Onychomycosis: strategies to improve efficacy and reduce recurrence

Updated Perspectives on the Diagnosis and Management of Onychomycosis

Onychomycosis is the most common nail disease encountered in clinical practice and can cause pain, difficulty with ambulation, and psycho-social problems. A thorough history and physical examination, including dermoscopy, should be performed for each patient presenting with nail findings suggestive of onychomycosis. Several approaches are available for definitive diagnostic testing, including potassium hydroxide and microscopy, fungal culture, histopathology, polymerase chain reaction, or a combination of techniques. Confirmatory testing should be performed for each patient prior to initiating any antifungal therapies. There are several different therapeutic options available, including oral and topical medications as well as device-based treatments. Oral antifungals are generally recommended for moderate to severe onychomycosis and have higher cure rates, while topical antifungals are recommended for mild to moderate disease and have more favorable safety profiles. Oral terbinafine, itraconazole, and griseofulvin and topical ciclopirox 8% nail lacquer, efinaconazole 10% solution, and tavaborole 5% solution are approved by the Food and Drug Administration for treatment of onychomycosis in the United States and amorolfine 5% nail lacquer is approved in Europe. Laser treatment is approved in the United States for temporary increases in clear nail, but clinical results are suboptimal. Oral fluconazole is not approved in the United States for onychomycosis treatment, but is frequently used off-label with good efficacy. Several novel oral, topical, and over-the-counter therapies are currently under investigation. Physicians should consider the disease severity, infecting pathogen, medication safety, efficacy and cost, and patient age, comorbidities, medication history, and likelihood of compliance when determining management plans. Onychomycosis is a chronic disease with high recurrence rates and patients should be counseled on an appropriate plan to minimize recurrence risk following effective antifungal therapy.

Dermatophytomas: Clinical Overview and Treatment

Dermatophytomas are characterized as a hyperkeratotic fungal mass in the subungual space, showing as dense white or yellow, typically in longitudinal streaks or patches. Masses can be visualized by traditional microscopy or histology. Newer technologies such as dermoscopy and optical coherence tomography also provide visual features for dermatophytoma diagnosis. The density of fungal mass, and lack of adherence to the nail structures, as well as possible biofilm development, may play a role in the reduction in drug penetration and subsequent lack of efficacy with traditional oral therapies such as terbinafine and itraconazole. A combination of drug treatment with mechanical or chemical debridement/avulsion has been recommended to increase efficacy. The topical antifungal solutions such as tavaborole, efinaconazole, and luliconazole may reach the dermatophytoma by both the transungual and subungual routes, due to low affinity for keratin and low surface tension. Current data indicates these topicals may provide efficacy for dermatophytoma treatment without debridement/avulsion. Similarly, fosravuconazole (F-RVCZ) has an improved pharmacological profile versus ravuconazole and may be an improved treatment option versus traditional oral therapies. The availability of improved treatments for dermatophytomas is crucial, as resistance to traditional therapies is on the increase.

Onychomycosis in children - review on treatment and management strategies

BACKGROUND

Onychomycosis is an uncommon condition in children with increasing global prevalence. Health practitioners should confirm the diagnosis through mycology examination and examine family members of affected individuals for onychomycosis and tinea pedis.

OBJECTIVE

To comprehensively summarize the treatment and management strategies for pediatric onychomycosis.

METHODS

We performed a comprehensive literature search in the PubMed database to identify clinical studies on treatment for mycologically-confirmed dermatophyte onychomycosis in children <18 years. The exclusion criteria were combination therapy, case reports, reviews, systematic reviews and duplicate studies.

RESULTS

Per-weight dosing regimens of systemic antifungal agents such as terbinafine, itraconazole, and fluconazole are found to be safe in children and are used off-label for the treatment of pediatric onychomycosis with high efficacy. Topical antifungal agents such as ciclopirox, efinaconazole, and tavaborole have established safety and efficacy in children. Children respond better than adults to topical therapy due to their thinner, faster growing nails. There is no data on the efficacy of medical devices for onychomycosis in children.

CONCLUSION

Efinaconazole topical solution 10% and tavaborole topical solution 5% are FDA approved for the treatment of onychomycosis in children ≥6 years; ciclopirox topical solution 8% nail lacquer is approved in children ≥12 years.

Fusarium: The versatile pathogen

Fusarium is an emerging human opportunistic pathogen of growing importance, especially among immunosuppressed haematology patients due to an increased incidence of disseminated infections over the past two decades. This trend is expected only to continue due to the advances in medical and surgical technologies that will prolong the lives of the severely ill, making these patients susceptible to rare opportunistic infections. Production of mycotoxins, enzymes such as proteases, angio-invasive property and an intrinsically resistant nature, makes this genus very difficult to treat. Fusarium is frequently isolated from the cornea and less commonly from nail, skin, blood, tissue, Continuous Ambulatory Peritoneal Dialysis (CAPD) fluid, urine and pleural fluid. Conventional microscopy establishes the genus, but accurate speciation requires multilocus sequence typing with housekeeping genes such as internal transcribed spacer, translation elongation factor-1α and RPB1 and 2 (largest and second largest subunits of RNA polymerase), for which expansive internet databases exist. Identifying pathogenic species is of epidemiological significance, and the treatment includes immune reconstitution by granulocyte-colony-stimulating factor, granulocyte macrophage-colony-stimulating factor and a combination of the most active species - specific antifungals, typically liposomal amphotericin-B and voriconazole. However, patient outcome is difficult to predict even with in vitro susceptibility with these drugs. Therefore, prevention methods and antifungal prophylaxis have to be taken seriously for these vulnerable patients by vigilant healthcare workers. The current available literature on PubMed and Google Scholar using search terms 'Fusarium', 'opportunistic invasive fungi' and 'invasive fusariosis' was summarised for this review.

Onychomycosis: Treatment and prevention of recurrence

Onychomycosis is a fungal nail infection caused by dermatophytes, nondermatophytes, and yeast, and is the most common nail disorder seen in clinical practice. It is an important problem because it may cause local pain, paresthesias, difficulties performing activities of daily living, and impair social interactions. The epidemiology, risk factors, and clinical presentation and diagnosis of onychomycosis were discussed in the first article in this continuing medical education series. In this article, we review the prognosis and response to onychomycosis treatment, medications for onychomycosis that have been approved by the US Food and Drug Administration, and off-label therapies and devices. Methods to prevent onychomycosis recurrences and emerging therapies are also described.

Trends in the utilization of, spending on, and prices for outpatient antifungal agents in US Medicaid programs: 1991-2009

BACKGROUND

The incidence of invasive fungal infections (IFIs) has increased substantially in the recent past. Advances in medical technology, including broad-spectrum antibiotics, may increase the risk for fungal infections. Moreover, immunocompromised patients with cancer, HIV/AIDS, and/or transplants are susceptible to IFIs. Meanwhile, superficial fungal infections (SFIs) are common and can be difficult to cure.

OBJECTIVE

To provide a historical perspective on a dynamic market with expensive medications, this study describes trends in the utilization of, spending on, and average per-prescription spending on outpatient antifungal medications individually, in classes (for IFIs or SFIs), and overall, by the US Medicaid programs from 1991 to 2009.

METHODS

The publicly available Medicaid State Drug Utilization Data, maintained by the Centers for Medicare & Medicaid Services, were used. Annual prescription counts and reimbursement amounts were calculated for each of the antifungals reimbursed by Medicaid. Average per-prescription spending as a proxy for drug price was calculated by dividing reimbursement by the number of prescriptions.

RESULTS

Overall utilization for Medicaid beneficiaries remained steady, with 4.56 million prescriptions in 1991 and 4.51 million in 2009. Expenditures rose from $93.87 million to $143.76 million (in current-year US$) over the same time period. The drop in the utilization of first-generation azoles over the last 5 years of the study period can be explained in part by the movement of dual-eligibles from Medicaid to Medicare Part D and in part to a rise in fungal infections better treated with second-generation azoles or echinocandins. Whereas the average per-prescription price for generic (oral) fluconazole was $8 in 2009, the price per prescription of branded (intravenous) voriconazole was $2178.

CONCLUSIONS

Overall spending by Medicaid on outpatient antifungal medications increased more slowly than did the growth of the Medicaid programs from 1991 to 2009. However, the utilization of antifungal agents for IFIs increased almost 10-fold over this period, far outpacing the rise in the number of Medicaid beneficiaries.

What is a combination treatment and how it may be used in onychomycosis

Combination treatment of onychomycosis is based on supplementation of systemic antifungal therapy with different topical techniques, which now include antifungal nail lacquers. Controversies in establishing potential and efficacy of combination treatment in onychomycosis may be overcome by rational administration of any treatment modality after careful evaluation of both the disease and the patient. Application of antifungal nail varnishes such as 8% ciclopirox offers several benefits in treating onychomycosis. With improved efficacy and safety, onychomycosis combination therapy appears to be less expensive and more reliable in terms of reduced rates of relapse and re-infection. Russian and international clinical trials and studies with ciclopirox nail lacquer have revealed the indications and proved the high effectiveness of certain algorithms of combination treatment.

Fifth toenail clinical response to systemic antifungal therapy is not a marker of successful therapy for other toenails with onychomycosis

BACKGROUND

Onychodystrophy is a major manifestation of onychomycosis. However, nail trauma may also result in onychodystrophy. The fifth toenail, due to its location, suffers repeated friction/pressure trauma from shoes.

OBJECTIVE

To test the hypothesis that treatment failure of fifth toenail onychomycosis is not a marker of treatment failure of other toenails with onychomycosis.

METHODS

Fifty patients who had fifth toenail deformity (with or without onychomycosis) and onychomycosis of the other toenails were treated with oral terbinafine, 250 mg/day, for 4 months.

RESULTS

Forty-three patients completed the study. Before the study, 26/43 (61%) had callus lateral to the fifth toe (suggesting mechanical pressure in that area). Twenty-one/43 (49%) of the fifth toenails had onychomycosis. At the end of the treatment period, only 4/21 (19%) of the fifth toenails (with initial onychomycosis), compared with 12/21 (57%) of the other toenails, were completely cured (CC). Out of the whole group (n=43), the clinical cure rate of the fifth toenail was 4/43 (9%) and for the other toenails, 20/43 (47%) (P<0.05). The mycological cure rates were 11/21 (52%) for the fifth toenail and 25/43 (58%) for the other toenails. Callus lateral to the fifth toe was associated with a poor clinical result (P<0.01).

CONCLUSIONS

Clinical improvement of the fifth toenail after systemic antifungal therapy is less favourable and does not correspond with the clinical cure of the other toenails, mostly because of mechanical factors. Therefore, patients should be told to adjust their expectations as to the visual results of their antifungal treatment.

Onychomycosis: beyond cosmetic distress

Onychomycosis, or fungal infection of the nail, is the most common nail disease affecting children (although to a lesser extent) as well as adults. The distress it provokes is not only of a cosmetic kind; it may impair the quality of life. The different clinical types of onychomycosis should be differentiated from similar-looking nail diseases. As far as therapy is concerned, the appearance of new antifungal drugs in the 1990s makes our job easier, but it does not allow us to cure 100% of the patients. Relapses still exist. The aim of this article is to help dermatologists achieve a tailor-made treatment for their patients. The clinical type, the compulsory mycological investigations, the age of the patient, his medical history (drug intake), as well as the use of nail cosmetics, must be considered.

Literature review. Onychomycosis

Onychomycoses have been divided into several categories depending on the site of nail penetration by the fungus. However, not all cases entirely fit with this classification, such as potentially the deep spread of superficial fungi, suggesting alternative penetration routes. A recent European study showed that the prevalence of onychomycosis may be as high as 26.9%. The main causative agent varies according to climate; dermatophyte infections are common worldwide (70% in Europe). Mycological examination is currently the preferred diagnostic method, despite a false-negative rate of 30%. A clinical diagnostic aid that can be used alongside mycological tests is currently being developed. Newer diagnostic approaches include calcofluor, which stains fungi in nails, and molecular genetic techniques for species recognition (e.g. RFLP). Restriction fragment length polymorphism (RFLP) can also distinguish between failed treatment and reinfection. Onychomycosis can be treated with numerous oral and topical agents alone or in combination. In some studies, combination therapy appears more effective than monotherapy.

Pulse versus continuous terbinafine for onychomycosis: A randomized, double-blind, controlled trial

BACKGROUND

Effective treatments for onychomycosis are expensive. Previous studies suggest that less costly, pulsed doses of antifungal medications may be as effective as standard, continuous doses. Terbinafine is the current treatment of choice for toenail onychomycosis.

OBJECTIVE

Our purpose was to determine whether pulse-dose terbinafine is as effective as standard continuous-dose terbinafine for treatment of toenail onychomycosis.

METHODS

We conducted a double-blind, randomized, noninferiority, clinical intervention trial in the Minneapolis Veterans Affairs Medical Center. The main inclusion criteria for participants were a positive dermatophyte culture and at least 25% distal subungual clinical involvement. Six hundred eighteen volunteers were screened; 306 were randomized. Terbinafine, 250 mg daily for 3 months (continuous) or terbinafine, 500 mg daily for 1 week per month for 3 months (pulse) was administered. The primary outcome measure was mycological cure of the target toenail at 18 months. Secondary outcome measures included clinical cure and complete (clinical plus mycological) cure of the target toenail and complete cure of all 10 toenails.

RESULTS

Results of an intent-to-treat analysis did not meet the prespecified criterion for noninferiority but did demonstrate the superiority of continuous-dose terbinafine for: mycological cure of the target toenail (70.9% [105/148] vs 58.7% [84/143]; P =.03, relative risk [RR] of 1.21 [95% confidence interval (CI), 1.02-1.43]); clinical cure of the target toenail (44.6% [66/148] vs 29.3% [42/143]; P =.007, RR =1.52 [95% CI, 1.11-2.07); complete cure of the target toenail (40.5% [60/148] vs 28.0% [40/143]; P =.02, RR=1.45 [95% CI, 1.04-2.01); and complete cure of all 10 toenails (25.2% [36/143] vs 14.7% [21/143]; P =.03, RR =1.71 [95% CI, 1.05-2.79). Tolerability of the regimens did not differ significantly between the groups (chi2 =1.63; P =.65).

LIMITATIONS

The study population primarily consisted of older men with severe onychomycosis.

CONCLUSIONS

This study demonstrated the superiority of continuous- over pulse-dose terbinafine. We also found this expensive therapy to be much less effective than previously believed, particularly for achieving complete cure of all 10 toenails.

Treatment options - development of consensus guidelines

BACKGROUND

There are currently three main treatment strategies for onychomycosis: topical, oral and combination. Amorolfine nail lacquer appears to be the most effective form of topical monotherapy. However, the best mycological and clinical cure rates are obtained with combination therapy. Combination therapy increases antifungal spectrum, fungicidal activity and safety. New antifungals (triazoles and echinocandins) were recently developed, enabling new protocols.

OBJECTIVES

To review available therapies. To design an algorithm for the management of onychomycoses in daily practice.

RESULTS

Therapeutic choice should be based on numerous factors including patient's age and health, aetiology, extent of involvement and clinical form. The consensus was that topical monotherapy is recommended when < 50% of the nail is affected without matrix area involvement. Oral monotherapy or combination therapy is indicated when > 50% of the nail, including the matrix area, is involved. Topical treatments should not be used alone when topical drug transport is suboptimal (i.e. when dermatophytoma, onycholysis or spikes are present). Chemical or mechanical removal should also be considered whenever applicable (interruption of drug transport).

CONCLUSION

In conclusion, treatment decision-making tools (e.g. an illustrated booklet or CD-ROM presenting each type of onychomycosis and criteria to be considered before selecting treatment regimen) would be valuable supports for the successful treatment of onychomycoses.

Pharmacotherapy of onychomycosis

Fungal infections of the nails are frequent in some segments of the population. Dermatophytes, yeasts and moulds are potential pathogens. A series of antifungal treatments are available to the clinician, differing by both their mechanistic nature and mode of administration. The pharmacodynamic and pharmacokinetic properties of each antifungal agent are distinct. This review focuses on the characteristics of amorolfine, bifonazole, ciclopirox, fluconazole, griseofulvin, itraconazole, ketoconazole, ravuconazole, R126638 and terbinafine. Single drug treatments and combined therapies are presented. None of the current drug regimens have demonstrated reliable efficacy against all cases of onychomycosis. Treatment failures, relapses and reinfections remain stubborn problems in the management of onychomycosis.