Clotrimazole

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Clotrimazole is an over-the-counter medication for fungal infections in man and animals, yeast infections of the mouth and vagina, as well as alipunga (athlete's foot) and hadhad (jock itch). It is given externally although a new product from abroad that comes in lozenges will need a prescription. This drug might be confused with co-trimoxazole.

Contents

Chemical nature

Clotrimazole, or 1-[(2-chlorophenyl)(diphenyl)methyl]-1H-imidazole as its systemic name, has a chemical formula of C22H17ClN2. It is related chemically to fluconazole, ketoconazole, itraconazole, and miconazole. This drug is poorly absorbed when taken by mouth. If ingested, it is a potent and very specific inhibitor of the enzyme cytochrome P450 oxidase. This enzyme changes how the body metabolizes the drugs it takes in.

Clotrimazole works by making the fungal cell wall more permeable. It also prevents some essential enzymes needed for the cell's upkeep from being produced. It kills non-invasive fungi such as dermatophytes (Microsporum, Trichophyton, and Epidermophyton) and yeasts (i.e. Candida and Malassezia furfur). Although this will lead to cell death, only the areas that were applied with the drug are affected and not the remaining fungal infection in other parts of the body. This drug is also active against Gram-positive bacteria and Trichomonas with no current reports of developing resistance.

Uses and common dosages

When using clotrimazole, it is best to follow the product information regarding how to use the product, especially if bought without prescription. Make sure that the affected area has been cleaned and dried before applying the medication. Wash hands thoroughly before and after applying the drug.

  • Fungal otitis externa - One percent otic solution of clotrimazole may be applied to the affected area twice or thrice daily depending on the doctor's instructions.
  • Skin fungal infections - One percent cream, ointment, lotion, or solution of clotrimazole may be applied on the affected area twice or thrice a day for 2 to 4 weeks. Sometimes, 1% powder may be used to prevent reinfection.
  • Vulvovaginal candidiasis - Dosages usually depend on the dose each vaginal tablet or suppository may contain. As a vaginal suppository, 100 milligrams is given for 6 days; if 200 milligrams, for 3 days; or, 500 milligrams given as single dose. When using clotrimazole cream, 1% is given for 6 days, a 2% cream for 3 days or 10% cream given one time.
  • Oropharyngeal candiasis - Each lozenge contains 10 milligrams of clotrimazole. A lozenge may be taken every 5 hours for 2 weeks. When used by patients receiving immunosuppressants, 1 lozenge every 8 hours is taken for the whole duration of the treatment.

Clotrimazole is highly effective against fungal infections of the skin, with healing rates of approximately 80% but will not be effective against fungal infections of the scalp and nails.

Side effects

Common side effects of clotrimzaole are burning, itching, or stinging sensation when the drug is applied. However, some people might report appearance of skin rash, hives, peeling, redness, and swelling. If persistent burning, swelling, or itching occurs especially on topically applied products, inform the healthcare provider immediately. For those using vaginal tablets, seek medical attention when abdominal pain, fever or foul-smelling discharge appears.

Precautions and contraindications

Contact with eyes and other mucous membranes (i.e. nasal cavities) must be avoided especially when the product is for topical application. Children younger than 3 years old as well as pregnant and breastfeeding women must seek medical advice before using this product. People who are allergic to azoles must not use this.

Although clotrimazole might not cause significant drug interactions, there are some medications that medical professionals are wary of when used concurrently with this product:

  • Anything with ergot (i.e. ergonovine, ergotamine) - It might counter the effect of clotrimazole.
  • Fentanyl, tacrolimus, or trimextrate - There is increased rate of some unwanted side effects.

Patients who use clotrimazole must remember to:

  • See a doctor especially if it is the first time vaginal infection is contracted or if symptoms return after 2 months;
  • Continue using topical clotrimazole even if symptoms improve as it will need 4 weeks to fully recover from the infestation;
  • Include the sexual partner in the treatment of vaginal candidiasis for better prognosis. Sexual intercourse during treatment is highly discouraged; and,
  • Avoid restrictive bandages over the affected area after application of the drug unless under medical advice.

Availability

Clotrimazole is available in the Philippines as a topical cream, lotion, vaginal suppository and tablets, solution, and ointment. Common brands that contain this drug are Canesten® and Candiva®. These are available as over-the-counter medications. When combined with corticosteroids, clotrimazole containing products need a prescription. Corticosteroids that may be mixed with this antifungal are betamethasone, beclometasone, hydrocortisone, and dexamethasone.

References