Abstract
This study was conducted to characterise the pharmacokinetics of a liposomal pharmaceutical product of amphotericin B (LAB) in three neutropenic cancer patients complicated by suspected fungal infections. LAB was administered at a constant dose of 50 mg/day over 1--6 h by intravenous infusion, and blood samples were obtained between two infusion intervals without complicating the systemic therapy of the patients. Quantitative analysis of amphotericin B (AB) in plasma was established by a validated reversed-phase high-performance liquid chromatographic (HPLC) assay. Model independent pharmacokinetic parameters were estimated using area and moment analysis. Administration of LAB to the first patient (day 1) diagnosed as malignant melanoma resulted in a mean maximum concentration (C(max)) of 679+/-6 ng/ml and a mean minimum concentration (C(min)) of 139+/-9 ng/ml of AB. Pre-dose, C(max) and C(min) values of AB, after multiple LAB dosing to the other two patients both having acute myeloblastic leukemia were found to be 440+/-6, 1140+/-10, 409+/-11 ng/ml (day 19) and 408+/-3, 1180+/-10, and 283+/-1 ng/ml (day 9), respectively. The area under the plasma concentration-time curve (AUC) and the mean residence time (MRT) calculated between the two infusion intervals were 6180 ngh/ml, 7.79 h (day 1) for the first patient; 13,700 ng.h/ml, 10.5 h (day 19) and 14,000 ng.h/ml, 9.93 h (day 9) for the other two patients, respectively. The pharmacokinetic profiles and non-compartmental parameters calculated were comparable for both patients diagnosed with acute myeloblastic leukemia after multiple dosing at steady state, which also demonstrated a twofold increase in their AUC values compared with the AUC of the first patient. Although C(min) values supported the assumption that there was AB accumulation in plasma and this accumulation could be increased at high doses, LAB was administered safely to these patients and well tolerated at the doses given.
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