Research & Development

Relationship of itraconazole levels to toxicity (audit)
Some patients who take itraconazole (ITZ) develop adverse events. This project was set to audit the relationship between ITZ concentrations and the probability of toxicity. Patients who received ITZ and underwent therapeutic drug monitoring (TDM) were identified from the Regional Mycology Laboratory database. The following information was obtained from patients’ medical records: age, gender, diagnosis, ITZ dosages and duration of treatment. All plasma ITZ concentrations were measured by bioassay. Toxicity was defined as any symptom, sign or biochemical disturbance that occurred during treatment and resolved or improved with ITZ withdrawal or dose-reduction. Observed features of toxicity were sub-classified as gastro-intestinal, cutaneous, metabolic disturbance, and symptoms of fluid retention. For patients with toxicity, the mean±SD ITZ concentration in the 3 months preceding an adverse event were calculated. These were compared to ITZ concentrations in an equivalent 3-month-period for patients without adverse events.  The relationship between mean ITZ concentrations and the probability of an adverse event was defined using logistic regression.