PubMed · 13173531
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F MODRZEJEWSKI, M KWIATKOWSKA. 1954. [Penicillin ointment].. https://pubmed.ncbi.nlm.nih.gov/13173531/
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This work is part of a study in which the possibility of NIR combined with some chemometrical methods is investigated as a suitable technique to classify clinical study samples of a cream. In this study, the influence of different preprocessing methods on the removal of spectral variations due to some variance sources has been investigated. The applied preprocessing methods are standard normal variate (SNV), detrend correction, offset correction, and first and second derivation. The investigated variance sources are different batches of ingredients, different samples of the same batch, different days and different positions of the sample cup in the sample drawer of the instrument. A nested ANOVA design has been applied in order to quantify the variances introduced by these variance sources. Since ANOVA is a univariate technique, the necessary variable (wavelength) selection has been performed by the Fisher criterion. The best results, i.e. largest reduction of interfering variability and clearest distinction between different clinical study samples, are obtained with the second derivative spectra.
Large number of washable (o/w type) creams were prepared for rheological investigation. The rheological functions known from the literature were determined in our studies. Rheological constants were determined by measurements and calculations. From these, we selected those ones which were applicable to characterize the energy status of the coherent structure and which gave the most information for practical work, elaboration of composition and evaluation of stability. These functions and parameters are the following: flow curves, viscosity vs shear time and viscosity vs temperature functions, Bingham-type yield value, plastic viscosity, structure breakdown rate constant, activation energy.
The present study dealt with the investigation of the physical characteristics of 18 polyethylene glycol ointment bases with the aim of finding out their suitability for use in tropical and subtropical climates. Different ratios of low and high molecular weight polyethylene glycols were helpful for preparation of these ointment bases. The investigated physical characteristics included the drop point, the congealing range and the spreadability properties of bases. The drop point was determined by the Ubbelohde apparatus, the congealing range by the double-walled Zhuckov flask, penetrability by penetrometer, and spreadability by the parallel plate extensometer. The results of these physical parameters indicated that PEG 400:PEG 4000 blend gave very good bases for use in tropical and subtropical areas. Furthermore, it was observed that, the type and the amount of PEG used would affect greatly the drop point, congealing range and consistency of the prepared bases. Results obtained with PEG 2000 and PEG 6000 bases showed less variability with respect to molecular weight and solid content.