a pharmaceutical composition for the controlled release of medicinal drugs , which has the property of adhering to biologic tissues is described . the characteristic features of the composition are a plurality of small - size units capable of ensuring a gradual release of the active ingredient they contain the units being coated with a bioadhesive polymer layer . the composition makes it possible to keep the release controlling function separate from the function providing bioadhesion and can be adapted inter alia to oral , ocular , rectal , vaginal , nasal or periodontal administrations . an advantageous process for making the composition is also disclosed .