Evaluation of Total Body Weight versus Adjusted Body Weight Liposomal Amphotericin B Dosing in Obese Patients

Liposomal amphotericin B (LAmB) is used for various fungal infections, but it is unclear which dosing weight to use in obese patients. The purpose of this study was to compare clinical outcomes of adjusted body weight (adjBW) versus total body weight (TBW) dosing of LAmB. This single-center, retrospective cohort study included patients who received LAmB for definitive therapy and whose TBW exceeded 120% of their ideal body weight (IBW). Analyses were conducted for 3 mg/kg for adjBW versus TBW and 5 mg/kg for adjBW versus TBW. A total of 238 patients were included. For the 68 patients who received LAmB at 3 mg/kg, there were no differences in safety or efficacy outcomes. For the 170 patients who received LAmB at 5 mg/kg, significantly more patients in the TBW group experienced the primary outcome of nephrotoxicity (57% versus 35% [P value of 0.016]) and had significantly higher rates of early discontinuation of LAmB due to toxicity (33% versus 17% [P = 0.030]). There was a trend toward increased 90-day mortality in the adjBW group (60% versus 45% [P = 0.079]); however, adjBW dosing was not associated with increased mortality in an adjusted model. Given the lower rates of nephrotoxicity but a possible trend toward increased mortality in patients whose TBW exceeds 120% of their IBW, dosing LAmB by adjBW may be reasonable in patients who are not critically ill and who have lower-risk infections. In critically ill patients or those with fungal pathogens or sites of infection associated with higher mortality risk, dosing by TBW can be considered.