Nádia Maria Volpato | PubMed Health

PubMed2006

New microencapsulation system for ascorbic acid using pea protein concentrate as coat protector.

Microencapsulation is essential to preserve biological activity of ascorbic acid (AA) and pea protein has not been used as a carrier in such processes. This work aimed to produce microparticles by a spray-drying process using pea protein (PPC) as wall material of AA and evaluate the retention of the core by HPLC, overall morphology SEM, size distribution by light scattering and release kinetics. Carboxymethylcellulose (CMC) and blends with maltodextrin (M) were produced for comparative analyses. The yields were compatible with the applied technology and the retention was above 84% for all materials. The PPC microparticles presented irregular and rough surfaces, CMC produced a regular and smooth surface and agglomeration was more intense in microparticles with M. Mean particle diameters were all below 8 microm. The microparticle release rates were lower than those with free AA, being best correlated to the Higuchi kinetic model. These results support the utilization of PPC for microencapsulation of AA.

Aerosols↗

PubMed2005

On-line solid-phase extraction coupled with high-performance liquid chromatography and tandem mass spectrometry (SPE-HPLC-MS-MS) for quantification of bromazepam in human plasma: an automated method for bioequivalence studies.

A validated method for on-line solid-phase extraction coupled with high-performance liquid chromatography tandem mass spectrometry (SPE-HPLC-MS-MS) is described for the quantification of bromazepam in human plasma. The method involves a dilution of 300 muL of plasma with 100 muL of carbamazepine (2.5 ng/mL), used as internal standard, vortex-mixing, centrifugation, and injection of 100 muL of the supernate. The analytes were ionized using positive electrospray mass spectrometry then detected by multiple reaction monitoring (MRM). The m/z transitions 316-->182 (bromazepam) and 237-->194 (carbamazepine) were used for quantification. The calibration curve was linear from 1 ng/mL (limit of quantification) to 200 ng/mL. The retention times of bromazepam and carbamazepine were 2.6 and 3.2 minutes, respectively. The intraday and interday precisions were 3.43%-15.45% and 5.2%-17%, respectively. The intraday and interday accuracy was 94.00%-103.94%. This new automated method has been successfully applied in a bioequivalence study of 2 tablet formulations of 6 mg bromazepam: Lexotan(R) from Produtos Roche Químicos e Farmacêuticos SA, Rio de Janeiro, Brazil (reference) and test formulation from Laboratórios Biosintética Ltda, São Paulo, Brazil. Because the 90% CI of geometric mean ratios between reference and test were completely included in the 80%-125% interval, the 2 formulations were considered bioequivalent. The comparison of different experimental conditions for establishing a dissolution profile in vitro along with our bioavailability data further allowed us to propose rationally based experimental conditions for a dissolution test of bromazepam tablets, actually lacking a pharmacopeial monograph.

Adult↗