Stability indicating spectrophotometric methods for quantitative determination of bromazepam and its degradation product

Potentiometric Sensor Arrays Based on Hybrid PFSA/CNTs Membranes for the Analysis of UV-Degraded Drugs

The degradation of drugs is a substantial problem since it affects the safety and effectiveness of pharmaceutical products, as well as their influence on the environment. A novel system of three potentiometric cross-sensitive sensors (using the Donnan potential (DP) as an analytical signal) and a reference electrode was developed for the analysis of UV-degraded sulfacetamide drugs. The membranes for DP-sensors were prepared by a casting procedure from a dispersion of perfluorosulfonic acid (PFSA) polymer, containing carbon nanotubes (CNTs), whose surface was preliminarily modified with carboxyl, sulfonic acid, or (3-aminopropyl)trimethoxysilanol groups. A correlation between the sorption and transport properties of the hybrid membranes and cross-sensitivity of the DP-sensor to sulfacetamide, its degradation product, and inorganic ions was revealed. The analysis of the UV-degraded sulfacetamide drugs using the multisensory system based on hybrid membranes with optimized properties did not require a pre-separation of the components. The limits of detection of sulfacetamide, sulfanilamide, and sodium were 1.8 × 10^-7, 5.8 × 10^-7, and 1.8 × 10^-7 M. The relative errors of the determination of the components of the UV-degraded sulfacetamide drugs were 2-3% (at 6-8% relative standard deviation). PFSA/CNT hybrid materials provided the stable work of the sensors for at least one year.

A Comparative Study between Screen-Printed and Solid-Contact Electrodes for the Stability-Indicating Determination of Bromazepam

Stability-indicating methods are awesome tools to ensure the safety and efficacy of active pharmaceutical ingredients (APIs). An accurate comparative study involving the use of potentiometric sensors for the determination of bromazepam (BRZ) in the presence of its main product of degradation and impurity was performed by the fabrication of two membrane electrodes. A screen-printed electrode (SPE) and a solid-contact glassy carbon electrode (SCE) were fabricated and their performance optimized. The fabricated sensors showed a linear electrochemical response in the concentration range 1.0 × 10−6 M to 1.0 × 10−2 M. The electrodes exhibited Nernstian slopes of 59.70 mV/decade and 58.10 mV/decade for the BRZ-SPE and BRZ-SCE membrane electrodes, respectively. The electrochemical performance was greatly affected by the medium pH. They showed an almost ideal electrochemical performance between pH 3.0 and pH 6.0. The fabricated membranes were applied successfully for the quantification of BRZ in the presence of up to 90% of its degradation product. Moreover, a successful application of the fabricated electrodes was performed for the sensitive and selective quantification of BRZ in its tablet form without any pretreatment procedure.

Simultaneous determination of ofloxacin and bromfenac in combined dosage form using four different spectrophotometric methods

Four simple, precise, accurate and validated spectrophotometric methods have been developed for the simultaneous determination of ofloxacin (OFL) and bromfenac sodium (BROM). Firstly, first and second derivative spectrophotometric methods (¹D &²D) using a zero-crossing technique utilizing 309.3 and 257.5 nm for OFL and 290.7 and 246.5 nm for BROM as optimum working wavelengths in a binary mixture, respectively. Secondly, the first derivative ratio spectrophotometric method (¹DD) in which peak amplitudes at 297.3 nm and 260.7 nm were chosen to simultaneously estimate OFL and BROM, respectively. Thirdly, dual wavelength (DW) method based on two selected wavelengths for each drug in such a way that the difference in absorbance is zero for the second one. At wavelengths 296.4, 348.4 nm BROM has equal absorbance values, therefore, these two wavelengths have been used to determine OFL. Similarly, 271.7 nm and 313.1 nm were selected to determine BROM in the combined formulation. Finally, the fourth method depends on ratio difference spectrophotometry (RDSM), in which the difference between amplitudes at 305.6 nm and 326.5 nm on the ratio spectrum of the mixture was directly proportional to the concentration of OFL; independent of the interfering components. Similarly, the difference between amplitudes at 265.1 nm and 275.4 nm on the ratio spectrum was used for the determination of BROM. The linearity was confirmed in the range of 4 - 18 µg/ml for OFL and BROM for the four methods. The proposed methods were used to determine both drugs in their laboratory prepared mixture and combined formulation with mean percentage recoveries of 99.41 ± 1.35% for OFL and 99.98 ± 1.30 % for BROM in method (A). In method (B), the mean percentage recoveries were 101.70 ± 1.61% for OFL and 101.90 ± 1.45% for BROM. In method (C) OFL was 99.57 ± 1.61% and 100.90 ± 1.62% for BROM. Finally, in method (D) the mean percentage recoveries were 99.37 ± 1.67% for OFL and 100.70 ± 1.59% for BROM. The developed methods were successfully employed for determination of OFL and BROM in laboratory prepared mixtures and combined formulation showing satisfactory recoveries. Methods validation was performed according to the International Conference on Harmonization (ICH) guidelines. The obtained results conformed to the accepted ranges of recovery, precision and repeatability.

Potentiometric Sensors for the Selective Determination of Benzodiazepine Drug Residues in Real Wastewater Effluents

The application of ion-selective electrodes (ISEs) in the detection and determination of environmental pollutants has become a very important mission in the last few years. Two selective and sensitive membrane electrodes were fabricated in the laboratory and intended to evaluate the electrochemical response of bromazepam (BRZ) using phosphotungstic acid (PTA) and sodium tetraphenylborate (TPB) as ion pairing agents. The linearity range of the fabricated electrodes was between 1 × 10−6 M to 1 × 10−3 M. Nernstian slopes of 54 mV/decade and 57 mV/decade were obtained for the BRZ-PTA and BRZ-TPB membrane electrodes, respectively. The performance of the fabricated membranes was optimum in the pH range of 3–6. Optimum electrochemical response was attained through the careful adjustment of all assay settings. The cited method was successfully applied for the selective determination of BRZ in either its pure form or real wastewater samples obtained from a pharmaceutical industrial plant. The main core of novelty in the suggested method lies in the application of the membranes for the sensitive, selective, and economic determination of BRZ in real wastewater effluents without the tedious sample pretreatment procedures. This can make the suggested method considered an eco-friendly method, as it minimizes the use of organic solvents and chemicals used in the pretreatment process.

Development and validation of a stability indicating RP-HPLC-DAD method for the determination of bromazepam

A reliable, selective and sensitive stability-indicating RP-HPLC assay was established for the quantitation of bromazepam (BMZ) and one of the degradant and stated potential impurities; 2-(2-amino-5-bromobenzoyl) pyridine (ABP). The assay was accomplished on a C18 column (250 mm × 4.6 mm i.d., 5 μm particle size), and utilizing methanol-water (70: 30, v/v) as the mobile phase, at a flow rate of 1.0 ml min-1. HPLC detection of elute was obtained by a photodiode array detector (DAD) which was set at 230 nm. ICH guidelines were adhered for validation of proposed method regarding specificity, sensitivity, precision, linearity, accuracy, system suitability and robustness. Calibration curves of BMZ and ABP were created in the range of 1-16 μg mL-1 with mean recovery percentage of 100.02 ± 1.245 and 99.74 ± 1.124, and detection limit of 0.20 μg mL-1 and 0.24 μg mL-1 respectively. BMZ stability was inspected under various ICH forced degradation conditions and it was found to be easily degraded in acidic and alkaline conditions. The results revealed the suitability of the described methodology for the quantitation of the impurity (ABP) in a BMZ pure sample. The determination of BMZ in pharmaceutical dosage forms was conducted with the described method and showed mean percentage recovery of 99.39 ± 1.401 and 98.72 ± 1.795 (n = 6), respectively. When comparing the described procedure to a reference HPLC method statistically, no significant differences between the two methods in regard to both accuracy and precision were found.