From the Guidelines
Fluconazole is an oral antifungal medication that can generally be prescribed without mandatory liver enzyme monitoring for short-term use in patients without pre-existing liver disease. For typical indications like vaginal candidiasis, a single 150mg dose is often sufficient, while other superficial fungal infections may require 50-200mg daily for 1-4 weeks depending on the condition 1. Terbinafine is another option that can be used for short courses without routine liver monitoring in healthy individuals, typically prescribed at 250mg daily for 1-2 weeks for conditions like tinea corporis or tinea pedis 1. However, baseline liver function tests are still recommended before starting any antifungal therapy, especially for longer treatment courses. These medications are considered relatively safe for short-term use because they have lower hepatotoxicity risk compared to other antifungals like ketoconazole. That said, patients should be educated about symptoms of liver problems (jaundice, dark urine, abdominal pain) and advised to seek medical attention if these develop during treatment.
Some key points to consider when prescribing fluconazole or terbinafine include:
- Fluconazole can be prescribed at a dose of 200-400mg daily for 14-21 days for esophageal candidiasis 1
- Terbinafine has broad and potent fungicidal effects against dermatophytes, particularly T. rubrum and T. mentagrophytes, but has lower fungistatic activity against Candida species than the azoles 1
- Baseline liver function tests and a complete full blood count are recommended in patients with a history of heavy alcohol consumption, hepatitis or haematological abnormalities before starting terbinafine therapy 1
- Fluconazole is generally well tolerated, but patients should be monitored for symptoms of liver problems and advised to seek medical attention if these develop during treatment 1
Overall, fluconazole and terbinafine are both effective and relatively safe options for the treatment of various fungal infections, but it is essential to carefully consider the individual patient's medical history and monitor for potential side effects.
From the Research
Oral Antifungals and Liver Enzyme Monitoring
- The use of oral antifungals can be associated with elevated liver enzyme levels, as reported in several studies 2, 3, 4, 5, 6.
- However, some antifungals are considered safer than others in terms of liver toxicity.
- Echinocandins, such as caspofungin, are considered to have minimal adverse effects, including liver toxicity 2, 6.
- Terbinafine is another option that can be used for dermatophyte infections, but its potential for liver toxicity is not well-studied in comparison to other antifungals 2.
- It is essential to note that liver function evaluation before treatment and periodic monitoring every three to six weeks after commencement of treatment is suggested for most antifungals 3.
Antifungals with Lower Risk of Liver Toxicity
- Caspofungin is an echinocandin with a low incidence of discontinuation of therapy due to adverse effects, including liver toxicity 6.
- Other echinocandins, such as anidulafungin and micafungin, also have a low risk of liver toxicity 6.
- Isavuconazole is another option that may have a lower risk of liver toxicity compared to other triazoles, such as posaconazole 5.
Important Considerations
- The development of liver function test abnormalities while on antifungal therapy may not always warrant a switch to an alternative antifungal, as hepatotoxicity is often multifactorial and generally resolves with time in the majority of patients 5.
- Clinicians should be aware of drug-drug interactions and adverse effects, including visual disturbances, elevations in liver transaminase levels, and skin rashes, when prescribing antifungals 2.