Evaluation of a vancomycin dosing nomogram in obese patients weighing at least 100 kilograms.

BACKGROUND: There remains variability in both practice and evidence related to optimal initial empiric dosing strategies for vancomycin. OBJECTIVE: Our primary objective was to describe the percentage of obese patients receiving vancomycin doses consistent with nomogram recommendations achieving targeted initial steady-state serum vancomycin concentrations. Secondary objectives were to describe the primary endpoint in subgroups based on patient weight and estimated creatinine clearance, to describe the rate of supratherapeutic vancomycin accumulation following an initial therapeutic trough concentration, and to describe the rate of vancomycin-related adverse events. METHODS: This single-center, IRB-approved, retrospective cohort included adult patients ≥ 100 kilograms total body weight with a body mass index (BMI) >30 kilograms/m2 who received a stable nomogram-based vancomycin regimen and had at least one steady-state vancomycin trough concentration. Data collected included vancomycin regimens and concentrations, vancomycin indication, serum creatinine, and vancomycin-related adverse events. Patients were divided into two cohorts by goal trough concentration: 10-15 mcg/mL and 15-20 mcg/mL. RESULTS: Of 325 patients screened, 85 were included. Goal steady-state concentrations were reached in 42/85 (49.4%) of total patients. CONCLUSIONS: Achievement of initial steady-state vancomycin serum concentrations in the present study (approximately 50%) was consistent with the use of published vancomycin dosing nomograms.

Evaluation of a vancomycin dosing nomogram in obese patients weighing at least 100 kilograms

Background: There remains variability in both practice and evidence related to optimal initial empiric dosing strategies for vancomycin. Objective: Our primary objective was to describe the percentage of obese patients receiving vancomycin doses consistent with nomogram recommendations achieving targeted initial steady-state serum vancomycin concentrations. Secondary objectives were to describe the primary endpoint in subgroups based on patient weight and estimated creatinine clearance, to describe the rate of supratherapeutic vancomycin accumulation following an initial therapeutic trough concentration, and to describe the rate of vancomycin-related adverse events. Methods: This single-center, IRB-approved, retrospective cohort included adult patients ≥ 100 kilograms total body weight with a body mass index (BMI) >30 kilograms/m2 who received a stable nomogram-based vancomycin regimen and had at least one steady-state vancomycin trough concentration. Data collected included vancomycin regimens and concentrations, vancomycin indication, serum creatinine, and vancomycin-related adverse events. Patients were divided into two cohorts by goal trough concentration: 10-15 mcg/mL and 15-20 mcg/mL. Results: Of 325 patients screened, 85 were included. Goal steady-state concentrations were reached in 42/85 (49.4%) of total patients. Conclusions: Achievement of initial steady-state vancomycin serum concentrations in the present study (approximately 50%) was consistent with the use of published vancomycin dosing nomograms

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Undetectable Vancomycin Concentrations Utilizing a Particle Enhanced Turbidimetric Inhibition Immunoassay in a Patient with an Elevated IgM Level.

BACKGROUND: A case of undetectable vancomycin concentrations with the use of a particle enhanced turbidimetric inhibition immunoassay is reported. METHODS: A 73-year-old woman with B-cell lymphoma, chronic neutropenia with myelodysplastic syndrome and elevated IgM levels displayed repeated undetectable vancomycin concentrations, despite appropriate empiric vancomycin dosing. The vancomycin concentrations were processed utilizing a particle enhanced turbidimetric inhibition immunoassay (PETINIA). Patients with high concentrations of paraproteins in their serum may have interference with the PETINIA. This may include patients with plasma cell dyscrasias and lymphoreticular malignancies associated with abnormal immunoglobulin synthesis. RESULTS: Repeated undetectable vancomycin drug concentrations prompted us to send a serum sample to an outside facility to utilize another standardized assay, enzyme multiplied immunoassay (EMIT), which resulted in a detectable vancomycin serum concentration. The patient's undetectable vancomycin drug concentrations with the PETINIA may have been due to abnormal immunoglobulin synthesis interference with the assay. A limited number of case reports have been published demonstrating undetectable or unexpectedly elevated vancomycin concentrations due to monoclonal immunoglobulin interference in patients with immunological disorders. CONCLUSIONS: A 73-year-old woman with B-cell lymphoma, chronic neutropenia with myelodysplastic syndrome and elevated IgM levels may have had interference with a PETINIA resulting in undetectable vancomycin concentrations.

Safety of Levalbuterol Compared to Albuterol in Patients With a Tachyarrhythmia.

Objective: To determine the safety of levalbuterol versus albuterol in patients with a tachyarrhythmia. Data Sources: A PubMed search was conducted using the MeSH search terms levalbuterol, albuterol, and tachyarrhythmia. Bibliographies of relevant articles were reviewed for additional citations. Study Selection and Data Extraction: Search results were limited to humans and randomized controlled trials. Those studies that excluded patients with predetermined tachyarrhythmias were excluded from this review. Trials that failed to compare levalbuterol and albuterol outcomes were excluded. Data Synthesis: Beta-2 receptor agonists are the mainstay of treatment in patients with respiratory disease, such as asthma or chronic obstructive pulmonary disease. Racemic albuterol has been linked to poor outcomes due to the fact that it contains both the S-isomer and the R-isomer. Levalbuterol, the "pure" R-isomer, has been thought to decrease cardiac side effects since it only contains the therapeutic component of the racemic mixture. Patients with tachyarrhythmias are at an increased probability to experience harmful, if not fatal, cardiac side effects from these drugs. Limitations of current studies include a lack of data in patient populations with baseline tachyarrhythmias. Conclusions: Tachyarrhythmias put a patient at increased risk of poor outcomes, including death. Evidence for using either racemic albuterol or levalbuterol for respiratory disease management in these patients is lacking and insufficient. Randomized controlled trials show that in intensive care unit patient populations there is no clear advantage to using levalbuterol over albuterol; however, this did not hold true in pediatric populations. No clinical trials exist that look at a direct comparison of these 2 agents in patients with underlying tachyarrhythmias. Further research into the most efficacious and safe ß-2 receptor agonists in this specialized patient population should be conducted to help reduce potential harmful outcomes.