Surface treatment of indomethacin agglomerates with eudragit.

Indomethacin is a widely used anti-inflammatory drug with serious side-effects. This drug was used as a model drug for the coating of agglomerates with a permeable film (Eudragit NE). The agglomeration of the crystals increased the flowability of the bulk crystals. The coating further improved the flowability, and also the uniformity of the mass of the filled capsules. The coating film also influenced the wetting of the samples. The coating decreased the surface free energy and therefore reduced the adhesion forces between both the dry and the wet particles. The modification of the flow properties and the even capsule filling can be explained by this phenomenon. Since coating film does not dissolve in the artificial gastric juice, the dissolution test was performed only in the artificial intestinal juice. The dissolution of indomethacin from the coated sample was changed significantly. Accordingly, coating of the crystals can be performed in order to protect the mucosa of the gastrointestinal tract or to promote the preparation of solid dosage form.

[The effect of surface phenomena on the processing of solid materials. I. Theoretical basis of surface phenomena of solid materials]. / A felületi jelenségek szerepe a szilárd anyagok feldolgozása során. I. Rész. A jelenségek elméleti háttere.

The functions of friction and adhesion in the processing of solid materials were evaluated in our work. The first part of our study dealt with the theoretical basis of these phenomena. The work of Podczek was used as a guideline. The negative and positive effects of these parameters were emphasized. The types of adhesion were discussed. The different types of forces (capillary, Lifshitz-van der Waals, electrical, etc.) and several other parameters (surface free energy, roughness, particle size and shape) causing these effects were analysed. Different mathematical models which can be used for the determination of surface free energy, adhesion force and spreading coefficient were considered.

[The effect of surface phenomena on the processing of solid materials. II. Experimental evaluation of surface phenomena of solid materials]. / A felületi jelenségek szerepe a szilárd anyagok feldolgozása során. II. Rész. A szilárd anyagok határfelületi jelenségeinek kísérleti vizsgálata.

The functions of friction and adhesion in the processing of solid materials were evaluated in our work. The second part of our study dealt with some practical examples from our practice. Indomethacin was used for the examination of adhesion, dimenhydrinate for the study of friction, and metronidazole for the determination of the spreading coefficient. Several technological methods (coating, granulation, pelletization and tableting) were used. The positive effects of the processes on the various phenomena (surface free energy, adhesion force and spreading coefficient) were emphasized. The influences of alteration in the parameters on the flowability, compressibility, compact texture, etc. were assessed.