CONTROLLED RELEASE DRUG FORMULATION

摘要

The invention provides pharmaceutical compositions with the property of targeted controlled release of active principles which act pharmacologically within the intestine and in particular within the colon and the terminal portion of the ileum. To attain this object the active principle is prepared in multiparticle multidose form and is covered with at least two membranes, one of pH-dependent solubility and the other insoluble but permeable to the intestinal fluids. While the covered active principle remains in the stomach and in the initial intestinal portion, ie while the pH is less than 5.5, it is not released. Only when it reaches an environment of higher pH (small intestine or colon) does the pH-dependent membrane dissolve to commence release of the active principle. From this moment the second membrane, which is pH-independent but permeable to the intestinal fluids, acts to slow down and control the dissolution of the medicament within the small intestine-colon tract.