Desiree E Kosmisky1, Carrie L Griffiths2, Megan A Templin3, James Norton4, Kelly E Martin5. 1. Critical Care Pharmacy Specialist, Carolinas Healthcare System , Charlotte, North Carolina. 2. Medical ICU Clinical Pharmacy Specialist, Carolinas Medical Center, Charlotte, North Carolina; Assistant Professor of Pharmacy, Wingate University School of Pharmacy, Wingate, North Carolina. 3. Statistician, Dickson Advanced Analytics Group, Carolinas Healthcare System , Charlotte, North Carolina. 4. Director of Biostatistics, Carolinas Healthcare System, Charlotte , North Carolina. 5. Infectious Diseases and Antimicrobial Stewardship Clinical Pharmacy Specialist, Carolinas Medical Center, Charlotte , North Carolina .
Abstract
BACKGROUND: Optimal dosing of vancomycin in morbidly obese patients (>100 kg and at least 140% of their ideal body weight) has not been determined. Conventional dosing strategies have led to the observation of supratherapeutic trough concentrations (>20 mcg/mL). OBJECTIVE: To evaluate the effectiveness of a new vancomycin dosing protocol in morbidly obese patients in achieving therapeutic trough concentrations between 10 and 20 mcg/mL and to determine patient-specific factors influencing the trough concentration attained. METHODOLOGY: A single-center, retrospective chart review included morbidly obese adult patients with a pharmacy-to-dose vancomycin consult and at least 1 trough concentration obtained at steady state. Patients were excluded if they had a creatinine clearance (CrCl) less than 35 mL/min or unstable renal function, were not dosed according to the revised protocol, or received vancomycin prior to initiation of the protocol. RESULTS: Of the 48 patients included, 17 (35.4%) achieved a therapeutic vancomycin trough concentration. Subtherapeutic concentrations (<10 mcg/mL) were observed in 27 patients (56.3%) and supratherapeutic concentrations were observed in 4 (8.3%) patients. Age less than 45 years and CrCl greater than 100 mL/min were associated with subtherapeutic trough concentrations. CONCLUSION: This study demonstrates that the revised vancomycin dosing protocol led to the attainment of therapeutic trough concentrations in 35.4% of patients. The majority had subtherapeutic concentrations, which increases the risk of treatment failures and resistance. Further study is needed to determine the optimal dosing strategy in this patient population.
BACKGROUND: Optimal dosing of vancomycin in morbidly obesepatients (>100 kg and at least 140% of their ideal body weight) has not been determined. Conventional dosing strategies have led to the observation of supratherapeutic trough concentrations (>20 mcg/mL). OBJECTIVE: To evaluate the effectiveness of a new vancomycin dosing protocol in morbidly obesepatients in achieving therapeutic trough concentrations between 10 and 20 mcg/mL and to determine patient-specific factors influencing the trough concentration attained. METHODOLOGY: A single-center, retrospective chart review included morbidly obese adultpatients with a pharmacy-to-dose vancomycin consult and at least 1 trough concentration obtained at steady state. Patients were excluded if they had a creatinine clearance (CrCl) less than 35 mL/min or unstable renal function, were not dosed according to the revised protocol, or received vancomycin prior to initiation of the protocol. RESULTS: Of the 48 patients included, 17 (35.4%) achieved a therapeutic vancomycin trough concentration. Subtherapeutic concentrations (<10 mcg/mL) were observed in 27 patients (56.3%) and supratherapeutic concentrations were observed in 4 (8.3%) patients. Age less than 45 years and CrCl greater than 100 mL/min were associated with subtherapeutic trough concentrations. CONCLUSION: This study demonstrates that the revised vancomycin dosing protocol led to the attainment of therapeutic trough concentrations in 35.4% of patients. The majority had subtherapeutic concentrations, which increases the risk of treatment failures and resistance. Further study is needed to determine the optimal dosing strategy in this patient population.
Entities:
Keywords:
dosing; obesity; therapeutic drug monitoring; vancomycin
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