Application of the capsaicin 8% cutaneous patch in neuropathic pain of the head and face: A case series

Study protocol of the TEC-ORL clinical trial: a randomized comparative phase II trial investigating the analgesic activity of capsaicin vs Laroxyl in head and neck Cancer survivors presenting with neuropathic pain sequelae

BACKGROUND

Neuropathic pain is common in cancer survivorship and is one of the most distressing symptoms for patients previously treated for head and neck cancer. Persistent neuropathic pain, when it is ongoing and uncontrolled, has a detrimental effect and erodes patients' quality of life. Patients treated for head and neck cancer are chronic opioid users to manage their post-treatment pain, which may entail an increased risk of addiction and overdose. We propose to evaluate the analgesic activity of high-concentration capsaicin patches for the treatment of head and neck cancer survivors presenting with neuropathic pain sequelae.

METHODS

TEC-ORL is a parallel, multicenter randomized comparative phase II study evaluating whether Capsaïcin patches (Qutenza®) reduce neuropathic pain when compared to Amitriptyline (Laroxyl®) in head and neck cancer survivors presenting with neuropathic pain sequelae. The primary efficacy outcome is the rate of patients with a pain reduction of at least two points at 9 months compared to baseline. Assuming that 5% of patients become lost to follow-up, 130 patients will need to be randomized to detect a 25% improvement (i.e., standard: 25%, experimental: 50%) using a one-sided chi-square test with an alpha of 0.05%. According to the recommendations for comparative phase II trials, the target differences and type I error rates are relaxed. Randomized patients will either be treated with a capsaicin 8% (Qutenza®) patch applied at three time intervals in the experimental arm or with Amitriptyline (Laroxyl®) (oral solution 40 mg/ml) taken for 9 months at the recommended daily dose of 25 mg to 75 mg in the control arm.

DISCUSSION

TEC-ORL is a randomized comparative phase II trial designed to comprehensively evaluate the analgesic activity of capsaicin compared to Laroxyl in Head and Neck Cancer survivors presenting with neuropathic pain sequelae.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04704453 Date of registration: 2021/01/13.

The Utility of Capsicum annuum L. in Internal Medicine and In Dentistry: A Comprehensive Review

Capsaicin is a chili peppers extract, genus Capsicum, commonly used as a food spice. Since ancient times, Capsaicin has been used as a "homeopathic remedy" for treating a wild range of pathological conditions but without any scientific knowledge about its action. Several studies have demonstrated its potentiality in cardiovascular, nephrological, nutritional, and other medical fields. Capsaicin exerts its actions thanks to the bond with transient receptor potential vanilloid subtype 1 (TRPV1). TRPV1 is a nociceptive receptor, and its activation starts with a neurosensitive impulse, responsible for a burning pain sensation. However, constant local application of Capsaicin desensitized neuronal cells and leads to relief from neuropathic pain. In this review, we analyze the potential adjuvant role of Capsaicin in the treatment of different pathological conditions either in internal medicine or dentistry. Moreover, we present our experience in five patients affected by oro-facial pain consequent to post-traumatic trigeminal neuropathy, not responsive to any remedy, and successfully treated with topical application of Capsaicin. The topical application of Capsaicin is safe, effective, and quite tolerated by patients. For these reasons, in addition to the already-proven beneficial actions in the internal field, it represents a promising method for the treatment of neuropathic oral diseases.

Capsaicin 8% Patch and Chronic Postsurgical Neuropathic Pain

(1) Background: Surgery is a frequent cause of persistent pain, defined chronic post-surgical pain (CPSP). The capsaicin 8% patch (Qutenza^®) is approved for the treatment of postherpetic neuralgia (PHN) and for diabetic peripheral neuropathy (DPN) of the feet. We propose a review of the literature on use of the capsaicin 8% patch to treat neuropathic pain associated with surgery; (2) Methods: We identified the articles by searching electronic databases using a combination of such terms as “capsaicin 8% patch”, “Qutenza^®”, and “chronic postsurgical pain”; (3) Results: We identified 14 selected studies reporting on a total of 632 CPSP cases treated with capsaicin 8% patch. Treatment with the capsaicin 8% patch significantly reduced the average pain intensity. Only 5 studies reported adverse events (AEs) after the patch application. The most common AEs were erythema, burning sensation and pain; (4) Conclusions: Our review indicate that capsaicin 8% patch treatment for CPSP is effective, safe and well tolerated, but randomized controlled trials on efficacy, safety and tolerability should be conducted.

Acute and Chronic Pain from Facial Skin and Oral Mucosa: Unique Neurobiology and Challenging Treatment

The oral cavity is a portal into the digestive system, which exhibits unique sensory properties. Like facial skin, the oral mucosa needs to be exquisitely sensitive and selective, in order to detect harmful toxins versus edible food. Chemosensation and somatosensation by multiple receptors, including transient receptor potential channels, are well-developed to meet these needs. In contrast to facial skin, however, the oral mucosa rarely exhibits itch responses. Like the gut, the oral cavity performs mechanical and chemical digestion. Therefore, the oral mucosa needs to be insensitive, to some degree, in order to endure noxious irritation. Persistent pain from the oral mucosa is often due to ulcers, involving both tissue injury and infection. Trigeminal nerve injury and trigeminal neuralgia produce intractable pain in the orofacial skin and the oral mucosa, through mechanisms distinct from those seen in the spinal area, which is particularly difficult to predict or treat. The diagnosis and treatment of idiopathic chronic pain, such as atypical odontalgia (idiopathic painful trigeminal neuropathy or post-traumatic trigeminal neuropathy) and burning mouth syndrome, remain especially challenging. The central integration of gustatory inputs might modulate chronic oral and facial pain. A lack of pain in chronic inflammation inside the oral cavity, such as chronic periodontitis, involves the specialized functioning of oral bacteria. A more detailed understanding of the unique neurobiology of pain from the orofacial skin and the oral mucosa should help us develop novel methods for better treating persistent orofacial pain.

Topical Capsaicin for the Treatment of Neuropathic Pain

BACKGROUND

Neuropathic pain (NP) is an egregious problem worldwide. Due to the side-effects of oral drugs, drugs delivered directly to the affected area of pain are preferred.

OBJECTIVE

Capsaicin, a chemical compound isolated from chili peppers, is used as an analgesic in topical ointments and dermal patches to alleviate pain. Objective of the study is to review the application and functionality of topical capsaicin in treatment of neuropathic pain.

DATA SOURCES

To systematically review capsaicin's functions on NP, we retrieved articles from the PubMed database published in the last ten years.

STUDY ELIGIBILITY CRITERIA

The inclusion criteria were capsaicin and the use of capsaicin for the treatment of NP; on the other hand, articles were excluded according to the mentioned criteria such as abstracts, articles written in any language other than English, incomplete articles, and conference papers.

PARTICIPANTS AND INTERVENTIONS

Out of 265 articles, 108 articles were selected after filtering through the inclusion and exclusion criteria. The data and knowledge currently existing for capsaicin treatment in NP are summarized.

RESULTS

This review indicates that capsaicin effectively improves NP treatment without affecting the motor and large nerve fibres involved in sensory function. Transient receptor potential channel vanilloid type 1 (TRPV1) is the capsaicin receptor expressed in central and peripheral terminals of a sensitive primary nerve cell. Conclusions and implications of key findings: Topical capsaicin has a sensible safety profile and is effective in reducing NP. Therefore, studies over the last decade suggest that capsaicin might be a potential drug for NP treatment.

Novel Agents in Neuropathic Pain, the Role of Capsaicin: Pharmacology, Efficacy, Side Effects, Different Preparations

PURPOSE OF REVIEW

Capsaicin is a natural substance used to treat neuropathic pain because of its ability to be used in a more direct form on patients and efficiently treat their pain without the amount of side effects seen in the use of oral medications.

RECENT FINDINGS

Currently, the treatments for neuropathic pain are, control of the underlying disease process, then focused on symptomatic relief with pharmacotherapy, topical analgesics, or other interventions. When all pharmacological agents fail to relieve the pain, interventional strategies can be considered, such as neural blocks, spinal cord stimulation, and intrathecal administered medications. The response to current treatment of neuropathic pain is only modest relief of symptoms. Multiple treatment options may be attempted, while ultimately leaving patients with refractory neuropathic pain. For these reasons, a better treatment approach to neuropathic pain is greatly needed. Overall, capsaicin has great potential for becoming a first- or second-line treatment for neuropathic pain, and for becoming a therapeutic option for many other neuropathic pain-related disease states.

[Postherpetic neuralgia of the left trigeminus nerve V1 : Successful therapy with capsaicin 8% patch]

A 68-year-old patient suffered from postzoster neuralgia with severe pain of the left trigeminal nerve V1. Despite medication with gabapentin 1800 mg/d, oxacarbazepine 600 mg, tapentadol 500 mg/d, amitriptyline 20 mg as well as ambroxol 20% ointment and lidocaine patch topically, the pain reached an intensity of 8-10 on the numeric rating scale (NRS). Wearing a CPAP (continuous positive airway pressure) mask at night to treat a sleep apnea was impossible or the mask was leaking under lidocaine patch, only topical ambroxol 20% brought a certain pain relief. Lack of sleep, a strongly reduced quality of life and massive exhaustion followed quickly. Due to a fall the systemic medication could not be increased. Also lidocaine infusions with dexamethasone and supraorbitalis blockades were unsuccessful, and a ganglionic local opioid analgesia (GLOA) was anatomically not feasible. Therefore, 8 weeks after the onset of the disease, treatment with capsaicin 8% for 60 min on the face was performed. After only one week, 20-30% pain relief was achieved, sometimes even freedom from pain. Six weeks after application, the average pain during the day was only NRS 3/10 despite a considerable reduction in oral medication. Three months after the second treatment, the patient was almost pain-free during the day. Topical capsaicin 8% patch is, in our opinion, also safe and successful to use on the face with appropriate experience of the user.

Effects of High-Dose Capsaicin on TMD Subjects: A Randomized Clinical Study

Temporomandibular joint disorder (TMD) is a complex musculoskeletal disorder that presents with pain, limited jaw opening, and abnormal noises in the temporomandibular joint. Despite the significant impact that TMD has in terms of suffering and financial burden, relatively few new treatments have emerged; therefore, development of novel treatments to treat TMD pain remains a high priority. The rationale of this study was to use a double-blind, vehicle-controlled clinical trial to evaluate the effects of a high-concentration (8%) capsaicin cream on TMD. This is based on the hypothesis that targeting TRP vanilloid subfamily member 1 (TRPV1) for pain control may provide a novel method for pain relief in TMD patients. TRPV1 is primarily expressed on a population of nociceptive-specific neurons and provides a candidate target for the development of pain treatments. Capsaicin is the primary agonist for TRPV1 and has been used previously in relatively low doses (0.025% to 0.075%) as a therapeutic for a variety of pain disorders, including postherpetic neuralgia and osteoarthritis; however, analgesic efficacy remains equivocal. TMD and healthy control subjects were assigned to either an active capsaicin or vehicle control group. The treatments were applied for 2 h and then removed. Quantitative sensory testing (QST) was completed prior to drug application (baseline), 2 h after drug application, and 1 wk later. Perceived pain intensity was measured using a visual analog scale (VAS) following capsaicin or vehicle cream application. Significantly lower pain was reported in the week after application in the capsaicin-treated TMD subjects. For QST measures, there was a decreased thermal pain threshold 2 h after capsaicin application for both the control and TMD groups, but this resolved within a week. Capsaicin had no effect on pressure pain threshold or mechanical sensitivity in both TMD and healthy individuals. This study demonstrates that 8% topical capsaicin therapy is a relatively safe, simple, and effective treatment for patients with TMD. Knowledge Transfer Statement: This study evaluated a novel topical capsaicin therapy for reducing orofacial pain. The results of this study can be used to provide another treatment option for patients with TMD.