ABSTRACT
Vesicular and colloidal delivery systems can be designed to control drug release spatially and temporally to improve drug efficacy and side effect profiles. Niosomes (vesicles prepared from nonionic surfactants in aqueous media) are gaining interest as an alternative vesicular delivery system as they offer advantages such as biocompatibility, chemical stability, low cost, high purity, and versatility. However, the physical stability of niosomes, like other vesicular systems, is limited by vesicle fusion, aggregation, and leakage. Proniosomes (dehydrated powder or gel formulations that spontaneously form niosomes on hydration with aqueous media) can overcome these physical stability problems and are more convenient for sterilization, storage, transport, distribution, and dosing. Proniosomes have mostly been explored for their potential to enhance transdermal and oral absorption. In this study we assess, for the first time, the potential for hydrated proniosomes to sustain systemic exposure and therapeutic effect after intravenous delivery. Proniosomes carrying the anti-inflammatory drug, flurbiprofen, were prepared by spraying different nonionic surfactants (span 20, span 40, and span 60 in varying ratios with span 80) and cholesterol onto a sorbitol carrier. The proniosome powders were characterized for surface morphology and flow properties. Niosome formation was assessed at three different hydration temperatures (25, 37, and 45 °C), and the niosomes were assessed for vesicle size, entrapment efficiency, and sterility. OLP proniosomes prepared with a high ratio of span 80 to span 20 were found to spontaneously form vesicles of small size and high drug loading on hydration with aqueous media. The OLP derived niosomes successfully sustained in vitro drug release, in vivo pharmacokinetics, and the anti-inflammatory effect of flurbiprofen in an acute (rat paw edema) model of inflammation when compared to a control solution formulation. The study demonstrates that hydrated proniosomes can prolong systemic drug exposure over 3 days and provide a sustained therapeutic effect. The developed proniosomes represent a novel approach to treat acute pain and inflammation with the potential to be administered as a single intravenous dose by a clinician at the time of injury or surgery that provides adequate relief for several days and reduces fluctuations in therapy. Similar systems loaded with different drugs have potential for broader application in anesthesia, anti-infective, antiemetic, and cancer therapy.
