139. Evaluation of Safety and Efficacy of a Vancomycin (VAN) Dosing Protocol Developed for Morbidly Obese (MO) Adult Patients
Session: Poster Abstract Session: Antimicrobial Stewardship: Adverse Drug Events
Thursday, October 8, 2015
Room: Poster Hall
Posters
  • Vancomycin Morbid Obesity ID Week Poster.png (158.3 kB)
  • Background: The 2009 ASHP/IDSA/SIDP consensus statement recommends VAN loading dose (LD) of 25-30mg/kg followed by maintenance dose (MD) of 15-20mg/kg Q8-12H. Prior studies suggested that MO patients might require lower mg/kg doses to achieve therapeutic trough concentrations (TTC) but the exact dosing strategy remains unknown. An internal review in June 2013 revealed 43% incidence of supratherapeutic trough concentrations (TC) and 39% incidence of VAN-associated nephrotoxicity in our MO patients receiving VAN doses consistent with 2009 consensus statement. Institutional dosing protocol for MO patients was revised to recommend: LD 25-30mg/kg (max 3000mg), MD 10-12.5mg/kg (max 2000mg) Q12H. We evaluated initial TTC attainment and VAN-associated nephrotoxicity post protocol revision.

    Methods: MO adult patients (BMI ≥ 40kg/m2) who received intravenous VAN between 6/1/2012-5/31/2013 and 8/1/2013-7/31/2014  were included. Perioperative VAN, one-time doses, pregnancy, hemodialysis and patients in acute renal failure and those receiving VAN prior to admission were excluded.  

    Results: A random sample of 69 patients was reviewed (pre-revision: 35, post-revision: 34). Demographics and initial VAN dosing are summarized in table 1. Pre vs post protocol-revision, initial TTC attainment and median initial TC were similar in the overall sample (TTC: 46% vs 44%, p = 0.89, TC: 18.1 vs 17.0 mcg/mL, p = 0.52) and in the subgroup which doses adhered to protocol (TTC: 43% vs 48%, p = 0.78, 21.2 vs 16.6 mcg/mL, p = 0.22). The revised protocol resulted in less initial TC > 30 mcg/mL (17% vs 9%, p = 0.31), more initial TC < 10 mcg/mL (3% vs 21%, p = 0.03) and decreased incidence of VAN-associated nephrotoxicity (23% vs 4%, p = 0.03). There were no differences in mortality (11% vs 0%, p = 0.11) and length of stay (16 vs 11 days, p = 0.31).

    Table 1

     

    Pre-Revision

    Post-Revision

    p-Value

    Age (years)*

    52 ± 14

    51 ± 16

    0.77

    Gender (male, %)

    31

    44

    0.28

    BMI (40kg/m2)*

    48 ± 11

    46 ± 12

    0.88

    Adherence with Dosing Protocol (%)

    86

    62

    0.02

    LD (%)

    31

    56

    0.04

    MD (mg/kg/day)*

    27 ± 7

    25 ± 9

    0.05

    *Data shown as mean ± SD

    Conclusion: A revised dosing protocol improved safety of VAN therapy in MO patients. Doses > 10-12.5mg/kg and increased utilization of LD may be necessary to minimize subtherapeutic initial TC.

    Zhe Han, PharmD1, Lea Mollon, PharmD2, Natasha Pettit, PharmD1 and Jennifer Pisano, MD3, (1)Pharmacy Services, The University of Chicago Medicine, Chicago, IL, (2)The University of Chicago Medicine, Chicago, IL, (3)Infectious Diseases and Global Health, The University of Chicago Medicine, Chicago, IL

    Disclosures:

    Z. Han, None

    L. Mollon, None

    N. Pettit, None

    J. Pisano, None

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