Analysis of Fixed-Dose Combination of Three Antihypertensive Drugs by a Green and Quality by Design Approach.

This paper presents the result of a combined employment of Analytical Quality-by-Design and Green Analytical Chemistry principles for the development of a robust high-performance liquid chromatography method for simultaneous determination of fixed-dose combination of three drugs, perindopril tert-butylamine, amlodipine besylate and indapamide. Optimum conditions were achieved on ZORBAX Eclipse XDB-C18 column (150 mm × 4.6 mm, 5 µm particle size), the mobile phase comprising acetonitrile and phosphate buffer (30 mM, pH 2.7) in the ratio 34:66 (v/v), the flow rate of 1 mL min-1, injection volume of 10 µL and UV detection at 210 nm. By assigning the design space from the overlay plot, the regions within which the robustness of the method is achieved were defined and confirmed by Dong's algorithm calculations. The proposed method was validated and shown to be applicable for the determination of the three drugs in commercially available tablets. In addition, the impact of the method on the environment was assessed through four different analytical tools: National Environmental Methods Index, Analytical Eco-Scale, Green Analytical Procedure Index and Assessment of Green Profile. The proposed method was determined to be greener, with minimal impact on the environment with regard to waste production, energy consumption and use of hazardous chemicals.

In Vitro Dissolution Profile of Antihypertensive Mixture: Comparison Between Multivariate Methods and Statistical and Graphical Representation of Different Univariate Spectrophotometric Data.

BACKGROUND: Triplixam® is a new antihypertensive drug combination consisting of perindopril, amlodipine, and indapamide, which have a synergistic mechanism of action in combination with each other. OBJECTIVE: Comparative study of different spectrophotometric approaches used for the simultaneous determination of perindopril, indapamide, and amlodipine in bulk powder and in dosage form Triplixam. METHOD: The methods include univariate and multivariate spectrophotometric methods depending on either mathematical calculation or graphical representation of data. For the univariate methods: perindopril was resolved from other components using constant multiplication followed by spectrum subtraction resolution technique, and then two base point, AUC, constant value, and concentration value (CNV) methods were applied. For both amlodipine and indapamide: constant multiplication resolution technique was used, and then constant value and CNV methods were applied. CNV depends on graphical representation of data rather than statistical data. PLS and PCR chemometric assisted spectrophotometric techniques were also applied. The proposed methods are considered a green alternative to the reported methods as the greenness of the proposed methods was evaluated qualitatively and quantitatively by four green analytical evaluation tools. RESULTS: The methods were applied for the analysis of the mixture in the pharmaceutical dosage form Triplixam and in vitro release at intestinal pH (7.4) using a USP dissolution tester. CONCLUSIONS: The proposed green analytical methods are considered to be greener than the reported methods and simpler, so they could be used as an alternative for routine analysis of the mixture in quality control laboratories for the reason of their accurate results beside minimum manipulation steps that reduced the error and time required of the analysis with no harmful effect on analyst health as well as the environment. HIGHLIGHTS: The study was the first in vitro dissolution profiling of perindopril, amlodipine, and indapamide. The developed methods were excellent green methods without compromising the analytical criteria.

A Validated HPLC Method for Simultaneous Determination of Perindopril Arginine, Amlodipine, and Indapamide: Application in Bulk and in Different Pharmaceutical Dosage Forms.

A simple, accurate, and precise LC method with a reversed stationary phase was developed and validated for the determination of perindopril (PER) arginine, amlodipine (AML), and indapamide (IND) alone and in binary mixtures (PER arginine is found in two dosage forms, i.e., with either AML or IND). Chromatographic separation was carried out on a BDS Hypersil® C18 column (100 × 3 mm, 5 µm). The mobile phase, consisting of 0.05 M potassium dihydrogen phosphate buffer (pH 2.6)-methanol (50 + 50, v/v), was pumped through the column whose temperature was maintained at 50°C at a flow rate of 0.6 mL/min using isocratic elution, and UV detection at 215 nm was performed. Acceptable values of linearity, accuracy, and precision of the method were found over the concentration ranges of 5-80 µg/mL PER, 2.5-80 µg/mL AML, and 0.5-20 µg/mL IND. The proposed chromatographic method was statistically compared to that of reference methods using one-way analysis of variance. The results showed that there was no significant difference between the methods. The developed method proved reliable for use in accurate QC of the drugs in their pharmaceutical preparations.

Setting local rank constraints by orthogonal projections for image resolution analysis: application to the determination of a low dose pharmaceutical compound.

Raman chemical imaging provides chemical and spatial information about pharmaceutical drug product. By using resolution methods on acquired spectra, the objective is to calculate pure spectra and distribution maps of image compounds. With multivariate curve resolution-alternating least squares, constraints are used to improve the performance of the resolution and to decrease the ambiguity linked to the final solution. Non negativity and spatial local rank constraints have been identified as the most powerful constraints to be used. In this work, an alternative method to set local rank constraints is proposed. The method is based on orthogonal projections pretreatment. For each drug product compound, raw Raman spectra are orthogonally projected to a basis including all the variability from the formulation compounds other than the product of interest. Presence or absence of the compound of interest is obtained by observing the correlations between the orthogonal projected spectra and a pure spectrum orthogonally projected to the same basis. By selecting an appropriate threshold, maps of presence/absence of compounds can be set up for all the product compounds. This method appears as a powerful approach to identify a low dose compound within a pharmaceutical drug product. The maps of presence/absence of compounds can be used as local rank constraints in resolution methods, such as multivariate curve resolution-alternating least squares process in order to improve the resolution of the system. The method proposed is particularly suited for pharmaceutical systems, where the identity of all compounds in the formulations is known and, therefore, the space of interferences can be well defined.

Preconcentration of indapamide from human urine using molecularly imprinted solid-phase extraction.

A simple, sensitive, and selective molecularly imprinted solid-phase extraction and spectrophotometric method has been developed for the clean-up and preconcentration of indapamide from human urine. Molecularly imprinted polymers were prepared by a non-covalent imprinting approach using indapamide as a template molecule, 2-(trifluoromethyl) acrylic acid as a functional monomer, ethylene glycol dimethacrylate as a crosslinker, N,N-azobisisobutyronitrile as a thermal initiator and acetonitrile as a porogenic solvent. A non-imprinted polymer was also prepared in the same way, but in the absence of template. Molecularly imprinted polymer and non-imprinted polymer sorbents were dry-packed into solid-phase extraction cartridges. Eluates from cartridges were analyzed using a spectrophotometer for the determination of indapamide by referring to the calibration curve in the range 0.14-1.50 µg/mL. Preconcentration factor, limit of detection, and limit of quantification were 16.30, 0.025 µg/mL, and 0.075 µg/mL, respectively. A relatively high imprinting factor (9.3) was also achieved and recovery values for the indapamide spiked into human urine were in the range of 80.1-81.2%. In addition, relatively low within-day (0.17-0.42%) and between-day (1.1-1.4%) precision values were obtained as well. The proposed molecularly imprinted solid-phase extraction and spectrophotometric method was successfully applied to selective extraction, preconcentration, and determination of indapamide from human urine samples.

Pharmacokinetics and bioequivalence study of two indapamide formulations after single-dose administration in healthy Chinese male volunteers.

The pharmacokinetics and relative bioavailability/bioequivalence of 2 formulations of indapamide were assessed in this paper. The study was conducted in 20 healthy Chinese male volunteers according to an open, randomized, single-blind, 2-way crossover study design with a wash-out phase of 7 days. Blood samples for pharmacokinetic profiling were taken up to 84 h post-dose, and indapamide concentrations in plasma were determined by a validated liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method. Based on the plasma concentration-time data of each individual in each period, pharmacokinetic parameters, Cmax, AUC0-τ, AUC0-∞ and t1/2, were calculated by non-compartmental analysis. Pharmacokinetic parameters for test and reference formulations were analyzed statistically to assess bioequivalence of the 2 formulations. The values of Cmax, Tmax, t1/2, AUC0-τ, AUC0-∞ for test and reference formulations were 49.53±5.53 and 47.79±4.68 ng/mL, 1.9±0.6 and 2.0±0.5 h, 22.49±5.93 and 23.23±4.48 h, 859.51±160.92 and 840.90±170.62 ng · h/mL, 934.35±190.60 and 919.52±179.74 ng · h/mL, respectively. The 90% confidence intervals of the T/R-ratios of logarithmically transformed data were within the accepted range of 80-125%. It showed that the 2 formulations of indapamide were bioequivalent. Both preparations were well tolerated and no adverse reactions were found throughout the study.

High-throughput NIR-chemometric methods for determination of drug content and pharmaceutical properties of indapamide powder blends for tabletting.

This paper describes the development and application of NIR-chemometric methods for active content assay and pharmaceutical characterization (granulometric analysis and flowability assessment) of indapamide powder blends for tabletting. Indapamide powder blends were prepared and their NIR spectra were recorded in reflectance mode. Partial least-squares (PLS) regression followed by leave-one-out cross-validation was used to develop calibration models for predicting the indapamide content and pharmaceutical properties. The method for indapamide assay was validated in terms of trueness, precision, accuracy. The near infrared based property predictions were compared with the reference method results and no significant differences were found between the reference and predicted characteristics. The developed NIR-chemometric methods can be useful tools for prediction of active content, granulometric properties and parameters related to flowability of pharmaceutical powders.

Assessing the removal of pharmaceuticals and personal care products in a full-scale activated sludge plant.

PURPOSE: This study aimed to investigate the removal mechanisms of pharmaceutical active compounds (PhACs) and musks in a wastewater treatment plant (WWTP). Biological removal and adsorption in the activated sludge tank as well as the effect of UV radiation used for disinfection purposes were considered when performing a mass balance on the WWTP throughout a 2-week sampling campaign. METHODS: Solid-phase extraction (SPE) was carried out to analyse the PhACs in the influent and effluent samples. Ultrasonic solvent extraction was used before SPE for PhACs analysis in sludge samples. PhAC extracts were analysed by LC-MS. Solid-phase microextraction of liquid and sludge samples was used for the analysis of musks, which were detected by GC-MS. The fluxes of the most abundant compounds (13 PhACs and 5 musks) out of 79 compounds studied were used to perform the mass balance on the WWTP. RESULTS: Results show that incomplete removal of diclofenac, the compound that was found in the highest abundance, was observed via biodegradation and adsorption, and that UV photolysis was the main removal mechanism for this compound. The effect of adsorption to the secondary sludge was often negligible for the PhACs, with the exceptions of diclofenac, etofenamate, hydroxyzine and indapamide. However, the musks showed a high level of adsorption to the sludge. UV radiation had an important role in reducing the concentration of some of the target compounds (e.g. diclofenac, ibuprofen, clorazepate, indapamide, enalapril and atenolol) not removed in the activated sludge tank. CONCLUSIONS: The main removal mechanism of PhACs and musks studied in the WWTP was most often biological (45%), followed by adsorption (33%) and by UV radiation (22%). In the majority of the cases, the WWTP achieved >75% removal of the most detected PhACs and musks, with the exception of diclofenac.

Highly sensitive transient isotachophoresis sample stacking coupling with capillary electrophoresis-amperometric detection for analysis of doping substances.

A simple and effective method of capillary electrophoresis-amperometric detection (CE-AD) coupled with transient isotachophoresis (tITP) was developed for the trace determination of doping substances. Compared with the conventional capillary electrophoresis method, the maximum enhancement factor in terms of peak heights was up to 5500-fold when the tITP technique was adopted. Under the optimum conditions, the detection limit (S/N=3) for methylephedrine (MDP), celiprolol (CEL), sotalol (SOT) and indapamide (IDP) were 4.2 x 10(-14), 6.3 x 10(-13), 5.8 x 10(-14) and 9.5 x 10(-13)molL(-1), respectively. The RSDs of four analytes were 1.0-2.3% for migration time and 2.6-3.8% for peak current, respectively. The proposed method was successfully applied to determine the contents of SOT and IDP in real urine sample, and the excretion curve of IDP within 48h was also investigated. The recoveries of the four doping in urine ranged from 90.0 to 102%.

Development and validation of a stability-indicating assay method for simultaneous determination of perindopril and indapamide in combined dosage form by reversed-phase high-performance liquid chromatography.

An approach of forced degradation study was successfully applied for the development of a stability-indicating assay method for simultaneous determination of perindopril and indapamide in a formulation in the presence of its degradation products. The method showed adequate separation of perindopril and indapamide from their associated main impurities and degradation products. Separation was achieved on an XTerra RP18, 5 microm, 150 x 4.6 mm id column at 55 degrees C by using the mobile phase NaH2PO4 buffer (pH 2.0; 0.005 M)-acetonitrile (75 + 25, v/v) at a flow rate of 1 mL/min and UV detection at 215 nm. Comprehensive stress testing of perindopril and indapamide was carried out according to the International Conference on Harmonization (ICH) guideline Q1A (R2). The specificity of the method was determined by assessing interference from the placebo and by stress testing of the drug (forced degradation). The drug was subjected to acid hydrolysis, base hydrolysis, oxidation, dry heat, and photolysis to apply stress conditions. There were no other coeluting, interfering peaks from excipients, impurities, or degradation products due to variable stress conditions, and the method was specific for determination of perindopril and indapamide in the presence of degradation products. The method was validated in terms of linearity, precision, accuracy, specificity, robustness, and solution stability. The linearity of the proposed method was investigated in the range of 24-56 microg/mL (r2 = 0.9993) for perindopril and 7.5-17.5 microg/mL (r2 = 0.9992) for indapamide. Degradation products produced as a result of stress studies did not interfere with the detection of perindopril and indapamide, and the assay can thus be considered stability indicating.

Solid state investigation and characterization of the polymorphic and pseudopolymorphic forms of indapamide.

Solid state investigation and polymorphic screening of indapamide, a diuretic drug generally used for the treatment of hypertension was carried out. Substantial differences were obtained in the solid state properties of crystals confirming the existence of a polymorphic and three pseudopolymorphic forms of indapamide. Detailed methods of preparation of the polymorphs and pseudopolymorphs are described. X-ray powder diffraction (XRPD), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed for the characterization of different crystalline forms of indapamide. The stoichiometric ratio of solvents associated with the drug molecules in the pseudopolymorphic forms were calculated using TGA, nuclear magnetic resonance (NMR) spectroscopy and headspace gas chromatographic (HS-GC) analysis.

Exploiting the oxidative coupling reaction of MBTH for indapamide determination.

The oxidative coupling reaction between aromatic amines and 3-methylbenzothiazolin-2-one hydrazone (MBTH) in the presence of cerium(IV) has been extensively used with quantitative analytical purposes. Nevertheless, a literature survey reveals that different wavelengths (visible range) can be used to monitor the reaction products when using MBTH and Ce(IV) as colour developing reagents. In the present work, the oxidative coupling reaction of indapamide (an oral antihypertensive diuretic drug) with MBTH in the presence of cerium(IV) was evaluated using distinct reaction approaches and was implemented in an automated multipumping flow system. The developed methodology was applied in the spectrophotometric control of the drug in pharmaceutical formulations. The optimization of the proposed multipumping flow system was performed by using an experimental design approach, namely by exploiting a Plackett-Burman factorial design and a central cubic faces design. This work revealed the formation of products with different reaction kinetics, chemical stabilities and absorbance spectra, depending on the sequence of addition of the reagents. By exploiting a specific sequence in the addition of reagents, the proposed automatic system allowed the rapid quantification of indapamide in pharmaceutical formulations, with a determination rate of about 25 h(-1), and a relative deviation under 2.1% when comparing with the reference procedure. Detection limit was approximately 1 mg L(-1).

A selective HPLC method for the determination of indapamide in human whole blood: application to a bioequivalence study in Chinese volunteers.

Indapamide was extracted from human whole blood with diethyl ether and was determined by a HPLC-UV method using an Inertsil ODS-3 column and an isocratic mobile phase consisting of 55% buffer solution (2 g KH(2)PO(4), 3 ml H(3)PO(4) and 3.5 ml triethylamine in 1l of H(2)O), 40% acetonitrile and 5% methanol for 12.5 min, and then a gradient flush from 100% isocratic to a mixture of 20% isocratic mobile phase and 80% methanol for 3 min. Indapamide and glipizide (internal standard) were eluted from the column at about 10.5 and 12.8 min, respectively. The method had within day precision values in the range +/- 1.2 to +/- 9.7% (n = 5) and between day precision in the range +/- 3.3 to +/- 9.7%. The method was linear over the range of 10-400 ng/ml of indapamide in blood (R = 0.999). The LOQ (s/n = 10) of the method was 10 ng/ml. The method was applied in a study of the pharmacokinetics and bioequivalence of generic indapamide capsules (2.5 mg) in comparison with reference indapamide tablets (2.5mg), in 20 healthy male Chinese volunteers. The mean values of major pharmacokinetic parameters of C(max), AUC(0-48), AUC(0-infinity), T(max), and t(1/2) of indapamide in healthy male Chinese volunteers after po a single 5 mg dose for the test product were 331.0 +/- 39.2 ng/ml, 6,193.7+/-873.5 ng h/ml, 7311.8+/-1,232.3 ng h/ml, 3.2+/-0.9h, and 17.3+/-2.8 h, respectively. There was no significant differences between the two formulations.

Optimization of two flow-injection spectrophotometric methods for the determination of indapamide in pharmaceutical dosage forms.

Multivariate experimental design has been used to optimize 2 flow-injection spectrophotometric methods for the determination of indapamide in pharmaceutical dosage forms, both pure and commercial tablets. The methods are based on the oxidation of this drug with iron (III) in acidic medium and the subsequent formation of an intensive orange-red complex between the liberated iron (II) and 2,2'-bipyridyl or 1,10-phenanthroline reagents. Plackett-Burman designs were applied as a screening method to evaluate the most significant factors with few experiments. Central composite 2(3)+ star designs were performed to evaluate the response surfaces. The methods have been fully validated and were applied successfully to the determination of indapamide in pure and pharmaceutical forms with good accuracy and precision. Therefore, the 2 proposed procedures are simple, inexpensive, and rapid flow methods for the routine determination of indapamide in pharmaceutical preparations.

Flow-injection inhibition chemiluminescence determination of indapamide based on luminol-ferricyanide reaction.

A novel and sensitive chemiluminescence (CL) method for the determination of indapamide coupled with flow-injection analysis (FIA) technique is developed in this paper. It is based on the inhibition effect of the studied drug on the chemiluminescence emission of luminol-potassium ferricyanide system. Under the optimum conditions, the decreased CL intensity is proportional with the concentration of indapamide in the range of 1 x 10(-8) to 1.0 x 10(-6) g ml(-1). The detection limit is 3.4 x 10(-9) g ml(-1) (3sigma). A complete analysis could be performed in 45 s including washing and sampling, giving a throughout of about 90 h(-1). The relative standard deviation (R.S.D.) for 11 parallel measurements of 1.0 x 10(-7) g ml(-1) indapamide is 3.0%. The proposed method has been applied for the determination of indapamide in its pharmaceutical formulations. The results obtained compared well with those by an official method. The possible inhibition mechanism of indapamide on luminol-potassium ferricyanide CL system was discussed briefly.

Spectrophotometric, spectrofluorimetric, and densitometric methods for the determination of indapamide.

Three sensitive spectrophotometric, spectrofluorimetric, and densitometric methods are described for the determination of indapamide. The first and second methods are based on the oxidative coupling reaction of indapamide with 3-methyl-2-benzothiazolinone hydrazone HCl (MBTH) in the presence of cerium(IV) ammonium sulfate in an acidic medium. The absorbance of the reaction product is measured at the lambdamax, 601 nm. With the same reaction, indapamide is determined by its quenching effect on the fluorescence of excess cerous ions at the emission lambdamax, 350 nm, and the excitation at lambdamax, 300 nm. The reaction conditions were optimized, and Beer's law was obeyed for indapamide at 1.2-9.6 microg/mL with mean recoveries of 99.92 +/- 0.83 and 99.97 +/- 1.11%, respectively. The third method, a stability-indicating densitometric assay, was developed for the determination of indapamide, using toluene-ethyl acetate-glacial acetic acid (69 + 30 + 1, v/v/v) as the developing system and scanning at the lambdamax, 242 nm, in the presence of the degradation product and related substance; for the indapamide concentration range of 0.6-6 microg/spot, the mean recovery was 99.73 +/- 0.71%. The proposed methods were successfully applied to the determination of indapamide in bulk powder and commercial tablets, and the results of the analysis agreed statistically with those obtained with the official method. Furthermore, the methods were validated according to the guidelines of the U.S. Pharmacopeia and also assessed by applying the standard additions technique.

Two derivative spectrophotometric determinations of indapamide in pharmaceutical dosage forms.

Simple, fast and reliable derivative spectrophotometric methods were developed for determination of indapamide in bulk and pharmaceutical dosage forms. The solutions of standard and the sample were prepared in methanol. The quantitative determination of the drug was carried out using the first-derivative values measured at 252.8 nm (N=6) and the second-derivative values measured at 260.4 nm (N=9). Calibration graphs constructed at their wavelengths of determination were linear in the concentration range of indapamide using peak to zero 1.00-30.00 microg ml(-1) for first-derivative and 1.00-35.00 microg ml(-1) for second-derivative spectrophotometric method. The developed methods were successfully applied for the assay of pharmaceutical dosage forms which do not require any preliminary separation or treatment of the samples. The details of the statistical treatment of analytical data are also presented. The results obtained from two derivative spectrophotometry were compared with a spectrophotometric method reported in literature and no significant difference was found statistically.

Comparison of spectrophotometric and an LC method for the determination perindopril and indapamide in pharmaceutical formulations.

A new sensitive, simple, rapid and precise reversed-phase high performance liquid chromatographic (HPLC) and two spectrophotometric methods have been developed for resolving binary mixture of perindopril and indapamide in the pharmaceutical dosage forms. The first method is based on HPLC on a reversed-phase column using a mobile phase of phosphate buffer pH 2.4 and acetonitrile (7:3 v/v) was used. Linearity range for perindopril and indapamide was 5.0-70.0 and 8.0-35.0 microg ml(-1). In the second method, the first derivative spectrophotometry with a zero-crossing technique of measurement is used for the simultaneous quantitative determination of perindopril and indapamide in binary mixtures without previous separation step. Linear calibration graphs of first derivative values at 225.7 and 255.4 nm for perindopril and indapamide, respectively. The third method is based on ratio derivative spectrophotometry, the amplitudes in the first derivative of the ratio spectra at 226.5 and at 255.3 nm were selected to determine perindopril and indapamide in the binary mixture. All the proposed methods showed good linearity, precision and reproducibility. The proposed methods were successfully applied to the pharmaceutical dosage forms containing the above-mentioned drug combination without any interference by the excipients.

Quantitative determination of indapamide in pharmaceuticals and urine by high-performance liquid chromatography with amperometric detection.

A high-performance liquid chromatographic method with amperometric detection for the determination of the diuretic indapamide using a muBondapak C18 column is developed. The mobile phase consists of an acetonitrile-water mixture (45:55, 5 mM) in KH2PO4-K2HPO4 (pH 4.0). The compound is monitored at +1200 mV with an amperometric detector equipped with a glassy carbon working electrode. A liquid-liquid or solid-liquid extraction is performed prior to chromatographic analysis to avoid the interferences found in urine matrix. Percentages of recovery are 88.3 +/- 5.6 and 82.9 +/- 7.8 for liquid-liquid and solid-liquid extraction, respectively. The developed method has a linear concentration range from 25 to 315 ng/mL with a reproducibility in terms of relative standard deviation of 4% for a concentration level of 0.5 microgram/mL and a quantitation limit of 1 ng/mL. The method is applied to the determination of indapamide in tablets and urine obtained from hypertensive patients after the ingestion of Tertensif (indapamide 2.5 mg).