**2.3.5 Non-traditional plasticizers**

It is advantageous to utilize plasticization effect of some pharmaceutical active agents or of some excipients possessing other functions in the formulated composition. In the literature, these are named as non-traditional, non-conventional, or multifunctional plasticizers. Several studies report the plasticization of polymers by ibuprofen, theophylline, salts of metoprolol and chlorpheniramin and other active ingredients. From the auxiliary compounds it is potentially promising the use of many surfactants, preservatives, solvents, cosolvents, desolvating and coacervating agents as plasticizers. These components of pharmaceutical preparations can act by various mechanisms, as lowering of intermolecular and intramolecular interactions, increasing of macromolecular or segmental mobility with the consequence of ameliorated thermal and mechanical properties, distensibility, adhesion, viscosity etc.

Ibuprofen was found to be very effective in plasticizing of the acrylic film. Ibuprofen interacts with the Eudragit RS 30 D polymer through hydrogen bonding. The glass transition temperature of the Eudragit RS 30 D polymer decreased with the increasing levels of ibuprofen in the polymeric film (Wu McGinity, 2001). Metoprolol tartrate, chlorpheniramine maleate and ibuprofen are efficient plasticizers for Eudragit RS as shown by the thermal and mechanical properties of drug-loaded polymeric film (Siepmann et al., 2006).

An advantage of the plasticizers of this type is a decrease in or a full prevention of their

Polyesters derived from aliphatic hydroxy acids are compounds which have been very intensively studied and employed as biodegradable and renewable thermoplastic materials with a potential of replacing the conventional polymers based on mineral oil products. These polyesters are used as carriers of active ingredients with a period of release of these substances for weeks to months. They are the products of polymerization of cyclic dimers, lactones via ring opening method, or the substances developed by a polycondensation reaction, e.g. poly(lactic acid), poly(lactide-co-glycolide). They are mostly polymers which in the glassy state have a small elongation at break. For their plasticization highly biocompatible, if possible completely biodegradable compounds are suitable. As the very suitable ones were demonstrated oligoesters or low-molecular polyesters of identical or similar aliphatic hydroxy acids as plasticized polymers (Martin & Avérous, 2001), and polyesteramides were also proposed (Ljungberg et al., 2005). Polyethylene glycols (PEG) are also suitable for these purposes, their miscibility decreases with molecular mass (Baiardo et al., 2003). PEG with a value of Mn 20 000 very effectively plasticized in a 40 % concentration of poly(L-lactic acid) (Kim et al., 2001). PEG in a concentration above 50 % possesses increased crystallinity, an increased module and decreased ductility (Sheth et al., 1997). Polypropylene glycol also exerts a plasticizing effect on poly(L-lactic acid), its effect on a decrease in crystallinity is lower than in PEG (Kulinski et al., 2006). A blend of two plasticizers called multiple plasticizer, triacetin and oligomeric poly(1,3-butanediol),

significantly influences the elastic properties and tensile strength (Ren et al., 2006).

It is advantageous to utilize plasticization effect of some pharmaceutical active agents or of some excipients possessing other functions in the formulated composition. In the literature, these are named as non-traditional, non-conventional, or multifunctional plasticizers. Several studies report the plasticization of polymers by ibuprofen, theophylline, salts of metoprolol and chlorpheniramin and other active ingredients. From the auxiliary compounds it is potentially promising the use of many surfactants, preservatives, solvents, cosolvents, desolvating and coacervating agents as plasticizers. These components of pharmaceutical preparations can act by various mechanisms, as lowering of intermolecular and intramolecular interactions, increasing of macromolecular or segmental mobility with the consequence of ameliorated thermal and mechanical properties, distensibility, adhesion,

Ibuprofen was found to be very effective in plasticizing of the acrylic film. Ibuprofen interacts with the Eudragit RS 30 D polymer through hydrogen bonding. The glass transition temperature of the Eudragit RS 30 D polymer decreased with the increasing levels of ibuprofen in the polymeric film (Wu McGinity, 2001). Metoprolol tartrate, chlorpheniramine maleate and ibuprofen are efficient plasticizers for Eudragit RS as shown by the thermal and mechanical properties of drug-loaded polymeric film

**2.3.4 Oligomeric and polymeric plasticizers** 

migration from materials (Rasal et al., 2010).

**2.3.5 Non-traditional plasticizers** 

viscosity etc.

(Siepmann et al., 2006).

The influence of methylparaben, ibuprofen, chlorpheniramine maleate and theophylline on the mechanical properties of polymeric films of Eudragit® RS 30 D was studied. The results demonstrated that the glass transition temperature of the Eudragit® RS 30 D decreased with increasing levels of methylparaben, ibuprofen and chlorpheniramine maleate in the polymeric coatings. The addition of methylparaben to Eudragit® RS 30 D resulted in significant changes in the mechanical properties, making the polymer softer and more flexible. The Tg of the polymer was significantly reduced (Wu McGinity, 1999).
