Butenafine hydrochloride (Mentax) cream for the treatment of hyperkeratotic type tinea pedis and its transfer into the horny layer, with or without concomitant application of 20% urea ointment (Keratinamin)

A tandem reduction of primary amines, carbonyl compounds, CO2, and boranes catalyzed by in situ formed frustrated Lewis pairs

A catalytic system combining 2-aminothiazole and borane efficiently catalyzes a four-component tandem reductive coupling of primary amines, carbonyl compounds, boranes, and CO2 (1 atm) and a broad range of functionalized tertiary N-methylamines are synthesized.

Urea-containing topical formulations

Urea is a well-known moisturiser and keratolytic topical agent. As it is widely used in dermatology, several formulations at different concentrations have been marketed: lotions, creams, foams, ointments, gels and lacquers. Availability of different vehicles and concentration may vary in different countries, but in general products at low, medium and high urea concentration are accessible worldwide. The proper formulation should be chosen according to the disorder to treat, its severity, body areas involved and patients' preference.

Clinical evidences of urea at medium concentration

Urea-based topical compounds at medium concentrations (15%-30%) represent useful dermatological agents for their humectant and keratolytic effects by enhancing stratum corneum hydration and by loosening epidermal keratin, respectively. The aim of this paper is to review the clinical evidences of the use of 15%-30% urea as single topical agent. Although limited evidence supports the use of these concentrations of urea in skin disorders characterised by xerosis and hyperkeratosis, in clinical practice they are largely used especially in xerosis of limited skin areas, in which the side effects are tolerable, or hyperkeratosis involving large or more sensitive (eg, face, genital region, etc) areas, in which higher concentration may be irritant. In addition, urea at medium concentrations is used in combination with other substances including topical antifungals as penetration enhancer.

Therapy of Skin, Hair and Nail Fungal Infections

Treatment of superficial fungal infections has come a long way. This has, in part, been through the development and evaluation of new drugs. However, utilising new strategies, such as identifying variation between different species in responsiveness, e.g., in tinea capitis, as well as seeking better ways of ensuring adequate concentrations of drug in the skin or nail, and combining different treatment methods, have played equally important roles in ensuring steady improvements in the results of treatment. Yet there are still areas where we look for improvement, such as better remission and cure rates in fungal nail disease, and the development of effective community treatment programmes to address endemic scalp ringworm.

Miconazole-Urea in a Buccal Film as a New Trend for Treatment of Resistant Mouth Fungal White Patches

A growing concern about Candida albicans is the emergence of high incidence of resistance against antifungal agents, which requires searching for new medications or improving the response to the existing members. The objective of this work was to evaluate the effectiveness of the miconazole in the absence and presence of urea, as a penetration enhancer, against C. albicans. In addition to, formulating both of them in a polymer film to be used topically for treatment of mouth fungal white patches caused by C. albicans. A synergistic effect was recorded between this imidazole and urea against the test strain. Miconazole MIC (32 mg/L) was dramatically reduced to 0.0625 mg/L following combination with urea. Transmission electron microscopy explained the mechanisms of action mediated by the test agents. Minimal fungicidal dose of miconazole combined with urea showed early apoptotic cells with condensed chromatin and small blebs. Cytoplasmic leakage and necrosis in some cells was observed at high fungicidal dose. Buccal bioadhesive films were prepared using increasing values of the drug MIC and urea. The physicochemical characters of the prepared films including; film weight, thickness, swelling index, drug content, folding endurance, surface pH, bioadhesion force and time and drug release kinetics, were studied. Microbiological evaluation of all prepared films showed an increase in the inhibition zone diameters for films containing increasing concentrations of both miconazole and urea in a concentration-dependent manner (30-40 mm) compared to miconazole alone (18 mm). Based on our results, the prepared films are promising for buccal administration of miconazole/urea showing synergistic effect for treatment of C. albicans infection.

Combination treatment of oral terbinafine with topical terbinafine and 10% urea ointment in hyperkeratotic type tinea pedis

Hyperkeratotic-type tinea pedis is chronic and recalcitrant to topical antifungal agents. Some topical antifungal agents are effective; however, long duration of therapy is required, which often reduce the treatment compliance of patients. To seek for short period therapy of hyperkeratotic type tinea pedis, in this study, we observed the efficacy and safety of treatment of topical terbinafine and 10% urea ointment combined oral terbinafine. Participants with hyperkeratotic type tinea pedis were randomly assigned to two groups. Patients in group I were treated with oral terbinafine for 2 weeks and topical terbinafine and 10% urea ointment for 4 weeks, whereas in group II, only the above topical agents were applied for 12 weeks. Clinical improvement rates and fungal eradication rates were compared between the two groups at 24 weeks after the initiation of treatment. The group I had stopped the topical therapy 8 weeks earlier than group II. There were no significant differences in mycological eradication rates and clinical improvement rates between the two groups, besides, no major side effects were noted in both groups. The short combination therapy with oral terbinafine was effective and safe; it should be a valuable option for patients with hyperkeratotic type tinea pedis.

Chiral N-benzyl-N-methyl-1-(naphthalen-1-yl)ethanamines and their in vitro antifungal activity against Cryptococcus neoformans, Trichophyton mentagrophytes and Trichophyton rubrum

In the search for new antifungal compounds and to explore structure activity relationships, a series of 24 chiral benzyl amine type antifungals was synthesised and characterised. In vitro testing against the human pathogen Cryptococcus neoformans revealed that several derivatives had MIC50 values similar to that of the commercial drug Butenafine. All of these contained a bulky group in the para position of the benzyl fragment. Eighteen compounds were also tested for activity against the dermatophytes Trichophyton mentagrophytes and Trichophyton rubrum. Of these (R)-N-(4-tert-butylbenzyl)-N-methyl-1-(naphthalen-1-yl)ethanamine (MIC50: 0.06 μg/mL) and a para-benzyloxy substituted derivative (MIC50: 0.125 μg/mL) possessed high activity. Testing of derivatives with a stereocentre at the benzylic carbon, revealed that (S)-stereochemistry was required for potency: a MIC50 value of 1 μg/mL was obtained for (S)-1-(4-tert-butylphenyl)-N-methyl-N-(naphthalen-1-ylmethyl)ethanamine. Preparation of the corresponding fluoromethyl compound was achieved employing lipase B from Candida antarctica as catalyst in the key step. A low antifungal activity was observed for the fluorinated derivative indicating the importance of the amine basicity for the antifungal potency of these compounds.

A simple and rapid method to assess butenafine hydrochloride in skin samples and a comparative cutaneous retention study of two marketed formulations

A new method for the quantification of butenafine hydrochloride (BTF) present in the main skin layers was validated and a study conducted with the aim of analyzing the penetration and/or the permeation of the drug. The quantification was performed by liquid chromatography. To evaluate the specificity of the method, the influence of the components of the skin was analyzed, as well as the skin in contact with the excipient ingredients. Linearity was assessed with concentrations in the range of 0.1-10 μg/mL (r(2) = 0.9999) and ANOVA showed non-significant linear deviation (p > 0.05). Adequate results were obtained for repeatability, intra-day precision and accuracy. The obtained values for the limit of quantification and the limit of detection were 68.4 and 17.7 ng/mL, respectively. Also, a comparative study of BTF cutaneous penetration through porcine skin was performed applying two different formulations: Tefin, present in the Brazilian market, and Lotrimin Ultra(®) , available in the American market. No statistical difference was found in the skin (epidermis plus dermis) and in the epidermis (p > 0.05), although in the dermis the difference was significant (p < 0.05). During the experimental period (8 h), no drug permeation from either formulation was detected in the receptor fluid.

In vitro sensitivity of dermatophytes to urea

OBJECTIVE

Urea is commonly used as a keratolytic substance in the treatment of onychomycoses to improve the penetration of antifungal drugs in the lesion sites. The aim of the present study was to investigate the inhibitory action of urea on samples of dermatophytes in vitro.

METHOD

Minimum inhibitory concentration of urea was determined for 31 samples of dermatophytes cultured in Sabouraud-dextrose broth containing different concentrations (7.5% up to 40%) of urea. Absence of growth was the criterion adopted to determine the minimum inhibitory concentration.

RESULTS

The majority of samples (87%) were sensitive to urea at 12.5%, or less. 2 isolates of Trichophyton tonsurans and 2 of Trichophyton rubrum required 30%, and 40% urea, respectively, to be completely inhibited.

CONCLUSION

In vitro results demonstrate inhibitory activity of urea on dermatophytes, suggesting that it could be used as an adjuvant in topical treatments.

Topical therapy for fungal infections

Fungi often infect the skin surface and subsequently invade the stratum corneum to avoid being shed from the skin surface by desquamation. Pharmacologic agents applied to the surface of the skin in the form of creams, lotions, or sprays, readily penetrate into the stratum corneum to kill the fungi (fungicidal agents), or at least render them unable to grow or divide (fungistatic agents). Thus, topical therapies work well to rid the skin of topical fungi and yeasts. Azole drugs such as miconazole, clotrimazole, and ketoconazole are fungistatic, limiting fungal growth but depending on epidermal turnover to shed the still-living fungus from the skin surface. Allylamines and benzylamines such as terbinafine, naftifine, and butenafine are fungicidal, actually killing the fungal organisms. Fungicidal drugs are often preferred over fungistatic drugs for treatment of dermatophytic fungal infections, since treatment times as short as one application daily for 1 week are associated with high cure rates. Furthermore, patients often stop treatments when the skin appears healed, usually after about a week of treatment. If this short-term treatment is stopped, fungi recur more often when fungistatic, rather than fungicidal, drugs have been used. Yeast infections such as those caused by Candida albicans respond less well to allylamine drugs. The azole drugs are often preferred for these types of infections. Nail infections are difficult to cure with topical therapies because the infections usually occur under the nail instead of on top of it and products penetrate poorly, if at all, through the nail plate. Infections of hair follicles, nails, and widespread infections often require systemic treatments. Antifungal agents are compounded into many different types of vehicles. Patients often prefer to treat weeping infections with spray formulations. Most physicians prescribe branded products in cream or lotion bases. Cost is a factor dictating prescription choice, especially since most products work well regardless of mechanism of action. Cost becomes especially important when infections involve large areas of the body surface. This article reviews various treatments of cutaneous fungal infections, with special emphasis on cure rates and rationales for choosing particular products.