Two phase pharmaceutical delivery system

A delivery system for the oral administration of a bi-phasic pharmaceutical composition comprising:

• a pharmaceutical composition comprising:
• a semi-solid hydrogel having a water content of at least 20% by weight, based on the total weight of the hydrogel, said hydrogel is a viscoelastic gel having an elastic modulus which is measured at 20° C. of 0.05 kPa to 500 kPa and which is prepared by heating an aqueous suspension of a hydratable polymeric material to induce formation of a liquid sol, followed by cooling the sol to induce gelling, and
• a plurality of coated active ingredient containing particles dispersed in said hydrogel,
• wherein less than 0.1 wt % of the active ingredient is detectable in the hydrogel 1 month after the preparation of the composition,
• at least one coating of said particles it triggered to disintegrate or dissolve by exposure to a particular pH range as a result of which the active ingredient is released, and
• a dispenser pouch formed from flexible laminate sheets,
• the hydrogel has a pH sufficiently different from the pH that triggers disintegration or dissolution of the at least one coating of the particles so as to require exposure of the pharmaceutical composition to an external stimulus in order to trigger disintegration or dissolution of the at least one coating of said particles and release of the active ingredient,
• wherein the hydrogel comprises a buffer system, and
• the at least one coating consists of:
• a) an ionic polymer;
• or b) non-ionic material selected from the group consisting of lipids, waxes, fats, fatty acids, mono-, di- and triglycerides, acetylated mono- and diglycerides, beeswax, and carnauba wax;
• and optionally c) at least one selected from the group consisting of pH modifiers, rheological modifiers, solvents, cross-linking agents, glidants, anti-tackifying agents, pigments, dyes, emulsifiers, stabilizers, flavours, sweeteners, and permeability enhancers.