Sustained analgesia achieved through esterase-activated morphine prodrugs complexed with PAMAM dendrimer.

Ward, Brent B; Huang, Baohua; Desai, Ankur; Cheng, Xue-Min; Vartanian, Mark; Zong, Hong; Shi, Xiangyang; Thomas, Thommey P; Kotlyar, Alina E; Van Der Spek, Abraham; Leroueil, Pascale R; Baker, James R

PURPOSE Design and evaluate the in vitro and in vivo efficacy of two extended release morphine formulations developed for IV administration by complexing esterase activated morphine prodrugs to surface-modified, generation 5 (G5) poly(amidoamine) (PAMAM) dendrimer. METHODS Prodrugs were synthesized, complexed with PAMAM dendrimer, characterized via ultra performance liquid chromatography (UPLC), nuclear magnatic resonance (NMR), and tested in vitro using rat plasma vs. saline control and in an in vivo rat and guinea pig pain model (modified Randall and Selitto test). RESULTS We demonstrated that complexation with dendrimer allowed the solubilization of the prodrugs for in vivo applications without the need for salt, and that the structural design of the morphine prodrugs allowed the controlled release of morphine which extended the action of morphine-induced analgesia in an animal pain model from 2 h (control) to 6 h (Morphine Prodrug A). CONCLUSION The concept of complexing/solubilizing appropriately designed esterase-sensitive prodrugs with dendrimer to enhance the sustained release of these drugs may be a useful pharmacokinetic strategy for a range of therapeutics.