Capsaicin-loaded nanolipoidal carriers for topical application: design, characterization, and in vitro/in vivo evaluation

I would think that Capsaicin applied to the skin would be great for environmental enrichment and following Margaret Yekutiel in the book, 'Sensory Re-Education of the Hand After Stroke' in 2001 and lead to better recovery? Cheap, easy to do, what is not to like about it except that your doctors have never done ANYTHING that smacked of innovation or thinking outside the box?  You, your children and your grandchildren will continue to be screwed from stroke as long as the existing stroke medical 'professionals' stay in charge. 
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Authors Wang XR, Gao SQ, Niu XQ, Li LJ, Ying XY, Hu ZJ, Gao JQ
Received 7 January 2017
Accepted for publication 28 March 2017
Published 22 May 2017 Volume 2017:12 Pages 3881—3898
DOI https://doi.org/10.2147/IJN.S131901
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Thiruganesh Ramasamy
Peer reviewer comments 2
Editor who approved publication: Dr Lei Yang

Xia-Rong Wang,¹ Si-Qian Gao,¹ Xiao-Qian Niu,¹ Long-Jian Li,² Xiao-Ying Ying,¹ Zhong-Jie Hu,² Jian-Qing Gao<sup>1,3

1</sup>Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, ²Zhejiang Provincial Corps Hospital of Chinese People’s Armed Police Forces, Jiaxing, Zhejiang, ³Jiangsu Engineering Research Center for New-Type External and Transdermal Preparations, Jiangsu, People’s Republic of China


Abstract: Capsaicin has been used in clinical applications for the treatment of pain disorders and inflammatory diseases. Given the strong pungency and high oil/water partition coefficient of capsaicin, capsaicin-loaded nanolipoidal carriers (NLCs) were designed to increase permeation and achieve the analgesic, anti-inflammatory effect with lower skin irritation. Capsaicin-loaded NLCs were prepared and later optimized by the Box–Behnken design. The physicochemical characterizations, morphology, and encapsulation of the capsaicin-loaded NLCs were subsequently confirmed. Capsaicin-loaded NLCs and capsaicin-loaded NLCs gel exhibited sustained release and no cytotoxicity properties. Also, they could significantly enhance the penetration amount, permeation flux, and skin retention amounts of capsaicin due to the application of NLCs. To study the topical permeation mechanism of capsaicin, 3,3'-dioctadecyloxacarbocyanine perchlorate (Dio) was used as a fluorescent dye. Dio-loaded NLCs and Dio-loaded NLCs gel could effectively deliver Dio up to a skin depth of 260 and 210 µm, respectively, primarily through the appendage route on the basis of version skin sections compared with Dio solution, which only delivered Dio up to 150 µm. In vivo therapeutic experiments demonstrated that capsaicin-loaded NLCs and capsaicin-loaded NLCs gel could improve the pain threshold in a dose-dependent manner and inhibit inflammation, primarily by reducing the prostaglandin E2 levels in the tissue compared with capsaicin cream and capsaicin solution. Meanwhile, skin irritation was reduced, indicating that application of NLCs could decrease the irritation caused by capsaicin. Overall, NLCs may be a potential carrier for topical delivery of capsaicin for useful pain and inflammation therapy.

Keywords: capsaicin-loaded NLCs, prescription optimization, analgesic, anti-inflammation, hot-plate test, carrageenan-induced paw edema

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