A sensitive and fast ultra performance liquid chromatography‐electrospray ionization‐tandem mass spectrometry (UPLC‐ESI‐MS/MS) method for measurements of N‐butylscopolamine in plasma was developed and validated. A single protein precipitation was proposed for the clean up of the plasma and N‐methylhomatropine was added as internal standard (IS). The analyses were carried out using a C18 column and mobile phase of acetonitrile: 5 mM ammonium acetate + 0.1% formic acid (90:10, v/v). The triple quadrupole mass spectrometer equipped with an electrospray source in positive mode, was set up in selective reaction monitoring, to detect precursor → product ion 360.0 → 194.0 m/z and 290.3 → 138.0 m/z transitions, for N‐butylscopolamine and IS, respectively. The method was linear in 0.03 (lower limit of quantitation; LLOQ) – 10.00 ng/ml range for N‐butylscopolamine. Satisfactory selectivity, linearity, precision, accuracy, and robustness were obtained for the UPLC‐ESI‐MS/MS method. The proposed method was successfully applied to a pharmacokinetic study of healthy human volunteers; the results showed that the two scopolamine butylbromide formulations tested are not bioequivalent in rate and extent of absorption. Copyright © 2012 John Wiley & Sons, Ltd.

This study was to evaluate and compare the pharmacokinetic and pharmacodynamic behavior of two formulations of furosemide (CAS 54-31-9) 40 mg tablets, administered as a single dose to healthy subjects. Plasma concentrations of furosemide were determined with a validated method by liquid chromatography coupled to mass spectrometry (LC-MS/MS). We obtained the parameters: AUC 0-t , AUC 0-∞ , K el , T 1/2 , C max e T max. The following parameters were determined in urine: Sodium, Potassium and Chlorine and the total volume. The 90% confidence intervals for the ratio of C max (93.63-121.92%), AUC 0-t (96.80-115.72%) and AUC 0-∞ (98.45-117.43%) respectively for test and reference. Statistical analysis of the similarity of the parameters for urinary volume, excretion of sodium, potassium and chlorine and assuming that both formulations reach the same plasma levels, we expect that the pharmacological effect is also the same. Whereas the rate and extent of absorption, both products can be considered therapeutic equivalents.

Secnidazole is an antimicrobial agent used primarily in the treatment of amoebiasis. For this bioequivalence study of secnidazole, twenty-eight healthy female volunteers were enrolled in a randomized crossover study. Each volunteer was given a single oral dose of secnidazole test preparation and then the reference preparation, or vice versa, with a wash out interval of two weeks. The plasma concentrations of secnidazole were determined by HPLC, and the samples were extracted with tert-butyl-methyl-ether: dicloromethane (60:40, v/v). Secnidazole and its parent compound metronidazole were separated on a C18 column with water:acetonitrile (85:15, v/v) as the mobile phase, and monitored at 310 nm. The ratio of mean C max , AUC 0−t and AUC 0−∞ values for the test and reference products were within the predetermined range established by ANVISA, demonstrating that the two formulations are bioequivalent in rate and extent of absorption. Uniterms:Oral formulas/bioequivalence study. Secnidazole/bioavailability. Antimicrobials/ bioavailability. Secnidazol é um agente antimicrobiano utilizado principalmente no tratamento da amebíase. Para este estudo de bioequivalência de secnidazol em voluntários saudáveis, foram incluídos vinte e oito voluntárias mulheres no estudo randomizado cruzado. Cada voluntária recebeu uma única dose oral de secnidazol do produto teste e referência para comparação, com um intervalo de wash-out de duas semanas. As concentrações plasmáticas de secnidazol foram determinados por CLAE, as amostras foram extraídas com terc -butil-metil-éter: dicloromethano (60:40, v/v). O secnidazol e seu padrão interno metronidazol foram separados em uma coluna (C18 ) com fase móvel água ultra-pura:acetonitrila (85:15, v/v) e monitorado em 310 nm. As razões entre as médias geométricas de C máx , ASC 0-t e ASC 0-∞ , encontraramse dentro do estabelecido pela ANVISA, demonstrando que as formulações são bioequivalentes quanto à taxa e extensão de absorção Unitermos: Formulações orais/estudo de bioequivalência. Secnidazol/biodisponibilidade. Antimicrobianos/biodisponibilidade.

A sensitive, selective, and rapid ultra-performance LC (UPLC)/MSIMS method was validated for the confirmation and quantification of clonazepam in human plasma. The analyte was extracted from human plasma with diethyl ether, reaching an average recovery of 64.02 and 66.48% for clonazepam and the internal standard, respectively. The separation was performed on a Waters ACQUITY UPLC BEH C18 column (50 x 2.1 mm id, 1.7 microm particle size) with gradient elution at a flow rate of 0.25 mL/min using a 0.5% formic acid solution (mobile phase A) and acetonitrile-methanol-formic acid (75+25 + 0.5, v/v/v; mobile phase B). Detection was performed on a triple-quadruple tandem mass spectrometer in the multiple reaction monitoring mode via electrospray ionization. Linear calibration curves were obtained in the concentration range of 0.3-50.0 ng/mL, with an LOQ of 0.3 ng/mL. The intraday and interday precision (CV) values were below 10%, and accuracy (relative error) ranged from -2.6 to 6.6% at all QC levels. The suggested method was successfully applied for the determination of clonazepam in human plasma in a bioequivalence study.