Clotrimazole
An imidazole antifungal used mostly on the skin, in the vagina and in the mouth, for thrush, ringworm and athlete's foot.
Drug card
- Class
- Azole antifungal
- How it works
- Inhibiting the fungal P450 enzyme that makes ergosterol for the cell membrane
- Used for
- Thrush of the vagina, penis, skin or mouth
- Ringworm and athlete's foot
- Fungal ear infection (as a solution)
- Known for
- Burning, stinging or irritation where applied
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does clotrimazole work?
Clotrimazole is an imidazole that blocks the fungal synthesis of ergosterol, so the cell membrane is damaged, leaks its contents and the cell breaks down. It is applied locally, as creams, pessaries, solutions, sprays and lozenges (troches), and is not used for systemic fungal infections.
Like other azole antifungals: Azoles inhibit lanosterol 14α-demethylase, the fungal cytochrome P450 enzyme that turns lanosterol into ergosterol, the main sterol of fungal membranes. Ergosterol runs short and 14α-methyl sterols build up, so the membrane fails and the fungus stops growing. Imidazoles such as clotrimazole are used mostly on skin and mucosa; triazoles such as fluconazole and itraconazole are taken by mouth or given IV.
Uses
What is clotrimazole used for?
- Thrush of the vagina, penis, skin or mouth
- Ringworm and athlete's foot
- Fungal ear infection (as a solution)
Side effects
Side effects of clotrimazole
- Burning, stinging or irritation where appliedKnown for
- Itching and redness of the skin
- Lower abdominal pain (vaginal use)
- Nausea and vomiting (lozenges)
- Raised liver enzymes (lozenges)
- Anaphylaxis (rare)Serious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Vaginal and genital products can weaken latex condoms and diaphragms during use and for at least 5 days after.
- Not for systemic fungal infections: those need an oral or IV antifungal.
- Vaginal products may interact with tacrolimus, so check before combining them.
Good to know: Mostly a local drug, used on the skin and in the vagina and mouth; unlike fluconazole or itraconazole, it is not given to treat infections deep in the body.
Remember it
A way to remember it
Azoles jam P450s: the fungus's and ours.
Their target, 14α-demethylase, is a fungal cytochrome P450 enzyme. Azoles also slow human P450 enzymes such as CYP3A4, which is why they raise the levels of so many other drugs.
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Its class
Azole antifungals
Other azole antifungals with a card:
Easily mixed up with allylamines, polyene antifungals and benzimidazole anthelmintics.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Antifungals and antiparasitics
Clotrimazole is one of 14 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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