Evaluation of a root extract gel from Urtica dioica (Urticaceae) as analgesic and anti-inflammatory therapy in rheumatoid arthritis in mice

Purpose: To develop and characterize an herbal gel prepared from methanol root extract of Urtica dioica (Urticaceae) (Stinging nettle) for the treatment of arthritis in mice. Methods: A methanol root extract from Urtica dioica was prepared, and a gel was then prepared using Carbopol 934. The prepared gel was subjected to various physical tests (color, appearance, pH, texture, viscosity) and in vivo evaluation, including primary skin irritation, analgesic, and anti-inflammatory tests, in arthritic mice and compared with 2 % indomethacin gel, which was used as standard. Results: The prepared herbal gel was of light gray color with a smooth texture. It showed a pH of 7.1 and a viscosity of 21.2 cps. The gel exhibited pseudoplastic rheology, as evidenced by shear thinning with increased shear rate. It was non-irritating to the skin in primary skin irritation test in mice and showed 55.05 % inhibition of paw edema in a carrageenan-induced hind rat paw edema model, comparable to that of the standard gel (53.93 %), after 24 h. The gel showed 58.21 % analgesia, versus 61.19 % analgesia for the indomethacin gel standard in writhing test. Conclusion: The topical gel from methanol root extract of U. dioica may be an efficacious and safe alternative to non-steroidal anti-inflammatory drugs in the treatment of rheumatoid arthritis but this requires further investigations to ascertain its safety and clinical efficacy.

In situ epicatechin-loaded hydrogel implants for local drug delivery to spinal column for effective management of post-traumatic spinal injuries

Purpose: To prepare hydrogels loaded with epicatechin, a strong antioxidant, anti-inflammatory, and neuroprotective tea flavonoid, and characterise them in situ as a vehicle for prolonged and safer drug delivery in patients with post-traumatic spinal cord injury. Methods: Five in situ gel formulations were prepared using chitosan and evaluated in terms of their visual appearance, clarity, pH, viscosity, and in vitro drug release. In vivo anti-inflammatory activity was determined and compared with 2 % piroxicam gel as standard. Motor function activity in a rat model of spinal injury was examined comparatively with i.v. methylprednisolone as standard. Results: The N-methyl pyrrolidone solution (containing 1 % w/w epicatechin with 2 to 10 % w/w chitosan) of the in situ gel formulation had a uniform pH in the range of 4.01 ± 0.12 to 4.27 ± 0.02. High and uniform drug loading, ranging from 94.48 ± 1.28 to 98.08 ± 1.24 %, and good in vitro drug release (79.48 ± 2.84 to 96.48 ± 1.02 % after 7 days) were achieved. The in situ gel prepared from 1 % epicatechin and 2 % chitosan (E5) showed the greatest in vivo anti-inflammatory activity (60.58 % inhibition of paw oedema in standard carrageenan-induced hind rat paw oedema model, compared with 48.08 % for the standard). The gels showed significant therapeutic effectiveness against post-traumainduced spinal injury in rats. E5 elicited maximum motor activity (horizontal bar test) in the spinal injury rat model; the rats that received E5 treatment produced an activity score of 3.62 ± 0.02 at the end of 7 days, compared with 5.0 ± 0.20 following treatment with the standard. Conclusion: In situ epicatechin-loaded gel exhibits significant neuroprotective and anti-inflammatory effects, and therefore can potentially be used for prolonged and safe drug delivery in patients with traumatic spinal cord injury.