A review of the mechanism of action of lasers and photodynamic therapy for onychomycosis

Long-pulsed 1,064-nm gallium arsenide laser surgical device treatment for improving symptoms of onychomycosis: a comparative analysis

BACKGROUND

Onychomycosis is the most common infective nail disease, and treatment includes topical and systemic antifungal medications. Recently, laser therapy has emerged as a therapeutic option for patients who are unable to take oral antifungal agents. We investigated the effectiveness and safety of a novel long-pulsed 1,064-nm gallium arsenide (GaAs) laser surgical device for onychomycosis.

METHODS

This 24-week single-center, single-blind, active-controlled exploratory clinical study comparatively evaluated the long-pulsed 1,064-nm GaAs laser (Healer1064) with the short-pulsed Nd:YAG laser surgical device in 20 participants randomly assigned to receive either test or control treatment at 4-week intervals during the 12-week treatment period. The rate of clinical improvement was evaluated by two independent dermatologist evaluators using the Onychomycosis Severity Index-score (OSI-score) and Turbidity Scale with standard photographs. Overall improvement and patient satisfaction were evaluated. Safety evaluation included pain intensity and adverse events.

RESULTS

In 44 (test: 25; control: 19) cases in 19 participants who completed treatment, the clinical improvement rate in the test and control groups was 52.00% (13/52 cases) and 44.44% (9/19 cases), respectively, with significantly lower pain scores in the test than the control group for every treatment visit (P < 0.05) and without severe adverse events.

CONCLUSIONS

The novel long-pulsed 1,064-nm GaAs laser showed greater, albeit nonsignificant, clinical improvement and was associated with less pain during treatment. Thus, the Healer1064 can provide satisfactory treatment outcomes through painless and effective improvement in onychomycosis symptoms.

Utility of devices for onychomycosis: a review

Onychomycosis is difficult to treat due to long treatment durations, poor efficacy rates of treatments, high relapse rates, and safety issues when using systemic antifungal agents. Device-based treatments are targeted to specific regions of the nail, have favorable safely profiles, and do not interfere with systemic agents. They may be an effective alternative therapy for onychomycosis especially with increasing reports of squalene epoxidase gene mutations and potential resistance to terbinafine therapy. In this review, we discuss four devices used as antifungal treatments and three devices used as penetration enhancers for topical agents. Lasers, photodynamic therapy, microwaves, and non-thermal plasma have the capacity to inactivate fungal pathogens demonstrated through in vivo studies. Efficacy rates for these devices, however, remain relatively low pointing toward the need to further optimize device or usage parameters. Ultrasound, nail drilling, and iontophoresis aid in improving the permeability of topical agents through the nail and have been investigated as adjunctive therapies. Due to the paucity in clinical data, their efficacy in treating onychomycosis has not yet been established. While the results of clinical studies point toward the potential utility of devices for onychomycosis, further large-scale randomized clinical trials following regulatory guidelines are required to confirm current results.

In vivo Guinea Pig Model Study for Evaluating Antifungal Effect of a Dual-Diode Laser with Wavelengths of 405 Nm and 635 Nm on Dermatophytosis

Background

Various laser- and light-based devices have been introduced as complementary or alternative treatment modalities for dermatophytosis, particularly for finger or toenail onychomycosis.

Objective

This study aimed to comparatively evaluate the antifungal effects of 405-nm and 635-nm dual-band diode lasers using an in vivo guinea pig model of dermatophytosis.

Materials and Methods

A guinea pig model was developed by the repetitive application of fungal spore preparations to the back skin of guinea pigs. Dual-diode laser treatment was delivered to the guinea pig skin at a power of 24 mW at a wavelength of 405 nm and 18 mW at 635 nm for 12 min. The treatments were administered three times weekly for 2 weeks, and a mycological study was performed.

Results

Mycological studies using scraped samples obtained from treatment groups A (N = 8) and B (N = 8) after dual-diode laser treatment revealed that seven of eight (87.5%) samples in each group had negative results for direct potassium hydroxide microscopy and fungal culture studies. Skin specimens from each infected laser-untreated guinea pig exhibited spongiotic psoriasiform epidermis with parakeratosis. Meanwhile, skin specimens from infected laser-treated guinea pigs in groups A and B demonstrated thinner epidermal thickness than those from infected untreated controls but thicker than those from uninfected treated controls without noticeable inflammatory cell infiltration in the dermis.

Conclusion

The guinea pig dermatophytosis model can be used to comparatively evaluate the efficacy and safety of various treatment modalities, including dual-diode lasers, for superficial fungal skin infection.

Medical Aesthetics - Current Trends and a Review of Its Applications

Medical aesthetics is the use of a procedure or product for a therapeutic indication which is conventionally used for aesthetics. Several medical conditions are now being treated with products, procedures or equipment that are conventionally used for aesthetic indications. This has widened the scope of treatment modalities available for dermatologists to treat various indications that fall outside the purview of aesthetic dermatology. The authors present aesthetic treatment modalities and procedures which can be used for medical aesthetics, their present-day status and usefulness in field of therapeutics with a review of published literature from "Medline" (via "PubMed"), "Cochrane," the Virtual Health Library, and Google Scholar.

Response surface methodological approach for optimization of photodynamic therapy of onychomycosis using chlorin e6 loaded nail penetration enhancer vesicles

Antimicrobial photodynamic inactivation (aPDI) has a tremendous potential as an alternative therapeutic modality to conventional antifungals in treatment of onychomycosis, yet the nail barrier properties and the deep-seated nature of fungi within the nails remain challenging. Therefore, the aim of this study was to prepare, optimize, and characterize Chorin e6 (Ce6) nail penetration enhancer containing vesicles (Ce6-nPEVs) and evaluate their photodynamic mediated effect against Trichophyton rubrum (T.rubrum); the main causative agent of onychomycosis. Optimization of the particle size and encapsulation efficiency of nPEVs was performed using a four-factor two-level full factorial design. The transungual delivery potential of the selected formulation was assessed in comparison with the free drug. The photodynamic treatment conditions for T.rubrum aPDI by free Ce6 was optimized using response surface methodology based on Box-Behnken design, and the aPDI effect of the selected Ce6-nPEVs was evaluated versus the free Ce6 at the optimized condition. Results showed that formulations exhibited high encapsulation efficiency for Ce6 ranging from 79.4 to 98%, particle sizes ranging from 225 to 859 nm, positive zeta potential values ranging from +30 to +70 mV, and viscosity ranging from 1.26 to 3.43 cP. The predominant parameters for maximizing the encapsulation efficiency and minimizing the particle size of Ce6-nPEVs were identified. The selected formulation showed 1.8-folds higher nail hydration and 2.3 folds improvement in percentage of Ce6 up-taken by nails compared to the free drug. Results of the microbiological study confirmed the reliability and adequacy of the Box-Behnken model, and delineated Ce6 concentration and incubation time as the significant model terms. Free Ce6 and Ce6-nPEVs showed an equipotent in vitro fungicidal effect on T.rubrum at the optimized conditions, however Ce6-nPEVs is expected to show a differential effect at the in vivo level where the advantage of the enhanced nail penetration feature will be demonstrated.

Photodynamic Therapy for the Treatment of Fungal Infections

Cutaneous fungal infections are common in humans and are associated with significant physical and psychological distress to patients. Although conventional topical and/or oral anti-fungal medications are commonly recommended treatments, drug resistance has emerged as a significant concern in this patient population, and safer, more efficacious, and cost-effective alternatives are warranted. Recent studies have reported effectiveness of photodynamic therapy (PDT) against fungal infections without severe adverse effects. In this review, we briefly discuss the mechanisms underlying PDT, current progress, adverse effects, and limitations of this treatment in the management of superficial and deep fungal infections.

Photodynamic disinfection and its role in controlling infectious diseases

Photodynamic therapy is witnessing a revival of its origins as a response to the rise of multi-drug resistant infections and the shortage of new classes of antibiotics. Photodynamic disinfection (PDDI) of microorganisms is making progresses in preclinical models and in clinical cases, and the perception of its role in the clinical armamentarium for the management of infectious diseases is changing. We review the positioning of PDDI from the perspective of its ability to respond to clinical needs. Emphasis is placed on the pipeline of photosensitizers that proved effective to inactivate biofilms, showed efficacy in animal models of infectious diseases or reached clinical trials. Novel opportunities resulting from the COVID-19 pandemic are briefly discussed. The molecular features of promising photosensitizers are emphasized and contrasted with those of photosensitizers used in the treatment of solid tumors. The development of photosensitizers has been accompanied by the fabrication of a variety of affordable and customizable light sources. We critically discuss the combination between photosensitizer and light source properties that may leverage PDDI and expand its applications to wider markets. The success of PDDI in the management of infectious diseases will ultimately depend on the efficacy of photosensitizers, affordability of the light sources, simplicity of the procedures, and availability of fast and efficient treatments.

Photodynamic therapy in dermatology: Beyond current indications

Photodynamic therapy (PDT) has long been used in dermatology as a therapeutic strategy for several malignant and premalignant conditions. Currently, it is approved in Europe for the treatment of actinic keratosis, squamous cell carcinoma in situ, and some forms of basal cell carcinoma, with favorable clearance rates associated with satisfying aesthetic results. Nonetheless, in the past few years, PDT has also demonstrated efficacy in many other conditions, including inflammatory and infectious dermatoses. These results, probably explained by its immunomodulatory, anti-inflammatory, and bactericidal effects, may lead to an expansion of PDT indications in the upcoming years. In this article, conditions where PDT may be useful are reviewed, thus highlighting the potential of this therapeutic modality for the dermatologist.

Laser-induced fluorescence diagnosis of stomach tumor

The purpose of this study is to demonstrate the capabilities of laser spectral and video fluorescence diagnosis used for stomach tumors using 5-ALA photosensitizer. The spectroscopic method is presented with an example of a characteristic fluorescence spectrum from stomach with 5-ALA and quantitative statistics. The laser excitation wavelength was 632.8 nm. The analysis of the video system is presented with clinical statistics. The penetration depth of 3-4 mm of the He-Ne laser during the spectroscopic study allowed for scanning the mucous and submucous layers of the stomach and for detecting tumorous growths in these layers. Registration of fluorescence using the spectral system enabled surgeons to conduct express estimation of dubious stomach tissues, to make biopsy from doubtful areas to reveal precancer and early cancer states. The video fluorescence analysis with the application of 5-ALA-induced PPIX may be recommended for the use as an express method of diagnosis including early diagnosis of malignant stomach diseases as well as for intraoperative assessment of tumor extension and detection of canceromatous foci during laparoscopy. The optimal time interval for the diagnosis (regardless of the nature of the study - endoscopic, laparoscopic, or intraoperative) is 2-4 h from the administration of photosensitizer. The optimal dose of the photosensitizer is 20 mg per 1 kg of the body weight.

Challenges and Opportunities in the Management of Onychomycosis

Onychomycosis is an increasingly common fungal nail infection, chiefly caused by dermatophyte fungi. The disease is notoriously difficult to treat due to the deep-seated nature of fungi within the nail plate, prolonged treatment requirements, poor patient adherence and frequent recurrences. Given the poor efficacy of currently available topical and systemic therapies, there is a renewed interest in exploring alternative treatment modalities for onychomycosis. Natural therapies, physical treatments and various combination therapies have all shown potential for the management of onychomycosis, though research on many of these methods is still in preliminary stages. Further large, well-designed, randomised controlled trials are necessary to confirm the efficacy of these novel treatments in order to make formal recommendations regarding their use in the management of onychomycosis.