Weight-based versus set dosing of vancomycin for coronary artery bypass grafting or aortic valve surgery.

OBJECTIVES: This study was undertaken to identify a preferred dosing strategy for patients undergoing coronary artery bypass grafting or valve replacement procedures with cardiopulmonary bypass. METHODS: Patients undergoing coronary artery bypass grafting, valve replacement surgery, or both were randomly assigned to receive either standard 1-g dosing with vancomycin before and after cardiopulmonary bypass or a single weight-based 20-mg/kg dose before surgery. The primary outcome was the percentage of time plasma concentrations were greater than 15 µg/mL during cardiopulmonary bypass and at surgical closure. Secondary outcomes included concentration of vancomycin in endothoracic tissue after vancomycin infusion, average time patients had vancomycin concentrations greater than 15 µg/mL, and vancomycin plasma and tissue pharmacokinetic parameters. RESULTS: Baseline characteristics were similar between the study dosing group (n = 10) and the standard dosing group (n = 10). From postinfusion to end of bypass, the median percentage of time vancomycin concentrations remained greater than 15 µg/mL was 100% (interquartile range [IQR], 72.6%-100%) for weight-based dosing versus 43.7% (IQR, 28.7%-53.4%) for standard dosing (P = .0005). From postinfusion to surgical closure, the percentage of time vancomycin concentrations remained greater than 15 µg/mL was significantly higher in the weight-based group (100% [IQR, 58.3%-100%] vs 34.6% [IQR, 25.3%-41.6%]; P = .0005). Weight-based dosing increased calculated time with vancomycin concentrations greater than 15 µg/mL and resulted in higher endothoracic tissue vancomycin concentrations. CONCLUSIONS: Weight-based vancomycin dosing before coronary artery bypass grafting or valve replacement results in vancomycin concentrations greater than 15 µg/mL consistently more than does standard 1-g dosing.

Fatal case of cephalexin-induced toxic epidermal necrolysis.

PURPOSE: To describe a case of toxic epidermal necrolysis likely caused by cephalexin with a review of the literature. CASE: An 80-year-old male with a known allergy to cephalosporins, residing at a long-term acute care hospital, received cephalexin for a urinary tract infection. And 1 day after starting therapy, the patient developed an extensive erythematous rash accompanied by skin sloughing; 4 days after receiving cephalexin, the patient was directly admitted to the burn intensive care unit and was diagnosed with toxic epidermal necrolysis involving 56% of the total body surface area. Progressive deterioration to multisystem organ failure ensued, and the patient died 5 days following his admission to the burn intensive care unit. At the time of death, ulcerations were noted over approximately 80% of his body. SUMMARY: The temporal association of the patient's ingestion of cephalexin for a urinary tract infection to his onset of toxic epidermal necrolysis suggests that this 80-year-old man developed toxic epidermal necrolysis following the administration of cephalexin for a urinary tract infection.

Effect of intravenous ondansetron on QT interval prolongation in patients with cardiovascular disease and additional risk factors for torsades: a prospective, observational study.

BACKGROUND: The 5-hydroxytryptamine type 3 antagonists, or setrons (eg, ondansetron), are commonly used for nausea and vomiting in the hospital setting. In 2001, droperidol was given a black box warning because it was found to prolong the QT interval and induce arrhythmias. The setrons share with droperidol the same potential proarrhythmic mechanisms, but limited data exist concerning their effects on the QT interval in individuals at high risk for torsades de pointes. METHODS: Forty hospitalized patients admitted for heart failure or acute coronary syndromes with one or more risk factors for torsades de pointes and an order for intravenous ondansetron 4 mg were enrolled in this prospective, observational study. The QT interval corrected for heart rate (QTc) was obtained via a 12-lead electrocardiogram on admission and again 120 minutes after the first dose of ondansetron in order to determine the mean change in QTc following ondansetron exposure. RESULTS: The mean time interval between obtaining the baseline electrocardiogram and the second electrocardiogram following ondansetron administration was 3.5 ± 2.14 hours. In the total population, the QTc interval was prolonged by 19.3 ± 18 msec (P < 0.0001) 120 minutes after ondansetron administration. For patients with an acute coronary syndrome and those with heart failure, QTc was prolonged by 18.3 ± 20 msec (P < 0.0001) and 20.6 ± 20 msec (P < 0.0012), respectively. Following ondansetron exposure, 31% and 46% in the heart failure and acute coronary syndromes groups, respectively, met gender-related thresholds for a prolonged QTc. CONCLUSION: Our study found QTc prolongation due to ondansetron administration similar to that found in previous studies. When used in patients with cardiovascular disease (eg, heart failure or acute coronary syndromes) with one or more risk factors for torsades de pointes, ondansetron may significantly increase the QTc interval for up to 120 minutes after administration. From a patient safety perspective, patients who are at high risk for torsades de pointes and receiving ondansetron should be followed via telemetry when admitted to hospital.