Solid delivery device

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. 

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. 

Delivery devices can have many morphologies, depending upon the materials and methods used in their preparation. In general, one can distinguish between two main groups of device architecture, depending on the way the core (solid or liquid) is distributed within the system (Figure 32.2) ... 

Delivery devices do not necessarily have a spherical shape, as illustrated in Figure 32.2e. A great variety of shapes can be obtained when a solid core material is encapsulated by a shell. Particle size is an important characteristic of these structures because it is one of the many parameters that can be tailored to control release rates of encapsulated ingredients. However, the production of microcapsules often gives a certain particle size polydispersity. The active ingredient release kinetics depends on the particle size distribution. It is thus necessary to determine both the mean particle size and the size distribution for the targeted delivery. 

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. 

The thermal properties of polymers are important parameters to consider as they play key roles in the mechanical properties of biomaterials used in bone repair and prosthesis materials. These properties may also influence the drug-release properties of drug-delivery devices. Information is provided about the mobility of the polymer chains within a material at a given temperature and about the crystallinity of this material (see also Section 2.4). This characterisation is also useful in order to determine whether a polymer material is a hard or soft solid or a liquid at a given temperature. 

Wu B M, Borland S W, Giordano R A, Cima L G, Sachs E M and Cima M J, Solid free-form fabrication of drug delivery devices , J. Controlled Release, 1996,40,77-87. 

M.F. Saettone, Solid polymeric inserts/disks as drug delivery devices, in "Biopharmaceutics of Ocular... 

Saettone, M.F. Solid polymeric inserts/disks as drug delivery devices. In Edman, P. (ed.) Biopharmaceutics of Ocular Drug Delivery, pp. 61-67. CRC Press, London (1993)... 

If it is desired to carry out the combined operations of stirring, refluxing, and addition of a liquid in a stream of gas, the apparatus of Fig. 77, 7, 12, a may be used the side tube for the gas is sealed on to the separatory funnel. For the passage of a gas into a stirred liquid, the aperture carrying the modified separatory funnel may be fitted with the device shown in Fig. 77, 7, 12, 6 the glass rod inside the tube is held in position by a short length of heavy-wall rubber tubing and is employed to clear the lower end of the gas delivery tube, should it become blocked with solid reaction product. 

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