Development, characterization and in vitro evaluation of clobetasol propionate emulgel for topical delivery in dermatological inflammatory disorders

The objective of the current investigation was to develop a novel clobetasol propionate (CP) emulgel to enhance the efficacy and minimize side effects during topical application. Preparation of CP loaded emulsion was carried out by the hot emulsification method. The emulsion consisted of combinations of surfactants (Span 20/Tween 20), cosolvent (polyethylene glycol 400), preservatives (methylparaben, propylparaben), with liquid paraffin as the oil phase. The selected emulsion (batch CP7) has nano-size (387.6 ± 58.49 nm), narrow and uniform particle size distribution (PDI, 0.221), spherical morphology and negative zeta potential (–36.4 ± 5.66 mV). The CP7 emulsion was further converted to emulgel by incorporating it in carbopol 934 (2% w/w). The rheology and mechanical characterization of the prepared emulgel indicate appropriate viscosity (~ 300,000 cP), enough spreadability (4.47 ± 0.40 cm), mild hardness (27 g), reasonable adhesiveness (0.6 mJ), and good bioadhesive strength (11.07 ± 1.14 g/cm²), which is ideal for topical use. The CP release from emulgel and hydrogel was found distinct with the emulgel formulation showing significantly (p < 0.0001) slower and delayed drug release. Results of the anti-inflammatory study demonstrated greater inhibition (94.60% at 600 µg/mL) by CP emulgel, compared to other tested groups. The skin irritation potential by the HET-CAM method showed lower irritation score (~ 2.18, p < 0.001) by the fabricated CP emulgel, which could be attributed to the encapsulation of CP within the emulsion. Overall, the developed CP emulgel demonstrated favorable characteristics for effective CP delivery, making it a promising option for the topical treatment of inflammatory skin disorders.