Capsule systems, multicomponent

For pharmaceutical formulations, the simplex method was used by Shek et al. [10] to search for an optimum capsule formula. This report also describes the necessary techniques of reflection, expansion, and contraction for the appropriate geometric figures. The same laboratories applied this method to study a solubility problem involving butoconazole nitrate in a multicomponent system [11],... 

In a previous publication [8] we described a systematic screening of the binary interactions between 36 polyanions and 40 polycations. As a result of this study it became clear that capsules prepared from simple binary polymer complexes would not be mechanically adequate and multicomponent polymer systems would offer advantages. The rationale for capsule improvement, and for the use of a multicomponent system, has been presented in the Introduction. We have elected to investigate the methods outlined in Sects. 1.2.7 and 1.2.8 (polymer... 

Typically, a binary system was selected as the base component of the recipe and the addition of polyelectrolytes to either side (core or receiving bath) was tested to evaluate the change in the capsule properties. The 33 successful multicomponent membrane systems are presented in Table 1. The components of the core material side (21 different chemical compositions) are listed in the first column, while the receiving bath components (20 different chemical compositions) are listed in the second column. With the exception of xanthan and CMC, the first polymer listed on the core side are gelling polymers which form beads with the appropriate ionotropic cation (salt). CMC can also be gelled by ions (alum), although they are considered to be non-compatible for cellular applications. The cations were tested both sequentially, usually with ionotropic cation first, and simultaneously. Walled capsules with adequate mechanical properties were often obtained through the simultaneous application of two polycations. Such a... 

Table 2 indicates that the most suitable capsular membranes comprised semi-or non-transparent systems. Generally, the multicomponent blending resulted in smooth capsules with the exception of the alginate/spermine-polymethylene-co-guanidine systems which were either irregularly shaped or mosaic. There was no correlation observed between the capsule turbidity and permeability. 

Our screening and testing of multicomponent capsules/beads is incomplete. However, it offers a novel approach for the material selection for immobilization devices, which permits the simultaneous control of permeability, mechanical stability, and compatibility. The alternative multicomponent systems presented herein offer new possibilities for biomaterials, particularly those employed in bio artificial organs. 

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