Osmotic-controlled drug delivery systems

Theeuwes and Higuchi1 applied the principle of osmotic pressure to a new generation of controlled drug delivery devices with many advantages over other existing controlled drug delivery systems. The first of these devices, the elementary osmotic pump, is considered a typical delivery system that operates on osmotic principles. 

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

The invention that positioned osmosis as a major driving force for controlled drug delivery was the elementary osmotic delivery system. ALZA has developed elementary osmotic delivery systems under the name OROS. A successful modification that overcame the disadvantages of the elementary osmotic pump was the Push-Pull osmotic drug delivery system. The following sections are devoted to the principal features of these systems. 

Chapter 7. Osmotic Controlled Drug Delivery Systems... 

Comparative pharmacokinetic profiles of nifedipine delivered from Procardia XL, an osmotic pressure-controlled drug delivery system, once-a-day versus that from Procardia, an immediate-release dosage form, taken on time 0, 8 and 16 in human volunteers. Modified from Y.W. Chien. Oral drug delivery and delivery systems. Y.W.Chien (ed.) (1992) Novel Drug Delivery Systems. Marcel Dekker, Inc. New York, pp. 139-196... 

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.

Osmotically controlled and pressure-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)... 

Design of the elementary osmotic controlled drug delivery system... 

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). 

Controlled Release Osmotic Drug Delivery Systems for Oral Applications... 

Numerous other examples of the use of solubility to control the delivery profile of drugs from the elementary osmotic pump can be found in the literature, especially the patent literature [35-40], These systems apply to drugs of moderate to high aqueous solubility where either the excipient or the salt form of the drug was used to control the drug solubility within the core formulation. 

---