Osmotically Controlled Drug Delivery Systems

As may be observed, the first (elementary) osmotically controlled drug delivery systems were composed of two primary regions, namely a tablet core (containing the drug and when required an osmotic pressure modifier) 

The rate of entry of biological fluid across the semi-permeable membrane into the tablet core will directly affect the rate of drug dissolution and may be defined using the following equation  

Ak is the osmotic pressure difference between the interior of the tablet and the surrounding biological fluids, and 

Design of the elementary osmotic controlled drug delivery system 

---

Key parameters that influence the design of osmotic controlled drug delivery systems... 

Chapter 7. Osmotic Controlled Drug Delivery Systems... 

Figure 5 Schematic presentation of osmotic-controlled drug delivery systems (A) one-chamber device (B) two-chamber device. The osmotically driven influx of water creates considerable hydrostatic pressure within the system, which pushes the drag out into the bulk fluid.

For drugs that possess low water solubility a number of formulation strategies have been examined to enhance their solubility and hence the rate of release from osmotically controlled drug delivery systems. Examples of these approaches include ... 

Other designs of osmotically controlled drug delivery systems have been reported (a. 159). 

---