Preparation and evaluation of intragastric buoyant preparations.

The design and preparation of two drug formulations which float in gastric juice are described. One, a buoyant tablet, consisted of powdered soybean protein, drug and sodium bicarbonate. The other, a laminated film-type preparation, consisted of a drug film, an effervescing film containing sodium bicarbonate and outer drug release regulating films. Cinnarizine, an acid-soluble drug, was chosen as model drug, and carboxyvinyl polymer, ethyl cellulose and hydroxypropyl cellulose were used in the preparation of the films. Both formulations showed favorable buoyancy in an in vitro acidic dissolution test medium and also sustained release properties. In an absorption study using beagle dogs, cinnarizine was found in the blood even 24 hr after oral administration of the buoyant tablet or film-type preparation. Similar buoyant tablets containing barium sulfate were administered orally to a healthy volunteer, and it was confirmed by roentgenography that the tablets floated for almost three hours.