From the Guidelines
Terbinafine can be used in patients with Gilbert's syndrome to treat fungal nail infections, as the condition does not significantly impact the drug's metabolism, and it is primarily processed by the liver through different pathways than bilirubin 1. The standard oral dose is typically 250 mg once daily for 6 weeks for fingernail infections or 12 weeks for toenail infections. Some key points to consider when using terbinafine in patients with Gilbert's syndrome include:
- Terbinafine works by inhibiting squalene epoxidase, disrupting fungal cell membrane synthesis, and has broad and potent fungicidal effects against dermatophytes 1.
- Patients should take the medication with food to minimize gastrointestinal side effects and complete the full treatment course even if improvement is seen earlier.
- Regular liver function monitoring may be prudent, especially in the first few weeks of treatment, though serious hepatotoxicity is rare, and terbinafine is generally well tolerated 1.
- Alternative topical treatments like ciclopirox nail lacquer could be considered for patients concerned about systemic therapy, though these typically have lower cure rates than oral terbinafine 1. It's also important to note that terbinafine has minimal drug–drug interactions, but 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 1. Overall, terbinafine is a effective treatment option for fungal nail infections in patients with Gilbert's syndrome, with a high cure rate and low risk of serious side effects, as demonstrated in the most recent and highest quality study 1.
From the Research
Terbinafine Use in Gilbert's Syndrome for Fungal Nail Infections
- Terbinafine is an effective antimicrobial agent against dermatophytes, cryptococcus, and other fungi, and it is the preferred drug to treat onychomycosis 2.
- However, severe acute hepatitis from oral terbinafine administration has been reported, and liver enzyme levels were found to have been increased significantly 2.
- The prognosis of severe acute liver injury caused by terbinafine is often good with appropriate treatment, and liver function assessment before treatment and periodic monitoring 4-6 weeks after initiation of treatment is recommended 2.
- In patients with Gilbert's syndrome, the use of terbinafine may require closer monitoring of liver function due to the potential risk of hepatotoxicity 3.
- A study found that oral terbinafine and itraconazole can be used with close follow-up, and baseline and regular laboratory monitoring for AST and ALT should be done to monitor liver toxicity 4.
Considerations for Terbinafine Use
- Terbinafine is effective in more than 50% of cases of fungal nail infections, but its cutaneous, hepatic, and haematological adverse effects can be severe in about 1 in 2000 patients and can be life-threatening 5.
- Patients should be advised to discontinue treatment and seek medical care when symptoms of DILI occur, such as jaundice, abdominal pain, and general malaise 6.
- The timeline of DILI onset varies significantly, but most cases occur between 4 and 6 weeks, and monitoring of liver function tests on terbinafine is not recommended 6.
Alternative Treatments
- Antifungal lacquers (5% amorolfine and 8% ciclopirox) applied to the nails can cure about 30% of fungal infections, and trimming, filing, or grinding the nail, in addition to these drug treatments, is likely to be beneficial 5.
- Chemical nail destruction with a combination of urea and bifonazole, followed by treatment with an antifungal ointment, can be used when the nail is markedly thickened 5.