Modified-Release Drug Delivery Systems: Rate-Programmed I

Rate-programmed DDS release drugs at controlled rates using approaches such as polymeric matrix, reservoir, osmotic pump, and microchip systems. Rate-programmed drug delivery systems include various types.

In a dissolution-controlled DDS, the release rate depends on the slow dissolution of the drug or the surrounding matrix.

Drugs with slow dissolution rates dissolve gradually, while others transform into slower-dissolving forms upon contact with GI fluids.

Another approach embeds drugs in slowly dissolving matrices or coats them with slow-dissolving materials to control fluid penetration.

In a diffusion-controlled DDS, the release rate depends on the diffusion of dissolved drug molecules through a rate-controlling element that is non-degradable and either water-swellable or insoluble.

Polymers such as xanthan gum, HPMC, and ethyl cellulose are commonly used in these drug delivery systems.

Dissolution and diffusion-controlled DDS combine both mechanisms, using materials that regulate drug release rate through dissolution and diffusion.