New Capsaicin Patch Helps to Reduce Diabetic Peripheral Neuropathy of the Feet
FDA approved a new capsaicin drug for treating diabetic peripheral neuropathy (DPN) of the feet in July 2020. Qutenza, from Averitas Pharma – the US subsidiary of the German pharmaceutical company Grünenthal – is a cutaneous patch that delivers prescription-strength capsaicin (8%) directly to the skin. Clinicians must apply the patch, which takes a little more than half an hour (details below). The therapy works by desensitizing and interfering with the function of the TRPV1 (transient receptor potential vanilloid 1) receptor, a protein involved in pain signaling. 1
The FDA approval was based on two multicenter studies. Both were 12-week, double-blind, randomized, dose-controlled studies. By Week 8 of the 12-week primary assessment study, participants in the Qutenza group experienced greater pain reduction than those in the control group: -18% for the low-dose control versus -29% for Qutenza. In the second study, the percent change in average pain from baseline to Week 8 was down by 26% in the low-dose control group and down by 33% in the Qutenza group. 2
Peripheral neuropathy is one of the most common complications of diabetes mellitus. Between 50 and 60% of people with DM will experience some form of nerve damage during their lifetimes. (Image: iStock)
Treating DPN Can be Challenging
Peripheral neuropathy is one of the most common complications of diabetes mellitus (DM). Between 50 and 60% of people with DM will experience some form of nerve damage during their lifetimes. 3,4 In patients with type one DM, distal polyneuropathy develops after many years of hyperglycemia; patients with type 2 DM may present with distal polyneuropathy within a few years of diagnosis. In each case, the illness is a significant source of morbidity and leads to great reduction in quality of life.
In addition to loss of sensation and weakness, neuropathy is also a significant source of pain for these individuals. 3 And that pain can be surprisingly challenging to treat.
“There is no cure [for DPN], and the pain can be quite disabling,” David M. Simpson, MD, said told PPM. Dr. Simpson is professor of neurology at the Icahn School of Medicine at Mount Sinai in New York and was lead investigator in the study. In the past, he said, mainstays of treatment have been analgesics, topical or oral, and anticonvulsants. Opioids are occasionally used as well. “Rarely, do we have an optimal reduction of pain, and all treatments had side effects.”
Traditional medications used for DPN include anticonvulsants, such as pregabalin and gabapentin, and antidepressants, including duloxetine and amitriptyline. In especially difficult cases, opioids, such as tramadol and oxycodone, are sometimes used. All of these medications, however, have potentially serious side effects or interactions that make their use problematic in some patients. 5
Clinical Application and Patient Selection
Qutenza patches are applied directly in-clinic to the most painful part of the feet. The patches can be cut to fit the area in need of treatment. The clinician applies a local anesthetic to the skin to reduce discomfort. The patch remains in place for 30 minutes and is then removed. The area is then cleaned with a gel provided with the drug.
Because Qutenza causes a burning sensation (as well as redness), clinicians are advised to wear gloves when administering the patch; the discomfort for the patient should be tolerable. No more than four patches should be used on the patient at one time. 6
“We treated over 300 people and not one asked to have [the patch] removed,” shared Dr. Simpson. It can take up to 3 weeks for the medication to have an effect, but the relief lasts for up to 12 weeks, he added. Other than burning and redness at the site of the patch, there are no other known side effects and no known drug interactions. The procedure can be repeated every 3 months, depending on the patient’s symptoms. 6
There is no data to date on what subset of DPN patients may most benefit from this treatment. However, any patient with DPN in the feet should be a candidate, according to Dr. Simpson.
Qutenza has been approved and used in Europe (for more than just DPN of the feet) for several years.6 However, this is a new therapy in the US and many physicians are not yet aware of it.
“The procedure is not like a pill that you just prescribe and the patient takes it on his own,” Dr. Simpson explained. “It requires medical supervision and doctors will have to get training before doing the procedure.” He also emphasized that with face-to-face contact limited in many parts of the country right now due to COVID, providers should take into account all public safety precautions.
The good news is that after many years with limited and sometimes risky options to treat DPN, clinicians now have a potentially safer and effective new drug to offer patients.
Clinical Trial: Topical Application of CBD Mitigates Neuropathy
San Diego, CA: The topical administration of CBD oil is associated with reduced pain in patients with peripheral neuropathy, according to clinical trial data published in the journal Current Pharmaceutical Biotechnology.
A team of investigators affiliated with Scripps Mercy Hospital in San Diego and Des Moines University in Iowa assessed the efficacy of topically delivered CBD oil in the management of neuropathic pain in a randomized, placebo-controlled clinical trial. Twenty-nine patients participated in the study. Each patient received both treatment and placebo at various intervals of the four-week trial.
Authors reported: "There was a statistically significant reduction in intense pain, sharp pain, cold and itchy sensations in the CBD group when compared to the placebo group. No adverse events were reported in this study."
They concluded: "Our findings demonstrate that the transdermal application of CBD oil can achieve significant improvement in pain and other disturbing sensations in patients with peripheral neuropathy. The treatment product was well-tolerated and may provide a more effective alternative compared to other current therapies in the treatment of peripheral neuropathy."
Full text of the study, "The effectiveness of cannabidiol oil in symptomatic relief of peripheral neuropathy of the lower extremities," appears in Current Pharmaceutical Biotechnology. Additional information regarding cannabis and neuropathy is available in the NORML Library.