Drug loading within resorbable alginate embolisation microspheres

Injectable microspheres are routinely used in the treatment of several diseases achieving combined targeted drug delivery and embolisation of blood vessels. Although this approach is generally deemed successful, there is a considerable drive for clinicians to transfer over to degradable, i.e. resorbable, microspheres. One such resorbable microsphere (SakuraBead™) consists of organic, biocompatible materials designed for the treatment of conditions such as knee osteoarthritis and adhesive capsulitis. To significantly expand the potential of these resorbable beads this study investigated the incorporation of two drugs, namely doxorubicin and irinotecan using isothermal titration calorimetry and microscopy. This process created drug loaded resorbable beads with a quantifiable maximum amount of drug loaded within the beads of 29.3 (±0.03) mg per mL of hydrated bead for doxorubicin and 11.0 (±0.1) mg per mL of hydrated bead for irinotecan. In addition, our degradation study observed that microsphere degradation in vitro was seen to increase from 24 h to 8 days with irinotecan and 26 days with doxorubicin, attributed to an increased crosslink density of the alginate network. Maximum drug loading values for the two drugs compares well with previous studies for non-resorbable beads and the extended degradation time confirms the potential of these microspheres for clinical use in drug-eluting bead transarterial chemoembolisation (DEB-TACE) of tumours, with the added avoidance of permanent occlusion of vessels when using non-resorbable beads.