Hydrophilic plasticizers

Adsorption of t-PA to process equipment surfaces consisting of either stainless steel or glass was minimized by adding the detergent polyoxyethylene sorbitan monooleate (Tween 80) to the semm-free culture conditioned media at 0.01% (vol/vol). The equipment was also rinsed, before use, with phosphate buffered saline (PBS) containing 0.01% Tween 80. Hydrophilic, plastic equipment was used whenever possible. AH buffers were sterile filtered. Sterile filtration of Hquids and gases is usually carried out using 0.2 or 0.45 p.m filters. 

Fisher (1977) found that the bactericidal effects varied from brand to brand and Fisher McCabe (1978) related this to chemical composition. Only cements which give rise to high alkalinity (pH = 11) are effective. These are the cements which are readily decomposed by water, and this relates to the plasticizer used. Hydrophilic plasticizers are required if these cements are to be clinically effective. 

Experiments have been performed with other carriers such as hydrophilic plastic foils and even textiles, but none of these products has come to market. 

Other excipients used in film-coating may influence the dissolution of the polymers [36], For instance, plasticizers may increase or decrease dissolution rate, depending on whether a lipophilic or a hydrophilic plasticizer was used. Using this effect, the time-to-action of a drug may be improved (e.g., by using a hydrophilic plasticizer like triethyl citrate). Usually these effects are not detectable, if... 

Triacetin is mainly used as a hydrophilic plasticizer in both aqueous and solvent-based polymeric coating of capsules, tablets, beads, and granules typical concentrations used are 10-35%... 

In a study by Bodmeier et al., it was demonstrated that plasticizer selection strongly influenced the rate of theophylline release in 0.1N HCl from beads coated with Aquacoai ECD (68). The results of this. study are shown in Figure 11. From this figure it can be seen that incomplete film formation resulted from plasticization with triacetin as a result of incompatibility between the hydrophilic plasticizer and the hydrophobic ethylcellulose latex particles. Complete film formation was achieved with all other investigated plasticizers TEC, Myvacet, tributyl citrate, DBS, and acetyl tributyl citrate however, faster drug release was seen with TEC due to the water solubility of TEC versus the water-insolubility of the other investigated plasticizers. 

Mangavel C., Barbot J., Gueguen X, Popineau Y Molecular determinants of the influence of hydrophilic plasticizers on the mechanical properties of cast vflieat gluten films, J. Agric. Food Chem. 51 (2003) 1447. 

A downside to the sustainable and extensive use of soy protein-based materials is their intrinsic reactivity and thus lower inertia when compared to most conventional petrochemical-based plastics. They are known to be sensitive to microbial spoilage and also to water due to hydrophilic nature of many amino acids constituting their primary structure and to the substantial amount of hydrophilic plasticizer required to impart thermo-processability and film flexibility. As a consequence, their mechanical properties and water vapor barrier properties in high moisture conditions are poor compared to synthetic films such as low-density polyethylene. 

The Hansen solubility parameters that were calculated according to Equation 16.4 are presented in Table 16.1. With 5 values of about 17-19 (J/cm ) all plasticizing molecules were within a narrow range only the polymer seemed to have a reduced dispersive solubility parameter value reading 13.13 (J/cm )°. A better discrimination was possible by comparison of the different values of the electrostatic interaction parameter 5 with a 5 value of 11.32 (J/cm )° the pure polymer was in the same range, compared to amorphous ibuprofen [11.89 (J/cm )° ] and the hydrophilic plasticizer TEC [8.62 (J/cm )° ], thus indicating an excellent miscibility. In contrast, both the values of DBS [3.29 (J/cm )° ] and ATBC [4.57 (J/cm )° ] showed an extended lipophilic character. 

---