Athlete’s Foot (Tinea Pedis)

BY Sana Ghassan & Aya Khraim

ATHLETES FOOT INFO Athlete’s foot (tinea pedis) is a

fungal infection. It most commonly causes itching and

weeping between the toes, although other areas of the foot may also be involved .

What causes Athlete’s Foot ? Athlete's foot (tinea pedis) is a fungal infection of the

skin of the foot. Most athlete's foot is caused by one of two types of fungus.

1. Trichophyton mentagrophytes often causes toe web or vesicular (blisterlike) infections. The infection appears suddenly, is severe, and is easily treated.

2. Trichophyton rubrum often causes moccasin-type infections. This condition lasts for a long time (chronic) and is difficult to treat.

• The fungi thrive in closed, warm, moist environments and feed on keratin, a protein found in hair, nails, and skin. Rarely, athlete’s foot can be caused by non-dermatophytes, like yeast (candida)

 Toe Web (Interdigital) Type

Vesicular Type

 Moccasin Type

Symptoms

Athlete's foot (tinea pedis) symptoms vary from person to person. Although some people have severe discomfort, others have few or no symptoms. Common symptoms include:

• Peeling, cracking, and scaling of the feet.• Redness, blisters, or softening and breaking

down (maceration) of the skin.• Itching, burning, or both.

Treatment

Preparations for athlete’s foot are available in a range of formulations, including ointments, creams, paints, sprays and powders. Powders are usually recommended for dusting into shoes, socks and stockings, either as adjuncts to creams and ointments or to prevent the recurrence of infection once

cleared, particularly in individuals who tend to be chronic sufferers. The powder formulation itself helps to inhibit the propagation of fungi by adsorbing moisture and preventing skin maceration .

Three groups of drugs are available for the treatment of athlete’s Foot :

1.antifungals2.keratolytic agents3.other antimicrobial compounds, contained in some products.

1. Antifungals

• Compounds available are:imidazoles

• Terbinafine• Griseofulvin• tolnaftate• undecenoates• benzoic acid.

Terbinafine & imidazoles

• Terbinafine (an allylamine derivative) and the imidazoles are widely accepted as being the most effective treatments for athlete’s foot.

MOA of Terbinafine & imidazoles

• They act by inhibiting the biosynthesis of ergosterol, a constituent of the fungal cell membrane , resulting in disruption of the cell.

Imidazoles

Imidazoles licensed for treatment of athlete’s foot without prescription are clotrimazole, econazole, ketoconazole, miconazole and sulconazole. They are

considered to have similar efficacy. These compounds also possess activity against

Gram-positive bacteria, which is useful, as secondary bacterial infection may complicate the fungal infection.

How to use it ?

Application two or three times daily is recommended, and treatment for at least 1 month is generally advised to ensure that this tenacious infection is eradicated.

Terbinafine

• as cream, gel or spray is used once or twice daily for 1 week.

• There is also a single-application cutaneous solution that, according to the manufacturer, forms a clear film that releases active ingredient into the skin for up to 13 days. Local irritation and sensitivity are possible with all compounds.

Griseofulvin and its MOA

Griseofulvin is an antifungal compound isolated from strains of

“Penicillium griseofulvum”. It is active exclusively against dermatophytes through inhibition of cellular mitosis. It also binds to host cell keratin and reduces its degradation by keratinases .It may also interfere with dermatophyte

DNA production.

How to use it ?

One spray is applied daily, increasing to three sprays daily for more severe or extensive infection affecting the sides or soles of the

feet. Treatment should be continued for 10 days after lesions have disappeared.

The treatment period should not exceed 4 weeks .

TolnaftateTolnaftate is used to treat skin infections such as athlete's foot. It is an antifungal that works by preventing the growth of fungus.

Tolnaftate comes as a cream, liquid, powder, gel, spray powder, and spray liquid for application to the skin. 

How should this medicine be used?Use this medication on the skin only. Clean and dry the area to be treated. Apply this medication to the affected skin, usually twice a day .

Some forms of tolnaftate (e.g., powder) need to be shaken before applying.. Apply enough medication to cover the affected area and some of the surrounding skin. After applying this medication, wash your hands.

Do not apply this medication in the eyes, nose, mouth.Use this medication regularly in order to get the most benefit from it.

Continue to use this medication until the full prescribed amount is finished, even if symptoms disappear after starting tolnaftate.

Stopping the medication too early may allow the fungus to continue to grow, which may result in a relapse of the infection.

Continue treatment for at least 2 weeks after symptoms disappear. A total of 4-6 weeks of treatment may be necessary.

What special precautions should I follow?

tell your doctor and pharmacist if you are allergic to tolnaftate or any other drugs.

tell your doctor and pharmacist what prescription and nonprescription medications you are taking, including vitamins.

tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while using tolnaftate, call your doctor.

Nystatinnystatin binds to ergosterol, a major component of the fungal cell membrane. When present in sufficient concentrations, it forms pores in the membrane that lead to K+ leakage and death of the fungus.

Keratolytic agentCompounds available

Salicylic acid is the only compound available.Mode of action and usage

Salicylic acid at concentrations above 2% has a keratolytic effect causing the keratin layer of the skin to shed. (Below this concentration it aids normal keratinisation.) Keratolysis is achieved by increasing the hydration of the stratum corneum (the outermost layer of dead cells), softening the cells and facilitating dissolution of the intracellular cement that bonds the cells together so that they separate and detach (desquamate). Moisture is essential to thisprocess and is provided by either the water in the formulation or the occlusive effect produced by its application to the skin.

• Salicylic acid alone has little or no antifungal activity but it facilitates the penetration of other drugs into the epidermis. Preparations for athlete’s foot containing salicylic acid therefore also contain antifungal constituents. Salicylic acid is present at a concentration of3%in Whitfield’s ointment. Although salicylic acid is readily absorbed through the skin, salicylate poisoning is highly unlikely to result from application

• to a small area for the limited period of treatment for athlete’s foot.

Product selection points* Terbinafine and imidazole antifungals are generally regarded as first-linetreatments. Griseofulvin and tolnaftate have also been shown to beclinically effective, but terbinafine and the imidazoles have additionalactivity against bacterial supra-infection. Undecenoates appear to be lesseffective than imidazoles for deeper-seated infections. Other treatmentsfor athlete’s foot offer no advantage over the above.

* Antifungal powders and sprays may be helpful in preventing recurrence of infection in chronic sufferers.

Product recommendationsFirst choice of treatment for athlete’s foot should be terbinafine or animidazole antifungal cream. Tolnaftate cream should be used for patientssensitive to these. Powders containing the above or undecenoates can be

dusted on to the feet and into hosiery and footwear as prophylaxis for chronic sufferers.

Advices

• Good foot hygiene is important for effective treatment, and patients should be advised to wash and dry their feet thoroughly before each application of medicament. They should not share towels with others (this helps to prevent the spread of infection), should change their socks, tights or stockings daily, and should be advised to avoid occlusive footwear. It is also important to emphasise the need to apply the medication well beyond the area that can be seen to be infected, and to use it regularly for the full recommended

• treatment period.