Two steps modification for improvement of cyclobenzaprine transdermal delivery: releasing from patch and penetrating through skin

Molecular perspective of efficiency and safety problems of chemical enhancers: bottlenecks and recent advances

Chemical penetration enhancer (CPE) is a preferred approach to improve drug permeability through the skin, due to its unique advantages of simple use and high compatibility. However, CPEs efficiency and safety problems frequently arise, which greatly restrains the further application in transdermal drug delivery systems (TDDS). To get access to the root of problems, the efficiency and safety of CPEs are reviewed especially from molecular perspectives, which include (1) the possible factors of CPEs low efficiency; (2) the possible contribution of CPEs in the evolution of safety problems such as skin irritation and allergic reaction; (3) the interactive relationship between CPEs efficiency and safety, as well as the bottlenecks of achieving their balance. More importantly, based on these, recent advances are summarized in improving efficiency or safety of CPEs, which offers a guidance of rationally selecting CPEs in future research.

Alternative therapy of rheumatoid arthritis with a novel transdermal patch containing Siegesbeckiae Herba extract

ETHNOPHARMACOLOGICAL RELEVANCE

Siegesbeckiae Herba (SiH) is a traditional anti-rheumatic herbal medicine in China. A SiH derived product, Phynova Joint and Muscle Relief Tablets™, has been granted the UK license in 2015. Although transdermal delivery provides better patient compliance and relative constant plasma drug concentration, the feasibility of transdermal delivery of SiH was not clear.

AIM OF THE STUDY

The aim of the present study was to develop a novel transdermal patch containing SiH extract for alternative therapy of rheumatoid arthritis.

MATERIALS AND METHODS

SiH extract containing 48.5% (w/w) of kirenol was prepared from Siegesbeckia pubescens Makino. Then transdermal patches containing SiH extract were prepared by the solvent evaporation technique. The formulation of the transdermal patch was optimized based on the in vitro skin permeation experiment. Finally, the anti-inflammatory and analgesic activity of the optimal patch were evaluated by chronic inflammation model induced by complete Freund's adjuvant (CFA) and writhing model induced by acetic acid, separately.

RESULTS

Oleic acid (OA) showed the maximum permeation enhancement effect with the enhancement ratio (ER) values of 3.32. Therefore, OA was used as a permeation enhancer in the transdermal patch. The optimal formulation consisted of SiH extract (10% of the matrix, w/w), OA (10% of the matrix, w/w), DURO-TAK® 87-2287 (pressure sensitive adhesive matrix) and Scotchpak™ 9701 (backing layer). The optimal transdermal patch containing SiH extract significantly reduced the degree of paw swelling and number of writhing in inflammation model and writhing model, respectively.

CONCLUSIONS

The developed transdermal patch containing Siegesbeckiae Herba extract showed good anti-inflammatory and analgesic effects, which demonstrated a great potential for alternative therapy of rheumatoid arthritis.