Drug delivery solid devices

Improved characterization of the morphological/microstructural properties of porous solids, and the associated transport properties of fluids imbibed into these materials, is crucial to the development of new porous materials, such as ceramics. Of particular interest is the fabrication of so-called functionalized ceramics, which contain a pore structure tailored to a specific biomedical or industrial application (e.g., molecular filters, catalysts, gas storage cells, drug delivery devices, tissue scaffolds) [1-3]. Functionalization of ceramics can involve the use of graded or layered pore microstructure, morphology or chemical composition. 

In the pharmaceutical sciences, the nonequilibrium thermodynamics approach has been particularly important in the design of osmotic drug delivery devices, as discussed in Chapter 11. It has also been used to describe the convective transport of a binding antibody in an in vitro model of a solid tumor [8], As our appreciation of the roles of convection and osmosis in drug delivery increases, the nonequilibrium thermodynamics approach may find wider appeal. 

For osmotic drug delivery systems, Eq. (2) is of critical importance. This equation demonstrates that the quantity of water that can pass a semipermeable film is directly proportional to the pressure differential across the film as measured by the difference between the hydrostatic and osmotic pressures. Osmotic delivery systems are generally composed of a solid core formulation coated with a semipermeable film. Included in the core formulation is a quantity of material capable of generating an osmotic pressure differential across the film. When placed in an aqueous environment, water is transported across the film. This transported water in turn builds up a hydrostatic pressure within the device which leads to expulsion of the core material through a suitably placed exit port. 

Solid oral dosage forms containing new chemical entities (NCEs) are commonly formulated into tablets or capsules as their first market image formulation. Subsequent drug product line extension development on these NCEs may evaluate more specialized drug delivery systems. Dissolution testing of standard oral tablets or capsules will commonly utilize the paddle or basket apparatus. In this chapter we focus primarily on the development and subsequent validation of dissolution testing methods that use these two devices. 

Discrete models of release behavior. A schematic cross-section of a drug delivery system is shown in Figure 1 we hypothesize that release of drug occurs as follows. Prior to release, solid particles of the drug are dispersed in a continuous polymer phase. Since the depth of the device is typically 1 mm and each particle is... 

One of the significant problems with the delivery of drugs in solution is that drug administration is pulsed, with an initial period of overdosage followed by a period of relative underdosage. The development of solid drug delivery devices has been an attempt to overcome this disadvantage. 

An implantable drug delivery system based on microactuation devices has been developed (36) (Fig. 4) by which doses can be controlled to an accuracy of 5 pL. One form of the invention can dispense solid drug, which of course is a more complex task, because of the... 

Implantable delivery systems extend the concept of sustained release beyond the capabilities of the strategies discussed so far in this section. Continual drug delivery lasting for months or even years has been achieved. Because these products must be administered as a solid rather than a liquid, they are usually supplied with a customised injection device. 

Poly(ortho esters) have been specifically developed as a drug delivery system and have been designed to undergo an erosion process confined predominantly to the surface layers of a solid device [57]. The development of poly(ortho esters) dates back to the early 1970s, and since that time four families of poly(ortho esters) have been... 

Use of MIPs as the tailor made sorbent for solid phase extraction (SPE) in selective enrichment, separation or pre-concentration of pharmaceuticals from the complex natural matrices is one of the important applications of the MIPs. MIPs are widely used as the stationary phase for analytical racemic separations of drugs. MIPs also find the use as in vitro controlled/sustained drug delivery devices, although its application in this field is just at a budding stage. 

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