Potentiation of ifosfamide toxicity by chlordiazepoxide, diazepam and oxazepam

The effects of chlordiazepoxide, diazepam and oxazepam on the lethal toxicity and metabolic activation of ifosfamide were investigated in mice. Ifosfamide was administered 24 h after the final injection of chlordiazepoxide, diazepam or oxazepam (100 mg/kg/d for 3 d, i.p.). The prior administration of chlordiazepoxide, diazepam or oxazepam enhanced the toxicity of ifosfamide (778 mg/kg, i.p.) during observation for 6 d after the administration of ifosfamide. In chlordiazepoxide-, diazepam- or oxazepam-treated mice, a higher concentration of active metabolite in the plasma after the administration of ifosfamide (200 or 600 mg/kg, i.p.) was observed as compared with that in mice treated with ifosfamide alone. On the other hand, chlordizepoxide, diazepam or oxazepam markedly enhanced the activity of ifosfamide oxidase in the liver microsomes. These results suggest that the potentiation of ifosfamide toxicity is due to stimulation of the metabolic activation of ifosfamide by chlordizepoxide, diazepam and oxazepam.     

Determination of temazepam and temazepam glucuronide by reversed-phase high-performance liquid chromatography.

A rapid and sensitive method for extracting temazepam from human serum and urine is presented. Free temazepam is extracted from plasma and urine samples using n-butyl chloride with nitrazepam as the internal standard. Temazepam glucuronide is analyzed as free temazepam after incubating extracts with beta-glucuronidase. Separation is achieved using a C8 reversed-phase column with a methanol-water-phosphate buffer mobile phase. An ultraviolet detector operated at 230 nm is used and a linear response is observed from 20 ng/ml to 10 micrograms/ml. The limit of detection is 15.5 ng/ml and the limit of quantitation is 46.5 ng/ml. Coefficients of variation are less than 10% for concentrations greater than 50 ng/ml. Application of the methodology is demonstrated in a pharmacokinetic study using eight healthy male subjects.     

Reduction of temazepam to diazepam and lorazepam to delorazepam during enzymatic hydrolysis

It has been previously reported that treatment of urinary oxazepam by commercial β-glucuronidase enzyme preparations, from Escherichia coli, Helix pomatia and Patella vulgata, results in production of nordiazepam (desmethyldiazepam) artefact. In this study, we report that this unusual reductive transformation also occurs in other benzodiazepines with a hydroxyl group at the C3 position such as temazepam and lorazepam. As determined by liquid chromatography-mass spectrometry analysis, all three enzyme preparations were found capable of converting urinary temazepam into diazepam following enzymatic incubation and subsequent liquid–liquid extraction procedures. For example, when H. pomatia enzymes were used with incubation conditions of 18 h and 50 °C, the percentage conversion, although small, was significant—approximately 1% (0.59–1.54%) in both patient and spiked blank urines. Similarly, using H. pomatia enzyme under these incubation conditions, a reductive transformation of urinary lorazepam into delorazepam (chlordesmethyldiazepam) occurred. These findings have both clinical and forensic implications. Detection of diazepam or delorazepam in biological samples following enzyme treatment should be interpreted with care.     

High-pressure liquid chromatographic analysis of diazepam, oxazepam and n-desmethyldiazepam in human blood

We describe a rapid method for precisely measuring concentrations of diazepam, oxazepam and N-desmethyldiazepam in blood by high-pressure liquid chromatography. The drugs, together with an internal standard, prazepam, are extracted from 2 ml of blood and analyzed isocratically on a reversed-phase column with a mobile phase consisting of acetonitrile-0.01 M sodium acetate buffer (35:65 v/v). The eluted drugs are detected by their absorption at 240 nm. The sensitivity of this method is 30 microgram/l for oxazepam and N-desmethyldiazepam, 40 microgram/l for diazapam, for 2-ml blood samples. Relative recovery of added drugs to blood varies from 91 to 110%. The day-to-day precision (coefficient of variation) established by 10 replicate analyses was 2.8 to 9.6%.     

Preparation of a novel sorptive stir bar based on vinylpyrrolidone‐ethylene glycol dimethacrylate monolithic polymer for the simultaneous extraction of diazepam and nordazepam from human plasma

A new monolithic coating based on vinylpyrrolidone‐ethylene glycol dimethacrylate polymer was introduced for stir bar sorptive extraction. The polymerization step was performed using different contents of monomer, cross‐linker and porogenic solvent, and the best formulation was selected. The quality of the prepared vinylpyrrolidone‐ethylene glycol dimethacrylate stir bars was satisfactory, demonstrating good repeatability within batch (relative standard deviation < 3.5%) and acceptable reproducibility between batches (relative standard deviation < 6.0%). The prepared stir bar was utilized in combination with ultrasound‐assisted liquid desorption, followed by high‐performance liquid chromatography with ultraviolet detection for the simultaneous determination of diazepam and nordazepam in human plasma samples. To optimize the extraction step, a three‐level, four‐factor, three‐block Box–Behnken design was applied. Under the optimum conditions, the analytical performance of the proposed method displayed excellent linear dynamic ranges for diazepam (36–1200 ng/mL) and nordazepam (25–1200 ng/mL), with correlation coefficients of 0.9986 and 0.9968 and detection limits of 12 and 10 ng/mL, respectively. The intra‐ and interday recovery ranged from 93 to 106%, and the relative standard deviations were less than 6%. Finally, the proposed method was successfully applied to the analysis of diazepam and nordazepam at their therapeutic levels in human plasma. The novelty of this study is the improved polarity of the stir bar coating and its application for the simultaneous extraction of diazepam and its active metabolite, nordazepam in human plasma sample. The method was more rapid than previously reported stir bar sorptive extraction techniques based on monolithic coatings, and exhibited lower detection limits in comparison with similar methods for the determination of diazepam and nordazepam in biological fluids.     

Determination of heat-exposure effects on the concentration of catecholamines in bovine plasma and milk

A reversed-phase high-performance liquid chromatographic method with electrochemical detection has been adapted for the determination of picogram concentrations of norepinephrine and epinephrine in bovine plasma and milk. This method has been used to monitor the levels of these catecholamines when lactating cows are exposed to heat stress under controlled conditions. In response to heat stress, epinephrine concentrations in milk and plasma were similar. However, norepinephrine concentrations in milk were one tenth of that in plasma.     

Pharmaceutical performance of solid dispersions containing poly(ethylene glycol) 6000 and diazepam or temazepam

Differential scanning calorimetry (DSC) data showed that the crystallinity of poly(ethylene glycol) 6000 in solid dispersions containing and diazepam or temazepam only slightly increased upon aging and that the twice folded modification of the polymer unfolded into the once folded modification during aging, while the once folded modification did not unfold. This unfolding was found to be time and temperature dependent. X-ray powder diffraction data revealed that the drug crystallinity in the solid dispersions slightly increased upon aging. The dissolution profiles of aged and non-aged solid dispersions were comparable. It was concluded that polymer unfolding did not have an impact on the pharmaceutical performance of the investigated dispersions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Melting behavior of pure polyethylene glycol 6000 and polyethylene glycol 6000 in solid dispersions containing diazepam or temazepam: a DSC study

The purpose of the present study was to investigate the melting behavior of polyethylene glycol 6000 (PEG 6000) as such as well as in solid dispersions containing diazepam or temazepam, prepared by solvent and fusion methods, using differential scanning calorimetry (DSC). It was shown that the melting behavior of pure PEG 6000 is influenced by the crystallization procedure applied. Fusion at 80°C followed by cooling always yielded three different crystal modifications. The rate of cooling (under controlled conditions) was found to have a significant influence on the relative distribution of the three modifications: the lower the cooling rate, the higher the relative amount of the extended modification. Crystallization from organic solution yielded mainly the once folded form. The presence of diazepam and temazepam influenced the relative amount of the different PEG 6000 modifications. Both drugs decreased the formation of the more stable modification, while the formation of the twice folded form was induced. However, in the case of temazepam the contribution of the extended form at higher drug levels increased in dispersions obtained from organic solutions.     

Determination of iodine in milk

A method of iodine determination in milk is described. Dry ashing and extraction of the ash with water is followed by photometric determination of the catalytic influence on the Ce-As reaction. Distillation proves to be unnecessary. Determination with this method can be performed in any laboratory, though not specially equipped for trace analyses.     

Determination of diazepam in cream biscuits by liquid chromatography

An analytical procedure was developed for the detection and quantitation of diazepam in cream biscuits, which were used to commit crime. The method involves the extraction of diazepam with ethanol at room temperature, and the extract is filtered, evaporated to dryness, and redissolved in the mobile phase, methanol-acetonitrile-tetrahydrofuran-water (15 + 55 + 4 + 26, v/v). The separation is achieved on a C18 reversed-phase column with the mobile phase and diode array detection (lambda(max)) at 230 nm. Medazepam is used as the internal standard is for quantification. The calibration plot for the determination of diazepam is based on linear regression analysis (y = 0.6687x + 0.0372; r2 = 0.995). The limit of detection for diazepam in the biscuit samples was estimated as 600 ng/mL. The limit of quantitation for diazepam was estimated as 1.75 microg/mL. The diazepam detected per piece of biscuit was found to be in the range of 0.27-0.45 mg. Pure diazepam was added to biscuit samples at 3 levels (100 and 500 microg/g, and 1 mg/g), and the recoveries were found to be 95%. The mean retention time of diazepam was 2.7 min and that of medazepam (IS) was 4 min. The relative standard deviations of the diazepam level in the biscuit samples were estimated to be 0.4% for retention time and 1.02% for peak area in intraday analysis, whereas the corresponding values were and 0.61 and 2.34% in interday analysis. The method is rapid and reliable for qualitative and quantitative analysis of cream biscuits laced with diazepam, and it can be used by law enforcement laboratories for routine analysis.     

Quantitation by gas chromatography with selected-ion monitoring mass spectrometry of "natural" diazepam, N-desmethyldiazepam and oxazepam in normal human serum.

During the past five years, the literature has tended to prove the occurrence of "natural benzodiazepines" in tissues and biological fluids of non-medicated humans. Several have been identified but very few papers deal with their quantitation in biological material. We present here a method for the specific and sensitive measurement of serum levels of diazepam, N-desmethyldiazepam and oxazepam by gas chromatography with selected-ion monitoring mass spectrometry in twenty human volunteers without medication. Diazepam was found over the whole population, in the range 7.3-32.0 pg/ml, identical in males and females. The other two were present in only some individuals (1.0-7.6 pg/ml for N-desmethyldiazepam and 2.0-13.0 pg/ml for oxazepam). The origin (endogenous, dietary or microbial) of these substances is still to be elucidated.     

液相色谱-串联质谱法测定牛奶和奶粉中卡巴氧和喹乙醇代谢物的残留量

建立了牛奶和奶粉中卡巴氧代谢物喹喔啉-2-羧酸(QCA)和喹乙醇代谢物3-甲基喹喔啉-2-羧酸(MQCA)残留量的液相色谱-串联质谱测定方法。将样品经0.6%(体积分数)的甲酸溶液进行消化,用Tris缓冲溶液调节pH后,加入Protease蛋白酶进行酶解,样品溶液用0.3 mol/L HCl溶液酸化后,采用阴离子交换固相萃取柱Oasis MAX进行净化和富集。分析样品以0.1%(体积分数)的甲酸溶液-甲醇-乙腈为流动相,经Inertsil ODS-3色谱柱分离,采用负离子扫描,在LC-MS/MS多反应监测模式下进行定性及定量分析。喹口恶啉-2-羧酸和3-甲基喹口恶啉-2-羧酸的方法测定下限牛奶为0.5μg/kg,奶粉为4.0μg/kg。对牛奶在0.5~5.0μg/kg,奶粉在4.0~40.0μg/kg添加水平的平均回收率为68.2%~82.5%,RSD为3.4%~12%。