Evaluation of a New Vancomycin Dosing Protocol in Morbidly Obese Patients. Issue 9 (October 2015)

• Record Type: Journal Article
• Authors: Kosmisky, Desiree E.; Griffiths, Carrie L.; Templin, Megan A.; Norton, James; Martin, Kelly E.
• Is Part Of: Hospital pharmacy. Volume 50:Issue 9(2015)
• Page Start: 789
• Page End: 797
• Publication Date: 2015-10
• Subjects: dosing -- obesity -- therapeutic drug monitoring -- vancomycin; Hospital pharmacies -- Periodicals; Pharmacy Service, Hospital; Hospital pharmacies; Periodicals; Periodicals; 615.1
• DOI: 10.1310/hpj5009-789
• Languages: English
• ISSNs: 0018-5787

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.