What is fluconazole?
Fluconazole is an antifungal medication used to treat fungal infections in pets and humans (Merriam-Webster, 2022). It works by preventing fungi from producing ergosterol, an essential component of fungal cell membranes. Without ergosterol, fungal cells cannot survive and replicate (Collins Dictionary, 2022).
Fluconazole is part of the drug class known as triazole antifungals. It can be used to treat infections caused by various fungal species, including Candida, Cryptococcus, Aspergillus, and dermatophytes (YourDictionary, 2022). Fluconazole is available in oral tablet and intravenous formulations.
Common brand names for fluconazole include Diflucan, Canesten, and Fulsol. It is frequently prescribed to treat systemic and localized fungal infections in pets, especially cats. Fluconazole exhibits broad-spectrum antifungal activity with fewer side effects than some older antifungal medications.
How does fluconazole work?
Fluconazole is an antifungal medication that belongs to a class of drugs called triazoles. It works by inhibiting an enzyme called lanosterol 14α-demethylase which is responsible for converting lanosterol to ergosterol. Ergosterol is an essential component of the fungal cell membrane. By inhibiting the production of ergosterol, fluconazole disrupts the integrity of the fungal cell membrane, leading to inhibition of fungal growth and replication.
Specifically, fluconazole achieves this antifungal effect by binding to the cytochrome P450 enzyme 14α-demethylase. This enzyme is responsible for converting lanosterol into ergosterol. Fluconazole competes with lanosterol for binding to the active site of 14α-demethylase. When fluconazole binds, 14α-demethylase can no longer convert lanosterol to ergosterol. This leads to depletion of ergosterol and accumulation of toxic methylated sterol precursors in the fungal membrane. The end result is disruption of membrane integrity, inhibition of growth, and fungal cell death.
What fungal infections can fluconazole treat in cats?
Fluconazole is commonly used to treat a variety of fungal infections in cats, including:
- Ringworm – Fluconazole is often prescribed for ringworm infections, which are caused by dermatophyte fungi.
- Yeast infections – Fluconazole can treat yeast infections throughout the body, such as oral thrush or candidiasis affecting the skin, ears, or urinary tract.
- Cryptococcosis – This systemic fungal infection most often affects the central nervous system in cats. Fluconazole may be used for treatment.
- Aspergillosis – This fungal infection typically occurs in the nasal cavity and sinuses. Fluconazole can sometimes be used to treat it.
- Histoplasmosis – This serious fungal infection affects multiple organs, especially the respiratory and digestive systems. Fluconazole is commonly prescribed.
- Blastomycosis – This systemic fungal disease can cause lesions on the skin, eyes, bones and internal organs. Fluconazole may be used for treatment.
So in summary, fluconazole is effective against dermatophyte fungi like ringworm, yeasts like Candida, and dimorphic systemic fungi like Cryptococcus, Histoplasma, and Blastomyces in cats. Fungal culture and sensitivity testing can help determine if fluconazole is likely to be effective.
Source: https://vcahospitals.com/know-your-pet/fluconazole
What is the typical fluconazole dosage for cats?
The typical dosage of fluconazole for cats depends on the weight of the cat and the type of fungal infection being treated. According to veterinary guidelines, the standard dosing range for cats is:
- 2.5-5 mg per kg body weight for ringworm
- 5-10 mg per kg body weight for yeast infections
- 5-20 mg per kg body weight for systemic mycoses
So for a 10 lb (4.5 kg) cat with ringworm, the dosage would be 11.25-22.5 mg once daily. For a yeast infection, the dose would be 22.5-45 mg once daily. For systemic mycoses, the dose could be as high as 90 mg once daily.
Fluconazole is typically formulated as 50, 100, 150 or 200 mg tablets. The appropriate tablet size and number of tablets needed per dose depends on the individual cat’s weight. It’s important to follow your veterinarian’s dosage instructions closely and calculate the exact mg amount based on your cat’s current body weight.
According to 1800PetMeds, the starting dose is often higher initially, then lowered once the infection starts to resolve. Your vet may adjust the frequency and duration of treatment as well depending on your cat’s specific condition.
How should fluconazole be administered to cats?
Fluconazole is typically administered orally to cats, either in tablet/capsule form or as an oral suspension or solution.
Tablets or capsules can be given directly into the cat’s mouth or hidden in food if the cat dislikes taking pills. According to PetMD, tablets should not be crushed or broken apart[1].
Oral suspensions or solutions can be administered using an oral syringe or mixed into the cat’s wet food. Make sure to stir the medication into a small portion of wet food that the cat will completely finish[2].
Fluconazole is best given with food, as this helps avoid upset stomach or vomiting. If your cat vomits after receiving fluconazole on an empty stomach, try giving the next dose with a meal[1].
Speak with your veterinarian about the best way to give your specific cat its fluconazole to ensure proper dosing and administration.
[1] https://www.petmd.com/pet-medication/fluconazole
[2] https://vcahospitals.com/know-your-pet/fluconazole
What are the side effects of fluconazole in cats?
Like any medication, fluconazole can potentially cause side effects in cats. Some of the more common side effects reported in cats include:
– Gastrointestinal upset like vomiting, diarrhea, or lack of appetite. Fluconazole can irritate the digestive tract, especially when given on an empty stomach.[1]
– Increased liver enzymes or liver toxicity. Long-term or high-dose fluconazole has been associated with liver damage in some cats. Periodic liver enzyme testing is recommended.[2]
– Skin reactions like rash or itchiness. Fluconazole is eliminated through the skin, which can occasionally cause mild dermatologic side effects.[1]
Rare but serious side effects like muscle tremors, seizures, or acute liver failure are possible. Cats should be closely monitored after starting fluconazole treatment. Veterinary guidance is important to minimize risks and catch any problems early.
Overall, short-term fluconazole is considered relatively safe for cats when used as directed. But any medication can cause side effects, so monitoring for gastrointestinal, skin, or liver issues is advised.
[1] https://www.petplace.com/article/drug-library/drug-library/library/fluconazole-diflucan/
[2] https://vcahospitals.com/know-your-pet/fluconazole-antifungal-for-pets
When should fluconazole not be used in cats?
Fluconazole should be avoided in certain situations in cats. According to VCA Animal Hospitals, fluconazole should not be used in cats who are allergic or hypersensitive to it or other similar antifungal medications [1]. It is also recommended to use caution when administering fluconazole to cats with liver or kidney disease, as it can cause further damage to these organs.
Additionally, PetMD states that fluconazole should be avoided in pregnant or nursing cats, as it may cause harmful effects on the developing fetuses or newborn kittens. Fluconazole is excreted in breast milk, so nursing kittens can ingest the drug through the mother’s milk [2].
Overall, vets do not recommend using fluconazole in cats with pre-existing liver or kidney issues, pregnant or nursing cats, or cats with known allergies to the drug. In these situations, alternate antifungal medications may be prescribed instead.
Are there any alternatives to fluconazole for cats?
There are several other antifungal medications that can be used as alternatives to fluconazole in cats:
Itraconazole – This antifungal medication can treat systemic fungal infections in cats, including blastomycosis and histoplasmosis. It is given orally and takes effect more slowly than fluconazole, but its effects last longer (https://www.merckvetmanual.com/pharmacology/systemic-pharmacotherapeutics-of-the-integumentary-system/antifungals-for-integumentary-disease-in-animals).
Ketoconazole – This drug is used to treat fungal infections on the skin, ears, and nails of cats. It is less expensive than fluconazole but can cause more side effects (https://www.dvm360.com/view/review-selected-systemic-antifungal-drugs-use-dogs-and-cats).
Terbinafine – Effective against dermatophyte infections like ringworm, terbinafine is given orally to cats and has few side effects. However, it is only effective against fungal infections limited to the skin (https://www.merckvetmanual.com/pharmacology/systemic-pharmacotherapeutics-of-the-integumentary-system/antifungals-for-integumentary-disease-in-animals).
Talk to your veterinarian about the best antifungal medication for your cat based on the type of fungal infection, your cat’s health history, and ease of administration.
How long does fluconazole take to work in cats?
Fluconazole can take some time before its full effects are seen when treating fungal infections in cats. According to VCA Animal Hospitals, fluconazole may take up to a few weeks before the medication reaches its maximum benefit.
The antifungal properties of fluconazole work by inhibiting the growth and spread of fungal infections. As fluconazole builds up to therapeutic levels in the bloodstream over the first 1-2 weeks of treatment, you may begin seeing gradual improvements in your cat’s symptoms. However, Mar Vista Animal Medical Center notes that full resolution of the fungal infection can take 4-6 weeks.
It’s important not to expect rapid results with fluconazole treatment. Cats should complete the full course of medication as prescribed by the veterinarian, even if symptoms start to improve. Stopping fluconazole too soon can allow the infection to return. Monitor your cat closely over the first few weeks of treatment and follow up with your veterinarian if the infection persists or worsens.
When to follow up with a vet after giving fluconazole
It’s important to follow up with your veterinarian after starting your cat on fluconazole, to monitor for side effects and ensure the medication is working properly. Here are some recommendations on when to schedule a recheck appointment:
- Within 5-7 days – This first recheck allows your vet to ensure your cat is tolerating the medication well and that it is not causing any concerning side effects like vomiting, diarrhea or liver problems. Your vet can make any needed dose adjustments at this time.
- 2-4 weeks after starting medication – At this point, your vet will re-evaluate the fungal infection to determine if it is responding to the fluconazole or if a different medication may be needed. Bloodwork may be recommended to monitor liver enzymes.
- Every 3-6 months – For cats on long-term fluconazole therapy, follow up appointments every 3-6 months allows your vet to monitor your cat’s health, evaluate liver function, and determine if ongoing medication is still required (https://vcahospitals.com/know-your-pet/fluconazole).
Don’t hesitate to contact your veterinarian sooner if your cat experiences any concerning symptoms while on fluconazole. Monitoring side effects and re-evaluating the fungal infection will help provide your cat with the best care while on this medication.