Development of extended release multiple unit effervescent floating drug delivery systems for drugs with different solubilities

The purpose of this study was preparation and evaluation of extended release multiple unit floating drug delivery systems based on CO2 formation with rapid and extended floating and good control over the release for drugs with different solubilities. The pellet systems were prepared by fluidized bed layering/coating techniques and evaluated by floating, drug release, medium uptake and swelling studies in 0.1 N HCl. Two different pellet systems were evaluated; the first consisted of drug-layered sugar cores, NaHCO3-layer and a polymeric top-coating, which ideally controlled both floating and release properties. The second, modified system consisted of drug-containing Eudragit® RS 30 D coated extended release pellets coated with NaHCO3-layer and Eudragit® RL 30 D top-coating. The Eudragit® RL coating resulted in sufficient medium penetration, a prerequisite for CO2 formation, and in high CO2 entrapment efficiency. Floating was maintained over a wide range of Eudragit® RL/RS combinations. Extended release from the first system could be achieved only for low solubility, high dose drugs because of high Eudragit® RL permeability. For high solubility drugs, separating floating and release “functions” was successful. Extended release pellets were used to achieve better drug release control, while floating was achieved by an Eudragit® RL top-coat.

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