Development of Capsaicin-Containing Analgesic Silicone-Based Transdermal Patches

Abstract

Transdermal therapeutic systems (TTSs) enable convenient dosing in drug therapy. Modified silicone-polymer-based patches are well-controlled and cost-effective matrix diffusion systems. In the present study, we investigated the substance release properties, skin penetration, and analgesic effect of this type of TTS loaded with low-dose capsaicin. Release properties were measured in Franz diffusion cell and continuous flow-through cell approaches. Capsaicin was detected with HPLC-UV and UV spectrophotometry. Raman spectroscopy was conducted on human skin samples exposed to the TTS. A surgical incision or carrageenan injection was performed on one hind paw of male Wistar rats. TTSs were applied to the epilated dorsal skin. Patches were kept on the animals for 6 h. The thermal hyperalgesia and mechanical pain threshold of the hind paws were detected. Patches exhibited controlled, zero-order kinetic capsaicin release. According to the Raman mapping, capsaicin penetrated into the epidermis and dermis of human skin, where the target receptors are expressed. The thermal pain threshold drop of the operated rat paws was reversed by capsaicin treatment compared to that of animals treated with control patches. It was concluded that our modified silicone-polymer-based capsaicin-containing TTS is suitable for the relief of traumatic and inflammatory pain.

Antimicrobial Properties of Capsaicin: Available Data and Future Research Perspectives

“…We would also like to note that capsaicin-sensitive neurons can release somatostatin [285,318] and it is already well known that somatostatin promotes anti-inflammatory and anti-nociceptive effects [319][320][321]; recently, capsaicin was shown to be able to induce the release of somatostatin from such nerve endings when applied in transdermal patches [322]. Somatostatin is also important in its immunomodulatory role in cases of infection-induced inflammation; despite some positive effects, the secretion of somatostatin seems to downregulate the immune system [323][324][325][326].…”