Simultaneous LC–MS–MS Analysis of Valsartan and Hydrochlorothiazide in Human Plasma

Development and validation of a stability-indicating, single HPLC method for sacubitril-valsartan and their stereoisomers and identification of forced degradation products using LC-MS/MS

The aim of this research work was to develop and validate a stability-indicating, single reversed-phase HPLC method for the separation of five impurities, including enantiomers, diastereomers, and degradation products in sacubitril-valsartan tablets. The method was developed using a Chiralcel OJ-RH column (150 × 4.6 mm, 5 μm) at 45°C with a gradient program of (T/%B) 0.01/25, 10.0/25, 25/38, 37.0/45, 39.0/25, and 45.0/25 at a flow rate of 0.8 ml/min. Mobile phase A consisted of 1 ml of trifluoroacetic acid in 1000 ml of Milli-Q water. Mobile phase B consisted of 1 ml of trifluoroacetic acid in a mixture of acetonitrile and methanol in the ratio of 950:50 (v/v). Sacubitril, valsartan, and their five impurities were monitored at 254 nm. Degradation was not observed when sacubitril-valsartan was subjected to heat, light, hydrolytic, and oxidation conditions. In acid degradation study (1 N HCl/60°C/2 h) impurity 1 (m/z 383.44) was formed, and in base degradation study (0.1 N NaOH/40°C/1 h) impurities 1 and 5 (m/z 265.35) were formed; both impurities were confirmed using LC-MS. The degradation products, enantiomers, and diastereomers were well separated from sacubitril and valsartan, proving the stability-indicating power of the method. The developed method was validated per the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines. The inter- and intra-day percentage relative standard deviation for sacubitril, valsartan, and their five impurities was less than 5.2%, recovery of the five impurities was between 93 and 105%, and linearity was ≥0.999. The limit of detection was 0.030-0.048 μg/ml, and the limit of quantification was 0.100-0.160 μg/ml.

Quantitative estimation of cilnidipine and valsartan in rat plasma by RP-HPLC: its pharmacokinetic application

Background

Cilnidipine (CLD) and valsartan (VAL) are antihypertensive agents used in the treatment of hypertension. So, pharmacokinetic study of CLD and VAL in rat plasma was carried out using chromatographic method. The chromatographic separation was performed on the Inertsil ODS column, using mobile phase methanol: water 85:15 v/v (pH 3.0) at the flow rate of 1.1 mL/min., detected at 254 nm.

Result

Cilnidipine (CLD) (1 mg/kg) and valsartan (VAL) (1 mg/kg) was administered orally in rats, and blood samples were collected at time intervals of 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, and 24 h after dosing. The retention time of plasma, CLD, and VAL was found to be 2.7, 6.6, and 4.3 min, respectively. The result was validated statistically and by recovery studies. Linearity was acceptable in the range of 1–5 and 8–40 μg/mL for CLD and VAL, respectively. Maximal concentration (Cmax) of CLD and VAL was observed to be 338 ± 13.85 and 1282.21 ± 39.23 (ng/mL). The half-life of CLD and VAL was found to be 1.08 ± 0.21 and 1.43 ± 0.12 h, respectively.

Conclusion

The present method was successfully applied to the pharmacokinetic study of cilnidipine (CLD) and valsartan (VAL) in rat plasma after oral administration.

Novel HPLC-UV method for simultaneous determination of valsartan and atenolol in fixed dosage form; Study of green profile assessment

Aim of this work was to develop the first simple, rapid, green, economical and selective HPLC method for simultaneous quantification of the cited drugs in their challenging binary mixture. The work was motivated by the global trends towards sustainable chemistry in designing eco-friendly mobile system without affecting the analysis parameters. The proposed method was subjected to a greenness profiles using some metrics as Eco-scale.

Materials and methods. This was accomplished under the following chromatographic conditions: HPLC column Discovery C18 (4.6 mm i.d. × 150 mm, 5 μm), column temperature 30 °C, flow rate 1.0 mL/min, mobile phase composed of 20% acetonitrile, 80% of 0.16% ammonium acetate and 0.2% of 1.5 M tetramethylammonium hydroxide (V/V) and signal monitoring at a wavelength of 225 nm and 237 nm.

Results. A conventional mixture of acetonitrile and 0.16% ammonium acetate was tried in different ratios, but the drugs were not well separated. The shortest aliphatic chain cationic ion pair reagent tetramethylammonium hydroxide should not be exchanged with other type similar with this, like tetramethylammonium hydrogen sulfate, it did not work to our experiments. Increasing salt concentration, ammonium acetate, more than 0.2%, pushes the peak of atenolol closer to dead volume, which is negative. Atenolol in their methods for multicomponent mixtures elutes in dead volume, or when retained longer, much stronger, hydrophobic mobile phase should be used if valsartan should be seen in same chromatogram at dissent time. The 237 nm can be chosen as compromise signal for nearly equal peaks height with high sensitivity is not essential. The 225 nm signal shows much higher sensitivity for atenolol and less increase for valsartan peaks, which can be used when higher sensitivities will be essential. Linearity was examined and proven at different concentration levels in the range of working concentration of valsartan (0.16–0.96 mg/mL) and atenolol (0.2–1.20 mg/mL). The high value of recoveries obtained for valsartan and atenolol indicates that the proposed method was found to be accurate. The results of proposed method found to be an excellent green analysis with a score of 84.

Conclusion. A new fast, simple and green, but selective, accurate, precise and robust HPLC-UV method for simultaneous determination of valsartan and atenolol in newly formulated dosage form was developed and many possible variations of the same were suggested. The developed method for the simultaneous quantification of valsartan and atenolol in their challenging binary mixture offers simplicity essential for quality control of a large number of samples in short time intervals, which is necessary for routine analysis. The method was subjected to greenness profile assessment.

Method Validation for Simultaneous Quantification of Olmesartan and Hydrochlorothiazide in Human Plasma Using LC-MS/MS and Its Application Through Bioequivalence Study in Healthy Volunteers

A new, simple, sensitive, selective, rapid, and high-throughput liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for simultaneous quantification of Olmesartan and hydrochlorothiazide in human plasma. Simple liquid–liquid extraction procedure was applied for plasma sample pretreatment using a mixture of diethyl ether and dichloromethane, as an extraction solution. Analytes were separated on UNISOL C18 150*4.6 mm, 5 µm column using methanol, and 2 mM ammonium acetate pH 5.5 (80:20, v/v) as a mobile phase and detected by electrospray ionization in the multiple reaction monitoring (MRM) mode. The mass transition ion pairs were followed in negative ion mode as m/z 445.20 → 148.90 for Olmesartan; m/z 451.40 → 154.30 for Olmesartan D₆ and m/z 295.80 → 205.10 for hydrochlorothiazide; m/z 298.90 → 206.30 for hydrochlorothiazide ¹³C D₂. The method showed excellent linearity (r² > 0.99) over the concentration range of 5.002–2,599.934 ng/ml for Olmesartan and from 3.005 to 499.994 ng/ml for hydrochlorothiazide. Precision (% CV) and accuracy (% bias) for Olmesartan were found in the range of 3.07–9.02% and −5.00–0.00%, respectively. Precision (% CV) and accuracy (% bias) for hydrochlorothiazide were found in the range of 3.32–8.21% and 1.99–3.80%, respectively. This as developed novel and high-throughput liquid–liquid extraction bioanalytical method has substantial innovative value with the benefits of cost effectiveness, good extraction efficiency, shorter analysis run time, low organic solvent consumption, and simpler procedure over the previously reported solid-phase extraction method. The application of this method in pharmacokinetic studies was further demonstrated successfully through a bioequivalence study conducted on healthy human subjects, following oral administration of combined formulation of Olmesartan medoxomil and hydrochlorothiazide in fixed-dose tablet.

Application of an LC-MS/MS method for the analysis of amlodipine, valsartan and hydrochlorothiazide in polypill for a bioequivalence study

A sensitive and selective method has been proposed for the simultaneous determination of amlodipine (AML), valsartan (VAL) and hydrochlorothiazide (HCTZ) in human plasma by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The analytes and their deuterated analogs were quantitatively extracted from 100 µL human plasma by solid phase extraction on Oasis HLB cartridges. The chromatographic separation of the analytes was achieved on a Chromolith RP_18e (100 mm × 4.6 mm) analytical column within 2.5 min. The resolution factor between AML and VAL, AML and HCTZ, and VAL and HCTZ was 2.9, 1.5 and 1.4, respectively, under isocratic conditions. The method was validated over a dynamic concentration range of 0.02–20.0 ng/mL for AML, 5.00–10,000 ng/mL for VAL and 0.20–200 ng/mL for HCTZ. Ion-suppression/enhancement effects were investigated by post-column infusion technique. The mean IS-normalized matrix factors for AML, VAL and HCTZ were 0.992, 0.994 and 0.998, respectively. The intra-batch and inter-batch precision (% CV) across quality control levels was ≤ 5.56% and the recovery was in the range of 93.4%–99.6% for all the analytes. The method was successfully applied to a bioequivalence study of 5 mg AML + 160 mg VAL + 12.5 mg HCTZ tablet formulation (test and reference) in 18 healthy Indian males under fasting. The mean log-transformed ratios of C_max, AUC_0–120h and AUC_0-inf and their 90% CIs were within 90.2%–102.1%. The assay reproducibility was demonstrated by reanalysis of 90 incurred samples.

Bioequivalence study between a fixed-dose single-pill formulation of nebivolol plus hydrochlorothiazide and separate formulations in healthy subjects using high-performance liquid chromatography coupled to tandem mass spectrometry

Systemic arterial hypertension is a major risk factor for cerebrovascular disease. Therefore, adequate control of blood pressure is of enormous importance. One of the many fixed-dose single-pill antihypertensive formulations available on the market is the combination of nebivolol and hydrochlorothiazide. The objective of this study was to develop two distinct high-performance liquid chromatography coupled to tandem mass spectrometry methods to simultaneously quantify nebivolol and hydrochlorothiazide in human plasma. The methods were employed in a bioequivalence study, the first assay involving a nebivolol fixed-dose single-pill formulation based on healthy Brazilian volunteers. Nebilet HCT™ (nebivolol 5 mg + hydrochlorothiazide 12.5 mg tablet, manufactured by Menarini) was the test formulation. The reference formulations were Nebilet™ (nebivolol 5 mg tablet, manufactured by Menarini) and Clorana™ (hydrochlorothiazide 25 mg tablet, manufactured by Sanofi). For both analytes, liquid-liquid extraction was employed for sample preparation and the chromatographic run time was 3.5 min. The limits of quantification validated were 0.02 ng/mL for nebivolol and 1 ng/mL for hydrochlorothiazide. Since the 90% CI for C_max , AUC_(0-last) and AUC_(0-inf) individual test/reference ratios were within the 80-125% interval indicative of bioequivalence, it was concluded that Nebilet HCT™ is bioequivalent to Nebilet™ and Clorana™.

Valsartan

Valsartan is an antihypertensive drug which selectively inhibits angiotensin receptor type II. Generally, valsartan is available as film-coated tablets. This review summarizes thermal analysis, spectroscopy characteristics (UV, IR, MS, and NMR), polymorphism forms, impurities, and related compounds of valsartan. The methods of analysis of valsartan in pharmaceutical dosage forms and in biological fluids using spectrophotometer, CE, TLC, and HPLC methods are discussed in details. Both official and nonofficial methods are described. It is recommended to use LC-MS method for analyzing valsartan in complex matrices such as biological fluids and herbal preparations; in this case, MRM is preferred than SIM method.

Clinical applications of fast liquid chromatography: a review on the analysis of cardiovascular drugs and their metabolites

One of the major challenges facing the medicine today is developing new therapies that enhance human health. To help address these challenges the utilization of analytical technologies and high-throughput automated platforms has been employed; in order to perform more experiments in a shorter time frame with increased data quality. In the last decade various analytical strategies have been established to enhance separation speed and efficiency in liquid chromatography applications. Liquid chromatography is an increasingly important tool for monitoring drugs and their metabolites. Furthermore, liquid chromatography has played an important role in pharmacokinetics and metabolism studies at these drug development stages since its introduction. This paper provides an overview of current trends in fast chromatography for the analysis of cardiovascular drugs and their metabolites in clinical applications. Current trends in fast liquid chromatographic separations involve monolith technologies, fused-core columns, high-temperature liquid chromatography (HTLC) and ultra-high performance liquid chromatography (UHPLC). The high specificity in combination with high sensitivity makes it an attractive complementary method to traditional methodology used for routine applications. The practical aspects of, recent developments in and the present status of fast chromatography for the analysis of biological fluids for therapeutic drug and metabolite monitoring, pharmacokinetic studies and bioequivalence studies are presented.

Simultaneous spectrofluorimetric determination of amlodipine besylate and valsartan in their combined tablets

Amlodipine, a dihydropyridine calcium channel blocker, and valsartan, an angiotensin II receptor blocker, are co-formulated in a single-dose combination for the treatment of hypertension. The combination is used by patients whose blood pressure is not adequately controlled on either component monotherapy. This work describes a simple, sensitive, and reliable spectrofluorimetric method for the simultaneous determination of the two antihypertensive drugs; amlodipine besylate (AML) and valsartan (VAL) in their combined tablets. The method involved measurement of the native fluorescence at 455 nm (λ(Ex) 360 nm) and 378 nm (λ(Ex) 245 nm) for AML and VAL, respectively. Analytical performance of the proposed spectrofluorimetric procedure was statistically validated with respect to linearity, ranges, precision, accuracy, selectivity, robustness, detection, and quantification limits. Regression analysis showed good correlation between fluorescence intensity and concentration over the concentration ranges 0.2-3.6 and 0.008-0.080 µg mL⁻¹ for AML and VAL, respectively. The limits of detection were 0.025 and 0.0012 µg mL⁻¹ for AML and VAL, respectively. The proposed method was successfully applied for the assay of the two drugs in their combined pharmaceutical tablets with recoveries not less than 98.85%. No interference was observed from common pharmaceutical additives. The results were favourably compared with those obtained by a reference spectrophotometric method.