Drug delivery systems reproducibility

Many proteins and protein-like materials are precipitated from aqueous solution by the application of heat or the addition of electrolyte, and this general reaction can be used to prepare solid particles with various particle size ranges. Under the right conditions these particles can be made reproducibly and serve as drug delivery systems in their own right, being especially suitable for the delivery of other proteins or polypeptides. 

When new drugs and drug-delivery systems are developed in the laboratory, the correlation of the necessary production equipment may be very difficult indeed. For example, the shear needed to create the desired particle size of an emulsion with the help of laboratory equipment may pose serious problems in the selection of plant equipment necessary to reproduce the attributes of the product. Recording the speed of a laboratory mixer is not sufficient by itself for this task definition of the operating principle and equipment design is necessary to accomplish the task. 

Reproduced from D. A. McClure, in Prodrugs as Novel Drug Delivery Systems (ed. T. Higuchi and V. Stella), American Chemical Society, Washington DC, 1975. 

Fig. 5.2 Cross-sectional view of a membrane-moderated transdermal drug delivery system showing major structural components. (Reproduced with permission from Chien (1985).)...

To control particle size and its distribution with their surface area is very important in technological applications. The size and monodispersity of a particle plays a very important role for its reproducibility in data and for its use of immunoassays as a diagnostics tool such as in drug delivery systems. 

Catgut has now been completely replaced by PLA and PLGA wires and meshes, which are degraded at a controlled and reproducible rate. Copolymers of different compositions have found their use in different domains, such as sutures, bone surgery, tissue reconstruction and drug-delivery systems, depending on their thermomechanical properties and... 

Controlled release drug delivery systems are used to deliver the drug locally or system cally at a predetermined rate for a specified period of time [55-57], These systems are used to provide desirable delivery profiles that can achieve therapeutic plasma levels [58,59,55]. In these systems, the drug release is dependent on polymer properties, thus the application of these properties can produce well-characterized and reproducible dosage forms [60]. This section will focus on the two major types of systems micro-spheres/nanoparticles and tablets. 

Size and size distribution of the particles are difficult to control, resulting in poor reproducibility in large-scale production for this reason the drug delivery system may fail to be approved. 

In order to commercialize a new drug delivery system, the economic aspect has to also be analyzed for the pharmaceutical industry but also for patients. The production of GMP grade of PLGA with specific selected properties can be very expensive. In addition, another limitation for the commercialization of nanoparticles is the scaling-up. There are many steps involved in the laboratory-scale production that are impossible to reproduce industrially. 

Fig. 15 T1O2 nanotubes in drug delivery system, (a) Magnetic nanoparticle filled nanotubes with attached drug (F) for magnetically guided site selective drug delivery. Release is triggered by photocatalytic chain scission upon UV irradiation. Inset an example where a blue fluorescent molecule is released from magnetically actuated nanotubes (reproduced with permission from Ref 276). (b) Amphiphilic nanotubes loaded with drugs or biomolecules which are released upon opening the hydrophobic cap with UV irradiation (reproduced with permission from Ref 202).

Figure 23.2 Transdermal drug delivery system in an adhesive. Reproduced from InTech Open Access [22].

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