Figure 3.

Reservoir drug delivery system. These systems typically contain many subunits (beads or pellets) containing the drug. Upon contact with water, the insoluble membrane becomes porous. (A) Swallowed intact: As water enters the system, water-soluble drug is released from the subunits and diffuses out through the pores in the membrane. The timing and rate of release of the drug can be modified by including a mixture of subunits with different drug-releasing characteristics (IR, DR, ER) in a single capsule, together with changing the thickness of the insoluble membrane and the size of the membrane pores. (B) Sprinkled: As an alternative to swallowing the capsule, it can be opened by the user, and the subunits can then be sprinkled onto a spoon of soft food. This mixture of food and drug is swallowed without chewing or crushing.