Routine blood monitoring of terbinafine or griseofulvin therapy unnecessary
December 21 2018
It is common practice to check liver tests and blood count in patients on antifungal therapy, partly because of the rare but serious cases of liver necrosis seen with ketoconazole, when it was first introduced. By default, this practice has extended to all antifungals including terbinafine and griseofulvin, despite the rarity of significant blood abnormalities.
Over 10 years in the USA, Diedre Stolmeier and colleagues studied laboratory data from 4985 patients with a mean age of 43 years. Of these 4,309 received terbinafine and 739 griseofulvin. Abnormal laboratory test results abnormalities occurred in fewer than 0.23% of patients and only 1 patient experienced hepatotoxicity related to terbinafine (0.023%) which resolved on stopping therapy.
The rate of blood test abnormalities was similar to baseline levels, as found in this population. The drug information leaflet for terbinafine describes blood dyscrasias (Neutropenia, agranulocytosis, thrombocytopenia, pancytopenia) as very rare (<1 in 10,000) and either elevated liver enzymes or hepatic failure as rare (<1 in 1,000 but >1 in 10,000). For griseofulvin, anaemia, hepatic disorders, leucopenia and neutropenia are described as rare or very rare.
The authors conclude that monitoring terbinafine and griseofulvin therapy with routine blood tests is not worthwhile, especially for short course of therapy, as what was detected was “equivalent to the baseline rates of abnormalities in this population.” They argue that: “Abandoning frequent laboratory monitoring can decrease unnecessary health care spending, decrease patient psychological angst associated with blood draws, and allow for expanded use of these effective oral medications.”
Utility of Laboratory Test Result Monitoring in Patients Taking Oral Terbinafine or Griseofulvin for Dermatophyte Infections. Stolmeier DA, Stratman HB, McIntee TJ, Stratman EJ. JAMA Dermatol. 2018 Dec 1;154(12):1409-1416. doi: 10.1001/jamadermatol.2018.3578.