Celso Henrique de Oliveira

Lansoprazole quantification in human plasma by liquid chromatography-electrospray tandem mass spectrometry.

An analytical method based on liquid chromatography with positive ion electrospray ionization (ESI) coupled to tandem mass spectrometry detection was developed for the determination of lansoprazole in human plasma using omeprazole as the internal standard. The analyte and internal standard were extracted from the plasma samples by liquid-liquid extraction using diethyl-ether-dichloromethane (70:30; v/v) and chromatographed on a C(18) analytical column. The mobile phase consisted of acetonitrile-water (90:10; v/v)+10 mM formic acid. The method has a chromatographic total run time of 5 min and was linear within the range 2.5-2000 ng/ml. Detection was carried out on a Micromass triple quadrupole tandem mass spectrometer by Multiple Reaction Monitoring (MRM). The intra- and inter-run precision, calculated from quality control (QC) samples, was less than 3.4%. The accuracy as determined from QC samples was less than 9%. The method herein described was employed in a bioequivalence study of two capsule formulations of lansoprazole.

House dust mites in Brazil - an annotated bibliography

House dust mites have been reported to be the most important allergen in human dwellings. Several articles had already shown the presence of different mite species at homes in Brazil, being Pyroglyphidae, Glycyphagidae and Cheyletidae the most important families found. This paper is an annotated bibliography that will lead to a better knowledge of house dust mite fauna in Brazil.

Quantification of methyldopa in human plasma by high-performance liquid chromatography–electrospray tandem mass spectrometry: Application to a bioequivalence study

A method based on LC-MS-MS is described for the determination of methyldopa in human plasma using dopa-phenyl-D3 as the internal standard. The method has a chromatographic run time of 5.5 min and was linear in the range of 20-5000 ng/ml. The limit of quantitation was 20 ng/ml, the intra-day precisions were 7.3, 5.4 and 4.3% and the intra-day accuracies were -8.0, -1.3 and -2.0% for 30, 600 and 3000 ng/ml, respectively. The inter-day precisions were 7.7, 0.5 and 0.7% and the inter-day accuracies were 0.2, -1.1 and -2.3%, respectively, for the above concentrations. This method was employed in a bioequivalence study of two tablet formulations of methyldopa.

Comparison of house dust mites found on different mattress surfaces

BACKGROUND House dust mites have been considered the most important source of allergens for humans. These allergens have been encountered at different indoor sites, mainly on mattresses and pillows. OBJECTIVE To evaluate the number and different specimens of mites on Brazilian bunk-bed mattresses. METHODS Dust samples were collected once using a standardized method on the upper mattress surface (US) and lower mattress surface (LS) (bed frame also included in the latter) of 58 mattresses. RESULTS The total number of mite bodies on the LS was 3.5-fold higher than on the US, with a mean concentration of 932 mites per gram of fine dust (mites/g) on the US (range, 0-3,375 mites/g) and 3,254 mites/g on the LS (range, 125-14,500 mites/g) (P < .001). Additionally, the number of house dust mite bodies on the LS was 2.4 higher than on the US (P < .001); the mean concentration was 750 mites/g on the US (range, 0-2,875 mites/g) and 1,816 mites/g on the LS (range, 0-10,875 mites/g). Approximately 91% (n = 52) of the US and all LS dust samples had more than the limit of 100 mites/g. The most frequent family was Pyroglyphidae in both mattress surfaces, with Dermatophagoides pteronyssinus the most important species found. Storage mites, including Glycyphagidae (P < .001), Acaridae (P < .001), and other families (P < .001), also showed significant differences in the number of mites between both sample counts. CONCLUSIONS This study shows a significant difference in US and LS mite counts, with higher counts on the LS. Mite allergen avoidance should include the LS and bed frame as potential targets.

Terbinafine quantification in human plasma by high-performance liquid chromatography coupled to electrospray tandem mass spectrometry: application to a bioequivalence study.

A method based on liquid chromatography with positive ion electrospray ionization and tandem mass spectrometry is described for the determination of terbinafine in human plasma using naftifine as internal standard. The method has a chromatographic run time of 5 minutes and was linear in the range 1.0 to 2000 ng/mL. The limit of quantification was 1.0 ng/mL; the intraday precision was 3.6%, 3.8%, 3.5%, and 4.1%; and the intraday accuracy was −2.7%, 7.7%, 4.8%, and −2.7% for 5.0, 80.0, 250.0, and 1500.0 ng/mL, respectively. The interday precision was 4.9%, 1.7%, 2.4%, and 4.6% and the interday accuracy was 0.3%, 5.8%, 6.5%, and −1.4% for the same concentrations. This method was used in a bioequivalence study of two tablet formulations of terbinafine. Twenty-four healthy volunteers (both sexes) received a single oral dose of terbinafine (250 mg) in an open, randomized, two-period crossover study. The 90% CI of geometric mean ratios between (Terbinafina®; Medley S/A Indústria Farmacêutica, Campinas, Brazil) and Lamisil® (Novartis Biociências S/A, São Paulo, Brazil) were 90.5% to 110.0% for C max , 92.2% to 108.1% for AUC last , and 91.3% to 107.5% for AUC 0–inf . Because the 90% CI for the above-mentioned parameters were included in the 80% to 125% interval proposed by the US FDA, the two formulations were considered bioequivalent in terms of rate and extent of absorption.

Mites in dust samples from mattress surfaces from single beds or cribs in the south Brazilian city of Londrina

The aim of this study was to investigate the mite fauna in mattresses dust samples from cribs or beds in the south Brazilian city of Londrina, State of Paraná. A total of 133 dust samples from upper and lower mattress surfaces, and bed frames were aspirated once from 38 dwellings (18 cribs and 21 beds), and one day nursery (six cribs). A total of 758 mite bodies were counted in slides: 233 (30.7%) from cribs and 525 (69.3%) from beds (p < 0.001). House dust mites – mainly Dermatophagoides pteronyssinus, represented 72% and 84% of total mite count in crib and bed dust samples, respectively. The mean HDM body concentration in crib or bed slides were, respectively, 289.9 ± 136.7 and 875.0 ± 183.6 mites/g. Statistical analysis showed a significantly higher mite bodies count on lower mattress surface compared with upper surface in bed samples only (p = 0.025). Data herein show that cribs like mattress have sufficient mite bodies to cause sensitization to humans. The use of mattress covers for cribs and beds should be encouraged in order to avoid allergens exposure.

Survey of acarine fauna in dust samplings of curtains in the city of Campinas, Brazil

The aim of this study was to investigate the mite fauna present in 33 living room and 22 bedroom curtain dust samples from 41 different homes in the southern Brazilian city of Campinas, SP. A total of 148 mite bodies were found. Of these, 83 were found in living-room curtain samples (56.1% of total) and 65 were in bedroom curtain dust samples (43.9%). The most frequently observed mite suborders were: Acaridida (n = 79; 53.4%), Actinedida (n=53; 35.8%), Oribatida (n=14; 9.5%), and Gamasida (n=2; 1.3%). The most frequent families were Pyroglyphidae (n=61; 41.2%), Eriophyidae (n=25; 16.9%), Tarsonemidae (n=15; 10.1%), and Glycyphagidae (n=13; 8.8%). No statistical difference was observed between the number of mites found in the samples from living room and bedroom curtains.

Quantification of chlordesmethyldiazepam by liquid chromatography–tandem mass spectrometry: application to a cloxazolam bioequivalence study

A rapid, sensitive and specific LC-MS/MS method was developed and validated for quantifying chlordesmethyldiazepam (CDDZ or delorazepam), the active metabolite of cloxazolam, in human plasma. In the analytical assay, bromazepam (internal standard) and CDDZ were extracted using a liquid-liquid extraction (diethyl-ether/hexane, 80/20, v/v) procedure. The LC-MS/MS method on a RP-C18 column had an overall run time of 5.0 min and was linear (1/x weighted) over the range 0.5-50 ng/mL (R > 0.999). The between-run precision was 8.0% (1.5 ng/mL), 7.6% (9 ng/mL), 7.4% (40 ng/mL), and 10.9% at the low limit of quantification-LLOQ (0.500 ng/mL). The between-run accuracies were 0.1, -1.5, -2.7 and 8.7% for the above mentioned concentrations, respectively. All current bioanalytical method validation requirements (FDA and ANVISA) were achieved and it was applied to the bioequivalence study (Cloxazolam -- test, Eurofarma Lab. Ltda and Olcadil -- reference, Novartis Biociências S/A). The relative bioavailability between both formulations was assessed by calculating individual test/reference ratios for Cmax, AUClast and AUC0-inf. The pharmacokinetic profiles indicated bioequivalence since all ratios were as proposed by FDA and ANVISA.