Fabrizio Balestrieri

Application of differential scanning calorimetry to the study of drug-excipient compatibility

Abstract Differential scanning calorimetry (DSC) has been used to investigate drug-excipient interactions and, in consequence, their compatibility. In particular, binary mixtures of nefazodone with magnesium stearate and lactose, and fosinopril with the same excipients were prepared and analysed, after proper conditioning. The thermoanalytical results were compared with those obtained by spectroscopic (UV, IR) and chromatographic (HPLC) analysis. We believe that changes in DSC runs cannot always be a sufficient condition to prove that some interaction occurs between drug and excipient during storage at room temperature. Some data on the spectroscopic characteristics of nefazodone and fosinopril drugs and their thermal behaviour are also reported.

Supervised pattern recognition to discriminate the geographical origin of rice bran oils: a first study

Supervised pattern recognition appears to be a useful tool to authenticate foodstuffs according to their geographical or varietal origin, when a set of samples whose classification is known a priori are available. In this work, linear discriminant analysis and artificial neural networks trained by the back-propagation algorithm have been used to discriminate rice bran oils manufactured in three different countries (Italy, Thailand and Switzerland) according to their geographical origin. The variables to be included in the mathematical models have been chosen by means of Fisher F-ratio value among the chemical indices routinely determined on vegetable oils (particularly fatty acids, triglycerides and sterol composition). The prediction ability of all the classifiers was 100% as evaluated by cross-validation.

Determination of fosinopril in pharmaceutical formulations containing hydrochlorothiazide by multiwavelength UV spectrophotometry

A sensitive, simple, rapid and precise method for the simultaneous determination of fosinopril (FOS) and hydrochlorothiazide (HCT) in pharmaceutical formulations is presented. These active ingredients are extracted in aqueous solution and measured by multiwavelength UV spectrophotometry using the program QUEST. HCT acts as an internal standard to verify the accuracy of the analysis. Some aspects of the chemical, spectroscopic and thermoanalytical behaviour of FOS are also reported.

UV-vis spectrophotometric method for the quantitation of all the components of Italian general denaturant and its application to check the conformity of alcohol samples.

A simple, fast and relatively inexpensive spectrophotometric method for the identification and the quantification of the individual components of the Italian general denaturant in alcohol samples is proposed. In particular, it is shown that bitrex (a quaternary ammonium salt), whose UV spectrum is completely masked by those of the other denaturant components, can be identified using its reaction with disulphine blue VN-150 (an anionic dye indicator), which leads to the formation of an intensely colored ion-association complex (mole ratio 1:1), easily extractable in chloroform. As far as the quantitative detection is involved, it is however necessary to shake the chloroform phase in the presence of 1 mol L(-1) NaClO(4) aqueous solution because of the fast adsorption of the ion pair on the walls of the glass cell. Perchlorate anion, due to mass action, substitutes the anionic dye indicator in the association complex: as a consequence, disulphine blue passes to the aqueous phase, where its absorbance at lambda=640 nm is measured. On the other hand, C.I. Reactive Red 24 dye is easily identifiable from the visible spectrum of the product without any further pretreatment: its concentration can be determined measuring the absorbance at lambda=542 nm. Thiophene, being significantly more concentrated than the other components, can be identified from the UV spectrum of a 1:100 diluted solution of the alcohol sample and quantitatively determined measuring the absorbance at lambda=230 nm. Lastly, methyl ethyl ketone (MEK) can be identified from the UV spectrum of a 1:5 diluted solution of the alcohol sample and quantitatively determined measuring the absorbance at lambda=273 nm. However, more accurate results can be obtained using a multiwavelength analysis in the range 220-250 and 250-310 nm for the determination of thiophene and MEK, respectively. Validation on standard denatured alcohol samples has proven the method to be both accurate and sufficiently precise (within- and between-days repeatability <5%) to be applied to the analysis of real commercial samples.

Artificial Neural Network to Classify Some Dairy Products.

Artificial neural networks are often used to recognise and classify commodities, among which food products have received considerable attention. In this work, neural networks are used to analyse chemical data from dairy products. The method was used to differentiate four of the most common milk types. Since it is possible to determine the percentage of buffalo-milk used to produce Mozzarella cheese, the actual composition of Mozzarella declared can be checked. The practica application of this approach is discussed. The results show that this analysis can furnish information that is just as meaningful as multivariate statistical analysis. The two approaches can complement one another as effective tools for characterising and/or classifying dairy products.