Design and study of ibuprofen disintegrating sustained-release tablets comprising coated pellets.

One challenge in tableting of sustained-release multiparticulates is maintaining the desired drug release after compaction. The aim of this study was to design sustained-release ibuprofen tablets which upon oral ingestion rapidly disintegrate into sustained-release pellets in which the integrity of the pellet core and/or coat is preserved. First free films composed of Eudragit RS 30D and RL 30D in 4:1 ratio and containing different levels of triethyl citrate (TEC) were prepared and tested to optimize the plasticizer level. Cured Eudragit based pellets with 60% ibuprofen loading which in our previous study showed proper mechanical properties for compression were coated with Eudragit RS 30D/RL 30D (4:1) containing 20% triethyl citrate at different coating levels. The mechanical properties of the coated pellets were tested. Polymer coated pellets were compacted into tablets either alone or with a blend of excipients comprising Avicel, PEG 4000, cross-linked PVP. A 3(2) full factorial design was used to optimize the filler blend composition. Effects of pellet to filler ratio, compression force and granulation of filler on tablet characteristics were investigated. Results of mechanical test showed that the coating of cured pellets had no significant effect on yield point and elastic modulus of the pellets. In the case of 5% coating level sustained release of ibuprofen over a period of 24h was achieved. The results obtained from tableting procedure showed that by selecting suitable filler blend (60% Avicel, 10% cross-linked PVP and 30% PEG 4000), compression force, and granulation of filler it was possible to prepare sustained-release tablets containing high ratio of coated pellets (even 80%) with desirable strength, disintegration time, and drug release rate. It was observed that compression force, pellet to filler ratio, composition of filler blend and granulation of fillers had no effect on drug release rate from compacted pellets but had significant influence on tablet strength, friability, and disintegration time. SEM graphs and in vitro release profiles for compacted pellets showed no apparent damage to the coated pellets as a result of the compaction process.