Population pharmacokinetic models have been developed and validated for piperacillin and tazobactam. Based on the pharmacokinetic/pharmacodynamic analysis, dosing recommendations are given considering the residual renal function of the patient and the MIC for the isolated bacteria.

The aim of this study was to assess the influence of renal function, in particular the presence of augmented renal clearance (ARC), on the pharmacokinetics of linezolid in critically ill patients. The effect of continuous infusion on the probability of therapeutic success from a pharmacokinetic/pharmacodynamic (PK/PD) perspective was also evaluated. Methods: Seventeen patients received linezolid (600 mg every 12 h) as a 30-min infusion and 26 as a continuous infusion (50 mg/h). The PK parameters were calculated and the probability of PK/PD target attainment (PTA) was estimated by Monte Carlo simulation (MCS) for different doses administered by intermittent (600 mg every 12 h or 600 mg every 8 h) or continuous infusion (50 mg/h or 75 mg/h). Results: In patients without ARC, the standard dose was adequate to attain the PK/PD target. However, linezolid clearance was significantly higher in ARC patients, leading to sub-therapeutic concentrations. Continuous infusion (50 mg/h) provided concentrations !2 mg/l in 70% of the ARC patients. MCS revealed that concentrations !2 mg/l would be reached in >90% of patients receiving 75 mg/h. Conclusions: ARC increases linezolid clearance and leads to a high risk of underexposure with the standard dose. Continuous infusion increases the PTA, but an infusion rate of 75 mg/h should be considered to ensure concentrations !2 mg/ml.

Domperidone, a dopamine antagonist that does not easily cross the blood-brain barrier, is considered the gold standard for treating gastrointestinal symptoms in patients with Parkinson's disease (PD) because the risk of developing extrapyramidal adverse effects is considered minimal. On the other hand, cardiotoxicity related to domperidone is not a new issue. In fact, arrhythmias, sudden death and cardiac arrest were reported with high intravenous doses in the 80s. Concern about the cardiotoxicity of oral domperidone has arisen more recently after the publication of two case-control studies which have questioned domperidone's safety even further, especially in patients > 60 years and in doses >30 mg/day. Very little is known about domperidone's cardiac effects in patients with PD. In addtion, pharmacoepidemiological data about specific antiemetic use in these patients is scarce, with almost anecdotal reports of inappropriate centrally acting antidopaminergic drugs like metoclopramide in the hospital setting. As a result, and even no cases of serious arrhythmias or sudden cardiac death associated with domperidone concerning patients with PD have been reported, no definitive conclusions can be drawn about its safety. In conclusion, despite domperidone is still recognized as the first choice for treating gastrointestinal symptoms PD, doses above 30 mg/daily should only be considered with special caution taking into account its potential cardiotoxic effects.

Antimicrobial treatment in critically ill patients remains challenging. The aim of this study was to develop a population pharmacokinetic model for linezolid in critically ill patients and to evaluate the adequacy of current dosing recommendation (600 mg/12 h). Forty inpatients were included, 23 of whom were subjected to continuous renal replacement therapies (CRRT). Blood and effluent samples were drawn after linezolid administration at defined time points, and linezolid levels were measured. A population pharmacokinetic model was developed, using NONMEM 7.3. The percentage of patients that achieved the pharmacokinetic/pharmacodynamic (PK/PD) targets was calculated (AUC24/MIC > 80 and 100% T>MIC). A two-compartment model best described the pharmacokinetics of linezolid. Elimination was conditioned by the creatinine clearance and by the extra-corporeal clearance if the patient was subjected to CRRT. For most patients, the standard dose of linezolid did not cover infections caused by pathogens with MIC ≥ 2 mg/L. Continuous infusion may be an alternative, especially when renal function is preserved.

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