Topical microgel Formulation containing Boswellia serrata bark extract and evaluation to treat arthritis in an animal model

Abstract

This study aimed to develop and evaluate a topical microgel formulation containing Boswellia serrata bark extract for its anti-arthritic and anti-inflammatory activities in rats. Twelve topical gel formulations were prepared using 1.5% Carbopol 934 (F1-F6) and Carbopol 940 (F7-F12) as gelling agents. These formulations were rigorously evaluated for physical appearance, homogeneity, viscosity, extrudability, pH, spreadability, in vitro diffusion profile, and primary skin irritation. Formulation F4, prepared with Carbopol 934, demonstrated superior organoleptic characteristics and active ingredient release.

The anti-arthritic activity of F4 was assessed using the Freund’s Complete Adjuvant (FCA)-induced arthritis model in Wistar rats. Parameters including body weight, paw volume, haematological profiles (haemoglobin, ESR, RBC, WBC), biochemical markers (SGPT, SGOT, total proteins, creatinine, uric acid, urea nitrogen), and histopathological examination were evaluated over 28 days.

The formulated gels were homogeneous, stable, and non-irritating to the skin, showing no erythema or oedema. Topical application of F4 significantly reduced paw volume (p<0.001) in arthritic rats compared to the diseased control group. Furthermore, F4 helped restore normal haematological and biochemical parameters, reduced spleen and thymus weights, and showed improvements in joint histopathology, comparable to the standard diclofenac gel. The in vitro release kinetics of F4 followed a zero-order model, indicating controlled release. These findings suggest that the developed Boswellia serrata topical microgel formulation (F4) possesses significant anti-arthritic and anti-inflammatory properties, offering a promising alternative for arthritis management with minimal systemic side effects.