Pharmaceutical preparations in retard form - with active materials in core having semipermeable coating of film former and polymer

摘要

Pharmaceutical prepn. in retard form comprises a core contg. >=1 active substance together with a carrier or excipient. The core is coated with a semipermeable coating of 20-90% water-insoluble film former (I) (e.g. ethyl cellulose) and 10-80% water-soluble polymer (II), e.g. PVP, PEG or methyl cellulose. The release of active substance is independent of pH in the body fluid over the whole period of its activity. The core pH may be reduced by inclusion of acidic material to reduce disintegration time. Dosage regimens are simplified, and initial very high blood levels may be avoided. The core may be in the form of a tablet. The coating pref. has the same permeability over its whole surface. The core may contain an organic food acid to reduce the disintegration time of the core, e.g. citric or tartaric acid is used. The coating may also contain up to 70% water insol. polymer e.g. cellulose acetate.