Modifying Drug Release for Intramuscular and Oral Delivery Using Drug-eluting Embolisation Beads

In recent years, polymer-based embolisation beads have been used to deliver drugs for the treatment of cancer directly to the site of action. Known to be biocompatible implants, these beads have become an ideal drug delivery vehicle for parenteral administration yet have not been considered for the more commonly used drug delivery routes such as oral and intramuscular drug delivery. This work describes the application of a type of polymer beads, formerly used for embolisation, as a formulation option for oral and intramuscular delivery of a model drug, namely imipramine. Following successful incorporation within the beads, dissolution analysis confirmed the potential to provide a modified drug release profile. Thermogravimetric analysis (TGA) permitted determination of the total water content within the beads (96.8%) and differential scanning calorimetry (DSC) indicated that not all of the water within the beads was able to freeze, apportioned as 15.8% non-freezing, 25.1% loosely bound and the remaining 55.9% unbound. In the presence of drug, the size of the beads decreased with a reduced water content (95.4%) comprised of 16.7% non-freezing, 20.5% freezing bound and the remaining 58.2% % unbound.In conclusion, the results presented in this study confirm the ability of TGA and DSC to separate the differing types of water within the beads and furthermore, the potential of such beads for a far wider variety of formulation options than those previously adopted.