Development and evaluation of Sahasthara Thai medicine remedy in a film-forming spray for topical anti-inflammatory therapy.

Background and purpose: The study aimed to develop a localized topical anti-inflammatory treatment using a Thai medicinal herbal remedy called "Sahasthara," known for its anti-inflammatory properties, to create a film-forming spray (FFS).

Experimental approach: This research evaluated and developed an FFS formulated with Sahasthara ethanolic extract (SHTe). Subsequently, the optimized formulation was investigated for in vitro anti-inflammatory activity, cell culture toxicity assessment, pharmacological effects, and stability studies.

Findings/results: An optimized formulation (F12) was identified, consisting of 1% w/w SHTe and PVP K90, glycerol, PEG 400, sesame oil, a eutectic blend, and ethanol. This clear, smooth surface, yellowish film releases 42.37%, 38.67%, and 68.93% at 8 h, corresponding to a flux of 20.94, 1.92, and 26.32 µg/cm2/h of piperine, plumbagin, and β-asarone, respectively. F12 was determined to have a viscosity, drying time, and spray angle of 20 cps, 4.57 min, and 66.0 degrees. In-vitro anti-inflammatory activity demonstrated nitric oxide (NO) inhibition with an IC50 of 9.18 µg/mL. No apparent toxicity was observed in a skin cell line. This formulation was developed to be physically stable after undergoing freeze-thaw cycles. Although thermodynamic stability studies under accelerated conditions revealed a minor decrease in piperine and β-asarone within the film, the results indicate no statistically significant changes in its anti-inflammatory activity.

Conclusion and implications: SHTe FFS offers optimal spray ability, a high in-vitro drug release profile, potent inhibition of anti-inflammatory markers, and stability under accelerated conditions. These findings suggest that SHTe FFS can serve as an innovative topical anti-inflammatory treatment.