Systemic Antifungal Drugs Require Close Monitoring

Debra Wood, RN

February 2011, Vol 2, No 1 - Meeting Highlights

Orlando, FL—The use of costly systemic antifungal drugs requires close monitoring to avoid the negative effects of drug interactions and side effects.

Barbara MetzkeBarbara Metzke, a pharmacist in the Department of Hematology and Oncology at the University Medical Center in Freiburg, Germany, and colleagues conducted a prospective analysis of the use of systemic antifungal drugs on 2 units at the hospital, an allogeneic stem-cell transplantation ward and one caring for primarily acute leukemia patients, enrolling consecutive patients receiving therapy or prophylaxis.

“The project came to light because of the rising cost of antifungals. Since 2004, the cost has more than doubled,” said Ms Metzke.

In 2009, systemic antifungal drugs accounted for 20% of the department’s inpatient drug expenses, including chemotherapeutics. Among the 120 patients studied, 70% did not exhibit any signs of fungal infection according to definitions from the European Organisation for Research and Treatment of Cancer/Mycoses Study Group criteria; 3% had a histologically proven invasive fungal infection.

Patients typically are started on empirical therapy if they have a fever or if a computed tomography scan of the lung identifies infiltrate, Ms Metzke said. The 5 drugs used were: liposomal amphotericin B, caspofungin, vori conazole, posaconazole, and fluconazole (which is given prophylactically to transplant patients).

Side effects leading to discontinuation of a drug were experienced by 13 patients. Of patients taking voriconazole, 6 developed side effects, including hallucinations/neurotoxicity and eleva ted liver enzymes.

Of patients taking amphotericin B, 5 stopped treatment as a result of skin reactions, declining renal function, and elevated liver enzymes. In addition, amphotericin B had the highest rate of potential drug interactions, with 48 of the 49 patients taking it exposed to at least 1 possible interaction and 35 patients exposed to ≥3 potential drug interactions.

“It’s challenging for the physician to select the right drug,” Ms Metzke suggested. She works with them on the units to check interactions.

The use and cost of systemic antifungals remains high at the hospital, but the team concluded that the reallife analysis of the drugs’ use is valuable because of the high number of side effects and potential drug interactions in patients receiving these agents.