European Journal of Biomedical and Pharmaceutical Sciences

FORMULATION OPTIMIZATION AND IN VITRO EVALUATION OF NLCS FOR TOPICAL DELIVERY OF ANDROGRAPHOLIDE AND THIOCOLCHICOSIDE

Anurag Kumar*, Vinod Dhote, Kanika Dhote

ABSTRACT

Nanostructured lipid carriers (NLCs) are advanced lipid-based nanocarriers that offer significant advantages for
topical drug delivery, including improved drug loading, enhanced stability, controlled release, and better skin
penetration. The present study focuses on the design, formulation optimization, and in vitro evaluation of
nanostructured lipid carriers for topical delivery of a combination of andrographolide and thiocolchicoside using a
Box–Behnken design (BBD) approach. Andrographolide, a bioactive diterpenoid with anti-inflammatory and
antioxidant properties, and thiocolchicoside, a muscle relaxant, were selected to achieve a synergistic therapeutic
effect. NLCs were prepared using an appropriate lipid blend consisting of solid and liquid lipids along with
suitable surfactants. A three-factor, three-level Box–Behnken design was employed to optimize formulation
variables, with particle size and entrapment efficiency considered as critical responses. Design-Expert® software
was used to evaluate the effect of independent variables and to predict the optimized formulation. The optimized
NLC formulation exhibited nanoscale particle size, high entrapment efficiency, and acceptable zeta potential,
indicating good physical stability. The optimized NLCs were further characterized for drug content, in vitro drug
release, and stability studies. In vitro release studies demonstrated a sustained and controlled release pattern of
both drugs, suggesting improved topical performance. Stability studies confirmed that the formulation remained
stable under accelerated storage conditions. Overall, the results indicate that the developed NLC-based topical
formulation is a promising carrier system for the effective delivery of andrographolide and thiocolchicoside, with
potential applications in the management of inflammatory and musculoskeletal conditions.

Keywords: Nanostructured lipid carriers; Topical drug delivery; Andrographolide; Thiocolchicoside; Box– Behnken design; Formulation optimization; In vitro evaluation.