An Inhaled Nanoemulsion Encapsulating a Herbal Drug for Non-Small Cell Lung Cancer (NSCLC) Treatment

<b>Background:</b> Celastrol (Cela), a phytochemical extracted from <i>Tripterygium wilfordii</i>, has been extensively investigated for its potential anti-inflammatory, anti-psoriatic, antioxidant, neuroprotective, and antineoplastic properties. However, its clinical translation is limited due to poor bioavailability, low solubility, and nonspecific toxicity. This study aimed to develop and evaluate an inhalable Cela-loaded nanoemulsion (NE) formulation to enhance targeted drug delivery and therapeutic efficacy in non-small cell lung cancer (NSCLC). <b>Methods:</b> The NE formulation was optimized using Capmul MCM (25%), Tween 80 (20%), Transcutol HP (5%), and water (50%) as the oil, surfactant, co-surfactant, and aqueous phase, respectively. Physicochemical characterization included globule size, zeta potential, and drug release in simulated lung fluid. In vitro aerosolization performance, cytotoxicity in NSCLC cell lines (A549), scratch and clonogenic assays, and 3D tumor spheroid models were employed to assess therapeutic potential. <b>Results:</b> The NE showed a globule size of 201.4 ± 3.7 nm and a zeta potential of -15.7 ± 0.2 mV. Drug release was sustained, with 20.4 ± 5.5%, 29.1 ± 10%, 64.6 ± 4.1%, and 88.1 ± 5.2% released at 24, 48, 72, and 120 h, respectively. In vitro aerosolization studies indicated a median aerodynamic particle size of 4.8 ± 0.2 μm, confirming its respirability in the lung. Cell culture studies indicated higher toxicity of NE-Cela in NSCLC cells. NE-Cela significantly reduced A549 cell viability, showing a ~6-fold decrease in IC₅₀ (0.2 ± 0.1 μM) compared to Cela alone (1.2 ± 0.2 μM). Migration and clonogenic assays demonstrated reduced cell proliferation, and 3D spheroid models supported its therapeutic activity in tumor-like environments. <b>Conclusions:</b> The inhalable NE-Cela formulation improved Cela's physicochemical limitations and demonstrated enhanced anti-cancer efficacy in NSCLC models. These findings support its potential as a targeted, well-tolerated therapeutic option for lung cancer treatment.