Dr. Keith Bley from Solimar Therapeutics and former SVP of Nonclinical R&D and a co-Founder of NeurogesX (www.neurogesx.com), talked about use of capsaicin, a pungent ingredient found in chili peppers, as treatment to relieve pain at www.bio2devicegroup.org.
There are many reasons why capsaicin has the potential to be effective pain reliever, said Bley. Capsaicin, the principal ingredient in chili peppers, has antioxidant, antibacterial qualities and its pungency deters ambulatory herbivore animals from eating the fruits. Birds however, do not respond to capsaicin and distribute seeds widely. Although topical capsaicin therapy may cause an intense burning sensation for the first couple of minutes, it does not cause permanent tissue damage. Capsaicin has unique receptors which selectively binds to heat activated sodium and calcium channels. Bley shared the long history of interest and use of capsaicin for medicinal purposes.
More recently, capsaicin has been used in topical ointments, frequently to relieve the pain of peripheral neuropathy or pain associated with shingles. Skin is the largest organ in the body and it is the primary sensing organ. Nociceptors or specialized sensory nerve endings often become pathophysiologically hyperactive due to many insults that may cause reduction of skin intervention due to trauma, viruses, metabolic diseases, as well as drugs. The idea is that if skin may contribute to pain then perhaps pain can be relieved by intervening at the level of the skin. Existing capsaicin therapy required multiple applications and compliance was seen to be poor, on account of burning pain associated with the application. NeurogesX combines the therapy into single application and increases the efficiency with higher concentration in its Qutenza 8% patch. Interestingly, flooding the nerves with increased capsaicin also leads to defunctionalization where the nerves stop functioning temporarily and the pain soon subsides.
Bley shared some data from the clinical trial that indicated that compared to low-concentration patches, the Qutenza patch showed greater decline in reported pain and for the relief lasted a longer period, before another application was required. While this data clearly favored Qutenza, of interest was also an absolutely strong and much more significant dip in reported pain, following both Qutenza and other low-concentration therapies, indicating a very strong placebo effect. If in fact, immediate pain after the application was greater with Qutenza, due to higher concentration, compared to other patches, then it is very likely that the placebo effect will be stronger and last longer. However, notwithstanding these concerns, given the subjective aspect of pain, Neurogesx was able to raise close to $150M and went IPO in 2007, got approval in Europe in 2008 and approval in US in 2009. Bley’s presentation was followed by Q&A along with animated discussion about pain, pain relief and healthcare costs associated with pain relief therapies. Keith Bley can be reached at firstname.lastname@example.org .