Population pharmacokinetics of ceftriaxone administered as continuous or intermittent infusion in critically ill patients.

OBJECTIVES: To describe the population pharmacokinetics and protein-binding characteristics of unbound ceftriaxone administered as continuous or intermittent infusion. Additionally, to determine the optimal dosing regimen in critically ill patients. METHODS: A pharmacokinetic study was performed in the ICU of a tertiary teaching hospital. Patients were treated with ceftriaxone as continuous or intermittent infusion. A population pharmacokinetic model was developed with non-linear mixed-effects analysis. Subsequently, the PTA of a 100% T>MIC was assessed for influential patient characteristics using Monte Carlo simulation. RESULTS: Fifty-five patients were included. The pharmacokinetics of ceftriaxone was best described by a one-compartment model with non-linear saturable protein binding including the following covariates: body weight, estimated CLCR, serum albumin concentration and mode of administration. For pathogens with an MIC of 1 mg/L, the simulation demonstrated that intermittent infusion of 2 g/24 h only resulted in a ≥90% PTA in patients with a reduced CLCR (0-60 mL/min). Intermittent infusion of 2 g/12 h led to sufficient exposure if CLCR was 0-90 mL/min and continuous infusion of 2 g/24 h led to a ≥90% PTA in all simulations (CLCR 0-180 mL/min). CONCLUSIONS: In the critically ill, the clearance of unbound ceftriaxone is closely related to CLCR. Furthermore, ceftriaxone protein binding is saturable, variable and dependent on serum albumin concentration. Intermittent dosing of 2 g/24 h ceftriaxone leads to subtherapeutic exposure in patients with a normal or increased CLCR. Treating these patients with continuous infusion of 2 g/24 h is more effective than an intermittent dosing regimen of 2 g/12 h.

Incidence of refeeding syndrome in internal medicine patients.

BACKGROUND: Refeeding syndrome is a potentially fatal shift of fluids and electrolytes that may occur after reintroducing nutrition in a malnourished patient. Its incidence in internal medicine patients is not known. We aimed at determining the incidence in a heterogeneous group of patients acutely admitted to a department of internal medicine. METHODS: All patients acutely admitted to the department of internal medicine of a teaching community hospital in Amsterdam, the Netherlands, between 22 February 2011 and 29 April 2011, were included. We applied the National Institute for Health and Care Excellence (NICE) criteria for determining people at risk of refeeding syndrome and took hypophosphataemia as the main indicator for the presence of this syndrome. RESULTS: Of 178 patients included in the study, 97 (54%) were considered to be at risk of developing refeeding syndrome and 14 patients actually developed the syndrome (14% of patients at risk and 8% of study population). Patients with a malignancy or previous malignancy were at increased risk of developing refeeding syndrome (p < 0.05). Measurement of muscle strength over time was not associated with the occurrence of refeeding syndrome. The Short Nutritional Assessment Questionnaire score had a positive and negative predictive value of 13% and 95% respectively. CONCLUSION: The incidence of refeeding syndrome was relatively high in patients acutely admitted to the department of internal medicine. Oncology patients are at increased risk of developing refeeding syndrome. When taking the occurrence of hypophosphataemia as a hallmark, no other single clinical or composite parameter could be identified that accurately predicts the development of refeeding syndrome.