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Browsing by Subject "multiparticulate systems"

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  • Knuutila, Kaisa (2010)
    As the development of new active ingredients is becoming more expensive and difficult, the development of new and better dosage forms, like multiparticulate systems, has become more attractive. Multiparticulate systems can be defined as oral dosage forms consisting of small discrete units together providing desired dose. Usually the small units are round pellets approximately 0.5-1.5mm in size. Multiparticulate systems can enhance the properties of already existing active ingredients or reduce the unwanted side effects. The properties can be alternated also by preparing the system as the enteric formulation, which resists the acidic environment of the stomach and releases the active ingredients in the small intestine due to the pH change. The enteric delivery is used mainly to enhance the absorption of acid-labile drugs or to reduce the side-effects of stomach irritating drugs, like iron. Prepared pellets contained iron in sulphate form and they were pelletized with Nica extruder/spheronization system. The pellets contained also ascorbic acid to maintain the iron in its reduced form during iron release and absorption. Microcrystalline cellulose enabled the pellet formation and Eudragit L 30 D-55 was used in the coating to protect the drug containing pellets from the stomach's acidic environment. Some of the pellets were subcoated before the enteric coating. The subcoating contained part of the ascorbic acid and iron sulphate and the film forming water soluble hydroxypropyl methylcellulose, HPMC. Other pellets were coated directly with the enteric coat while 100% of the ascorbic acid and iron sulphate were located in the core pellets. The coating was performed in fluidized bed. The iron concentration was determined with UV-Vis spectrophotometer. Iron itself did not absorb light but with o-phenanthroline it formed orange-red complex which absorbed visible light absorption maximum being at the wavelength of 510 nm. In order to ensure the full absorption the enteric iron products need to release the iron rabidly after they enter the small intestine. Approximately 15-20% (w/w) of enteric coating was needed to fulfill the 5% release limit per hour in dissolution test in 0.1 HCl defined by authorities. The release rate was comparable to a commercially available product. The subcoating did not have a considerable effect to the release rate. The iron precipitated to the pellet surface either during extrusion/spheronization process or drying. 1% Tween 80, 3% Kollidon K-25 and 5 and 10% Eudragit L 30 D-55 solutions were used as pelletizing liquid in order to reduce the precipitation. The 3% Kollidon K-25 produced visually best pellets but some pellets were clued together during the process. The possible retardation in release was not tested.