T edizolid phosphate, the prodrug of the active moiety tedizolid, is approved for the treatment of acute bacterial skin and skin structure infections (1, 2). Population pharmacokinetic (PK) analyses demonstrated similar levels of tedizolid exposure across numerous patient factors, including age, sex, race, body weight, body mass index (BMI), and renal or hepatic function (3). The covariate accounting for the greatest variability in tedizolid PK was ideal body weight (IBW), an anthropometric measurement based on height and sex that approximates lean body weight (4). However, no clinically meaningful effects on tedizolid PK were seen across a wide range of IBW (3). It should be noted that the PK of linezolid, another oxazolidinone, but with fairly different elimination pathways in the body, was found to correlate best with total body weight (5, 6).Our group recently presented results from a phase 1 study suggesting that tedizolid exposure was about 25% lower in end-stage renal disease (ESRD) patients than in severely renally impaired subjects and matched controls (7). In order to better understand this modest difference, and considering the new information highlighting the role of IBW in tedizolid PK, we performed a post hoc analysis of our previously published data. The goal of this analysis was to evaluate whether between-group differences in IBW might explain the lower tedizolid levels in our ESRD subjects.To this end, we determined for each subject enrolled in that study the following data: area under the concentration-time curve from time zero to infinity (AUC 0 -ϱ ), which is the PK parameter most predictive of efficacy (8), and IBW calculated using the Devine formula (9). In the study, patients with ESRD requiring long-term hemodialysis, subjects with severe renal impairment (estimated glomerular filtration rate [eGFR] Ͻ30 ml/min/1.73 m 2 ) but not undergoing hemodialysis, and control subjects matched for age, sex, and BMI to severely renally impaired subjects were enrolled (n ϭ 8 each). All subjects received a single 200-mg intravenous dose of tedizolid phosphate. In the ESRD group, infusions were administered either before or within 1 h of completing hemodialysis in a crossover fashion. Detailed methodology and results of this study have been published previously (clinicaltrials.gov registration number NCT01452828) (7). For subjects in the ESRD group, we limited the analysis to PK data obtained when tedizolid was infused postdialysis (although any potential impact of hemodialysis on tedizolid exposure was previously shown to be negligible [7]). The mean (standard deviation) AUC 0 ϱ values were 23.27 (7.50) g · h/ml in the ESRD group, 29.99 (8.97) g · h/ml in the severe renal impairment, and 32.43 (9.53) g · h/ml in the control group. Overall median IBW was 67.05 kg. The ESRD group had more subjects in the upper half of the IBW range (n ϭ 7) than the severe renal impairment (n ϭ 3) and control (n ϭ 2) groups. The mean (standard deviation) IBW was highest in the ESRD group (70.73 [11.52]