Population Pharmacokinetic-Pharmacodynamic Analysis of Anidulafungin in Adult Patients with Fungal Infections

To evaluate the exposure-response relationships for efficacy and safety of intravenous anidulafungin in adult patients with fungal infections, a population pharmacokinetic-pharmacodynamic (PK-PD) analysis was performed with data from 262 patients in four phase 2/3 studies. The plasma concentration data were fitted with a previously developed population PK model. Anidulafungin exposures in patients with weight extremities (e.g., 40 kg and 150 kg) were simulated based on the final PK model. Since the patient population, disease status, and efficacy endpoints varied in these studies, the exposure-efficacy relationship was investigated separately for each study using logistic regression as appropriate. Safety data from three studies (n = 235) were pooled for analysis, and one study was excluded due to concomitant use of amphotericin B as a study treatment and different disease populations. The analysis showed that the same dosing regimen of anidulafungin can be administered to all patients regardless of body weight. Nonetheless, caution should be taken for patients with extremely high weight (e.g., >150 kg). There was a trend of positive association between anidulafungin exposure and efficacy in patients with esophageal candidiasis or invasive candidiasis, including candidemia (ICC); however, adequate characterization of the effect of anidulafungin exposure on response could not be established due to the relatively small sample size. No threshold value for exposure could be established, since patients with low exposure also achieved successful outcomes (e.g., area under the curve <40 mg.h/liter in ICC patients). There was no association between anidulafungin exposure and the treatment-related adverse events or all-causality hepatic laboratory abnormalities.