Amlexanox-loaded nanoliposomes showing enhanced anti-inflammatory activity in cultured macrophages: A potential formulation for treatment of oral aphthous stomatitis

Oral aphthous stomatitis is a common disorder treated with the immunomodulatory drug Amlexanox (AMX), that was administered as a mucoadhesive paste (Aphthasol®). This product was discontinued by FDA in 2014 due to the associated undesired adverse reactions of the formulation. Here, we have developed AMX-loaded nanoliposome formulation as a potential alternative for the localised oromucosal delivery of AMX. Nanoliposomes were prepared using Soya phosphatidylcholine (SPC) and Cholesterol (Chol) mixtures at three different molar ratios to formulate vesicles using thin-film hydration, and were characterised for size, zeta potential and entrapment efficiency. The optimal formulation was found to be SPC:Chol 3:1 with drug entrapment efficiency of 94%, post sonication. To evaluate anti-inflammatory activity, macrophages developed by differentiation of human leukaemia monocytic cell line, THP-1, were polarised by Interferon gamma (IFNγ) and lipopolysaccharide (LPS) to M1 state. Macrophages M1 cells treated with D-L1 formulation (SPC:Chol 3:1, 500 μg/mL total lipid, and 27.6 μM AMX) showed a significant suppression in TNF-α expression levels (43 ± 2.7% of untreated control, p < 0.05) compared to those treated with either empty liposomes or AMX alone. Notably, % TNF-α dramatically decreased to 57 ± 4.05% of control, for cells treated with drug-free liposomes (500 μg/mL total lipid) indicating the anti-inflammatory activity of SPC lipid component per se, which led to synergistic effect as evident from the augmentation of AMX anti-inflammatory activity in D-L1 formulation. Our findings highlight the potential of using AMX nanoliposomes as a promising advanced formulation for reviving AMX treatment for management of inflammatory conditions of oral mucosa.