Antifungal drugs, topical

Definition

Topical antifungal drugs are preparations applied to the skin, nails or mucous membranes to treat infections caused by fungi.

Description

“Fungus” a general term for non-chlorophyll producing plants which includes the mushrooms, yeasts and molds. Fungi are very common in nature, and very few of them are capable of causing disease. However, some can and do cause infection. When the infection affects the entire body, it can be a serious problem, and difficult to treat; more commonly, fungal infections are superficial and can be treated with creams and ointments. Most skin and nail infections are not serious, but when a fungus is found in the genitourinary tract, it has the potential for causing serious problems, particularly if it invades the kidneys.

Candida species, most commonly Candida albicans is a relatively common skin infection which can appear anywhere, but is most common in skin folds. Candida can also infect the lower urinary tract, particularly in patients who have been catheterized as part of a medical procedure. In immunocompromised patients, patients with cancer or HIV and in transplant patients, Candida has the potential to cause a serious systemic infection. Vulvovaginal candidiasis is common, and candida infections of the nails can occur, particularly after a manicure or pedicure with improperly sterilized equipment.

Dermatophytoses are infections that require keratin, a component of skin, to grow, and include infections of the head and nails. Infections of the scalp are termed Ringworm or Tinea capitis while infections of the beard area are called Tinea barbae. When ringworm is seen on the trunk or extremities, it is called Tinea corporis while the same infection in the groin area is Tinea cruris, although the term “jock itch” is commonly used. Finally, dermatophyte infections of the foot, or athlete's foot, is properly termed Tinea pedis. While these are infections of the skin, systemic treatment such as antifungal pills might be the best choice. Even so, some topical treatments might be appropriate, particularly in mild cases.

Fungal infections of the nails are relatively common, and it has been estimated that 10% of the United States population has some form of nail infection. Although these are superficial infections, the best treatment is with systemic medication. Ciclopirox is available as a nail lacquer, but is rarely effective as sole treatment. It can be used as an adjunct to systemic therapy.

Infections around the nails are usually a combination of both bacteria and fungi, and so require combination treatment.

There are a large number of topical antifungal drugs available. The topical antifungals currently available in the United States are:

• Butenafine hydrochloride: butenafine has been used against all the dermatophytoses.
• Ciclopirox: available for treatment of nail infections, but should probably be used in combination with a systemic drug rather than used alone.
• Clotrimazole: this is a versatile product which is available for application to the skin, as a vaginal suppository, or an oral lozenge. It has been used to treat fungal infections on the skin, in the mouth, and in the vulvovaginal area.
• Econazole nitrate: this antifungal has been used for most skin infections, and has been useful in treatment of Tinea versicolor which is an infection by the fungus Malassezia fufur.
• Gentian violet: a traditional and reliable treatment for athlete's foot.
• Sertaconazole nitrate: used to treat athlete's foot.
• Ketoconazole: used for both the dermatophytoses and for Candida infections of the skin.
• Miconazole nitrate: has been used for both dermatophytoses and Candida particularly in the vulvovaginal region. Miconazole is available in a large number of forms including sprays, creams, lotions and vaginal suppositories.
• Naftifine: has been used to treat both dermatophytoses and Candida. It is available only for skin application.
• Nystatin: used both topically and systemically for treatment of Candida.
• Oxiconazole nitrate: used to treat dermatophytoses and Tinea versicolor.
• Suconazole nitrate: used to treat dermatophytoses and Tinea versicolor.
• Terbinafine hydrochloride: used to treat the dermatophytoses, it is used both topically and systemically.
• Tolnaftate: used to treat dermatophytoses and Tinea versicolor.
• Undecylinic acid and related compounds: zinc containing compounds which are used to treat superficial infections such as athlete's foot.

QUESTIONS TO ASK YOUR PHARMACIST

• What over-the-counter formulation should I use?
• How often should I apply the product?
• Is there any inactive ingredients that I may be allergic to?

Precautions

These products should not be used by anyone who has shown sensitivity to any of the ingredients.

Many of these products are available without prescription. Their uses are based on effectiveness against species of fungus that commonly infect specific areas, and the descriptive terms “ringworm,” “athlete's foot” and so on, apply to the area of the body affected, but do not specify the species of fungus causing the infection. Failure to respond to treatment can indicate a resistant fungus, or a species of fungus different from the ones normally seen. If treatment fails, professional medical treatment is needed.

Side effects

When these drugs are used on the skin, adverse effects are normally limited to local irritation, itching , burning sensations and possible rash. These same drugs may have more severe adverse effects when taken systemically. Because the likelihood of systemic absorption is increased when the products are applied to abraded skin, or to a mucous membrane such as the mouth or vaginal wall, review product specific literature before using.

Interactions

When antifungal drugs are applied to the skin, interactions are unlikely.

Caregiver concerns

Fungal infections may take a long time to resolve. Follow dosage instructions for the full required period.

KEY TERMS

Cream —A semi-solid dosage form for external application, relatively soft and non-greasy.

Gel —A semi-solid dosage form for external application, usually translucent, non-greasy but may be drying.

Lotion —A liquid dosage form for external application, softer than a cream.

Ointment —A semi-solid dosage form for external application, may be greasy but has a longer duration of action than other semi-solids.

Oropharynx —The part of the throat that is located below the soft palate and above the larynx.

Systemic —The entire body.

Tinea versicolor —A skin fungus that is recognized because it causes skin discoloration.

Tinea pedis —Athlete's foot.

Tinea capitis —Ringworm.

Tinea cruris —Fungal infection of the groin area.

Topical —Applied to the area of infection.

Vulvovaginal —Pertaining to the vulva and vagina.

If over-the-counter products do not provide satisfactory results, get professional medical attention.

Resources

BOOKS

Blumenthal, M. The Complete German Commission E Monographs. Austin, TX: American Botanical Council, 1998.

Fry, L. An Atlas of Dermatology Taylor and Francis, 1997.

Osol, A, and G Farrar (eds). The Dispensatory of the United States of America 25th ed. Philadelphia: J. B. Lippincott Co, 1955

Reynolds, J (ed). Martindale the Extra Pharmacopoeia 30th ed. London: The Pharmaceutical Press, 1993.

Roberts, S, R Hay, and D Mackenzie. A Clinician's Guide to Fungal Disease. Honolulu: Informa, 1984.

PERIODICALS

Loo, DS. “Cutaneous fungal infections in the elderly.” Dermatol Clin. 2004 Jan 22(1):33–50

Martin, ES, and BE Elewski. “Cutaneous fungal infections in the elderly.” Clin Geriatr Med. (Feb 2002) 18(1):59–75.

Gupta, AK, TR Einarson, RC Summerbell, et al. “An overview of topical antifungal therapy in dermatomycoses. A North American perspective.” Drugs. (May 1998) 55(5):645-74.

McClellan KJ, LR Wiseman, and A Markham. “Terbinafine. An update of its use in superficial mycoses.” Drugs. (July 1999) 58(1):179-202.

Alavi A, K Woo, and RG Sibbald. “Common nail disorders and fungal infections.” Adv Skin Wound Care. (June 2007) 20(6):346-57; quiz 357-9.

Trent JT, and RS Kirsner. “Identifying and treating mycotic skin infections.” Adv Skin Wound Care. (May-Jun 2003) 16(3):122-9; quiz 130-1.

OTHER

http://online.factsandcomparisons.com/

http://www.doctorfungus.org/

http://www.medscape.com

http://www.tinactin.com/

http://www.uspharmacist.com/oldformat.asp?url=newlook/

files/cons/acf375b.htm&pub_id=8&article_id=777

http://www.merck.com/mmpe/index.html

http://www.aocd.org/skin/dermatologic_diseases/fungus_preventing.html

http://www.ncemi.org/cse/cse1117.htm

http://medlineplus.gov/

http://www.pdrhealth.com/home/home.aspx

http://www.emedicine.com/derm/index.shtml#fungal

Sam Uretsky PharmD