What is the recommended dose of terbinafine (Lamisil) and frequency of liver function tests (LFTs) for a kidney transplant patient with a toe infection?

From the Guidelines

For kidney transplant patients with a toe infection requiring terbinafine (Lamisil), the recommended dose is typically 250 mg once daily, with dose reduction to 125 mg daily or 250 mg every other day for patients with significant renal impairment (GFR <50 mL/min). Liver function tests (LFTs) should be performed at baseline before starting therapy, then monitored every 4-6 weeks throughout the treatment course, which usually lasts 6-12 weeks for toenail infections 1. This frequent LFT monitoring is particularly important in transplant patients due to their immunosuppressive medications, which may interact with terbinafine and increase the risk of hepatotoxicity.

Some key points to consider when prescribing terbinafine to kidney transplant patients include:

• Baseline liver function tests and a complete full blood count are recommended in adult patients with a history of hepatotoxicity or haematological abnormalities 1
• Terbinafine has minimal drug–drug interactions, but the only potentially significant drug interaction with terbinafine is with drugs metabolized by the cytochrome P450 2D6 isoenzyme 1
• Treatment should be discontinued if LFT abnormalities develop or if the patient experiences symptoms of liver dysfunction such as unexplained nausea, anorexia, fatigue, jaundice, or right upper quadrant pain
• A comprehensive medication review should be conducted before initiating terbinafine to identify potential drug interactions with immunosuppressants like tacrolimus, cyclosporine, or sirolimus, as terbinafine can affect the metabolism of these medications through the CYP450 enzyme system 1.

It is essential to prioritize the patient's safety and adjust the treatment plan accordingly, considering the potential risks and benefits of terbinafine therapy in kidney transplant patients with toe infections 1.

From the FDA Drug Label

Take terbinafine exactly as your doctor tells you to take it. Terbinafine comes as a tablet that you take by mouth Terbinafine is usually taken: 1 time each day for 6 weeks to treat fungal infections of your fingernail, or 1 time each day for 12 weeks to treat fungal infections of your toenail Your doctor should do a blood test to check you for liver problems before you take terbinafine. Measurement of serum transaminases (ALT and AST) is advised for all patients before taking terbinafine tablets

The recommended dose of terbinafine for a toe infection is 1 time each day for 12 weeks. It is advised to check liver function tests (LFTs), specifically serum transaminases (ALT and AST), before taking terbinafine tablets. However, the frequency of LFT monitoring after starting treatment is not specified in the provided drug label. 2

From the Research

Recommended Dose of Terbinafine

• The recommended dose of terbinafine for a kidney transplant patient with a toe infection is 250 mg daily 3, 4, 5.

Frequency of Liver Function Tests (LFTs)

• There is no clear consensus on the frequency of LFTs for kidney transplant patients taking terbinafine, but some studies suggest that LFTs should be monitored during treatment 3, 4.
• However, another study found that laboratory monitoring may not be useful in detecting terbinafine-induced severe liver injury, and instead recommends that patients be advised to discontinue treatment and seek medical care if symptoms of liver injury occur 6.

Important Considerations

• Terbinafine can interact with cyclosporin A, a common immunosuppressant used in kidney transplant patients, and may decrease its blood levels 3.
• Kidney transplant patients taking terbinafine should be closely monitored for signs of liver injury, such as jaundice, dark urine, and pruritus 6.
• The use of terbinafine in kidney transplant patients with severe onychomycosis has been shown to be effective and relatively safe, but requires careful monitoring and management 4.