The determination of bromazepam in plasma by reversed-phase high-performance liquid chromatography

A Simple and Reliable Liquid Chromatographic Method for Simultaneous Determination of Five Benzodiazepine Drugs in Human Plasma

Benzodiazepines (BZDs) are one of the most important drugs that have been used in the treatment of neuropsychological disorders. Indeed, BZDs are abused by drug addicts regardless of their therapeutic uses. Therefore, it was important in forensic and clinical toxicology to reach an easy and reliable method for the screening and quantification of BZDs in the human plasma matrix. In the current work, five BZDs, namely bromazepam, clonazepam, lorazepam, nordiazepam and diazepam were simultaneously separated and detected by a simple and reliable RPLC method in a human plasma matrix. Isocratic mobile elution consisting of 20 mmol L−1 phosphate buffer (pH 7.0) and methanol (50:50, v/v) on a Symmetry C18 column was employed. The flow rate, wavelength and column temperature were fixed at 1.0 mL min−1, 214 nm and 40 °C, respectively. The proposed method was validated, giving a linearity within the concentration ranges 5–500 ng mL−1 for bromazepam and diazepam, 3–500 ng mL−1 for clonazepam and lorazepam and 1–500 ng mL−1 for nordiazepam with a determination coefficient (R2) more than 0.9992. The LOD values for the selected BZDs ranged from 0.54 to 2.32 and from 1.78 to 7.65 ng mL−1 for standard methanolic and plasma matrices, respectively. Precision, accuracy, selectivity, stability, and robustness were some of the terms considered in validating the current RPLC method. Based on these results, a simple and reliable RPLC method was successfully applied to quantify BZDs in human plasma matrix appearing with recoveries ranging from 96.5 to 107.5% and interday RSD less than 4%. The current developed method was useful for rapidly screening the most commonly used BZDs in the market within their therapeutic concentration ranges.

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.

Analytical methods for determination of benzodiazepines. A short review

Benzodiazepines (BDZs) are generally commonly used as anxiolytic and/or hypnotic drugs as a ligand of the GABAA-benzodiazepine receptor. Moreover, some of benzodiazepines are widely used as an anti-depressive and sedative drugs, and also as anti-epileptic drugs and in some cases can be useful as an adjunct treatment in refractory epilepsies or anti-alcoholic therapy. High-performance liquid chromatography (HPLC) methods, thin-layer chromatography (TLC) methods, gas chromatography (GC) methods, capillary electrophoresis (CE) methods and some of spectrophotometric and spectrofluorometric methods were developed and have been extensively applied to the analysis of number of benzodiazepine derivative drugs (BDZs) providing reliable and accurate results. The available chemical methods for the determination of BDZs in biological materials and pharmaceutical formulations are reviewed in this work.

Drug facilitated sexual assault: detection and stability of benzodiazepines in spiked drinks using gas chromatography-mass spectrometry

Benzodiazepines are detected in a significant number of drug facilitated sexual assaults (DFSA). Whilst blood and urine from the victim are routinely analysed, due to the delay in reporting DFSA cases and the short half lives of most of these drugs in blood and urine, drug detection in such samples is problematic. Consideration of the drinks involved and analysis for drugs may start to address this. Here we have reconstructed the 'spiking' of three benzodiazepines (diazepam, flunitrazepam and temazepam) into five drinks, an alcopop (flavoured alcoholic drink), a beer, a white wine, a spirit, and a fruit based non-alcoholic drink (J2O) chosen as representative of those drinks commonly used by women in 16-24 year old age group. Using a validated GC-MS method for the simultaneous detection of these drugs in the drinks we have studied the storage stability of the benzodiazepines under two different storage conditions, uncontrolled room temperature and refrigerator (4°C) over a 25 day period. All drugs could be detected in all beverages over this time period. Diazepam was found to be stable in all of the beverages, except the J2O, under both storage conditions. Flunitrazepam and temazepam were found not to be stable but were detectable (97% loss of temazepam and 39% loss of flunitrazepam from J2O). The recommendations from this study are that there should be a policy change and that drinks thought to be involved in DFSA cases should be collected and analysed wherever possible to support other evidence types.

Development of a validated HPLC method for the determination of four 1,4-benzodiazepines in human biological fluids

A simple and sensitive HPLC method was developed and validated for the determination of four frequently prescribed 1,4-benzodiazepines: alprazolam (ALP), bromazepam (BRZ), diazepam (DZP), and flunitrazepam (FNZ). Separation was achieved on an Inertsil C8 analytical (250 mm x 4 mm, 5 microm) column, after selective extraction of benzodiazepine drugs from biological matrices by means of SPE. Isocratic elution was performed with a mobile phase consisting of CH3COONH4, 0.05 M CH3OH, and CH3CN (33:57:10 by volume). Quantification was performed at 240 nm with mefenamic acid (6 ng/microL) as the internal standard. DSC-18 Supelco cartridges provided high absolute recoveries (81-115%). The developed method was fully validated in terms of selectivity, linearity, accuracy, precision, stability, and sensitivity. Repeatability (n = 8) and between-day precision (n = 8) revealed RSD <12%. Recoveries from biological samples ranged from 81.2 to 115%. The detection limit of the method was calculated as 3.3-10.2 ng in blood plasma and 2.6-12.6 ng in urine for 20 microL injection volume. The method was applied to spiked biological matrices. Moreover, the method was applied to real samples of urine after an oral administration.

On-Line Solid-Phase Extraction Coupled With High-Performance Liquid Chromatography and Tandem Mass Spectrometry (SPE-HPLC-MS-MS) for Quantification of Bromazepam in Human Plasma

A validated method for on-line solid-phase extraction coupled with high-performance liquid chromatography tandem mass spectrometry (SPE-HPLC-MS-MS) is described for the quantification of bromazepam in human plasma. The method involves a dilution of 300 muL of plasma with 100 muL of carbamazepine (2.5 ng/mL), used as internal standard, vortex-mixing, centrifugation, and injection of 100 muL of the supernate. The analytes were ionized using positive electrospray mass spectrometry then detected by multiple reaction monitoring (MRM). The m/z transitions 316-->182 (bromazepam) and 237-->194 (carbamazepine) were used for quantification. The calibration curve was linear from 1 ng/mL (limit of quantification) to 200 ng/mL. The retention times of bromazepam and carbamazepine were 2.6 and 3.2 minutes, respectively. The intraday and interday precisions were 3.43%-15.45% and 5.2%-17%, respectively. The intraday and interday accuracy was 94.00%-103.94%. This new automated method has been successfully applied in a bioequivalence study of 2 tablet formulations of 6 mg bromazepam: Lexotan(R) from Produtos Roche Químicos e Farmacêuticos SA, Rio de Janeiro, Brazil (reference) and test formulation from Laboratórios Biosintética Ltda, São Paulo, Brazil. Because the 90% CI of geometric mean ratios between reference and test were completely included in the 80%-125% interval, the 2 formulations were considered bioequivalent. The comparison of different experimental conditions for establishing a dissolution profile in vitro along with our bioavailability data further allowed us to propose rationally based experimental conditions for a dissolution test of bromazepam tablets, actually lacking a pharmacopeial monograph.

Determination of bromazepam in human plasma by high-performance liquid chromatography with electrospray ionization tandem mass spectrometric detection: application to a bioequivalence study

A simple method using a one-step liquid-liquid extraction (LLE) followed by high-performance liquid chromatography (HPLC) with positive ion electrospray ionization tandem mass spectrometric (ESI-MS/MS) detection was developed for the determination of bromazepam in human plasma, using lorazepam as internal standard. The acquisition was performed in the multiple reaction monitoring mode, monitoring the transitions: m/z 316 > 182 for bromazepam and m/z 321 > 275 for lorazepam. The method was linear over the studied range (1-100 ng ml(-1)), with r(2) > 0.98, and the run time was 2.5 min. The intra- and inter-assay precisions were 2.7-14.6 and 4.1-17.3%, respectively and the intra- and inter-assay accuracies were 87-111 and 75.8-109.5%, respectively. The mean recovery was 73.7%, ranging from 64.5 to 79.7%. The limit of quantification was 1 ng ml(-1). At this concentration the mean intra- and inter-assay precisions were 14.6 and 7.1%, respectively, and the mean intra- and inter-assay accuracies were 102.5 and 104%, respectively. Bromazepam stability was evaluated and the results showed that the drug is stable in standard solution and in plasma samples under typical storage and processing conditions. The method was applied to a bioequivalence study in which 27 healthy adult volunteers (14 men) received single oral doses (6 mg) of reference and test bromazepam formulations, in an open, two-period, randomized, crossover protocol. The 90% confidence interval of the individual ratios (test formulation/reference formulation) for C(max) (peak plasma concentration), AUC(0-96) and AUC(0-inf) (area under the plasma concentration versus time curve from time zero to 96 h and to infinity, respectively) were within the range 80-125%, which supports the conclusion that the test formulation is bioequivalent to the reference formulation regarding the rate and extent of bromazepam absorption.

Stability of benzodiazepines in whole blood samples stored at varying temperatures

Study has been undertaken to determine the stability of four benzodiazepines: clonazepam, midazolam, flunitrazepam and oxazepam in whole blood samples. Spiked blood was stored at four different temperatures (room temperature, 4 degrees C, -20 degrees C and -80 degrees C) and analysed at selected times during one year. Determination was performed on the first, third and seventh day during the first week, then once a week for three weeks, once every two weeks for four weeks, then once a month for 4 months and finally, once every 2 months. Extraction was performed using liquid-liquid extraction with 1-chlorobutane, while quantification was carried out using high performance liquid chromatography equipped with a photodiode-array ultraviolet detector. At room temperature, the concentration of all benzodiazepines decreased over one year to 100 and 70% for low and high concentrations, respectively. At 4 degrees C, the decrease was between 90 and 100% for low concentrations and between 50 and 80% for high concentrations. At -20 degrees C, the measured decrease was between 10 and 20% for high and low concentrations, respectively. At -80 degrees C, the measured loss was not significant at high concentration except for midazolam. However, at low concentration the determined decrease was between 5 and 12%. The data collected suggests that quantitative results concerning long-term stored samples should be interpreted with caution in forensic cases. Further investigations concerning the stability of drugs in whole blood or other biological samples, additional methods of identification and determination as well as the establishment of optimal storage conditions should be undertaken in forensic cases.

Methods for the measurement of benzodiazepines in biological samples

A review of methods for the measurement of benzodiazepines in biological specimens published over the last five years is presented. A range of immunoassay procedures using EIA, ELISA, FPIA, agglutination or kinetic interaction of microparticles, or RIA methods are now available. Cross reactivities to benzodiazepines are variable such that no one kit will recognise all benzodiazepines and their relevant metabolites at concentrations likely to be encountered during therapeutic use. Prior hydrolysis of urine to convert glucuronide metabolites to immunoreactive substances improves detection limits for many benzodiazepines. Several radioreceptor assays have now been published and show good sensitivity and specificity to benzodiazepines and offer the advantage (over immunoassay) of being able to detect these drugs with equal sensitivity. Solvent extraction techniques using a variety of solvents were still popular and offer acceptable recoveries and lack of significant interference from other substances. A number of papers describing solid phase extraction procedures were also published. Direct injection of specimens into a HPLC column with back flushing were also successfully described. Seventy two chromatographic methods using HPLC, LC-MS, GC and GC-MS methods were reviewed. HPLC was able to achieve detection limits for many benzodiazepines using UV or DAD detection down to 1-2 ng/ml using 1-2 ml of urine or serum (blood). ECD detectors gave detection limits better than 1 ng/ml from 1 ml of specimen, which was an order of magnitude lower than for NPD. EI-MS offered similar sensitivity, whilst NCI-MS was capable of detection down to 0.1 ng/ml. Methods suitable for the separation of enantiomers of benzodiazepines have been described using HPLC. Electrokinetic micellar chromatography has also been shown to be capable of the analysis of benzodiazepines in urine.

Sensitive determination of bromazepam in human tissues using capillary gas chromatography-mass spectrometry

A reliable and sensitive gas chromatographic-mass spectrometric method was devised to determine the levels of bromazepam in human tissues. Bromazepam was extracted from body tissues using a three-step solvent extraction procedure. N-Desmethyldiazepam served as the internal standard. Selected ion monitoring with m/z 317 for bromazepam and m/z 270 for internal standard was used for quantitation. Calibration curves in all body tissues were linear over the concentration range from 50-500 ng/g. The lower detection limit in body tissues was 2-5 ng/g and the absolute recovery in body tissues was 27.8-68.0%. This method was used to determine the levels of bromazepam in tissues of an autopsied individual who had been prescribed psychotropic drugs and who was found dead in a car.