| Popis: |
One of the strengths of the drug delivery field is the number and variety of drug delivery systems available to the formulation scientist. Systems are available for delivery of drug to essentially every site and orifice for both humans [1,2] and animals [3,4]. Such systems can be classified in many ways, but one would be to subdivide the systems into those intended for immediate release of drug ( 1 hr) such as solutions or conventional tablets and capsules, and those intended for long periods (4 hr) such as coated multiparticulates or dispersions of drug in biodegradable matrices. For the latter, some means must be incorporated into the system to prolong the release of drug beyond what would arise from the normal dissolution characteristics of the solid drug particles in the dosage form. Almost invariably, this long-acting delivery is achieved through the use of polymeric materials that in some way affect the rate of diffusion of the drug to the surface of the delivery system. |
