Polymeric particles are an alternative to liposomes, but they fall short of commercial liposomes in a scientific sense. The term "polymeric particles" is self-explanatory; it refers to spherical polymer systems in matrix structures composed of biodegradable polymers, which may be synthetic or natural. The advantages of these materials are comparable to those of liposomes; their production is extremely simple and it is possible to develop new shapes as needed. Unfortunately, they are not free of limitations either. The most important ones are the difficulties in the industrial adaptation of production technologies, the use of organic solvents in the production processes, and the premature release of the therapeutic agent from the carrier .