Topical antifungaldrugs are used to treat fungal infections on the skin, scalp, nails, vagina or inside the mouth. These medications come as creams, gels, lotions, ointments, powders, shampoos, tinctures and sprays. Most antifungal drugs induce fungal cell death by destroying the cell wall of the fungus. These drugs inhibit the production of ergosterol, which is a fundamental component of the fungal cell membrane and wall.
Antifungal drugs are generally classified according to their chemical structures and their corresponding mechanism of actions. The four classes of topical antifungal drugs are azole antifungals, polyene antifungals, allylamine antifungals, and other antifungals. Azole antifungals inhibit the enzyme that converts lanosterol into ergosterol. Common examples of azole antifungals include clotrimazole, econazole, ketoconazole, miconazole, and tioconazole. The only polyene antifungal available topically is nystatin, which works by binding to ergosterol thus disrupting the integrity of the fungal cell membrane. Similar to azoles, allylamines disrupt the fungal cell wall synthesis through inhibition of the squalene epoxidase enzyme that converts squalene into ergosterol. Examples of allylamines antifungals comprise amorolfin, naftifine and terbinafine. The last group consists of antifungal drugs with a different mechanism of action than the other three classes. These drugs include benzoxaborole antifungals, ciclopirox olamine antifungals, thiocarbamate antifungals and undecylenic alkanolamide antifungals. Topical antifungal drugs may come with side effects such as itching and local irritation. They can also interact with food and different medications. Therefore, topical antifungals should be used with caution and with advice from medical professionals.
The general mechanism of action for topical antifungal drugs is the disruption of the cell membrane. The unique components found in fungal cell membranes are usually the drug targets of antifungal drugs, in particular ergosterol. It is a sterol, which is important in maintaining proper membrane fluidity and normal functions of the cell membrane. Ergosterol replaces cholesterol found in the cell membranes of mammalian cells. Antifungal medications that target ergosterol synthesis are selectively toxic to the fungi, hence, killing and stopping the growth of fungi in the body. When ergosterol is damaged, it causes the contents inside the fungal cells to leak out, preventing further reproduction of fungal cells. Lastly, antifungal agents contribute to fungal cell death.[ citation needed ]
Fungal infections are commonly caused by dermatophytes, yeasts or molds. Yeasts are normal inhabitants of our skin but sometimes they grow unheeded which can result in symptomatic infections. Molds are uncommon causes of fungal infections but they can lead to tinea nigra (painless brown or black patches on the skin) or hard-to-treat nail infections. Common examples of fungal infections include Pityriasis capitis (Dandruff). Oral candidiasis (oral thrush), onychomycosis (nail infection), tinea pedis (athlete's foot), Pityriasis Versicolor, tinea capitis, tinea corporis (ringworm), tinea cruris (jock itch) and tinea manuum. Most antifungal agents treat both dermatophyte and yeast infections. However, some, such as nystatin, are not suitable for dermatophyte fungal infections. Therefore, different types of antifungals can selectively remove fungal pathogens from the host with minimum toxicity.[ citation needed ]
Topical antifungals are generally safe to use in adults, seniors and children, Different dosages may be required for patients of different age groups. Discuss with healthcare professionals before the use of topical antifungal agents. [1] [2]
Prior to using topical antifungals, wash the affected area with soap and water and dry it completely, Wash both hands thoroughly after applying topical preparations. Apply a thin layer of topical antifungals to the area of infection. Avoid using occlusive dressings or wrappings unless otherwise directed by a clinician.[ citation needed ]
Topical antifungal medications usually come with side effects. Some patients may develop itching or local irritations after the application of these products. Consult a pharmacist or clinician if the treated area shows signs of increased irritation or possible sensitization such as erythema, pruritus, burning, blistering, swelling, or oozing. These drugs can also interact with food and various medications. Inform pharmacists or clinicians of existing or contemplated concomitant therapy, including prescription and Over-the-counter drugs, dietary or herbal supplements and any concomitant illnesses. Therefore, topical antifungals should be used with caution after seeking advice from medical professionals.[ citation needed ]
Azole antifungals are generally divided into two groups, imidazoles and triazoles. Common examples of imidazoles include clotrimazole, econazole, miconazole, ketoconazole, while fluconazole, itraconazole, posaconazole and voriconazole fall under triazoles group. Both groups cause substantial damage in fungal membrane integrity by lowering ergosterol levels, along with the loss of cytoplasmic components, thus bringing similar effects to the polyene antifungals. [3] [4]
Azole antifungal drugs exert their effects by inhibiting the synthesis of the sterol components of the fungal membrane. Azoles are predominantly fungistatic which inhibit the growth of the fungus instead of killing the fungus. These drugs target the ergosterol biosynthetic pathway by inhibiting the C-14 α-demethylase, a cytochrome P450 enzyme, thus preventing the demethylation of lanosterol to ergosterol which is an essential component of the fungal cell membrane. The impaired synthesis of ergosterol leads to a cascade of membrane defects. Hence, fungal cell growth is inhibited due to the disrupted structure and function of the membrane. [5] [6]
Most topically used azole antifungals belong to the imidazole group, listed below are some of the most common azole antifungals according to the British National Formulary. [7]
Avoid contact with eyes and mucous membranes using topically. Avoid intravaginal preparations (particularly those that require the use of an applicator) in young girls who are not sexually active, unless there is no alternative (in children).
Polyene antifungals do not work well orally so they are mostly seen as a solution or given topically or intravenously as a systemic antifungal. They are not suitable for dermatophyte fungal infections.[ citation needed ]
Polyene antifungals have high affinity for ergosterol in fungal cell membranes. Upon binding to the fungal cell membrane and forming pores, membrane permeability and transport in fungus are altered. As a result, fungal cell death occurs. Nystatin is the only polyene antifungal that is available for topical administration. The drug is derived from Streptomyces noursei and has activity against Candida but not dermatophytes.
Nystatin is used topically for the treatment of Candida infections of the skin and mucous membranes. [9]
Patients who are concurrently using latex contraceptives should be reminded that some intravaginal preparations of nystatin may damage the contraceptive. Additional contraceptive measures may be needed during the treatment duration.
Allylamines are a new type of antifungal drug that is highly selective for the fungal enzyme but has a minimal effect on humans. They work in a similar way as azoles but have their effects earlier on in the ergosterol synthesis pathway. Allylamines allow the active ingredients in the medication to accumulate well within the stratum corneum of the skin and nails to exert their actions. They inhibit the enzyme squalene epoxidase which converts squalene into ergosterol. This inhibition results in decreased amounts of sterols, causing cell death and the disruption of the fungal cell wall synthesis. They are known to be quite effective against dermatophytes, yeast, and molds. [10]
Common allylamine antifungals are naftifine and terbinafine. They are usually used topically for the treatment of skin infections. [11]
Benzoxaborole antifungals are a newer class of antifungal medication. They work by blocking the ability of the fungus to produce proteins in a highly specific way. Hence, disrupting the action of yeast cytoplasmic enzymes involved in the translation process. A common example of this class of antifungal is Tavaborole. [12]
Ciclopirox and ciclopirox olamine are synthetic antifungal agents. The exact mechanism of action of Ciclopirox olamine antifungals is not well understood. It appears that the medication works by causing depletion of important substrates such as amino acids and/or ions within fungal cells, resulting in the inhibition of transport of these substances across fungal cell membranes. Finally, it disrupts the synthesis of DNA, RNA and proteins in fungal cells and leads to cell death. Ciclopirox may also exert its antimycotic effects by altering fungal cell permeability. However, the leakage of cellular constituents resulting from the decreased cell permeability is only apparent at high drug concentrations. [1]
Ciclopirox olamine comes in different formulations, which can be used topically in a wide variety of fungal infections. [13] [14]
In general, ciclopirox and ciclopirox olamine preparations are well tolerated by patients when used topically for treatment of fungal infections. Pain, itchiness and burning sensations may occur following topical application of the medication. For patients using ciclopirox nail lacquers, redness of the skin around the nail and the proximal nail fold may occur, while a few of them develop nail disorders such as ingrown nails, changes in shape, and discoloration. [15]
The above adverse reactions are usually mild and self-terminating. They are rarely severe enough to require discontinuation of the drug.
Thiocarbamate antifungals have a similar mechanism of action as allylamine antifungals. They both inhibit the enzyme squalene-epoxidase, which converts squalene to lanosterol, the raw material for producing ergosterol in fungal cells. By blocking the sterol synthesis in fungal cells and cell extracts, the integrity of fungal cell membranes will be interrupted, thus leading to impeded fungal growth.
Tolnaftate is one example of thiocarbamate antifungals.
Side effects are rare with tolnaftate, these side reactions may include irritation, burning, pruritus (itchiness), and contact dermatitis.[ citation needed ]
Undecyclenic alkanolamide antifungals, also referred to as undecylenic acid and undecenoic acid, is a type of unsaturated fatty acid that inhibits fungal growth on the skin. [16]
Although undecylenic acids possess antifungal properties, the drug itself is seldom used on its own for antifungal purposes. Salts of undecylenic acid such as zinc undecenoate and calcium undecenoate are commonly formulated into antifungal creams, ointments, solutions or powders. Undecenoic acid and its salt forms are applied topically to treat superficial dermatophytosis, in particular tinea corporis (ringworm), tinea pedis (athlete's foot), and tinea cruris (jock itch). Undecenoic acid is also formulated into several other salts and derivatives such as methyl, phenyl and propyl undecenoate, which are also used to treat fungal infections on the skin. There has been limited evidence showing the effectiveness of undecylenic acid in treating nail and scalp fungal infections. [17]
Irritation may occur in some patients after topical application of undecylenic acid or its salts and derivatives.[ citation needed ]
Tinea cruris (TC), also known as jock itch, is a common type of contagious, superficial fungal infection of the groin and buttocks region, which occurs predominantly but not exclusively in men and in hot-humid climates.
An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as cryptococcal meningitis, and others. Such drugs are usually obtained by a doctor's prescription, but a few are available over the counter (OTC). The evolution of antifungal resistance is a growing threat to health globally.
Nystatin, sold under the brand name Mycostatin among others, is an antifungal medication. It is used to treat Candida infections of the skin including diaper rash, thrush, esophageal candidiasis, and vaginal yeast infections. It may also be used to prevent candidiasis in those who are at high risk. Nystatin may be used by mouth, in the vagina, or applied to the skin.
Ketoconazole, sold under the brand name Nizoral among others, is an antiandrogen, antifungal, and antiglucocorticoid medication used to treat a number of fungal infections. Applied to the skin it is used for fungal skin infections such as tinea, cutaneous candidiasis, pityriasis versicolor, dandruff, and seborrheic dermatitis. Taken by mouth it is a less preferred option and only recommended for severe infections when other agents cannot be used. Other uses include treatment of excessive male-patterned hair growth in women and Cushing's syndrome.
Miconazole, sold under the brand name Monistat among others, is an antifungal medication used to treat ring worm, pityriasis versicolor, and yeast infections of the skin or vagina. It is used for ring worm of the body, groin, and feet. It is applied to the skin or vagina as a cream or ointment.
Athlete's foot, known medically as tinea pedis, is a common skin infection of the feet caused by a fungus. Signs and symptoms often include itching, scaling, cracking and redness. In rare cases the skin may blister. Athlete's foot fungus may infect any part of the foot, but most often grows between the toes. The next most common area is the bottom of the foot. The same fungus may also affect the nails or the hands. It is a member of the group of diseases known as tinea.
Tolnaftate (INN) is a synthetic thiocarbamate used as an anti-fungal agent that may be sold without medical prescription in most jurisdictions. It is supplied as a cream, powder, spray, liquid, and liquid aerosol. Tolnaftate is used to treat fungal conditions such as jock itch, athlete's foot and ringworm.
Terbinafine is an antifungal medication used to treat pityriasis versicolor, fungal nail infections, and ringworm including jock itch and athlete's foot. It is either taken by mouth or applied to the skin as a cream or ointment. The cream and ointment should not be used for fungal nail infections.
Dermatophyte is a common label for a group of fungus of Arthrodermataceae that commonly causes skin disease in animals and humans. Traditionally, these anamorphic mold genera are: Microsporum, Epidermophyton and Trichophyton. There are about 40 species in these three genera. Species capable of reproducing sexually belong in the teleomorphic genus Arthroderma, of the Ascomycota. As of 2019 a total of nine genera are identified and new phylogenetic taxonomy has been proposed.
Tinea corporis is a fungal infection of the body, similar to other forms of tinea. Specifically, it is a type of dermatophytosis that appears on the arms and legs, especially on glabrous skin; however, it may occur on any superficial part of the body.
Ciclopirox is a synthetic antifungal agent for topical dermatologic treatment of superficial mycoses. It is most useful against tinea versicolor. It is often used clinically as ciclopirox olamine, the olamine salt of ciclopirox.
Dermatophytosis, also known as tinea and ringworm, is a fungal infection of the skin, that may affect skin, hair, and nails. Typically it results in a red, itchy, scaly, circular rash. Hair loss may occur in the area affected. Symptoms begin four to fourteen days after exposure. The types of dermatophytosis are typically named for area of the body that they affect. Multiple areas can be affected at a given time.
Onychomycosis, also known as tinea unguium, is a fungal infection of the nail. Symptoms may include white or yellow nail discoloration, thickening of the nail, and separation of the nail from the nail bed. Fingernails may be affected, but it is more common for toenails. Complications may include cellulitis of the lower leg. A number of different types of fungus can cause onychomycosis, including dermatophytes and Fusarium. Risk factors include athlete's foot, other nail diseases, exposure to someone with the condition, peripheral vascular disease, and poor immune function. The diagnosis is generally suspected based on the appearance and confirmed by laboratory testing.
Sertaconazole, sold under the brand name Ertaczo among others, is an antifungal medication of the Benzothiophene class. It is available as a cream to treat skin infections such as athlete's foot.
Butenafine, sold under the brand names Lotrimin Ultra, Mentax, and Butop, is a synthetic benzylamine derived antifungal drug.
Tinea nigra, also known as superficial phaeohyphomycosis and Tinea nigra palmaris et plantaris, is a superficial fungal infection, a type of phaeohyphomycosis rather than a tinea, that causes usually a single 1–5 cm dark brown-black, non-scaly, flat, painless patch on the palms of the hands and the soles of the feet of healthy people. There may be multiple spots. The macules occasionally extend to the fingers, toes, and nails, and may be reported on the chest, neck, or genital area. Tinea nigra infections can present with multiple macules that can be mottled or velvety in appearance, and may be oval or irregular in shape. The macules can be anywhere from a few mm to several cm in size.
Trichophyton rubrum is a dermatophytic fungus in the phylum Ascomycota. It is an exclusively clonal, anthropophilic saprotroph that colonizes the upper layers of dead skin, and is the most common cause of athlete's foot, fungal infection of nail, jock itch, and ringworm worldwide. Trichophyton rubrum was first described by Malmsten in 1845 and is currently considered to be a complex of species that comprises multiple, geographically patterned morphotypes, several of which have been formally described as distinct taxa, including T. raubitschekii, T. gourvilii, T. megninii and T. soudanense.
Naftifine hydrochloride is an allylamine antifungal drug for the topical treatment of tinea pedis, tinea cruris, and tinea corporis.
Clotrimazole, sold under the brand name Lotrimin, among others, is an antifungal medication. It is used to treat vaginal yeast infections, oral thrush, diaper rash, tinea versicolor, and types of ringworm including athlete's foot and jock itch. It can be taken by mouth or applied as a cream to the skin or in the vagina.