Analgesic effect of topical oral capsaicin gel in burning mouth syndrome

Effect of repeated topical capsaicin gel administration on oral thermal quantitative sensory testing: A two-arm longitudinal study

OBJECTIVES

Few studies used thermal quantitative sensory testing to assess the effects of repeated capsaicin gel administration in the oral cavity. This study aimed to investigate thermal sensory and pain thresholds before and after repeated capsaicin gel administration.

SUBJECTS AND METHODS

Ten healthy females (22 ± 2 years) applied a capsaicin gel on the gingival mucosa twice daily for 14 days, and heat pain threshold, warm detection threshold, cold pain threshold, and cold detection threshold were assessed on the oral mucosa. Measurements were performed before and after the 14 days and were compared to a control sample (n = 10, all females, 23 ± 3 years).

RESULTS

Capsaicin increased heat pain threshold in the anterior maxilla by 2.9°C (95% CI: 1.6-4.2) (p < 0.001) and in the anterior mandible by 2.2°C (95% CI: 1.0-3.4) (p = 0.001), similar to warm detection threshold that increased by Δ1.1°C (95% CI: 0.3-1.9) (p = 0.009). No significant changes were found in the controls.

CONCLUSIONS

These findings encourage the use of thermal quantitative sensory testing in the oral cavity to assess thermal sensation, which might be useful for assessing the effects of therapies aimed at reducing pain.

Time-course of pain and salivary opiorphin release in response to oral capsaicin differ in burning mouth syndrome patients, temporomandibular disorders patients and control subjects

OBJECTIVES

Opiorphin is an analgesic peptide released by salivary glands and capsaicin an agonist of TRPV1 receptors eliciting burning sensations. The primary objective of this study was to assess opiorphin release after stimulation of the tongue by capsaicin (STC). The secondary objectives were to compare opiorphin release after STC in 3 groups of subjects [healthy (CTRL), Burning Mouth Syndrome (BMS), painful Temporomandibular disorders (TMDp)] and pain evoked by STC in these 3 groups.

MATERIALS AND METHODS

Salivary opiorphin was assessed with high-performance liquid chromatography at 3 different time points (baseline, after 5 min and 20 min of STC). Pain was self-reported on a (0-10) numeric rating scale.

RESULTS

Three groups (N = 16) of adults were recruited at the Clinical Hospital Centre and School of Dental Medicine in Zagreb. Opiorphin levels were higher (1) in TMDp compared to CTRL in 1st (2.23 ± 1.72 pg/ul vs. 0.67 ± 0.44 pg/ul, p = 0.002) and 3rd sampling (2.44 ± 2.01 pg/ul vs. 0.74 ± 0.52 pg/ul, p = 0.020) and (2) within BMS group at 3rd sampling vs. baseline (p < 0.025). Pain scores were higher in BMS compared to TMDp (p < 0.025) and CTRL (p < 0.025).

CONCLUSION

This study evidenced (1) a differential basal amount of opiorphin in two pain conditions and control subjects (2) a differential kinetic of release of opiorphin after STC in CTRL, BMS and TMDp (3) a differential pain perception after STC in BMS and TMDp vs. CTRL, which can provide a readout for animal models.

CLINICAL RELEVANCE

The specific regulation of opiorphin release in patients with orofacial painful conditions provides valuable insights for clinicians and researchers in physiology and pathology and encourages further research in this area.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04694274. Registered on 01/05/2021.

Photobiomodulation alleviates Burning Mouth Syndrome pain: Immediate and weekly outcomes explored

Burning Mouth Syndrome (BMS) is an intraoral chronic burning or dysesthetic sensation, without clinically evident causative lesions on clinical examination and investigation.

AIM

To assess immediate and weekly effects of photobiomodulation (PBM) on BMS patients.

METHODS

Thirty BMS patients were treated intra-orally with photobiomodulation 940(±10) nm (InGaAsP) 3 W, semi-conductor diode, weekly, for up to 10 weeks. Pain intensity, measured using the Visual Analogue Scale (VAS), and characteristics were recorded immidiately after each treatment, along with a weekly average VAS.

RESULTS

Immediate mean VAS score decreased from a starting score of 7.80 ± 1.83 to 2.07 ± 2.55 (p < 0.001). The mean weekly VAS score for the week after the final treatment session was higher (5.73 ± 2.80, p < 0.001) than the immediate response, but still significantly lower than the starting score (p = 0.017). We observed a trend of pain improvement with more treatments, but this was only statistically significant up to the third treatment. Male gender and unilateral pain correlated with better PBM efficacy (p = 0.017, 0.022, respectively).

CONCLUSION

PBM provides significant immediate pain relief for BMS patients after each treatment; however, the efficacy decreases notably over the following week. A trend of increasing pain relief across treatments was observed, statistically significant up to the third treatment.

Diagnosis and treatment of taste disorders in Japan

Though 270,000 patients with complaints of taste abnormalities visited medical institutions annually in 2019 survey, there are no drugs for the treatment of taste disorders that are covered by health insurance in Japan. In the survey, the number of patients with taste disorders was correlated with age, and the need for medical treatment for taste disorders is expected to increase in the future because of the super-aging society. The pathophysiology of taste disorders varies widely. There is an obvious need to decide the site and the causes of the disorder and understand the mechanism, by performing various examinations. It needs to first adjust the causative systemic diseases and medications in the treatment for taste disorder. Damage of taste cells due to zinc deficiency is the main pathophysiological mechanism of taste disorders, and zinc supplementation is a standard treatment in Japan. Oral zinc therapy is the treatment for taste disorders due to zinc deficiency or idiopathic taste disorder; though a double-blind study was conducted, it was considered low-level evidence in a clinical review. In Japan, the off-label use of polaprezinc for taste disorders was approved in 2011, and zinc acetate hydrate was approved for hypozincemia in March 2017, making it easier to use oral zinc therapy in general. In some cases, psychotherapy or herbal medicine therapy has been used with remarkable success, although its effectiveness has not been clearly tested. It might be expected to offer some help to patients. In the treatment of elderly patients with taste disorders, physicians need to consider the difference between "age-related changes in taste in healthy people" and "taste disorders in elderly persons", and they should separate them. Aggressive treatment is desirable regardless of age, because no significant difference in the efficacy of various treatments was found between patients older and younger than 65 years.

Capsaicin: A Potential Treatment to Improve Cerebrovascular Function and Cognition in Obesity and Ageing

Impaired cognition is the primary symptom of dementia, which can lead to functional disability and reduced quality of life among an increasingly ageing population. Ageing is associated with increased oxidative stress, chronic low-grade systemic inflammation, and endothelial dysfunction, which reduces cerebrovascular function leading to cognitive decline. Chronic low-grade systemic inflammatory conditions, such as obesity, exacerbate this decline beyond normal ageing and predispose individuals to neurodegenerative diseases, such as dementia. Capsaicin, the major pungent molecule of chilli, has recently demonstrated improvements in cognition in animal models via activation of the transient receptor potential vanilloid channel 1 (TRPV1). Capsaicin-induced TRPV1 activation reduces adiposity, chronic low-grade systemic inflammation, and oxidative stress, as well as improves endothelial function, all of which are associated with cerebrovascular function and cognition. This review examines the current literature on capsaicin and Capsimax, a capsaicin supplement associated with reduced gastrointestinal irritation compared to capsaicin. Acute and chronic capsaicin treatment can improve cognition in animals. However, studies adequately assessing the effects of capsaicin on cerebrovascular function, and cognition in humans do not exist. Capsimax may be a potentially safe therapeutic intervention for future clinical trials testing the effects of capsaicin on cerebrovascular function and cognition.

WWOM VII: Effectiveness of systemic pharmacotherapeutic interventions in the management of BMS: A systematic review and meta-analysis

OBJECTIVES

To determine the effectiveness of systemic pharmacotherapeutic interventions compared to placebo in burning mouth syndrome (BMS) randomized controlled trials (RCTs) based on the core outcome domains recommended by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT).

METHODS

A systematic literature review of RCTs, concerning systemic pharmacotherapeutic interventions for BMS, published from January 1994 through October 2019, and meta-analysis was performed.

RESULTS

Fourteen RCTs (n = 734 participants) were included. Of those, nine were eligible for the quantitative assessment due to the availability/homogeneity of data for at least one of the IMMPACT domains. Pain intensity was the only domain reported in all RCTs. Weighted mean changes in pain intensity, based on visual analogue scale (ΔVAS), were reported in three RCTs at 6 ± 2 weeks and only one RCT at 10+ weeks follow-ups. Quantitative assessment, based on ΔVAS, yielded very low evidence for the effectiveness of alpha-lipoic acid and clonazepam, low evidence for effectiveness of trazodone and melatonin, and moderate evidence for herbal compounds.

CONCLUSIONS

Based on the RCTs studied, variable levels of evidence exist that suggest that select pharmacological interventions are associated with improved symptoms. However, the underreporting of IMMPACT domains in BMS RCTs restricts the multidimensional assessment of systemic interventions outcomes. Standardized outcome measures need to be applied to future RCTs to improve understanding of intervention outcomes.

Treatments for Burning Mouth Syndrome: A Network Meta-analysis

The aim of this systematic review and network meta-analysis (NMA) of randomized controlled trials was to evaluate the effectiveness of treatments for pain relief of burning mouth syndrome (BMS). Five databases and gray literature were searched. Independent reviewers selected studies, extracted data, and assessed the risk of bias. The primary outcome was pain relief or burning sensation, and the secondary outcomes were side effects, quality of life, salivary flow, and TNF-α and interleukin 6 levels. Four comparable interventions were grouped into different network geometries to ensure the transitivity assumption for pain: photobiomodulation therapy, alpha-lipoic acid, phytotherapics, and anxiolytics/antidepressants. Mean difference (MD) and 95% CI were calculated for continuous outcomes. The minimal important difference to consider a therapy beneficial against placebo was an MD of at least -1 for relief of pain. To interpret the results, the GRADE approach for NMA was used with a minimally contextualized framework and the magnitude of the effect. Forty-four trials were included (24 in the NMA). The anxiolytic (clonazepam) probably reduces the pain of BMS when compared with placebo (MD, -1.88; 95% CI, -2.61 to -1.16; moderate certainty). Photobiomodulation therapy (MD, -1.90; 95% CI, -3.58 to -0.21) and pregabalin (MD, -2.40; 95% CI, -3.49 to -1.32) achieved the minimal important difference of a beneficial effect with low or very low certainty. Among all tested treatments, only clonazepam is likely to reduce the pain of BMS when compared with placebo. The majority of the other treatments had low and very low certainty, mainly due to imprecision, indirectness, and intransitivity. More randomized controlled trials comparing treatments against placebo are encouraged to confirm the evidence and test possible alternative treatments (PROSPERO CRD42021255039).

Design, Formulation, and Evaluation of Aloe vera Gel-Based Capsaicin Transemulgel for Osteoarthritis

Topical treatments are a potential therapeutic option for the therapy of osteoarthritis, with significant data supporting the effectiveness and safety of topical formulation. Topical gel formulations may offer an alternative to oral formulations to relieve osteoarthritis (OA) pain while decreasing systemic exposure. Topical capsaicin transemulgel may represent an effective and safe alternative. The transemulgel was prepared from aqueous Aloe vera gel and Carbopol 934 with capsaicin in clove oil emulsion. The optimized transemulgel of capsaicin showed a pH of 6.1 ± 0.1 and viscosity of 15263–998 cps. Data from in vitro diffusion demonstrated improved permeability properties. The formulation caused no skin irritation when applied topically. The optimal transemulgel spreadability was found to be 20.23 g·cm/s. In vitro and ex vivo studies of the optimized formulation were performed. The skin irritant test was performed on rat skin with an optimized and marketed formulation. Both showed no irritation on the skin. The transemulgel of the capsaicin with Aloe vera gel was proven to be effective for osteoarthritis therapy.

Comparison of Clonazepam and Tongue Protector in the Treatment of Burning Mouth Syndrome

Background: BMS is a chronic pain syndrome affecting the oral mucosa. It consists of experiencing a burning or dysesthetic sensation. BMS prevalence varies, with up to 15% among women. An effective treatment is still unattainable. Material and Methods: A total of 60 patients with BMS qualified for a randomised trial, divided in two groups: the clonazepam-treated and tongue protector group. Treatment was provided for 4 weeks in both groups. In the former, the oral dosage of clonazepam 0.5 mg; in the latter, a tongue protector was used. Clinical oral examination was performed, and the presence of taste disorder and pain intensity, on the visual analogues scale, were recorded. Psychological domains were explored with the Beck depression inventory (depression), Athens insomnia scale (insomnia), Eyesenck personality questionnaire-revised (personality traits), and WHO quality of life questionnaire (quality of life). Results: Complete recovery was observed in three patients after clonazepam and one patient after tongue guard treatment. A greater improvement in the VAS scores, from baseline to the control values, was demonstrated in the clonazepam group, and it was statistically significant. In women, the level of depression significantly correlated with all domains of quality of life. Conclusions: BMS is an ongoing multi-specialist challenge. The development of new pathophysiological concepts of BMS offers hope for more effective treatment. Considering the influence of BMS on the quality of life and mental disorders in most patients, further research on the possibilities of therapy seems to be very important.

Burning mouth syndrome: a review of therapeutic approach

Burning mouth syndrome (BMS) is described by an intense burning sensation of the tongue or other oral areas without a clear etiopathology. The diagnosis of BMS is challenging due to variations of manifestations. The management of BMS is complicated due to the complex etiology of the disease. Many medications and treatment methods have been recommended for BMS management, but no one confirmed as the standard method. In this study, the therapeutic approaches of BMS were evaluated. The data of the article was obtained from PubMed/MEDLINE, Cochrane Library, and Web of Science. The following terms including "burning mouth syndrome", "therapy", and "treatment" were used for search in the databases. A wide range of articles about the therapeutic approach of BMS was searched and reviewed. Pharmacological and non-pharmacological approaches have been used for BMS management. Pharmacological treatments are including Capsaicin, Clonazepam, Low-dose aripiprazole, Alpha-lipoic acid, Duloxetine, Amitriptyline, Gabapentin, and Pregabalin, and ultra-micronized palmitoylethanolamide. Non-pharmacological therapies for BMS are cognitive therapy, Electroconvulsive therapy, Laser therapy, Acupuncture and auriculotherapy, Transcranial Magnetic Stimulation (rTMS), Salivary Mechanical Stimulation, and Botulinum Toxin. A detailed assessment of the etiology and pathophysiology of BMS, and having information about novel therapeutic interventions are essential for the management of BMS.

Formulation design and mechanism study of hydrogel based on computational pharmaceutics theories

Formulation design and mechanism study of the drug delivery system (DDS) is an important but difficult subject in pharmaceutical research. The study of formulation factors is the most time- and labor-consuming work of formulation design. In this paper, a multiscale computational pharmaceutics strategy was developed to guide the systematic study of formulation factors of a typical polymer-based DDS, hydrogel, and further to guide the formulation design. According to the strategy, the combination of solubility parameter (δ) and diffusion coefficient (D) calculated by the AA-MD simulation was suggested as the general evaluation method for the matrix screening of the hydrogels at the pre-formulation stage. At the formulation design stage, the CG-MD simulation method was suggested to predict the morphology and drug-releasing behavior of the hydrogels under different formulation factors. The influence mechanism can be explained by the combination of multiple parameters, such as the microstructure diagram, the radius of gyration (Rg), the radial distribution function (RDF), and the free diffusion volume (V_diffusion). The simulation results are in good agreement with the in vitro release experiment, indicating that the strategy has good applicability.

Neuropathic and Psychogenic Components of Burning Mouth Syndrome: A Systematic Review

The pathophysiology of primary burning mouth syndrome (BMS) has been extensively debated but is poorly understood despite a large number of hypotheses attempting to explain its etiopathogenic mechanisms. The aim of the present work was to systematically review papers that could provide arguments in favour of the neuropathic and psychogenic components of primary BMS for a better understanding of the disease. This systematic review (SR) was registered in PROSPERO (CRD42021224160). The search was limited to articles in English or French from 1990 to 01 December 2020. A total of 113 articles were considered for data extraction. We divided them into four subgroups: pharmacological and nonpharmacological management studies (n = 23); neurophysiological studies (n = 35); biohistopathological studies (n = 25); and questionnaire-based studies (n = 30). Several of these studies have shown neuropathic involvement at various levels of the neuraxis in BMS with the contribution of quantitative sensory testing (QST), functional brain imaging, and biohistopathological or pharmacologic studies. On the other hand, the role of psychological factors in BMS has also been the focus of several studies and has shown a link with psychiatric disorders such as anxiety and/or depression symptoms. Depending on the patient, the neuropathic and psychogenic components may exist simultaneously, with a preponderance of one or the other, or exist individually. These two components cannot be dissociated to define BMS. Consequently, BMS may be considered nociplastic pain.

Vitamin B and Zinc Supplements and Capsaicin Oral Rinse Treatment Options for Burning Mouth Syndrome

Background and Objectives: Burning mouth syndrome (BMS) is an enigmatic, idiopathic, chronic, often painful clinical entity, where patients experience oral burning without clear clinical changes on the oral mucosa. There are yet to be well established standardized and validated definitions, diagnostic criteria or classifications for burning mouth syndrome. The aim of this study is to determine whether vitamin B complex and zinc supplements or 0.02% topical capsaicin rinse, can help alleviate BMS pain/burning levels. The objectives: (1) Gather data before and after treatment with vitamin B complex and zinc supplements (2) After the vitamin B complex and zinc protocol gather data before and after treatment with 0.02% topical capsaicin rinse (3) Data analysis and assessment for both treatment methods. Materials and Methods: 89 patients took part in the vitamin B and zinc supplement treatment regimen, out of those 20 patients took part in the capsaicin rinse treatment regimen. Before and after each treatment pain/burning levels were determined using the Visual analogue scale, salivary flow was also determined. Results: Both treatment methods showed statistically significant data in reducing pain/burning levels. There were no statistically significant changes in the salivary flow after any treatment. Conclusion: vitamin B and zinc supplement therapy and topical capsaicin rinse therapy can be an effective way to decrease pain/burning sensation levels in patients with BMS. More research should be conducted to determine the benefit of either vitamin B and zinc supplement therapy or topical capsaicin rinse therapy, so that BMS patients have treatment options, that have as few side-effects as possible.

Neuropathic Pain and Burning Mouth Syndrome: An Overview and Current Update

Burning mouth syndrome/glossodynia and trigeminal neuropathic conditions can have serious negative impact on a patient's overall quality of life. These conditions are often hard to diagnose and even harder to fully treat and manage, but it is important for dentists/oral and maxillofacial surgeons to be aware of these conditions and modalities of their treatment. Often the only method for arriving at the proper diagnosis is for patients to undergo traditional approaches for treatment of presenting signs and symptoms, and it is the unexpected failure of interventional therapies that leads ultimately to a proper diagnosis.

Characterization of burning mouth syndrome profiles based on response to a local anaesthetic lozenge

OBJECTIVE

Burning mouth syndrome (BMS) is a chronic oral pain condition with unknown aetiology but assumed to involve peripheral/central neuropathological and immune-mediated inflammatory factors. We aimed at characterizing inflammatory and neurogenic profiles and oral symptomatology of patients with BMS based on response to a local anaesthetic lozenge.

METHODS

Patients with BMS were divided into an Effect (n = 13), No effect (n = 8) or Unspecified (n = 2) group according to their response to a local anaesthetic lozenge on oral pain. Inflammation was assessed in blood plasma and saliva by analyses of IL-6, IL-8, IL-17A, IL-23 and TNF-α levels. The degree of inflammation and distribution of oestrogen receptor, NGF, NGF-receptor, TRPV-1 and IL-17F in buccal mucosal tissue were investigated by immunohistochemistry.

RESULTS

Immunoreactivity to the oestrogen receptor was most intense in the Effect group, whereas the No effect group tended to have higher plasma levels of the pro-inflammatory cytokines.

CONCLUSIONS

Our findings indicate that the response to treatment with local anaesthesia enables subgrouping of patients with BMS according to the potential pathogenic mechanisms. Effect of local anaesthesia indicates a peripheral neuropathology involving lack of oestrogen and upregulation of oestrogen receptors, and no effect indicates a systemic inflammation-induced mechanism leading to increased levels of plasma cytokines.

Topical drug therapeutics for neuropathic pain

INTRODUCTION

Neuropathic pain (NP) is a particularly severe and intractable chronic condition that is not well treated by commonly recommended systemic pharmacological therapies, partly due to dose-limiting side effects or adverse events. The use of topical therapeutics for NP is growing and benefits from the reduced potential for adverse effects, as well as the ability to directly target peripheral pathological processes.

AREAS COVERED

The current review defines and describes the limitations of various commonly prescribed systemic pharmacological therapies for NP. It also provides a justification for increased research aimed at developing topical therapeutics for NP, particularly localized and peripheral NP. The review discusses the various classes of topical treatments used for NP, including agents that: block sensory inputs; activate inhibitory systems; provide mechanism-based therapeutics; are used in mucosal tissues; and include combinations that produce multimodal therapeutic effects.

EXPERT OPINION

There are arguments that the current topical therapeutics for NP rely too heavily on the use of local anesthetics and capsaicinoids, and more research is certainly needed on topical therapies that are multimodal and/or are targeted at the peripheral sources of pathology. The potential for novel topical therapeutics may be enhanced by further research on topical co-drugs, drug-drug salts, co-crystals and hydrates, and ionic liquids.