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Clotrimazole, Broad-spectrum Antifungal

Clotrimazole is an antibiotic that is inhibitory to wide range of filamenous fungi, including Aspergillus and dermatophytes; yeasts such as Candida, and other fungi. Because clotrimazole is inactivated by hepatic enzymes in the liver, it is reserved for topical administration cream, lotion, solution, tincture, and vaginal cream) for superficial fungal infections (nail, scalp, and skin infections). It is also used for oral fungal infections and canine nasal aspergillosis in dogs.2

Drug Action

Clotrimazole prevents fungal organisms from manufacturing the vital proteins they require for growth and function. Clotrimazole begins killing susceptible fungi shortly after contact. The effects may not be noticeable for several days or weeks.3

Drug Administration

A 1% solution in polyethylene glycol is infused through the nares into the nasal cavity and nasal sinuses (60mL per side in medium to large-breed dogs) of the anesthesized patient and allowed to sit for 1 hour. Rotating the head after each 15 min has been recommended to enhance drug distribution. A 1% solution in propylene glycol is available commercially. This preparation has been implicated as causing pharyngeal inflammation and edema in one dog that developed upper airway obstruction. In most cases commercial preparations have been used without adverse effects.5

Use of Clotrimazole to Treat Fungal Infections in Humans

The drug is used in humans to treat Candida vaginitis infections.sup>1

Although only a small number of otitis externa are caused by fungi, clotrimazole ear drops have been shown to be useful in the treatment of this ear disease. Otitis externa is treated by the inhibited growth and death of fungal cells.4

Clotrimazole as Environmental Pollutant

Clotrimazole belongs to the group of 14a-demethylase inhibiting fungicides. It is widely used in human and veterinary medicine and has been identified as a priority pollutant for the marine environment. It induces changes in cycling of photoprotective xanthophyll biological pigments in marine algae and adversely effects its growth 6. Amphibian populations are declining world-wide and one of the suggested reasons is environmental pollutants. The findings indicate that reproduction in wild frogs might be impaired by estrogenic compounds in the environment such as clotrimazole.7


  1. Antimicrobial therapy in veterinary medicine. John Francis Prescott, J. Desmond Baggot, Robert D. Walker
  2. The desk encyclopedia of microbiology. Moselio Schaechter, Joshua Lederberg
  3. Johns Hopkins Complete Home Guide to Pills & Medicines edited by Simeon Margolis
  4. Prescription Drugs: Alternative Uses, Alternative Cures. Kevin Loughlin, Joyce Generali
  5. Small animal clinical pharmacology. Jill E. Maddison, Stephen W. Page, David B. Church
  6. Toxicity of the pharmaceutical clotrimazole to marine microalgal communities Porsbring, T. / Blanck, H. / Tjellstrom, H. / Backhaus, T. , Aquatic Toxicology, 91 (3), p.203-211, Feb 2009
  7. Endocrine Disruption in Amphibians: Developmental Effects of Ethynylestradiol and Clotrimazole on the Reproductive System Gyllenhammar, Irina , Jan 2008