Simultaneous determination of indapamide, perindopril and its active metabolite perindoprilat in human plasma using UPLC-MS/MS method.

Lots of studies showed the combination therapy of perindopril, indapamide and amlodipine could increase BP lowering efficacy and the benefits of high-risk patients. To evaluate potential pharmacokinetic interaction, a simultaneous UPLC-MS/MS quantification method of perindopril, perindoprilat and indapamide in human plasma was developed and validated. The plasma samples were prepared by solid phase extraction, and then separated on an X-terra MS C18 (2.1 mm × 150 mm, 3.5 µm) with isocratic elution. The ion transitions at m/z 369.165 â†’ 172.000 (perindopril), m/z 341.146 â†’ 170.112 (perindoprilat), m/z 366.010 â†’ 132.100 (indapamide), m/z 389.120 â†’ 206.200 (S10211-1, IS1) and m/z 394.080 â†’ 160.200 (S1641, IS2) were monitored under the positive ion mode of electrospray ionization with multiple reaction monitoring. This method exhibited great sensitivity, linearity, accuracy, and precision for the determination of perindopril, perindoprilat and indapamide over the range of 0.250-50.0 ng/mL. The average extraction recovery of perindopril, perindoprilat and indapamide samples at low, medium, and high concentration levels were between 85.9% and 93.6%, respectively. The stability of analytes over different storage and processing conditions in the whole study was also validated. The method is fast, accurate, sensitive and reproducible, which is suitable for the detection of the concentration of perindopril, perindoprilat and indapamide in human plasma.

Stability-Indicating RP-HPLC and CE Methods for Simultaneous Determination of Bisoprolol and Perindopril in Pharmaceutical Formulation: A Comparative Study.

Two fast, accurate and selective stability-indicating methods were developed and validated for the simultaneous determination of bisoprolol, perindopril and three of their possible degradation products. The first proposed method was a gradient reversed phase-high-performance liquid chromatography (HPLC) method, whereas the second was a capillary electrophoresis method. The structures of the obtained degradation products were elucidated using infrared and mass spectrometry. They were also confirmed to be either a drug impurity in the British Pharmacopoeia or a precursor to such impurity. The linearity for bisoprolol and perindopril was achieved in the range of 1-20 µg mL-1 and 5-30 µg mL-1 for HPLC and capillary electrophoresis methods, respectively. The proposed methods were validated according to the International Conference on Harmonisation guidelines. The HPLC method proved to be more sensitive and succeeded in the quantitative determination of the obtained degradation products. Also, it was able to quantify perindopril impurity up to three times lower than the desired limit set by the British Pharmacopoeia. They were successfully employed in the determination of bisoprolol and perindopril in their combined pharmaceutical formulation.

Comparative Solid-State Stability of Perindopril Active Substance vs. Pharmaceutical Formulation.

This paper presents the results obtained after studying the thermal stability and decomposition kinetics of perindopril erbumine as a pure active pharmaceutical ingredient as well as a solid pharmaceutical formulation containing the same active pharmaceutical ingredient (API). Since no data were found in the literature regarding the spectroscopic description, thermal behavior, or decomposition kinetics of perindopril, our goal was the evaluation of the compatibility of this antihypertensive agent with the excipients in the tablet under ambient conditions and to study the effect of thermal treatment on the stability of perindopril erbumine. ATR-FTIR (Attenuated Total Reflectance Fourier Transform Infrared) spectroscopy, thermal analysis (thermogravimetric mass curve (TG-thermogravimetry), derivative thermogravimetric mass curve (DTG), and heat flow (HF)) and model-free kinetics were chosen as investigational tools. Since thermal behavior is a simplistic approach in evaluating the thermal stability of pharmaceuticals, in-depth kinetic studies were carried out by classical kinetic methods (Kissinger and ASTM E698) and later with the isoconversional methods of Friedman, Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa. It was shown that the main thermal degradation step of perindopril erbumine is characterized by activation energy between 59 and 69 kJ/mol (depending on the method used), while for the tablet, the values were around 170 kJ/mol. The used excipients (anhydrous colloidal silica, microcrystalline cellulose, lactose, and magnesium stearate) should be used in newly-developed generic solid pharmaceutical formulations, since they contribute to an increased thermal stability of perindopril erbumine.

Investigation of the energy barrier to the rotation of amide CN bonds in ACE inhibitors by NMR, dynamic HPLC and DFT.

The isomerizations of Enalapril, Perindopril, Enalaprilat and Lisinopril have been investigated using NMR spectroscopic, dynamic chromatographic, unified equation and DFT theoretical calculations. The thermodynamic parameters (ΔH, ΔS and ΔG) were determined by varying the temperature in the NMR experiments. At the coalescence temperature, we can evaluate the isomerization barrier to the rotation (ΔG(≠)) around the amide bond. Using dynamics chromatography and an unified equation introduced by Trap, we can determine isomerization rate constants and Gibbs activation energies. Molecular mechanics calculations also provided evidence for the presence of low energy conformers for the ACE due to restricted amide rotation. With the value of barriers (ΔE) between them of the order of (20kJmol(-1)), which is in agreement with the dynamic NMR results and DFT calculations.

Evaluation of drug-carrier interactions in quaternary powder mixtures containing perindopril tert-butylamine and indapamide.

Interactions occurring between components in the quaternary powder mixtures consisting of perindopril tert-butylamine, indapamide (active pharmaceutical ingredients), carrier substance and hydrophobic colloidal silica were examined. Two grades of lactose monohydrate: Spherolac(®) 100 and Granulac(®) 200 and two types of microcrystalline cellulose: M101D+ and Vivapur(®) 102 were used as carriers. We determined the size distribution (laser diffraction method), morphology (scanning electron microscopy) and a specific surface area of the powder particles (by nitrogen adsorption-desorption). For the determination of the surface energy of powder mixtures the method of inverse gas chromatography was applied. Investigated mixtures were characterized by surface parameters (dispersive component of surface energy, specific interactions parameters, specific surface area), work of adhesion and cohesion as well as Flory-Huggins parameter χ23('). Results obtained for all quaternary powder mixtures indicate existence of interactions between components. The strongest interactions occur for both blends with different types of microcrystalline cellulose (PM-1 and PM-4) while much weaker ones for powder mixtures with various types of lactose (PM-2 and PM-3).

Dissolution profiles of perindopril and indapamide in their fixed-dose formulations by a new HPLC method and different mathematical approaches.

A new HPLC method was introduced and validated for simultaneous determination of perindopril and indapamide. Validation procedure included specificity, sensitivity, robustness, stability, linearity, precision and accuracy. The method was used for the dissolution test of perindopril and indapamide in three fixed-dose formulations. The dissolution procedure was optimized using different media, different pH of the buffer, surfactants, paddle speed and temperature. Similarity of dissolution profiles was estimated using different model-independent and model-dependent methods and, additionally, by principal component analysis (PCA). Also, some kinetic models were checked for dissolved amounts of drugs as a function of time.

Novel Spectrofluorimetric Method for the Determination of Perindopril Erbumine Based on Fluorescence Quenching of Rhodamine B.

A novel, simple and specific spectrofluorimetric method was developed and validated for the determination of perindopril erbumine (PDE). The method is based on the fluorescence quenching of Rhodamine B upon adding perindopril erbumine. The quenched fluorescence was monitored at 578 nm after excitation at 500 nm. The optimization of the reaction conditions such as the solvent, reagent concentration, and reaction time were investigated. Under the optimum conditions, the fluorescence quenching was linear over a concentration range of 1.0-6.0 µg/mL. The proposed method was fully validated and successfully applied to the analysis of perindopril erbumine in pure form and tablets. Statistical comparison of the results obtained by the developed and reference methods revealed no significant differences between the methods compared in terms of accuracy and precision. The method was shown to be highly specific in the presence of indapamide, a diuretic that is commonly combined with perindopril erbumine. The mechanism of rhodamine B quenching was also discussed.

Development and in vitro/in vivo evaluation of immediate release perindopril tablets.

Perindopril erbumine (PE) is a BCS (Biopharmaceutics Classification System) class 3 drug with high solubility and low permeability. It is an inhibitor of the enzyme that converts angiotensin I (Angiotensin Converting Enzyme, ACE) into angiotensin II as well as causing the degradation of the vasodilator bradykinin into an inactive heptapeptide. The aim of this study was to develop an alternative drug product by using a different salt of perindopril and to evaluate the bioequivalence between PE, not still licensed, and perindopril arginine (PA), licensed in many countries, and to prepare PE tablets by using direct compression method. Many different formulations were prepared, among which F3-coded formulation was only selected due to releasing of 98.03% active substance at 45th minute. Bioequivalence study was planned as a cross-designed, randomized, open-labeled, single-dose, single-center study and conducted in 24 male healthy volunteers via peroral route. The results of bioequivalence study were evaluated for Perindopril and Perindoprilat according to Cmax, tmax and AUC criteria. The geometric mean ratios (90% CI) of perindopril and perindoprilat followed test and reference drug were calculated for AUC0-t and Cmax, 105.946% (100.218-112.002%) and 110.437% (102.534-118.948%); 109.542% (98.364-121.992%) and 115.729% (101.031-132.565%), respectively. The 90% confidence intervals of them were found within the standard bioequivalence range (80-125%).

Stability-indicating RP-HPLC method for the quantitative analysis of perindopril erbumine in tablet dosage form.

A specific, stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the estimation of perindopril erbumine (PDE) in tablet dosage form. The HPLC method showed adequate separation of PDE from its degradation products. The separation was achieved on a Phenomenex Luna C18 column (250 × 4.6 mm × 5 µm) using a mobile phase composition of 0.2% trifluoroacetic acid buffer and acetonitrile in the ratio of 60:40 (pH adjusted to 3 with ammonia) at a flow rate of 1 mL/min. The injection volume was 20 µL and the wavelength of detection was kept at 215 nm. Stress studies were performed with 1 mg/mL of each drug, starting with mild conditions and followed by stronger conditions to achieve sufficient degradation at approximately 5-20%. The linearity of the proposed method was investigated in the range of 2.5 to 50 µg/mL for PDE. The limits of detection and quantification were found to be 0.75 and 2.3 µg/mL, respectively.

Application of independent component analysis on Raman images of a pharmaceutical drug product: pure spectra determination and spatial distribution of constituents.

Independent component analysis (ICA) was used as a blind source separation method on a Raman image of a pharmaceutical tablet. Calculations were performed without a priori knowledge concerning the formulation. The aim was to extract the pure signals from the initial data set in order to examine the distribution of actives and major excipients within the tablet. As a method based on the decomposition of a matrix of mixtures of several components, the number of independent component to choose is a critical step of the analysis. The ICA_by_blocks method, based on the calculation of several models using an increasing number of independent components on initial matrix blocks, was used. The calculated ICA signals were compared with the pure spectra of the formulation compounds. High correlations between the two active principal ingredient spectra and their corresponding calculated signals were observed giving a good overview of the distributions of these compounds within the tablet. Information from the major excipients (lactose and avicel) was found in several independent components but the ICA approach provides high level of information concerning their distribution within the tablet. However, the results could vary considerably by changing the number of independent components or the preprocessing method. Indeed, it was shown that under-decomposition of the matrix could lead to better signal quality (compared to the pure spectra) but in that case the contributions due to minor components or effects were not correctly identified and extracted. On the contrary, over-decomposition of the original dataset could provide information about low concentration compounds at the expense of some loss of signal interpretability for the other compounds.

Sustained release of prindopril erbumine from its chitosan-coated magnetic nanoparticles for biomedical applications.

The preparation of magnetic nanoparticles coated with chitosan-prindopril erbumine was accomplished and confirmed by X-ray diffraction, TEM, magnetic measurements, thermal analysis and infrared spectroscopic studies. X-ray diffraction and TEM results demonstrated that the magnetic nanoparticles were pure iron oxide phase, having a spherical shape with a mean diameter of 6 nm, compared to 15 nm after coating with chitosan-prindopril erbumine (FCPE). Fourier transform infrared spectroscopy study shows that the coating of iron oxide nanoparticles takes place due to the presence of some bands that were emerging after the coating process, which belong to the prindopril erbumine (PE). The thermal stability of the PE in an FCPE nanocomposite was remarkably enhanced. The release study showed that around 89% of PE could be released within about 93 hours by a phosphate buffer solution at pH 7.4, which was found to be of sustained manner governed by first order kinetic. Compared to the control (untreated), cell viability study in 3T3 cells at 72 h post exposure to both the nanoparticles and the pure drug was found to be sustained above 80% using different doses.

An orthorhombic polymorph of a cyclization product of perindopril.

Low-temperature X-ray diffraction experiments were employed to investigate the crystal structures of an orthorhombic polymorph of the intramolecular cyclization product of perindopril, a popular angiotensive-converting enzyme (ACE) inhibitor, namely ethyl (2S)-2-[(3S,5aS,9aS,10aS)-3-methyl-1,4-dioxo-5a,6,7,8,9,9a,10,10a-octahydro-3H-pyrazino[1,2-a]indol-2-yl]pentanoate, C19H30N2O4, (Io), and its tetragonal equivalent, (It), which was previously reported at ambient temperature [Bojarska et al. (2013). J. Chil. Chem. Soc. 58, 1415-1417]. Polymorph (Io) crystallizes in the orthorhombic space group P2(1)2(1)2(1) with two molecules in the asymmetric unit, while tetragonal form (It) crystallizes in the space group P4(1)2(1)2 with one molecule in the asymmetric unit. The geometric parameters of (Io) are very similar to those of (It). The six-membered rings in both polymorphs adopt a slightly deformed chair conformation and the piperazinedione rings are in a boat conformation. However, the proline rings adopt an envelope conformation in (Io), while in (It) the ring exists in a slightly deformed half-chair conformation. The most significant difference between the two structures is the orientation of the ethyl pentanoate chain. Molecules associate in pairs in a head-to-tail manner forming infinite columns. In (Io), molecules are related by a twofold screw axis forming identical columns, while in (It), molecules in successive neighbouring columns are related by alternating twofold screw axes and fourfold screw axes. In both cases, the crystal packing is stabilized by weak intermolecular C-H···O interactions only.

Validated chromatographic methods for determination of perindopril and amlodipine in pharmaceutical formulation in the presence of their degradation products.

Two specific, sensitive, and precise stability-indicating chromatographic methods have been developed, optimized and validated for determination of perindopril arginin (PER) and amlodipine besylate (AML) in their mixtures and in the presence of their degradation products. The first method was based on thin-layer chromatography (TLC) combined with densitometric determination of the separated bands. Adequate separation was achieved using silica gel 60 F254 TLC plates and ethyl acetate-methanol-toluene-ammonia solution, 33% (6.5:2:1:0.5 by volume), as a developing system. The second method was based on high-performance liquid chromatography, by which the proposed components were separated on a reversed-phase C18 analytical column using a mobile phase consisting of phosphate buffer (pH 2.5, 0.01 M)-acetonitrile-tetrahydrofuran (60:40:0.1% by volume) with ultraviolet detection at 218 nm. Different parameters affecting the suggested methods were optimized for maximum separation of the cited components. System suitability parameters of the two developed methods were also tested. The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for the quantification of PER and AML in their commercial tablets. Both methods were also statistically compared to each other and to the reference methods with no significant differences in performance.

Comparative study of Mg/Al- and Zn/Al-layered double hydroxide-perindopril erbumine nanocomposites for inhibition of angiotensin-converting enzyme.

The intercalation of a drug active, perindopril, into Mg/Al-layered double hydroxide for the formation of a new nanocomposite, PMAE, was accomplished using a simple ion exchange technique. A relatively high loading percentage of perindopril of about 36.5% (w/w) indicates that intercalation of the active took place in the Mg/Al inorganic interlayer. Intercalation was further supported by Fourier transform infrared spectroscopy, and thermal analysis shows markedly enhanced thermal stability of the active. The release of perindopril from the nanocomposite occurred in a controlled manner governed by pseudo-second order kinetics. MTT assay showed no cytotoxicity effects from either Mg/Al-layered double hydroxide or its nanocomposite, PMAE. Mg/Al-layered double hydroxide showed angiotensin-converting enzyme inhibitory activity, with 5.6% inhibition after 90 minutes of incubation. On incubation of angiotensin-converting enzyme with 0.5 µg/mL of the PMAE nanocomposite, inhibition of the enzyme increased from 56.6% to 70.6% at 30 and 90 minutes, respectively. These results are comparable with data reported in the literature for Zn/Al-perindopril.

Influence of different types of commercially available microcrystalline cellulose on degradation of perindopril erbumine and enalapril maleate in binary mixtures.

Influence of some commercially available types of microcrystalline cellulose (MCC) on the stability of certain active pharmaceutical ingredients (APIs), when in contact, has been investigated. Two structurally similar APIs, perindopril erbumine (PER) and enalapril maleate (EM), both well-known angiotensin-converting enzyme inhibitors were used. The main properties of an MCC that could determine the stability for each API were measured and correlated to the stability of these two APIs in binary mixtures. The stability of these APIs differed when in contact with different types of MCC. The dominant properties of MCC from one manufacturer were surface features that influenced the stability of PER and acidity that influenced the stability of EM. In the case of MCC from other manufacturers, unbound water was stability determining for both substances.

Validation of an oil-in-water microemulsion liquid chromatography method for analysis of perindopril tert-butylamine and its impurities.

This paper describes the development and validation of a microemulsion liquid chromatography (MELC) method for simultaneous determination of perindopril tert-butylamine and its impurities in bulk active substances and the pharmaceutical dosage form of tablets. An appropriate resolution with reasonable retention times was obtained for a microemulsion containing 0.24% (w/v) butyl acetate, 0.30% (w/v) ethyl acetate, 2% (w/v) sodium dodecyl sulfate, 7.75% (w/v) n-butanol, and 20.0 mM potassium dihydrogen phosphate, the pH of which was adjusted to 3.70 with 85% orthophosphoric acid. Separations were performed on a Nucleosil 120-5 butyl modified (C4), 250 x 4 mm, 5 microm particle size silica column at 40 degrees C, with a mobile phase flow rate of 1.25 mL/min. UV detection was performed at 254 nm. The established method was subjected to method validation, and required validation parameters were defined. Robustness testing, an important part of method validation, was performed as well. Since robustness validation can be conducted using different experimental designs, the Plackett-Burman design was applied due to its possibility of testing many factors at the same time. The validated MELC method was found to be suitable for the simultaneous determination of perindopril tert-butylamine and its impurities in pharmaceuticals.

Effects of ACE inhibitors on cardiac angiotensin II and aldosterone in humans: "Relevance of lipophilicity and affinity for ACE".

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitors differ in their lipophilic/hydrophilic index that determines their tissue bioavailability and affinity to ACE, which may result in major differences in the degree of blockade of cardiac ACE. We evaluated the hypothesis that in patients with chronic heart failure (CHF) and activated cardiac renin-angiotensin-aldosterone system (RAAS), lipophilic ACE inhibitors with high affinity for ACE (perindopril and quinapril) will cause marked blockade of cardiac angiotensin (Ang) II and aldosterone generation, but not a hydrophilic ACE inhibitor with low affinity for ACE (lisinopril). METHODS: Patients were randomized to receive perindopril (8 mg/day), quinapril (40 mg/day), or lisinopril (20 mg/day) for 3-4 weeks before cardiac catheterization. The coronary sinus-aortic root gradients for Ang I and II, and aldosterone were determined. RESULTS: A total of 19 patients completed the study. Compared to a healthy control group, all three ACE inhibitors decreased circulating Ang II and aldosterone to a similar extent. There were only minor differences between the three ACE inhibitors for the Ang II gradient between the coronary sinus and aortic root. The gradient for aldosterone tended to be positive in the quinapril group and absent/negative in the lisinopril and perindopril groups. Despite the lowest pulmonary capillary wedge pressure (PCWP), gradients between the coronary sinus and aortic root for Ang II and aldosterone were actually the highest in the quinapril group. CONCLUSIONS: These findings do not support the concept that a hydrophilic ACE inhibitor is less effective in blocking the cardiac RAAS as compared to lipophilic ACE inhibitors.

Stability of new potential ACE inhibitor in the aqueous solutions of different pH.

Angiotensin-converting enzyme (ACE) inhibitors are a group of active substances binding to an active site of ACE. Many authors who studied the structure activity relationship suggested the structural elements needed for a potent ACE inhibitor. While many authors studied the activity of ACE inhibitor substances only a few structure stability studies have been presented. In this paper the stability properties of molecule xPRIL were studied by determination of degradation path and rate of degradation in aqueous solutions with different pH (2.0, 6.8 and 12.0) and temperatures (40, 60 and 80 degrees C). The degradation of molecule through two main degradation paths was identified and confirmed by liquid chromatography and mass spectroscopy (LC-MS). Stability properties of xPRIL were determined in a stability study evaluated by high-performance liquid chromatography (HPLC). The first order kinetics of degradation reaction of xPRIL and Arrhenius equations for each pH were determined at observed conditions. xPRIL showed the highest stability at pH 2 solution. The degradation kinetics of xPRIL was compared to the degradation kinetics of enalapril maleate (EM) and perindopril (PER) in bio relevant solutions with pH 2.0 and 6.8. In addition to the stability study of xPRIL the forced degradation study of all three molecules at rigorous conditions was conducted. From the obtained results the structural element having the highest influence on stability properties of the studied molecules was identified. The fragmentation paths of xPRIL, its cyclization degradation product and its hydrolysis degradation product were identified and confirmed by MS/MS method.

Molecular structure and stability of perindopril erbumine and perindopril L-arginine complexes.

The methods of theoretical chemistry have been used to elucidate molecular properties of the antihypertensive, cardiovascular protective and antithrombotic perindopril ((2S,3aS,7aS)-1-[(2S)-2-[[(2S)-1-ethoxy-1-oxopentan-2-yl]amino]propanoyl]-2,3,3a,4,5,6,7,7a-octahydroindole-2-carboxylic acid). The geometries and energies of various neutral and ionized complexes of perindopril erbumine and perindopril l-arginine have been computed using HF/6-31G(d) and Becke3LYP/6-31G(d) methods. The calculations showed that in both, the isolated state and water solution perindopril erbumine exists as a neutral complex. In the gas-phase perindopril l-arginine both neutral and ionic complexes are, at the HF level of theory, almost equally stable. The B3LYP level of theory slightly favors single proton transfer complex perindopril l-arginine (by about 14 kJ mol(-1)). In polar solvents like water, the ionized form of perindopril l-arginine becomes much more favored. According to our calculations l-arginine is bound to perindopril more strongly (by about 25 kJ mol(-1)) than erbumine.

The use of microcalorimetry and HPLC for the determination of degradation kinetics and thermodynamic parameters of Perindopril Erbumine in aqueous solutions.

Perindopril Erbumine (PER) is one of the newly used angiotensin-converting enzyme inhibitors (ACE inhibitors) and is used for the treatment of patients with hypertension and symptomatic heart failure. It has two main degradation pathways, i.e. the degradation by hydrolysis and the degradation by cyclization. An isothermal heat conduction microcalorimetry (MC) and high pressure liquid chromatography (HPLC) were used for the characterization of aqueous solutions of PER and its stability properties. The rates of heat evolved during degradation of perindopril were measured by MC as a function of temperature and pH and from these data rate constant and change in enthalpy of the reactions were determined. With the HPLC method the concentration of perindopril and its degradation products were measured as a function of time in aqueous solutions of different pH that were stored at different temperatures. We demonstrated that reactions of degradation of perindopril at observed conditions follow the first order kinetics. The Arrhenius equation for each pH was determined. At pH 6.8 only one degradation pathway is present, i.e. the degradation by hydrolysis. Degradation constants for this pathway calculated from MC data are in good agreement with those obtained from HPLC. MC as a non-specific technique was shown to be useful in studies of PER when one reaction was present in the sample and also when more chemical and physical processes were simultaneously running.