Poloxamine-based nanomaterials for drug delivery

Poloxamines (Tetronic^®) are X-shaped amphiphilic block copolymers formed by four arms of poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) blocks bonded to a central ethylenediamine moiety. Such a structure confers multi-responsive behaviour, namely temperature and pH-sensitiveness. At relatively low concentrations but above the critical micellar concentration (CMC), poloxamines generate polymeric micelles. Due to the presence of a hydrophobic core, these nanocarriers are useful in the solubilization and stabilization of poorly water-soluble drugs. Moreover, chemical modification of the micellar core is feasible. These remarkable and unique features, compared to the well-known linear poloxamers, have motivated an increasing interest in the study and application of the branched derivatives in different emerging disciplines. The present review concisely overview the most important developments comprising the application of poloxamines in drug delivery, mainly as micellar carriers capable of enhancing drug solubility and stability, and also as surface modifiers in the technology of stealth polymeric nanoparticles. Their potential for the administration of drugs by different routes and the improvement of the drug bioavailability and therapeutic effect are discussed.