1381. Impact of Total Body Weight on Efficacy of Ceftriaxone in Obese Patients
Session: Poster Abstract Session: PK/PD Studies
Friday, October 5, 2018
Room: S Poster Hall
  • ID Week_CTX_FINAL.pdf (395.0 kB)
  • Background:

    Ceftriaxone (CRO), while highly protein bound, retains a small volume of distribution. Obese patients have larger volumes of distributions and higher clearance than non-obese patients. The effect of these differences on the pharmacokinetics and efficacy of CRO remain unclear.


    This retrospective cohort study included adult inpatients who received CRO for ≥72 hours (h) as definitive monotherapy from July 2015 to July 2017. Patients were excluded if there was a lack of adequate source control at 72h or if there was a polymicrobial infection requiring multiple antibiotics. Obesity was defined as BMI ≥30 kg/m2. The primary outcome was clinical treatment failure, defined as changing therapy at >72h due to clinical worsening, leukocytosis (WBC>10x109/L), fever (single temperature >100.9°F)for >72h, or readmission to the hospital within 30 days for re-infection. Secondary outcomes included discharge disposition and 30-day readmission.


    One hundred one patients were included: 39 obese patients and 62 non-obese patients. Median [IQR] age was 62 [51-70] years; 55% males. Median weight was 103 [95-120] kg in obese patients versus 66 [58-77] kg in non-obese patients (p<0.001). There were no differences in comorbidities (Charlson 3[1-5] obese vs 2[1-4] non-obese; p=0.293). Infection sources were similar: urinary tract (54% obese vs 52% non-obese; p=0.827), respiratory (28% obese vs 23% non-obese; p=0.524), bloodstream (20% obese vs 23% non-obese; p=0.806). The most common causative organism was E. coli(48%). There were no differences in CRO regimen between groups (1g q24h: obese 54% vs non-obese 69%; p=0.115). Treatment failure occurred in 24 (61%) obese patients compared to 25(40%) non-obese patients (p=0.038). Obese patients had delayed resolution of leukocytosis (54% vs 29%, p=0.013). Eight patients died (13% obese vs 5% non-obese; p=0.255); 82% of patients were not readmitted within 30 days.


    Obese patients treated with ceftriaxone had higher rates of treatment failure compared with non-obese patients. While not statistically significant, there was numerically higher mortality in obese patients compared with non-obese patients. Obese patients may be slow to recover from infection when treated with CRO.

    Jamie L. Wagner, PharmD, J. Taylor Loper, PharmD Candidate, Austin R. Morrison, PharmD Candidate, Kayla R. Stover, PharmD, BCPS and Katie E. Barber, PharmD, University of Mississippi School of Pharmacy, Jackson, MS


    J. L. Wagner, None

    J. T. Loper, None

    A. R. Morrison, None

    K. R. Stover, None

    K. E. Barber, None

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