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. [13]. Guidance for Industry. Food-Effect Bioavailability and Fed Bioequivalence Studies. U.S. Department of Health and Human Services Food and Drug Administration, Center for Drug Evaluation and

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, sensitive, and reproducible bioanalytical methods for bioequivalence (BE) studies. Unfortunately, mometasone furoate in nasal spray is poorly absorbed into the systemic circulation with minimal bioavailability (<1%) because of its lipophilicity and extensive

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Acta Chromatographica
Authors:
L. S. Teixeira
,
I. M. Mundim
,
W. C. Souza
,
D. R. Ramos
,
K. B. Bellorio
, and
K. R. Rezende

Summary

A simple, sensitive, and rapid liquid chromatography-mass detection (LC-MS/MS) method for the analysis of betamethasone (BET) from intramuscular injection of phosphate and dipropionate BET produgs was developed for bioequivalence studies in human plasma. The calibration curve was linear over the range of concentrations (0.5–50.0 ng mL−1; r 2 = 0.99), showing a very high sensitivity without interferences at the retention times of BET (0.8 min) and the internal standard (IS) triamcinolone acetonide (0.95 min). Both drug (D) and IS were extracted from human plasma by liquid-liquid extraction, showing average recovery values of 94.0 and 98.9%, respectively. Within- and between-run precision studies demonstrated a variation coefficient <10% at all tested concentrations. Therefore, our analytical method proved to be validated according to the worldwide-accepted FDA guidelines and successfully applied for bioequivalence studies of parenteral formulations containing BET dipropionate (5 mg mL−1) and BET sodium phosphate (2 mg mL−1).

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Summary

A rapid, selective, and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay has been proposed for the determination of aripiprazole in human plasma. The analyte and propranolol as internal standard (IS) were extracted from 200 μL of human plasma via liquid-liquid extraction using methyl tert-butyl ether under alkaline conditions. The best chromatographic separation was achieved on an Aquasil C18 (100 × 2.1 mm, 5 μm) column using methanol-deionized water containing 2 mM ammonium trifluoroacetate and 0.02% formic acid (65:35, v/v) as the mobile phase under isocratic conditions. Detection of analyte and IS was done by tandem mass spectrometry, operating in positive ion and multiple reaction monitoring (MRM) acquisition mode. The method was fully validated for its selectivity, interference check, sensitivity, carryover check, linearity, precision and accuracy, reinjection reproducibility, recovery, matrix effect, ion suppression/enhancement, stability, ruggedness, and dilution integrity. The assay was linear over the concentration range of 0.10–100 ng mL−1 for aripiprazole. The intra-batch and inter-batch precision (%CV) was ≤4.8%, while the mean extraction recovery was >96% for aripiprazole across quality control levels. The method was successfully applied to a bioequivalence study of 10 mg aripiprazole orally disintegrating tablet formulation in 27 healthy Indian subjects under fasting and fed condition. The reproducibility in the measurement of study data was demonstrated by reanalysis of 260 incurred samples.

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B. Madadian 2010 J. Bioequivalence Bioavailability 2 135 . [24]. US Department of HealthHuman

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and detection of different individual diuretic agents in the biological fluids for bioequivalence studies and drug screening purposes which is highly desirable. Fig. 1. Structures of ( R )- and( S )-Indp By the same token, and in view of the mandatory

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Summary

A sensitive and selective liquid chromatographic tandem mass spectrometric (LC-MS-MS) method for analysis of lovastatin in human plasma has been developed and validated. Ethyl acetate extraction was used for plasma sample preparation and simvastatin was used as internal standard. Chromatographic separation was achieved on a C18 column by isocratic elution with 83:17:0.1 (v/v) methanol-2 μM aqueous sodium acetate-formic acid as mobile phase, delivered at 1.0 mL min−1. MS-MS detection was performed using positive electrospray ionization and multiple-reaction monitoring with argon for collision-induced dissociation. Calibration plots were generated over the concentration range 0.05 to 20 ng mL−1 (r > 0.999) with a lower limit of quantification (LLOQ) of 0.05 ng mL−1. Intra and inter-day precision and accuracy were determined at four different concentrations, 0.05, 0.5, 2.0, and 10.0 ng mL−1, and precision ranged from 0.4 to 11.4% with the deviation always less than 15% (n = 5). Extraction recoveries were from 86.8 to 94.1% for lovastatin and approximately 88.0% for simvastatin. The validated method was successfully applied to a bioequivalence study of two lovastatin tablets in 20 healthy volunteers.

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sulfoxide from sheep plasma samples. The study was conducted in order to propose a method suitable for high-throughput bioavailability and bioequivalence studies using a simple, fast and inexpensive sample preparation method, short analytical runtime and

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Summary

A simple, rapid, and sensitive reversed-phase HPLC method was developed and validated for determination of metronidazole and tinidazole in human plasma samples under identical chromatographic conditions. This method involves liquid-liquid extraction using chloroform: isopropylalcohol (95:5). Chromatographic separation was performed using a μ-bondapack C18 (250 mm × 4.6 mm) column. The mobile phase consisted of potassium dihydrogen phosphate solution (0.005 M)/acetonitrile (80/20 v/v). The final pH of the mobile phase was adjusted to 4 ± 0.1 with orthophosphoric acid. The calibration curves were linear over the concentration range 0.1–15 μg/mL for metronidazole and tinidazole with the detection limit of 30 ng/mL. Within- and between-day precision and accuracy did not exceed 9.83% and 10.48%, respectively. Metronidazole and tinidazole were found to be stable in plasma samples with no evidence of degradation during 3 freeze-thaw cycles and 3 months storage in −70 °C. The current validated bio-analytical method was finally applied in bioequivalence studies of two different metronidazole and tinidazole products according to a standard two-way cross-over design with a two-week washout period. No statistically significant difference was observed between the logarithmically transformed AUC0-∞ and C max values. Therefore, generic products were considered bioequivalent with those of standards which could be used interchangeably.

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The most current in vitro and in vivo results in the BioArena system and under greenhouse conditions provide a good opportunity for a fundamental renewal of biological detections and interactions in layer liquid chromatography. The adsorbent bed in a column liquid arrangement is not suitable for biological detection because the living cells do not grow there. Contrarily, the planar adsorbent layer enables the in situ biodetection of antimicrobials and the interactions among separated compounds, cells, and further various cofactors (molecules), making the study of mechanisms of action possible. The basic elements of the time- and dose-dependent quadruple immune response of plants to pathogens in relation to the function and reactions of formaldehyde and its reaction products (mainly endogenous ozone) were demonstrated. This finding opens a new horizon in the field of disease resistance in plants and perhaps in general in the biological world. These results give a good basis and possibility for studying and understanding the unique high-dilution phenomena as well, and at that time, they promise the elimination of century contradictions in this field.

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