From the Guidelines
Monitoring Lamisil (terbinafine) treatment requires baseline and periodic liver function tests (LFTs) and complete blood counts (CBCs). Before starting therapy, obtain baseline LFTs including ALT, AST, bilirubin, and alkaline phosphatase, as well as a CBC. During treatment, repeat these tests every 4-6 weeks, particularly for patients on long-term therapy (typically 6-12 weeks for fingernail infections and 12-16 weeks for toenail infections) 1. Additional testing may be needed for patients with pre-existing liver disease, those over 65 years old, or patients taking multiple medications. This monitoring is essential because Lamisil can cause hepatotoxicity in rare cases, with symptoms including fatigue, anorexia, nausea, dark urine, or jaundice. If LFT values exceed three times the upper limit of normal or if symptoms of liver dysfunction develop, discontinue the medication immediately. Renal function tests may also be appropriate for patients with kidney disease or those on prolonged therapy, as terbinafine is primarily eliminated through the kidneys.
Some key points to consider when monitoring Lamisil treatment include:
- Baseline LFTs and CBCs are recommended before starting therapy 1
- Repeat LFTs and CBCs every 4-6 weeks during long-term therapy 1
- Additional testing may be needed for patients with pre-existing liver disease, those over 65 years old, or patients taking multiple medications
- Monitor for symptoms of liver dysfunction, such as fatigue, anorexia, nausea, dark urine, or jaundice
- Discontinue the medication immediately if LFT values exceed three times the upper limit of normal or if symptoms of liver dysfunction develop
It's also important to note that the British Association of Dermatologists' guidelines for the management of onychomycosis recommend baseline liver function tests and a complete full blood count for patients with a history of hepatotoxicity or haematological abnormalities 1. Additionally, the guidelines suggest that terbinafine is generally well tolerated, but rare reports of serious adverse reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis, have been reported 1.
From the FDA Drug Label
Before prescribing terbinafine tablets, liver function tests should be performed since hepatotoxicity may occur in patients with and without pre-existing liver disease. Periodic monitoring of liver function tests is recommended. Measurement of serum transaminases (ALT and AST) is advised for all patients before taking terbinafine tablets. In patients with known or suspected immunodeficiency, physicians should consider monitoring complete blood counts if treatment continues for more than six weeks.
The lab tests to monitor Lamisil (terbinafine) treatment include:
- Liver function tests: to monitor for hepatotoxicity, before and periodically during treatment
- Serum transaminases (ALT and AST): to monitor liver function, before treatment
- Complete blood counts: in patients with known or suspected immunodeficiency, if treatment continues for more than six weeks 2, 2
From the Research
Lab Tests to Monitor Lamisil Treatment
To monitor Lamisil (terbinafine) treatment, the following lab tests are relevant:
- Alanine aminotransferase (ALT) levels: to assess liver health and detect potential liver injury 3, 4, 5, 6
- Aspartate aminotransferase (AST) levels: to assess liver health and detect potential liver injury 3, 4, 5, 6
- Complete blood cell count (CBC): to monitor for potential hematologic abnormalities 4, 5, 6
- Liver function tests, including alkaline phosphatase, total bilirubin, and albumin levels: to assess overall liver health 6
- Prothrombin time: to assess coagulation and liver function 6
- Hepatitis B and C testing: to rule out viral hepatitis as a cause of abnormal liver test results 3, 4, 6
- Ferritin and iron levels: to assess for potential iron overload or deficiency 4, 6
- Right upper quadrant abdominal ultrasonography: to evaluate liver morphology and detect potential liver disease 6
Frequency of Lab Tests
The frequency of lab tests to monitor Lamisil treatment is not well established, but studies suggest that routine interval laboratory test result monitoring may be unnecessary in adults and children without underlying hepatic or hematologic conditions taking terbinafine for dermatophyte infections 7, 5. However, patients should be advised to discontinue treatment and seek medical attention if symptoms of liver injury occur 7.
Patient Evaluation
Patients with abnormal liver test results should be evaluated to determine the etiology, including a review of medical and family histories, substance use, and drugs, including over-the-counter drugs and herbal supplements 6. Physical examination results and additional tests, such as imaging studies, should be based on patient-specific risk factors and the pattern of abnormal liver test results 6.