The stability of carotenoids was studied in marigold oil extracts prepared with following solvents: Myritol 312?, paraffin oil, almond oil, olive oil, sunflower oil, grape seed oil, and soybean oil. The concentration of the carotenoids was determined by spectroscopic measurement at 450 nm. Degradation rate showed a first order dependence on the concentration of carotenoids with a faster first stage (which lasted 35-50 days, depending on the solvent) and a slower second stage. The highest degradation rates were observed in extracts prepared with linoleic acid rich solvents (sunflower oil, soybean oil and grape seed oil), while the lowest were found in oil with saturated fatty acids (Myritol 312?) and paraffin oil. These results confirm the connection between the degradation of carotenoids and lipid autoxidation, and suggest that the influence of the oil solvents on the stability of oil extracts of Calendula officinalis is a factor that must be considered when selecting a solvent for the production of marigold oil extracts.

Pemulens(R) (BF Goodrich) are hydrophobically-modified copolymers of acrylic acid (Acrylates/C10-C30 alkyl acrylates) that could act both as primary emulsifiers for o/w emulsions and viscosity enhancing agents. The aim of this study was to assess the influence of different processing conditions (mixing equipment, speed and time of agitation) on the aesthetic characteristics, viscosity and physical stability of o/w emulsion gels based on the polymeric emulsifier (Pemulen TR-2 NF). This objective was achieved by applying a two-factor three-level experimental design at two sets: using a laboratory mixer and a disperser. Independent variables were mixing speed and time and dependant variables i.e. responses, were millimetres of oil phase separated after centrifugation at 3500 rpm in a laboratory centrifuge, and viscosity at shear rate 180 l/s. The responses were fitted into a second order model by means of a multiple regression analysis. For the samples prepared on the laboratory mixer it was shown that mixing time and speed produce a statistically important influence on viscosity, but not on physical stability: with increasing mixing speed and time the viscosity linearly increases. If we assume that greater energy input obtained by increasing the mixing speed and time produces a decrease in drop size and polydispersity and better developed gel network, then the optimal processing conditions will be at the point where maximal viscosity is attained. This result was in accordance with the centrifugation test - the best stability appeared when maximal mixing speed and time were applied, although this effect appeared not to be statistically significant. For samples prepared using dispersers no statistically important influence of processing variables on viscosity and physical stability was found. Additionally, emulsion samples prepared using the laboratory mixer appeared homogenous, while in samples prepared using the disperser, undispersed polymer lumps appeared. Based on physical characteristics of the emulsions, it could be concluded that the disperser is an inappropriate tool for processing the emulsions based on Pemulen polymers.

Etodolaclp-cyclodextrin (Eto/p-CD) dispersions were prepared with a view to study the influence of p-CD on the solubility and dissolution rate of this poorly soluble drug. Two systems were used: physicai mixture of Eto/p-CD and kneading solid dispersion of Etolp-CD. Physical characterization of the prepared systems was carried out by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), x-ray, and IR studies. The solubility and dissolution rate of Eto were increased with p-CD physicul mixture as well us with Eto/p-CD kneading solid dispersion. However, enhancement was not statistically different among various cyclodextrin dispersions. 1 I23 Copyright ' i3 1997 by Marcel Dekker, Inc Drug Dev Ind Pharm Downloaded from informahealthcare.com by Michigan University on 11/02/14 For personal use only.

No abstract

The objective of pharmaceutical-technological development is to find a procedure of transforming an active substance (a drug) into a drug dosage form which is not only acceptable for application, but also enables the active substance to be released following administration, pursuant to therapy objectives. The aim is that the concentration of the active substance in the action location rapidly reaches a therapeutic level and maintains an approximately constant level in the course of a particular time, according to the established therapeutic goal. The primary objective is to present the active ingredient (drug) in the form and concentration/quantity that enables the corresponding therapeutic response, i.e. to control the site and rate of medicinal substance release from the drug, as well as the rate at which it reaches the membranes and surfaces to which it is absorbed, while applying a common method of administration. The procedures used to achieve this goal are becoming highly complex and demanding and are aiming at sophisticated drug delivery systems and functional packaging material. Development from the existing drug molecule, through the conventional drug dosage form, to a new system of drug "delivery" (novel delivery system), can improve the drug (active substance) characteristics significantly in view of compliance (acceptability by the patient), safety and efficiency. The paper presents an overview of the most important examples of pharmaceutical forms with controlled release and advanced drug "carriers"