be used for clinical medication guidance of losartan and CDST to avoid the occurrence of adverse reactions.

Rapid determination of losartan and losartan acid in human plasma by multiplexed LC-MS/MS

A rapid LC-MS/MS method has been developed and validated for the determination of losartan (LOS) and its metabolite losartan acid (LA) (EXP-3174) in human plasma using multiplexing technique (two HPLC units connected to one MS/MS). LOS and LA were extracted from human plasma by SPE technique using Oasis HLB cartridge without evaporation and reconstitution steps. Hydroflumethiazide (HFTZ) was used as an internal standard (IS). The analytes were separated on Zorbax SB C-18 column. The mass transition [M-H] ions used for detection were m/z 421.0 --> 127.0 for LOS, m/z 435.0 --> 157.0 for LA, and m/z 330.0 --> 239.0 for HFTZ. The proposed method was validated over the concentration range of 2.5-2000 ng/mL for LOS and 5.0-3000 ng/mL for LA with correlation coefficient > or = 0.9993. The overall recoveries for LOS, LA, and IS were 96.53, 99.86, and 94.16%, respectively. Total MS run time was 2.0 min/sample. The validated method has been successfully used to analyze human plasma samples for applications in 100 mg fasted and fed pharmacokinetic studies.

Permeation of losartan across human respiratory epithelium: an in vitro study with Calu-3 cells

The potential for nasal delivery of losartan, a drug with poor oral bioavailability, was investigated using Calu-3 cells. Epithelial permeation of the drug with or without dimethyl-beta-cyclodextrin (DM-beta-CD) and glycocholate was investigated. Possible transport mechanism of the compound and epithelial mucosal tolerance were screened. Reversibility of epithelial membrane perturbation was also investigated by measuring transepithelial electrical resistance (TEER) recovery over a 24-h period following drug formulation exposure. The permeability coefficient of losartan was 1.3 + or - 0.5 x 10(-6) cm s(-1). This flux was not significantly different from that of formulations containing DM-beta-CD (0.5 and 1.0%) or glycocholate (0.5%). However, the formulation with 1.0% glycocholate significantly increased losartan permeation 7-fold. Losartan flux across the cells was concentration-dependent. Serosal to mucosal permeation was significantly higher than mucosal to serosal permeation. Concentration-dependency, as well as polarity in transport indicated that the flux of the compound across Calu-3 cells was not limited to passive diffusion. Cells exposed to DM-beta-CD (0.5 and 1.0%) and glycocholate (0.5%) caused no significant change in TEER and mitochondrial dehydrogenase activity (MDH). The results of the study showed that losartan may be a suitable drug candidate for nasal delivery.

Pharmacokinetic study of a new angiotensin-AT1 antagonist by HPLC

Recently an innovative novel class angiotensin-AT1 antagonist has been developed by Rottapharm. In this study, we present a validated method for detecting CR 3834 in biological matrices using high-performance liquid chromatography (HPLC) with diode array detection. After oral administration (30mg/kg) to Wistar rats, the plasma and urine concentrations of CR 3834 and its potential metabolic products were determined. Moreover, the plasmatic time course in rats has been determined after intravenous (IV) administration of CR 3834 (5mg/kg). Biological samples (0.5ml of plasma and 1ml of urine) were purified using solid-phase extraction (SPE) of analytes and the internal standard Idebenone, 2,3-dimethoxy-5-methyl-6-(10-hydroxydecyl)-1-4-benzoquinone. A chromatographic separation was performed on an Adsorboshere C18 at 25 degrees C, with a pre-column of the same matrix; the eluent was made up of acetonitrile/acidified water with CF3COOH (pH 2.01) in ratio of 75:25 (v/v); the flow rate was 1.0ml/min and a 100microl loop. The lower limit of detection (LOD) was taken as 25ng/ml in plasma and 50ng/ml in urine samples. The lower limit of quantification (LOQ) was taken as 0.1 and 0.2microg/ml in plasma and urine samples, respectively. The procedures were validated according to international standards with a good reproducibility and linear response (r=0.9916 in plasma; r=0.9997 in urine). The coefficients of variation inter assay ranged between 2.579 and 4.951% in plasma, and between 0.813 and 2.460% in urine. Mean recovery for CR 3834 was 79% in plasma and 97% in urine samples. The experiments performed demonstrated that the method presented was suitable for determining this new angiotensin-AT1 antagonist in rat plasma and urine.

Simultaneous determination of losartan, EXP-3174 and hydrochlorothiazide in plasma via fully automated 96-well-format-based solid-phase extraction and liquid chromatography–negative electrospray tandem mass spectrometry

An automated, sensitive and high-throughput liquid chromatographic/electrospray tandem mass spectrometric (LC-MS/MS) assay was developed for the simultaneous determination of losartan (LOS), its major circulating metabolite EXP-3174 and hydrochlorothiazide (HCTZ) in human plasma. LOS and HCTZ coexist in the same drug formulation, and this is the first method that enables the simultaneous determination of both drugs along with the active metabolite of LOS. Since these drugs have different physicochemical properties, the employment of a liquid-liquid extraction (LLE) protocol was precluded. A fully automated solid-phase extraction (SPE) protocol, based on 96-well format plates, was used to isolate these compounds and furosemide (internal standard, IS) from plasma. Washing and elution steps were amended accordingly in order to minimize any matrix effect from components of the plasma without reducing the elution of the molecules of interest. The compounds were eluted from a C18 column and detected with an API 3000 triple-quadrupole mass spectrometer using negative electrospray ionization and multiple reaction monitoring (MRM). The assay was linear over the range 1.00-400 ng/mL for LOS and EXP-3174 and 0.500-200 ng/mL for HCTZ, respectively, when 200 microl of plasma was used in the extraction. The overall intra- and interassay variations were within acceptance limits. The analysis time for each sample was 4 min, and more than 300 samples could be analyzed in one day by running the system overnight. The assay was simple, highly sensitive, selective, precise, fast, and it enables the reliable determination of LOS, EXP-3174 and HCTZ in pharmacokinetic or bioequivalence studies after per os administration of a single tablet containing both drugs.

Optimizationvia experimental design of an SPE-HPLC-UV-fluorescence method for the determination of valsartan and its metabolite in human plasma samples

A chemometric approach was applied for the optimization of the extraction and separation of the antihypertensive drug valsartan and its metabolite valeryl-4-hydroxy-valsartan from human plasma samples. Due to the high number of experimental and response variables to be studied, fractional factorial design (FFD) and central composite design (CCD) were used to optimize the HPLC-UV-fluorescence method. First, the significant variables were chosen with the help of FFD; then, a CCD was run to obtain the optimal values for the significant variables. The measured responses were the corrected areas of the two analytes and the resolution between the chromatographic peaks. Separation of valsartan, its metabolite valeryl-4-hydroxy-valsartan and candesartan M1, used as internal standard, was made using an Atlantis dC18 100 mm x 3.9 mm id, 100 angstroms, 3 microm chromatographic column. The mobile phase was run in gradient elution mode and consisted of ACN with 0.025% TFA and a 5 mM phosphate buffer with 0.025% TFA at pH 2.5. The initial percentage of ACN was 32% with a stepness of 4.5%/min to reach the 50%. A flow rate of 1.30 mL/min was applied throughout the chromatographic run, and the column temperature was kept to 40+/-0.2 degrees C. In the SPE procedure, experimental design was also used in order at achieve a maximum recovery percentage and extracts free from plasma interferences. The extraction procedure for spiked human plasma samples was carried out using C8 cartridges, phosphate buffer (pH 2, 60 mM) as conditioning agent, a washing step with methanol-phosphate buffer (40:60 v/v), a drying step of 8 min, and diethyl ether as eluent. The SPE-HPLC-UV-fluorescence method developed allowed the separation and quantitation of valsartan and its metabolite from human plasma samples with an adequate resolution and a total analysis time of 1 h.

Sensitive SPE–HPLC method to determine a novel angiotensin-AT1 antagonist in biological samples

A high-performance liquid chromatography (HPLC)-method after solid-phase extraction (SPE) has been developed in order to determine a new angiotensin-AT1 antagonist, i.e. CR 3210 (C27H24N8; MW = 460.54), 4-[4-[(2-ethyl-5,7-dimethylimidazo[4,5-b]pyridin-3-yl)methyl]phenyl]-3-(2H-tetrazol-5-yl)quinoline in rat plasma and urine after oral administration to Sprague-Dawley rats. CR 3210 and the internal standard (IS) CR 1505 (loxiglumide), i.e. 4-[(3,4-dichlorobenzoyl)amino]-5-[(3-methoxypropyl)pentylamino]-5-oxopentanoic acid, were isolated from rat urine and plasma by solid-phase extraction. The procedure was optimized regarding the sorbent extraction material, the pH in the conditioning solution, the washing step, the dry time and the type of elution solvent. The separation was performed by reversed-phase high-performance liquid chromatography with ultraviolet detection. The samples were injected onto the analytical column (Tracer Extrasil ODS1) and detected at 238 nm, giving a capacity factor of 1.87 for CR 3210 and 1.10 for the internal standard. The selectivity of the method was satisfactory. The mean recovery of CR 3210 from spiked rat plasma was 68.5 at 75 ng/ml and 80.9 at 3000 ng/ml; the mean recovery of CR 3210 from spiked rat urine was 69.9 at 75 ng/ml and 78.6 at 3000 ng/ml. The lower limit of detection (LOD) was 14 ng/ml in plasma and 22 ng/ml in urine samples. The lower limit of quantification (LOQ) was taken as 30 ng/ml, the lowest calibration standard using 500 microl rat plasma and urine. The procedures were validated according to international standards with a good reproducibility and linear response from 30 to 3000 ng/ml, for either plasma or urine. The sensitivity of the method allowed for its application to pharmacokinetic studies.

Determination of a novel angiotensin-AT1 antagonist CR 3210 in biological samples by HPLC

A simple and sensitive method for the determination of a new angiotensin-AT(1) antagonist i.e. CR 3210, 4-[4-[(2-ethyl-5,7-dimethylimidazo[4,5-b]pyridin-3-yl)methyl]phenyl]-3-(2H-tetrazol-5-yl)quinoline, is described. The assay was utilised to describe the pharmacokinetic profile of the title compound after intravenous and intraperitoneal administration to Sprague Dawley rats. CR 3210 and the internal standard CR 1505 (loxiglumide, 4-[(3,4-dichlorobenzoyl)amino-5-[(3-methoxypropyl)pentylamino]-5-oxopentanoic acid) were isolated from rat plasma by solid-phase extraction. The sorbent extraction material along with the pH in the conditioning solution and the washing volume were considered pivotal parameters for the optimisation of the procedure. The separations were performed by reversed-phase high-performance liquid chromatography with ultraviolet detection. The samples were injected onto the analytical column (Tracer Extrasil ODS1) and detected at 238 nm, giving a retention time of 6.19 min for CR 3210 and 4.39 min for the internal standard, respectively. The selectivity of the method showed to be satisfactory. The mean recovery of CR 3210 from spiked rat plasma was 80.3 at 1 microg/ml and 79.9 at 2 microg/ml. The lower limit of detection (LOD) was taken as 0.014 microg/ml in plasma samples. The lower limit of quantification (LOQ) was taken as 0.02 microg/ml, the lowest calibration standard using 500 microg rat plasma. The procedures were validated according to international standards with a good reproducibility and linear response from 0.02 to 2 microg/ml. The sensitivity of the method allowed for its application to pharmacokinetic studies. The maximal concentration was detected 5' after the IV administration, whereas no significant absorption was evident after IP administration of CR 3210 to Sprague-Dawley rats. Our study suggests the absence of extensive bio-transformation of the drug in vivo, supported by the evidence that no metabolites were detected in plasma samples.