Optimisation of floating matrix tablets and evaluation of their gastric residence time

The present investigation concerns the development of the floating matrix tablets, which after oral administration are designed to prolong the gastric residence time, increase the drug bioavailability and diminish the side effects of irritating drugs. The importance of the composition optimisation, the technological process development for the preparation of the floating tablets with a high dose of freely soluble drug and characterisation of those tablets (crushing force, floating properties in vitro and in vivo, drug release) was examined. Tablets containing hydroxypropyl methylcellulose (HPMC), drug and different additives were compressed. The investigation shows that tablet composition and mechanical strength have the greatest influence on the floating properties and drug release. With the incorporation of a gas-generating agent together with microcrystalline cellulose, besides optimum floating (floating lag time, 30 s; duration of floating, > 8 h), the drug content was also increased. The drug release from those tablets was sufficiently sustained (more than 8 h) and non-Fickian transport of the drug from tablets was confirmed. Radiological evidence suggests that, that the formulated tablets did not adhere to the stomach mucus and that the mean gastric residence time was prolonged (> 4 h). (C) 2000 Elsevier Science B.V. All rights reserved.