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Biomedical subjects

E Bruna

Publications and source records attributed to E Bruna.

8 recordsLinked to original sources
PubMed2002

The effect of gamma-irradiation on drug release from bioerodible microparticles: a quantitative treatment.

The two major objectives of this study were: (i) to monitor the effect of different gamma-irradiation doses (4-33 kGy) on the release kinetics from 5-fluorouracil (5-FU)-loaded poly(D,L-lactide-co-glycolide) (PLGA)-based microparticles, and (ii) to analyze the obtained experimental data with a new mathematical model giving insight into the occurring mass transport phenomena. Drug release was found to depend significantly on the applied gamma-irradiation dose. Interestingly, the obtained release profiles were all biphasic: a rapid initial drug release phase ("burst") was followed by a slower, approximately constant drug release phase. Surprisingly, only the initial rapid drug release was accelerated by gamma-irradiation; the subsequent zero-order phase was almost unaffected. Importantly, the new mathematical model which is based on Fick's second law of diffusion and which considers polymer degradation was applicable to all the investigated systems. In addition, the gamma-irradiation dose could be quantitatively related to the resulting drug release rate. In conclusion, diffusion seems to be the dominating release rate controlling mechanism in all cases, with a significant contribution of the polymer degradation process.

Antimetabolites, Antineoplastic↗
PubMed1988

Subpicogram determination of malondialdehyde by gas-liquid chromatography with nitrogen phosphorus detector. I. Standardization.

A method for the measurement of malondialdehyde (MDA) using GLC with a nitrogen phosphorus detector (GLC/NPD) is described and evaluated. The method uses 2-hydrazinobenzothiazole (HBT) which forms condensation derivatives with MDA, acetoacetaldehyde, and acetylacetone (AA). GC/MS and 13C NMR studies of the three derivatives obtained showed that they are 2-(pyrazol-1'-yl)benzothiazoles and that they can be separated by GLC/NPD. Any one of these derivatives can be used as an internal standard for the measurement of the other two. The optimal conditions for the measurement of MDA were studied. At pH 2.5 and 70 degrees C, the condensation derivative is quantitatively formed in 30 min. Its extraction is obtained by a mixture of n-hexane/isoamyl alcohol 98/2 (v/v) containing HBT-AA as internal standard. The GLC detection limit is 0.04 pmol. Inter- and intrassay coefficients of variation were 2.9 and an average of 4.0%, respectively. The method is specific, and there was no interference from other carbonyl compounds. The artifactual formation of MDA from carbohydrates during the derivatization reaction is negligible. The method is proposed as a reference method for the standardization of working solutions of MDA or MDA-generating solutions.

Acetaldehyde↗