Maha Farouk

Comparative study between univariate spectrophotometry and multivariate calibration as analytical tools for simultaneous quantitation of Moexipril and Hydrochlorothiazide.

Three simple, accurate, reproducible, and selective methods have been developed and subsequently validated for the simultaneous determination of Moexipril (MOX) and Hydrochlorothiazide (HCTZ) in pharmaceutical dosage form. The first method is the new extended ratio subtraction method (EXRSM) coupled to ratio subtraction method (RSM) for determination of both drugs in commercial dosage form. The second and third methods are multivariate calibration which include Principal Component Regression (PCR) and Partial Least Squares (PLSs). A detailed validation of the methods was performed following the ICH guidelines and the standard curves were found to be linear in the range of 10-60 and 2-30 for MOX and HCTZ in EXRSM method, respectively, with well accepted mean correlation coefficient for each analyte. The intra-day and inter-day precision and accuracy results were well within the acceptable limits.

Comparative study between univariate spectrophotometry and multivariate calibration as analytical tools for quantitation of Benazepril alone and in combination with Amlodipine

Four simple, accurate, reproducible, and selective methods have been developed and subsequently validated for the determination of Benazepril (BENZ) alone and in combination with Amlodipine (AML) in pharmaceutical dosage form. The first method is pH induced difference spectrophotometry, where BENZ can be measured in presence of AML as it showed maximum absorption at 237nm and 241nm in 0.1N HCl and 0.1N NaOH, respectively, while AML has no wavelength shift in both solvents. The second method is the new Extended Ratio Subtraction Method (EXRSM) coupled to Ratio Subtraction Method (RSM) for determination of both drugs in commercial dosage form. The third and fourth methods are multivariate calibration which include Principal Component Regression (PCR) and Partial Least Squares (PLSs). A detailed validation of the methods was performed following the ICH guidelines and the standard curves were found to be linear in the range of 2-30μg/mL for BENZ in difference and extended ratio subtraction spectrophotometric method, and 5-30 for AML in EXRSM method, with well accepted mean correlation coefficient for each analyte. The intra-day and inter-day precision and accuracy results were well within the acceptable limits.

Simultaneous determination of three neonicotinoid insecticide residues and their metabolite in cucumbers and soil by QuEChERS clean up and liquid chromatography with diode-array detection

A new sensitive, selective and validated HPLC-DAD method was developed for the simultaneous determination of three neonicotinoid insecticides named dinotefuran, thiamethoxam and Clothianidin with their metabolite 1-methyl-3-nitroguanidine in cucumbers and soil based on QuEChERS as a pretreatment procedure. In the QuEChERS procedure, cucumber samples were extracted with acetonitrile and cleaned using C18, while soil samples were extracted with a mixture of acetonitrile : dichloromethane (1 : 2). The HPLC conditions were optimized where the neonicotinoids were separated using a gradient elution of water : acetonitrile and a Synergy Hydro RP C18 column. Matrix matched calibration standards were prepared in cucumbers and soil to eliminate the interference of the matrix. Relative standard deviations (RSDs) were less than 2.08% for all of the recovery tests. The limits of detection (LODs) and quantification (LOQs) for the neonicotinoids were in the ranges of 0.01–0.08 μg g−1 and 0.03–0.24 μg g−1, respectively. The method was applied successfully to determine residues and rates of disappearance of the three neonicotinoids from cucumbers and soil and their half lives.

Different techniques for determination of imidacloprid insecticide residues

Three sensitive, selective and precise methods for determination of imidacloprid insecticide residues in tomatoes have been developed. The first method is TLC-Densitometry where imidacloprid was extracted with acetonitrile without the need for a clean up step then the extract was applied to TLC plates using toluene: acetonitrile (7:3) as a solvent system. The recoveries ranged from 92.57 to 96.31% in tomato samples. The limit of detection of the method was 1.39 mg/kg. The second method depends on indirect fluorimetric determination of imidacloprid by quenching anthracene synchronous fluorescence. The recoveries ranged from 96.16 to 99.83% in tomato samples. The limit of detection of the method was 0.32 mg/kg. The third method is high-performance liquid chromatography with UV detection where imidacloprid was extracted with acetonitrile followed by clean up using column chromatography. The recovery of imidacloprid in tomato samples ranged from 85.20 to 93.15%. The limit of detection of the method was 0.12 mg/kg. The three methods were used to study the kinetic disappearance of imidacloprid from tomatoes. It was found to follow a first order reaction with t1/2 = 5.31 ± 0.3 days, whereas K (reaction rate constant) was found to be 0.13 ± 0.008 day−1.

Liquid Chromatography-Electro Spray Ionization Tandem Mass Spectrometry for Simultaneous Determination of Amlodipine, Benazepril and its Active Metabolite Benazeprilat in Human Plasma

Abstract A selective, sensitive, rapid, and reproducible liquid chromatographyelectro spray ionization tandem mass method has been developed and subsequently validated for the simultaneous determination of Amlodipine (AML), Benazepril (BENZ), and its active metabolite Benazeprilat (BENZT) in spiked human plasma, using Moexipril (MOX) as an internal standard (IS). Various modes were tried and the Multiple Reaction Monitoring (MRM) mode was found the most suitable one. The three analytes and Moexipril (IS) were extracted from human plasma by simple protein precipitation using acetonitrile as the precipitating solvent. The stationary phase used was a C18 Sunfire column while water and acetonitrile at 0.1 % formic acid (30:70, v/v) was used as a mobile phase. The flow rate used was 0.8 mL/min. FDA guidelines were followed for the method validation. The linearity range was found to be 10-200 ng/mL for Amlodipine, 0.5-100 ng/mL for Benazepril and 5-200 ng/mL for Benazeprilat and the correlation coefficient was more than 0.9980 for each analyte. The equation of the calibration curve was: y=0.0068x - 0.0072 (r2=0.9981, n=3) for Amlodipine, y=0.6098x - 0.135 (r2 = 0.9988, n=3) for Benazepril and y=0.0173x - 0. 0312 (r2=0.9987, n=3) for Benazeprilat. Results for accuracy and precision showed satisfactory results. Also the method was compared with reported HPLC method and no significant difference was found.

Stability Study of the Calcium Channel Blocker Lercanidipine and its Determination by Reversed Phase Chromatography in Pharmaceutical Formulation and Plasma

Abstract A sensitive, selective, and rapid stability indicating RP-HPLC method was developed and validated for determination of Lercanidipine (LERC) in presence of its acidic, basic, and oxidative degradation products in bulk powder, pharmaceutical formulation, and human plasma, using benazepril (BENZ) as an internal standard (IS). The method uses Inertsil C18 column (250 x 4.6mm, 5µ) and acetonitrile-potassium hydrogen phosphate buffer pH = 3.5 (55/45 v/v) as a mobile phase. The flow rate was 1.0 mL/min and the detection wavelength was 235 nm. A detailed validation of the method was performed following the ICH guidelines and the standard curve was found to be linear in the range of 1-30 µg/mL for Lercanidipine. Statistical comparison was done between the proposed method and the reported one where no significant difference was found between the two methods. Also the method was applied to spiked human plasma.

Univariate calibrations with or without chemometric assistance for determination of drugs lacking peak maxima in their zero-order profiles

Trandolapril has no sharp peak in its zero-order spectrum and therefore, it is difficult to be measured by direct spectrophotometry. In this manuscript, several univariate and multivariate spectrophotometric methods were developed and validated for determination of Trandolapril (TR) and Verapamil (VR) combination. The first method for measuring Trandolapril is Constant Multiplication-Spectrum Subtraction (CM-SS), where Trandolapril was measured at 210 nm in its zero-order curve after elimination of Verapamil spectrum. Second and third methods are two Base Points (2BP) and area under the curve (AUC) to measure Trandolapril concentration without depending on the shoulder peak. The fourth method for Trandolapril is Derivative Subtraction (DS) that utilizes the sharp peak appeared in the first order spectrum of Trandolapril. Verapamil was determined by two methods, Constant Multiplication (CM) and Derivative Subtraction-Constant Multiplication (DS-CM). Also, two multivariate methods were developed for measurement of the mixture, Partial Least Squares (PLS) and Principal Component Regression (PCR). All the developed methods were validated as per ICH guidelines and the results proved that the developed methods are accurate and selective. Moreover, a statistical comparison between the developed methods and a reference method was done. Also, One-way ANOVA statistical test was done between all the proposed univariate and multivariate spectrophotometric methods.

Comparative pharmacokinetics of trandolapril, its active metabolite, and verapamil in human plasma of Egyptian population using HPLC–MS/MS

Trandolapril and verapamil are commonly used antihypertensive drugs. However, there is a lack of available data on the change of their pharmacokinetics in patients with liver or kidney impairment and hence the need for dose adjustment. In this article, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed and validated for the monitoring of trandolapril, its active metabolite trandolaprilat, and verapamil in human plasma of patients with renal impairment and/or liver insufficiency. The chromatographic separation was achieved on a Gemini C18 reversed phase column using a gradient elution mode with a run time of 10 minutes. The mobile phase consisted of a mixture of methanol and 2% acetic acid. The electrospray ionization MS/MS analysis was performed in multiple reaction monitoring (MRM) mode. The assay was validated as per Food and Drug Administration (FDA) guidelines for bioanalytical method validation and proved to be suitable for the determination of therapeutic drug levels in plasma. The inter-group changes in pharmacokinetic data were compared to that of healthy volunteers. The comparison showed a significant difference in the pharmacokinetic parameters between the studied groups. The presented results exhibit the benefits of the proposed assay as a validated analytical tool for the continuous drug monitoring.

Stepwise Optimization Strategies Utilizing Recent Univariate and Multivariate Methods for Determination of the Partially Overlapped Mixture Perindopril and Indapamide

Abstract Recently, different novel univariate methods were presented for determination of mixtures of drugs having partially overlapped UV spectra. These methods are used when one component is more extended than the other. In this study, these methods were tested for determination of Perindopril and Indapamide. The main problem with Perindopril is the absence of a sharp peak in the zero-order spectrum. The main concern was to test the applicability of the already developed methods for the determination of this type of analytes when present in mixture form. The utilized univariate methods for the determination of Perindopril were; ratio subtraction (RS), ratio subtraction-two base points (RS-2BP), ratio subtraction-area under the curve (RS-AUC), derivative subtraction (DS), derivative subtraction-two bas points (DS-2BP), and derivative subtraction-area under the curve (DS-AUC). While Indapamide was determined by ratio subtraction-constant multiplication (RS-CM), and derivative subtraction-spectrum subtraction (DS-SS) methods. Also, two multivariate spectrophotometric methods were developed and validated, Principal Component Regression (PCR) and Partial Least Squares (PLSs). Validation of the developed methods was done as per ICH guidelines. Also, a statistical comparison with the reported methods was done showing no significant difference.

Different Approaches in Determination of Lercanidipine in Presence of its Degradation Products by Stability Indicating Univariate and Multivariate Calibrations

Abstract For quantitative determination of Lercanidipine (LERC) in presence of its acidic and basic degradation products, three spectrophotometric methods were developed. The methods were applied on both the bulk powder and the pharmaceutical formulation. They are precise, accurate, selective, and stability indicating methods. The first method is the new extended derivative ratio method for determination of the drug in presence of the basic (BAS) and acidic (ACD) degradation products. The second and third methods are chemometric methods namely Principal Component Regression (PCR) and Partial Least Squares (PLSs). Full validation of the methods was done according to the ICH guidelines. The calibration curve for the drug was found linear in the range of 5-50 μg / mL for with accepted mean correlation coefficient. A reported HPLC method was compared with the methods and no significant differences were found.