Polymers osmotic pumps

BG Kabra, SH Gehrke. Hydrogels for driving an osmotic pump. Polym Prepr 30 490-491, 1989. 

Semipermeable membrane-forming polymers for osmotic pumps... 

Implantable delivery systems offer a number of advantages over more traditional delivery routes, particularly for biological macromolecules (including peptides, proteins, and oligonucleotides). Some specific delivery mechanisms to date include polymer depots (e.g., Gliadel Wafer, prolifeprosan 20 with carmustine implant) and osmotic pumps (e.g., Viadur leuprolide acetate implant). 

The controlled release of drugs can be realised with many types of active devices, such as mechanical and osmotic pumps, systems of controlled diffusion, chemically-controlled systems composed from bio- or non-biodegradable polymers, magnetically-controlled systems, and not in the last instance chemomechanical systems. Figure 4.39 [136, 137]. 

FIGURE 8 The Theeuwes elementary osmotic pump. This simple device consists of a core of water-soluble drug surrounded by a coating of a water-permeable polymer. A hole Is drilled through the coating to allow the drug to escape. 

The two common ways to achieve this result are swelling-controlled systems and so-called osmotic pumps. Swelling-controlled systems are simpler. The most common case consists of a slab of a dry, water-soluble polymer containing a dispersion of... 

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