Validated Chromatographic Methods for the Simultaneous Determination of Sodium Cromoglycate and Oxymetazoline Hydrochloride in a Combined Dosage Form

Two chromatographic methods were developed and validated for the simultaneous determination of Sodium Cromoglycate (SCG) and Oxymetazoline Hydrochloride (OXMT). SCG and OXMT are administered in combination for effective treatment of nasal congestion and allergy. The first chromatographic method was based on usingaluminum TLC plates pre-coated with silica gel GF254 as the stationary phase and chloroform: methanol: toluene: triethylamine (5: 2: 4:1, by volume) as the mobile phase followed by densitometric measurement of the separated bands at 235 nm. The second method is a high performance liquid chromatographic method for separation and determination of SCG and OXMT using reversed phase C18 column with isocratic elution. The mobile phase composed of acetonitrile: methanol (2: 1, v/v) at flow rate of 1.0 mL/ min. Quantitation was achieved with UV detection at 220 nm. The validity of the proposed methods was assessed using the standard addition technique. The obtained results were statistically compared with those obtained by the official methods, showing no significant difference with respect to accuracy and precision at p = 0.05

Electrophoretic behavior of charge regulated zwitter ionic buffers in covalently and dynamically coated fused silica capillaries

In this work, the electrophoretic behavior of zwitterionic buffers is investigated in the absence of electroosmotic flow (EOF). Electro mobilization of capillary contents is noted when zwitterionic buffers are employed as the background electrolyte at a pH where the buffering moiety carries a net charge. The bulk flow of capillary contents was demonstrated via monitoring the migration of a neutral marker as well as a free and micellar negatively charged marker and SDS–protein complexes. This electrolyte-driven mobilization (EDM) was investigated in detail using 4-(2-hydroxyethyl)piprazine-1-ethanesulfonic acid (HEPES) buffer over a wide pH range (pH 4.0–8.0). Results confirmed that at a pH where HEPES molecules carry a net negative charge, a bulk flow toward the anode is observed. This was attributed to the migration of HEPES ions toward the anode along with their hydration shells. The relatively large difference in size and solvation number between the ionic buffering moiety and its counter-migrating ions (Na+ or H+) resulted in such a net movement. Results indicated that at constant voltage, plotting the measured current versus buffer pH can be used for determination of the isoelectric point of the zwitterionic buffering moiety. Furthermore, this novel mobilization modality was demonstrated using five different HEPES analogs over pH range 5.0–8.0. More in depth investigations are required in order to explore the applicability of EDM in coated capillaries of different wall chemistries and dimensions

Investigation of the profile and kinetics of degradation of rivaroxaban using HPLC, TLC-densitometry and LC/MS/MS: Application to pre-formulation studies

Rivaroxaban (RIVA), an amide group-containing oral anticoagulant was subjected to stress conditions commonly required for the registration of pharmaceuticals: base and acid-catalyzed hydrolysis (0.1 M, 60 °C, 3–6 h), oxidation (10% H2O2, 24 h), photodegradation (300–800 nm, 24 h) and thermal decomposition (50 °C, 6 h). Two major degradation products were separated and identified using TLC and LC/MS/MS, respectively. An orthogonal stability-indicating testing protocol (RP-HPLC and NP-TLC-densitometry) was developed and validated according to ICH guidelines. Both assays enabled the determination of RIVA in the presence of its degradation products as well as the kinetics of degradation. Determination was carried out over a concentration range of (5.00–50.00 μg/mL) and (0.40–12.00 μg/band) with an accuracy of (100.81% ± 1.03) and (100.29% ± 1.08) for HPLC and TLC-densitometry, respectively. Results indicated that RIVA was stable towards oxidation, photodegradation and thermal decomposition but extremely sensitive to hydrolysis. Two major degradation products were detected in the case of base-catalyzed hydrolysis while only one degradation product was detected upon acid-catalyzed hydrolysis. This could be attributed to the presence of amide groups in RIVA structure of different stability profiles. The kinetics of hydrolysis was investigated in more detail and the reaction was found to follow the pseudo first order kinetics, as confirmed by the results of both HPLC and TLC-densitometric assays. The applicability of the assay for the determination of RIVA content and dissolution pattern of the innovator product as well as three generic formulations was demonstrated

Development and Validation of Stability Indicating Spectrophotometric Methods for Determination of Sulbutiamine in Tablet Dosage Form

Five sensitive, selective and precise stability-indicating spectrophotometric methods for the determination of Sulbutiamine (SUL) in the presence of its alkali-induced degradation product (DEG) were developed and validated. Method A is differential dual wavelength (D1 DWL) applied in the analysis of SUL in binary mixture via its first derivative spectra using the difference between two points with equal amplitudes in the alkali-induced degradation product, thus DEG acts as zero contribution. Method B is second derivative spectrophotometry (D2 ), which allowed the determination of SUL at 300.0 nm. Method C is second derivative of the ratio spectra (DD2 ) in which SUL was determined by measuring the peak amplitude at 301.0 nm. Method D is the ratio difference spectrophotometry (RD), where the difference between amplitudes of the absorbance ratio spectra at 237.2 and 274.0 nm were recorded and Method E; Ratio subtraction (RSM) where the zero order spectra of pure SUL were extracted from their laboratory prepared mixtures, and consequently SUL can be analyzed at its maxima. The linearity for SUL was obtained within concentrations ranging from 5.00 - 50.00 μg/mL with percentage recovery of 100.58 + 0.98, 99.62 ± 1.16, 100.70 ± 1.38, 100.06 + 1.00 and 99.56 + 1.00 for the five methods, respectivel

Development and validation of LC–MSMS assay for the determination of the prodrug dabigatran etexilate and its active metabolites in human plasma

Dabigatran etexilate (DABE) is a low-molecular-weight prodrug that is converted after oral administration to dabigatran (DAB)—a directly acting oral anticoagulant. In this study, an LC–MSMS assay was developed and validated for the determination of DABE, free DAB and its equipotent O-glucuronide conjugates in plasma. Owing to the susceptibility of DABE and DAB to chemical hydrolysis, cleavage of the O-glucuronide moiety was carried out using -glucuronidase enzyme. Free and total plasma concentrations of DAB were determined in incurred plasma samples before and after enzymatic cleavage (50 C and 3 h), respectively. RP-HPLC separation was carried out using acetonitrile: water (30:70, v/v), adjusted to pH 3.0 using formic acid. Tandem mass spectrometric detection at positive electrospray ionization in the MRM mode was then employed for the determination of DABE and DAB. The analysis was carried out within 5.0 min over a linear concentration range of 1.00–600.00 ng/mL for the prodrug and its active metabolite. Validation was carried out according to FDA guidelines for bioanalytical method. The recov- eries were higher than 89.48%, the accuracy was within 98.33–110.12% and the RSD was below 10% for the studied compounds in both incurred plasma and quality control samples. Results of incurred sample re-analysis and incurred sample stability revealed less than 10% variability. This indicated good assay precision and sufficient stability of target analytes in their real matrix at the employed experimental conditions. The applicability of the assay for therapeutic drug monitoring and the determination of the pharmacokinetic parameters were demonstrated

Development and validation of LC-MS/MS assay for the determination of Butoconazole in human plasma: Evaluation of systemic absorption following topical application in healthy volunteers

Butoconazole is an imidazole antifungal that is more effective than miconazole and clotrimazole for treatment of vaginal candidiasis. A highly sensitive tandem mass spectrometric assay was developed and validated to evaluate systemic absorption of Butoconazole following intravaginal administration. Chromatographic separation was achieved using Waters Xterra C18 column (3 µm, 3.0 Ã 50.0 mm). Liquid-liquid extraction using tert-butyl methyl ether was used for preparation of plasma samples. The mobile phase was solvent A: 0.1% formic acid in water and solvent B: acetonitrile: methanol (30:70, v/v), using gradient elution mode at 0.5 mL/min. Detection at positive electrospray ionization in the MRM mode was then employed. Analysis was carried out within 5.5 min over a linear concentration range of 0.10â30.00 ng/mL. Validation was carried out according to US FDA guidelines for bioanalytical method validation. Matrix effect, recovery efficiency and process efficiency have been investigated for the analyte and internal standard in neat solvent, post-extraction matrix and plasma. The mean percentage recoveries were higher than 80%, the accuracy was 93.51â106.85% and the RSD was below 10% throughout the studied concentration range. Results indicated sufficient stability of the target analyte in plasma at the employed experimental conditions. Results of incurred sample re-analysis and incurred sample stability revealed less than 5% variability. The applicability of the assay for monitoring of the systemic absorption of Butoconazole following intra vaginal application to healthy volunteers was demonstrated. Results confirmed that Butoconazole was detected shortly after intra vaginal administration with Cmax and tmax of 30 ng/mL and 6 h, respectively. Keywords: Butoconazole, LC-MS/MS, Matrix effect, Process efficiency, Recovery efficienc

Development and Validation of a Modified QuEChERS Protocol Coupled to LC-MS/MS for Simultaneous Determination of Multi-class Antibiotic Residues in Honey

LC-MS/MS assay was developed and validated according to EU guidelines for determination of nitrofuran metabolites and nitroimidazole residues in honey. Crude samples were acid-treated to liberate matrix-bound residues and a modified QuEChERS protocol was employed. liberate matrix-bound residues and a modified QuEChERS protocol was employed. metabolites AHD, AOZ, AMOZ and SEM, respectively while nitroimidazole residues; ronidazole (RNZ) and dimetridazole (DMZ) were determined directly. For all analytes, neat standard calibration curves, after correction for matrix effect were successfully employed

On-column decaffeination and HPLC analysis of epigallocatechin gallate in green tea nutraceuticals

Green tea (GT) derived epigallocatechin gallate (EGCG) is a commonly used nutraceutical for its antioxidant activity. Caffeine is the second major component and interferes with extraction of EGCG. On-column decaffeination was optimized to enable selective enrichment of EGCG, though less retained than caffeine. EGCG recovery and loss in caffeine were determined using RP-HPLC. Results indicated a significant improvement in caffeine removal and EGCG recovery. The SPE-HPLC protocol represents a model for an efficient and economic approach for improving dynamic capacity, selectivity, and sensitivity towards less retained analytes. This is particularly important for analysis of inherently complex samples of nutraceutical products

Simultaneous determination of linezolid, meropenem and theophylline in plasma

The data presented in this article are related to the research article entitled “Voltammeric monitoring of linezolid, meropenem and theophylline in plasma” (A.K. Attia, M.A. Al-Ghobashy, G.M. El-Sayed, S.M. Kamal, accepted in Anal. Biochem. 2018). This article describes a sensitive square wave voltammetric (SWV) method for simultaneous monitoring of linezolid (LIN), meropenem (MERO) and theophylline (THEO) in spiked plasma and in plasma of healthy volunteers. Keywords: Voltammetry, Determination, Linezolid, Meropenem, Theophylline, Plasm

Two new Spectrophotometric Approaches to the Simultaneous Determination of Ezetimibe and Atorvastatin Calcium

Two rapid, simple and sensitive spectrophotometric methods for the quantitative analysis of ezetimibe (EZB) and atorvastatin calcium (ATVC) in bulk powder and combined tablet form have been developed and validated. The first method is bivariate calibration and the second method is ratio subtraction in conjunction with second derivative (D )spectrophotometry. These methods are tested by analyzing synthetic binary mixtures of the above drugs and they are applied to commercial pharmaceutical preparation of the subjected drugs. Standard deviation is < 2 in the assay of raw materials and tablets. Methods are validated as per ICH guidelines and statistical comparison of the suggested methods with the reported spectrophotometric one using F and t tests showed no significant difference regarding both accuracy and precision.International Journal of Chemical Studie