pH-sensitive niosomes: effects on cytotoxicity and on inflammation and pain in murine models

pH-sensitive nonionic surfactant vesicles (niosomes) by polysorbate-20 (Tween-20) or polysorbate-20 derivatized
by glycine (added as pH sensitive agent), were developed to deliver Ibuprofen (IBU) and Lidocaine
(LID). For the physical-chemical characterization of vesicles (mean size, size distribution, zeta potential, vesicle
morphology, bilayer properties and stability) dynamic light scattering (DLS), small angle X-ray scattering
and fluorescence studies were performed. Potential cytotoxicity was evaluated on immortalized human
keratinocyte cells (HaCaT) and on immortalized mouse fibroblasts Balb/3T3. In vivo antinociceptive activity
(formalin test) and anti-inflammatory activity tests (paw edema induced by zymosan) in murine models
were performed on drug-loaded niosomes. pH-sensitive niosomes were stable in the presence of 0 and
10% fetal bovine serum, non-cytotoxic and able to modify IBU or LID pharmacological activity in vivo. The
synthesis of stimuli responsive surfactant, as an alternative to add pH-sensitive molecules to niosomes,
could represent a promising delivery strategy for anesthetic and anti-inflammatory drugs.