Towards clinical adherence monitoring of oral endocrine breast cancer therapies by LC-HRMS-method development, validation, comparison of four sample matrices, and proof of concept.

Oral endocrine therapies (OET) for breast cancer treatment need to be taken over a long period of time and are associated with considerable side effects. Therefore, adherence to OET is an important issue and of high clinical significance for breast cancer patients' caregivers. We hypothesized that a new bioanalytical strategy based on liquid chromatography and high-resolution mass spectrometry might be suitable for unbiased adherence monitoring (AM) of OET. Four different biomatrices (plasma, urine, finger prick blood by volumetric absorptive microsampling (VAMS), oral fluid (OF)) were evaluated regarding their suitability for AM of the OET abemaciclib, anastrozole, exemestane, letrozole, palbociclib, ribociclib, tamoxifen, and endoxifen. An analytical method was developed and validated according to international recommendations. The analytical procedures were successfully validated in all sample matrices for most analytes, even meeting requirements for therapeutic drug monitoring. Chromatographic separation of analytes was achieved in less than 10 min and limits of quantification ranged from 1 to 1000 ng/mL. The analysis of 25 matching patient samples showed that AM of OET is possible using all four matrices with the exception of, e.g., letrozole and exemestane in OF. We were able to show that unbiased bioanalytical AM of OET was possible using different biomatrices with distinct restrictions. Sample collection of VAMS was difficult in most cases due to circulatory restraints and peripheral neuropathy in fingers and OF sampling was hampered by dry mouth syndrome in some cases. Although parent compounds could be detected in most of the urine samples, metabolites should be included when analyzing urine or OF. Plasma is currently the most suitable matrix due to available reference concentrations.

Undeclared Doping Substances are Highly Prevalent in Commercial Sports Nutrition Supplements.

Sports nutrition supplements have previously been reported to contain undeclared doping substances. The use of such supplements can lead to general health risks and may give rise to unintentional doping violations in elite sports. To assess the prevalence of doping substances in a range of high-risk sports nutrition supplements available from Dutch web shops. A total of 66 sports nutrition supplements - identified as potentially high-risk products claiming to modulate hormone regulation, stimulate muscle mass gain, increase fat loss, and/or boost energy - were selected from 21 different brands and purchased from 17 web shops. All products were analyzed for doping substances by the UK life sciences testing company LGC, formerly known as the Laboratory of the Government Chemist, using an extended version of their ISO17025 accredited nutritional supplement screen. A total of 25 out of the 66 products (38%) contained undeclared doping substances, which included high levels of the stimulants oxilofrine, ß-methylphenethylamine (BMPEA) and N,ß-dimethylphenethylamine (NBDMPEA), the stimulant 4-methylhexan-2-amine (methylhexaneamine, 1,3-dimethylamylamine, DMAA), the anabolic steroids boldione (1,4-androstadiene-3,17-dione) and 5-androstene-3ß,17α-diol (17α-AED), the beta-2 agonist higenamine and the beta-blocker bisoprolol. Based upon the recommended dose and the potential variability of analyte concentration, the ingestion of some products identified within this study could pose a significant risk of unintentional doping violations. In addition to inadvertent doping risks, the prescribed use of 3 products (4.5%) could likely impose general health risks.

Tyrosine Induced Metabolome Alterations of Penicillium roqueforti and Quantitation of Secondary Key Metabolites in Blue-Mold Cheese.

To map qualitative and quantitative metabolome alterations when Penicillium roqueforti is grown in an environment where l-tyrosine levels are perturbed, the recently established differential off-line LC-NMR (DOLC-NMR) approach was successfully applied in connection with an absolute metabolite quantitation using a quantitative 1H NMR protocol following the ERETIC 2 (Electronic REference To access In vivo Concentrations) methodology. Among the 23 influenced metabolites, amino acid degradation products like 2-(4-hydroxyphenyl)acetic acid and 2-(3,4-dihydroxyphenyl)acetic acid underwent a tremendous upregulation in the amino acid perturbed approach. Moreover, the output of secondary metabolites like andrastin A, eremofortin B, and the tetrapeptide d-Phe-l-Val-d-Val-l-Tyr was affected in the case of the presence or absence of the added aromatic amino acid. Furthermore, the isolated secondary metabolites of P. roqueforti have been quantified for the first time in five divergent Penicillium isolates by means of a validated LC-ECHO-MS/MS method. This technique is used to compensate the effect of co-extracted matrix compounds during the analysis and to utilize quasi-internal standards to quantify all metabolites of interest accurately. This screening outlined the great variety between the different fungi of the same species. The metabolite spectra of wild-type fungi included more toxic intermediates compared to a selected fungi used as a starter culture for blue-mold cheese production. In addition, these secondary metabolites were quantified in commercially available white- and blue-mold cheese samples. The main differences between the analyte profiles of white and blue cheeses were linked to the impact of the used starter culture. Specific metabolites detected from P. roqueforti like andrastin A and B or roquefortine C could not be detected in white cheese. Among the blue cheese samples, different metabolite pattern could be observed regarding various P. roqueforti starter cultures.

Identification of the designer steroid Androsta-3,5-diene-7,17-dione in a dietary supplement.

A liquid chromatography-mass spectrometry (LC-MS) screen for known anabolic-androgenic steroids in a dietary supplement product marketed for "performance enhancement" detected an unknown compound having steroid-like spectral characteristics. The compound was isolated using high performance liquid chromatography with ultraviolet detection (HPLC-UV) coupled with an analytical scale fraction collector. After the compound was isolated, it was then characterized using gas chromatography with simultaneous Fourier Transform infrared detection and mass spectrometry (GC-FT-IR-MS), liquid chromatography-high resolution accurate mass-mass spectrometry (LC-HRAM-MS) and nuclear magnetic resonance (NMR). The steroid had an accurate mass of m/z 285.1847 (error-0.57 ppm) for the protonated species [M + H]+ , corresponding to a molecular formula of C19 H24 O2 . Based on the GC-FT-IR-MS data, NMR data, and accurate mass, the compound was identified as androsta-3,5-diene-7,17-dione. Although this is not the first reported identification of this designer steroid in a dietary supplement, the data provided adds information for identification of this compound not previously reported. This compound was subsequently detected in another dietary supplement product, which contained three additional active ingredients.

Development and validation of an UPLC-MS/MS method for the therapeutic drug monitoring of oral anti-hormonal drugs in oncology.

A liquid chromatography-mass spectrometry assay was developed and validated for simultaneous quantification of anti-hormonal compounds abiraterone, anastrozole, bicalutamide, Δ(4)-abiraterone (D4A), N-desmethyl enzalutamide, enzalutamide, Z-endoxifen, exemestane and letrozole for the purpose of therapeutic drug monitoring (TDM). Plasma samples were prepared with protein precipitation. Analyses were performed with a triple quadrupole mass spectrometer operating in the positive and negative ion-mode. The validated assay ranges from 2 to 200 ng/mL for abiraterone, 0.2-20 ng/mL for D4A, 10-200 ng/mL for anastrozole and letrozole, 1-20 ng/mL for Z-endoxifen, 1.88-37.5 ng/mL for exemestane and 1500-30,000 ng/mL for enzalutamide, N-desmethyl enzalutamide and bicalutamide. Due to low sensitivity for exemestane, the final extract of exemestane patient samples should be concentrated prior to injection and a larger sample volume should be prepared for exemestane patient samples and QC samples to obtain adequate sensitivity. Furthermore, we observed a batch-dependent stability for abiraterone in plasma at room temperature and therefore samples should be shipped on ice. This newly validated method has been successfully applied for routine TDM of anti-hormonal drugs in cancer patients.

Steroidogenic Metabolism of Galeterone Reveals a Diversity of Biochemical Activities.

Galeterone is a steroidal CYP17A1 inhibitor, androgen receptor (AR) antagonist, and AR degrader, under evaluation in a phase III clinical trial for castration-resistant prostate cancer (CRPC). The A/B steroid ring (Δ5,3ß-hydroxyl) structure of galeterone is identical to that of cholesterol, which makes endogenous steroids with the same structure (e.g., dehydroepiandrosterone and pregnenolone) substrates for the enzyme 3ß-hydroxysteroid dehydrogenase (3ßHSD). We found that galeterone is metabolized by 3ßHSD to Δ4-galeterone (D4G), which is further converted by steroid-5α-reductase (SRD5A) to 3-keto-5α-galeterone (5αG), 3α-OH-5α-galeterone, and 3ß-OH-5α-galeterone; in vivo it is also converted to the three corresponding 5ß-reduced metabolites. D4G inhibits steroidogenesis and suppresses AR protein stability, AR target gene expression, and xenograft growth comparably with galeterone, and further conversion by SRD5A leads to loss of several activities that inhibit the androgen axis that may compromise clinical efficacy. Together, these findings define a critical metabolic class effect of steroidal drugs with a Δ5,3ß-hydroxyl structure.

HPLC Methods for Quantitation of Exemestane-Luteolin and Exemestane-Resveratrol Mixtures in Nanoformulations.

Two HPLC-DAD assays for the simultaneous quantitation of exemestane (EXE) and resveratrol (RES)-Mix 1-and EXE and luteolin (LUT)-Mix 2-in novel breast cancer therapy nanoformulations were developed. Calibration curves 15-30 µg/mL and samples were injected through an Inertsil ODS-3 (250 × 4.6 mm, 5 µm) column. The gradient elution for Mix 1 was methanol : 0.05% (v/v) acetic acid in water (60 : 40 to 80 : 20, linear over 2 min), and for Mix 2, it was methanol : water (60 : 40 for 4 min, then ramped linearly to 90 : 10, over 12 min) pumped at 1.5 mL/min for 4 min, then 1 mL/min till the end of run. EXE, RES, LUT and flutamide (internal standard (IS)) were measured at 246, 307, 350 and 300 nm, respectively. For Mix 1, RES, EXE and IS eluted at 3.5, 6.8 and 7.4 min, respectively, while for Mix 2, LUT, EXE and IS eluted at 7.5, 11.4 and 12.7 min, respectively. The mean r(2) for the standard curves was ≥0.99, and percentage coefficient of variation and % error of the mean were <2. Both assays successfully quantitated Mix 1 and Mix 2 in their nanoformulations. The two developed assays were sensitive and selective for the analysis of EXE-LUT and EXE-RES mixtures in nanoformulations according to International Conference on Harmonization guidelines.

Suitability of bovine bile compared to urine for detection of free, sulfate and glucuronate boldenone, androstadienedione, cortisol, cortisone, prednisolone, prednisone and dexamethasone by LC-MS/MS.

The administration of boldenone and androstadienedione to cattle is forbidden in the European Union, while prednisolone is permitted for therapeutic purposes. They are pseudoendogenous substances (endogenously produced under certain circumstances). The commonly used matrices in control analyses are urine or liver. With the aim of improving the residue controls, we previously validated a method for steroid analysis in bile. We now compare urine (a 'classic' matrix) to bile, both collected at the slaughterhouse, to understand whether the detection of steroids in the latter is easier. With the aim of having clearer results, we tested the presence of the synthetic corticosteroid dexamethasone. The results show that bile does not substantially improve the detection of boldenone, or its conjugates, prednisolone and prednisone. Dexamethasone, instead, was found in 10 out of 53 bovine bile samples, but only in one urine sample from the same animals. Bile could constitute a novel matrix for the analysis of residues in food-producing animals, and possibly not only of synthetic corticosteroids.

Detection of boldenone, its conjugates and androstadienedione, as well as five corticosteroids in bovine bile through a unique immunoaffinity column clean-up and two validated liquid chromatography-tandem mass spectrometry analyses.

The presence of ß-boldenone II phase metabolites and prednisolone in urine samples, owing to endogenous or natural origin or illicit treatment, is under debate within the European Union. The detection of ß-boldenone conjugates, α-boldenone conjugates at concentrations higher than 2 ng mL(-1) and prednisolone above the cut-off level of 5 ng mL(-1) in urine have been, until now, critical in deciding if illegal drug use has occurred. The use of urine sometimes is not entirely satisfactory, especially when the drug is administrated at low doses or when its metabolic conversion is very fast. This subsequently would hamper its detection in urine. The introduction of a new, advantageous matrix where the illicit treatment can be investigated would be highly appreciated. In this study, we have developed and validated a simple and unique immunoaffinity clean-up procedure, which was applied to bovine bile samples, followed by two different analytical liquid chromatography-electrospray-tandem mass spectrometry methods. The first method tests androstadienedione, α- and ß-boldenone sulphate, glucuronate and related free forms, while the other method assays prednisolone, prednisone, dexamethasone, cortisone, and cortisol. The methods were validated according to European Commission Decision 2002/657/EC. The evaluated parameters were linearity, specificity, precision (repeatability and intra-laboratory reproducibility), recovery, decision limit and detection capability. The decision limits (CCα) were between 0.38 and 0.45 ng mL(-1) for anabolic steroids, and 0.13 and 0.15 ng mL(-1) as far as corticosteroids were concerned. Intra- and inter-day repeatability was below 15.8 and 19.9% for all analytes, respectively. The methods were applied to the analysis of some bile samples collected from untreated young bulls in order to investigate the presence of the studied steroids in this matrix.

Simultaneous quantitative determinations of fluticasone propionate and salmeterol xinafote in diskus inhalers.

In the present study, two new methods were developed for the quantitative determination of active components of Seretide(®), commercially available pharmaceutical preparation in the diskus form. One of these methods was based on derivative spectrophotometry and used a zero-crossing technique. The determinations of fluticasone propionate and salmeterol xinafoate were performed by first order derivatisation at 216.5 nm and second order derivatisation at 250 nm, respectively. The concentration ranges were 5.0-32.5 µg/mL for fluticasone propionate and 2-12 µg/mL for salmeterol xinafoate. The second method developed also included high performance liquid chromatography. In this method, a methanol-water mobile phase mixture (95:5, v/v) and a C18 chromasil column as a stationary phase were used. The wavelength of the diode array UV detector was 260 nm; the flow rate was 1 mL/min. The concentration ranges were 2-16 µg/mL for fluticasone propionate and 1-8 µg/mL for salmeterol xinafoate. The results for both methods from diskus are in the pharmacopea limits. For the statistical determination of these results, these two methods were compared with t-test for the means and with F-test for the standard deviations.

Detection and characterization of urinary metabolites of boldione by LC-MS/MS. Part II: Conjugates with cysteine and N-acetylcysteine.

The occurrence of boldione metabolites conjugated with cysteine and N-acetylcysteine in human urine was evaluated. Methods based on precursor ion scan of the protonated aminoacid (m/z 122 and m/z 164 for cysteine and N-acetylcysteine respectively) and neutral losses of the aminoacids (121 Da and 163 Da for cysteine and N-acetylcysteine respectively) were applied for the open detection of conjugates. Results for urine samples collected before and after boldione administration were compared. Using this approach, 24 metabolites (eleven conjugates with cysteine and thirteen conjugated with N-acetylcysteine) were detected. The metabolites were characterized by mass spectrometry and their potential structures were proposed based on this information. The structures of nine of these metabolites were confirmed by the synthesis of the conjugates. According to these results, a metabolic pathway for boldione involving this type of conjugation was presented. Up to our knowledge this is the first time that cysteine conjugates are presented for exogenous anabolic androgenic steroids and the first report of N-acetylcysteine conjugates for steroids.

Detection and characterization of urinary metabolites of boldione by LC-MS/MS. Part I: Phase I metabolites excreted free, as glucuronide and sulfate conjugates, and released after alkaline treatment of the urine.

Boldione (1,4-androstadien-3,17-dione) is included in the list of prohibited substances, issued by the World Anti-Doping Agency (WADA). Endogenous production of low concentrations of boldione has also been reported. The objective of this study was to assess boldione metabolism in humans. Detection of boldione metabolites was accomplished by analysis by liquid chromatography coupled to tandem mass spectrometry of urine samples obtained after administration of the drug and subjected to different sample preparation procedures to analyze the different metabolic fractions (free, glucuronides, sulpfates and released in basic media). In addition to boldione, eight metabolites were detected in the free fraction. Four of them were identified by comparison with standards: 6ß-hydroxy-boldenone (M3), androsta-1,4,6-triene-3,17-dione (M5), (5α)-1-androstenedione (M6) and (5α)-1-testosterone (M8). Metabolite M7 was identified as the 5ß-isomer of 1-androstenedione, and metabolites M1, M2 and M4 were hydroxylated metabolites and tentative structures were proposed based on mass spectrometric data. After ß-glucuronidase hydrolysis, five additional metabolites excreted only as conjugates with glucuronic acid were detected: boldenone, (5ß)-1-testosterone (M9), and three metabolites resulting from reduction of the 3-keto group. Boldenone, epiboldenone, and hydroxylated metabolites of boldione, boldenone and 1-testosterone were detected as conjugates with sulfate. In addition, boldione and seven metabolites (boldenone, M2, M3, M4, M5, M7 and M9) increased their concentration in urine after treatment of the urine in alkaline conditions. In summary, 15 boldione metabolites were detected in all fractions. The longer detection time was observed for metabolite M4 after alkaline treatment of the urine, which was detected up to 5 days after boldione administration.

Influence of dentures on residual inhaled corticosteroids in the mouths of elderly asthma patients.

BACKGROUND: The influence of dentures on residual inhaled corticosteroids (ICSs) in the mouths of elderly asthmatic patients and the appropriate time for gargling after inhaling ICSs are unclear. METHODS: Twenty elderly patients in whom moderate persistent asthma was stably controlled using fluticasone propionate Diskus (FP, n = 10) or hydrofluoroalkane-beclomethasone dipropionate (HFA-BDP, n = 10) for more than 3 months and who wore dentures daily were switched to the other type of ICS for 4 weeks in a crossover manner. The residual amount of each ICS in their mouths after inhalation was measured along with determination of peak inspiratory flow (PIF) and pharyngeal culture for detecting Candida albicans. RESULTS: The total amounts of residual ICSs in gargling fluids (µg) with HFA-BDP were significantly greater than those with FP (15.6 ± 14.6 vs. 11.5 ± 13.8, p = 0.028). The residual amounts of HFA-BDP were significantly greater in the patients with complete dentures than in those with partial dentures. The residual amounts of FP were significantly correlated with the PIF values in the FP treatment (p = 0.013) but not in the HFA-BDP treatment (p = 0.202). No residual ICSs remained after the third gargling in either treatment. The occurrence of candidiasis during the HFA-BDP period was significantly higher than that during the FP treatment (p = 0.046). CONCLUSION: The dentures of elderly asthmatics affect the oral residues of ICSs and occurrence of candidiasis in HFA-BDP treatment; meanwhile, the PIF values affected these factors in FP treatment. Three times gargling after inhaling ICSs is required.

On-chip microelectrophoresis for the study of in vitro nonhomologous end-joining DNA double-strand break repair.

Oligomerization of linearized plasmids by nuclear proteins extracts, a recognized measure of nonhomologous end-joining (NHEJ) repair capacity, is typically assessed through agarose gel electrophoresis, a labor-intensive procedure. In the current study, a more convenient NHEJ assay was developed using microchips that allow scaled-down separation and quantification. This microchip method allows a considerable reduction in sample amount and analysis time with similar costs and comparable or slightly better precision. Data obtained with quercetin and wortmannin show that the method can be applied to the screening of food components and natural products for positive and negative modulators of NHEJ, potential chemopreventive and indirect genotoxic compounds, respectively.

The determination of budesonide and fluticasone in human sputum samples collected from COPD patients using LC-MS/MS.

A bioanalytical method for the quantitative determination of budesonide and fluticasone in human sputum was developed. Sputolysin(®) Reagent was added to the sputum samples. After incubation (37°C; 60-70 min under shaking) and automated solid phase extraction the extracts were analysed using LC-MS/MS. Budesonide and fluticasone showed good linearity (r>0.99) over the range 0.1-100 nM in the first and second validation batch, and over the range 0.25-10,000 nM in the third and fourth validation batch. The lower limit of quantification (LLOQ) achieved was 5 nM for budesonide and fluticasone in 100 µL human sputum. Intra-run and inter-run RSD for four quality control levels (5-100 nM) were within 6.9% (budesonide) and 8.0% (fluticasone). The accuracy ranged from -11.4% to -1.6% (budesonide), and from -11.8% to 0.4% (fluticasone). The validated method was applied to clinical sputum samples from COPD patients.

Development and validation of stability indicating method for the determination of exemestane by reverse phase high performance liquid chromatography.

Exemestane is an aromatase inhibitor used in the treatment of breast cancer. A selective stability-indicating reversed-phase high performance liquid chromatography (RP-HPLC) method has been developed which can separate and accurately quantitate low levels of exemestane. The stability-indicating capability of the method was demonstrated by adequate separation of exemestane and all the degradation product peaks from exemestane peak and also from each other in stability samples of exemestane. Chromatographic separation of exemestane and its degraded products were achieved by using isocratic elution at a flow rate of 1.0 mL/min on a C18 reverse phase column (Phenomenex, size: 250 × 4.60 mm, particle size 5 µm) at ambient temperature. The mobile phase used for the analysis was acetonitrile-water (60:40, %v/v) with UV visible detection at 242 nm. The proposed method was used to study the degradation behavior of drug under various stress conditions as per ICH recommended guidelines.

Analysis of fluticasone propionate in induced sputum by mass spectrometry.

Although evaluation of induced sputum has shown promise as a marker of eosinophilic airway inflammation in asthmatic subjects, most studies, to date, do not adequately address the potential effect that inhaled corticosteroids may have on sputum eosinophilia. This study was designed to prospectively evaluate analysis of fluticasone propionate (FP) in whole sputum by mass spectrometry as a tool to determine recent administration of inhaled FP. Induced sputum of nonsmoking asthmatic subjects was prospectively analyzed 16-24 hours after witnessed administration of orally inhaled FP. FP was extracted from whole sputum via an acetonitrile protein precipitation followed by methylene chloride liquid extraction of the supernatant (AB 4000; AB Sciex). A portion of the reconstituted sample was analyzed by liquid chromatography tandem mass spectrometry using a triple quad tandem mass spectrometer. Results were compared with those from nonsmoking asthmatic subjects not receiving inhaled FP. Twenty-two asthmatic subjects on FP and 9 asthmatic subjects without FP underwent sputum induction 16-24 hours following witnessed administration of FP. Sufficient sputum for analysis was obtained from 30 of 31 subjects. FP was detected in 22 of 22 asthmatic subjects receiving FP (range, 29-133,000 pg/mL) and was undetectable in 8 of 8 subjects not receiving FP. The sensitivity and specificity of tandem mass spectrometry's ability to detect FP in sputum was 100% and 100%, respectively. Analysis of FP in induced sputum is a reliable method to verify recent administration of inhaled FP. Induced asthmatic sputum from one induction may be used to concomitantly assess sputum eosinophilia as well as recent administration of FP.

Determination of fluticasone propionate in nasal sprays by a validated stability-indicating MEKC method.

A micellar electrokinetic chromatography method (MEKC) is developed and validated for the analysis of fluticasone propionate (FP) in nasal sprays. The MEKC method is performed on a fused-silica capillary (50 mum i.d.; effective length, 40 cm). The background electrolyte consists of 25 mM borate and 25 mM anionic detergent SDS solution at pH 9. The capillary temperature is maintained at 35 degrees C, and the applied voltage is 20 kV. The injection is performed using the hydrodynamic mode at 50 mbar for 6 s with detection at 238 nm. The method is linear in the range of 2-80 mug/mL (r(2) = 0.9956). The specificity and stability-indicating capability are proven through forced degradation studies inclusive by mass spectrometry, which also shows that there is no interference of the excipients. The limit of detection and limit of quantitation are 0.56 and 2 mug/mL, respectively. Moreover, method validation demonstrates acceptable results for accuracy, precision, and robustness. The proposed method was successfully applied for the quantitative analysis of FP nasal sprays, and the results were compared to a validated reversed-phase liquid chromatographic method, showing non-significant difference (P > 0.05).

Air permeability of powder: a potential tool for Dry Powder Inhaler formulation development.

Dry Powder Inhalers have drawn great attention from pharmaceutical scientists in recent years in particular those consisting of low-dose micronized drug particles associated with larger carrier particles and called interactive mixtures. However, there is little understanding of the relation between bulk powder properties such as powder structure and its aerodynamic dispersion performance. The aim of this work was to develop a simple method to measure the air permeability of interactive mixtures used in Dry Powder Inhalers by using Blaine's apparatus--a compendial permeameter and to relate it to the aerodynamic behaviour. The study was done with fluticasone propionate and terbutaline sulphate as drug models that were blended with several lactoses having different particle size distribution thus containing different percentages of fine particle lactose. The quality of the blends was examined by analysing the drug content uniformity. Aerodynamic evaluation of fine particle fraction was obtained using a Twin Stage Impinger. A linear correlation between a bulk property--air permeability of packed powder bed--and the fine particle fraction of drug was observed for the tested drugs. The air permeability reflects the quantity of the free particle fraction in the interparticulate spaces of powder bed that leads to fine particle fraction during fluidization in air flow. A theoretical approach was developed in order to link the air permeability of powder bed and drag force acting on powders during aerosolization process. The permeability technique developed in this study provides a potential tool for screening Dry Powder Inhaler formulations at the development stage.

A high-throughput liquid chromatography tandem mass spectrometry method for the comparative determination of fluticasone propionate by reversed-phase liquid chromatography and capillary electrophoresis methods in pharmaceutical nasal sprays.

A simple, specific, rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the analysis of fluticasone propionate (FP) in pharmaceutical formulations was developed and validated using deflazacort as internal standard (IS). The LC-MS/MS method was carried out on a C8 column (50 mm) with a mobile phase consisted of methanol : water (95 : 5, v/v) 100 mM formic acid-50 mM ammonium acetate (90 : 5 : 5, v/v/v). The mass spectrometry method was performed employing positive atmospheric pressure chemical ionization technique, operating in multiple reaction monitoring mode. The chromatographic separation was obtained within 1.5 min and it was linear in the concentration range of 10-1000 ng mL(-1). Moreover, method validation demonstrates acceptable results for the specificity, accuracy, precision and robustness. The proposed method was successfully applied for the quantitative analysis of FP nasal sprays and the results were compared to validated liquid chromatography and capillary electrophoresis methods with photodiode array detectors showing non-significant difference (P > 0.05).