Sonia Luque

Trough colistin plasma level is an independent risk factor for nephrotoxicity: a prospective observational cohort study

BackgroundData regarding the most efficacious and least toxic schedules for the use of colistin are scarce. The aim of this study was to determine the incidence and the potential risk factors of colistin-associated nephrotoxicity including colistin plasma levels.MethodsA prospective observational cohort study was conducted for over one year in patients receiving intravenous colistin methanesulfonate sodium (CMS). Blood samples for colistin plasma levels were collected immediately before (Cmin) and 30 minutes after CMS infusion (Cmax). Renal function was assessed at baseline, on day 7 and at the end of treatment (EOT). Severity of acute kidney injury (AKI) was defined by the RIFLE (risk, injury, failure, loss, and end-stage kidney disease) criteria.ResultsOne hundred and two patients met the inclusion criteria. AKI related to CMS treatment on day 7 and at the end of treatment (EOT) was observed in 26 (25.5%) and 50 (49.0%) patients, respectively. At day 7, Cmin (OR, 4.63 [2.33-9.20]; P < 0.001) was the only independent predictor of AKI. At EOT, the Charlson score (OR 1.26 [1.01-1.57]; P = 0.036), Cmin (OR 2.14 [1.33-3.42]; P = 0.002), and concomitant treatment with ≥ 2 nephrotoxic drugs (OR 2.61 [1.0-6.8]; P = 0.049) were independent risk factors for AKI. When Cmin was evaluated as a categorical variable, the breakpoints that better predicted AKI were 3.33 mg/L (P < 0.001) on day 7 and 2.42 mg/L (P < 0.001) at EOT.ConclusionsWhen using the RIFLE criteria, colistin-related nephrotoxicity is observed in a high percentage of patients. Cmin levels are predictive of AKI. Patients who receive intravenous colistin should be closely monitored and Cmin might be a new useful tool to predict AKI.

Comparative effects of olive oil-based and soyabean oil-based emulsions on infection rate and leucocyte count in critically ill patients receiving parenteral nutrition

Soyabean oil-based emulsions high in linoleic acid used in parenteral nutrition (PN) could interfere with immune function and may increase the risk of septic complications. Olive oil-based emulsions, high in oleic acid, could have fewer immune effects. We compared the effects of a soyabean oil-based emulsion v. an olive oil-based emulsion on infection rate, appearance of new infection episodes, leucocyte count (peak and evolution), acute-phase proteins, and major health outcomes in intensive care unit (ICU) adult patients receiving PN. The study was designed as an observational, retrospective, single-centre, cohort study in a general ICU. Patients in the SOYA cohort (n 16) received a soyabean oil-based emulsion and patients in the OLIVE cohort (n 23), an olive oil-based emulsion. Both cohorts had similar basal characteristics and received a similar energy load. The SOYA cohort received an oleic acid:linoleic acid ratio of 0.43 and the OLIVE cohort 2.99 (P < 0.001). No differences were observed in infection rate and appearance, acute-phase proteins, and major health outcomes. At the end of PN, blood leucocyte count decreased by 3.25 x 109 cells/l in the SOYA cohort and increased by 4.51 x 109 cells/l in the OLIVE cohort from baseline values (P = 0.036). Peak leucocyte count presented a trend for a higher value in the OLIVE cohort v. the SOYA cohort (18.86 v. 15.28 x 109 cells/l; P = 0.078). The use of an olive oil-based emulsion in PN had no effect on infection, acute-phase proteins, major health outcomes, and presented higher leucocyte count at the end of PN and a trend to higher peak leucocyte count when compared with soyabean oil-based emulsion in ICU patients.

Plasma and peritoneal fluid population pharmacokinetics of micafungin in post-surgical patients with severe peritonitis

OBJECTIVES Limited information about the pharmacokinetics of micafungin in the peritoneal cavity is available. The aim of this study was to explore the pharmacokinetics/pharmacodynamics of micafungin in plasma and peritoneal fluid in post-surgical critically ill patients with proven or suspected intra-abdominal fungal infection. METHODS Patients were administered 100 mg/day micafungin. Serial blood and peritoneal fluid samples were collected on day 1 and day 3 (steady-state) of treatment. Concentrations were determined by validated chromatography and were subject to a population pharmacokinetic analysis with Pmetrics(®). Monte Carlo simulations were performed for AUC0-24/MIC ratios in plasma. The PTA was calculated using AUC0-24/MIC cut-offs: 285 for Candida parapsilosis and 3000 for non-parapsilosis Candida spp. RESULTS Ten patients were included; six were male. The median (range) age, APACHE II score and Mannheim peritonitis index were 72 (43-85) years, 15 (11-36) and 26 (8-37), respectively. On day 1, median (SD) penetration of micafungin into the peritoneal cavity was 30% (30%-40%). A three-compartment model adequately described the data. The mean (SD) estimates for clearance and volume of distribution of the central compartment were 1.27 (0.75) L/h and 9.26 (1.11) L, respectively. In most patients, the PTA in plasma was ≥ 90% for MICs of 0.008-0.016 mg/L for Candida spp. and 0.125-0.25 mg/L for C. parapsilosis. CONCLUSIONS After the first dose, micafungin at 100 mg/day achieves pharmacokinetic/pharmacodynamic targets in plasma for Candida spp. and C. parapsilosis MICs of 0.008-0.016 and 0.125-0.25 mg/L, respectively.

Micafungin pharmacokinetic/pharmacodynamic adequacy for the treatment of invasive candidiasis in critically ill patients on continuous venovenous haemofiltration

OBJECTIVES To explore the pharmacokinetics (PK) and pharmacodynamics (PD) of micafungin in patients undergoing continuous venovenous haemofiltration (CVVH). PATIENTS AND METHODS Ten patients receiving CVVH treated with 100 mg/day micafungin were included (April-December 2012). CVVH was performed using polyethersulphone or polysulphone haemofilters. Dialysis membranes were not changed on sampling days. On Days 1 and 2, blood samples from arterial pre-filter and venous post-filter ports and ultrafiltrate samples were collected at the start and end of the infusion and at 3, 5, 8, 18 and 24 h. Concentrations were determined using HPLC. Values for the area under the concentration-time curve (AUC0-24) were calculated. Monte Carlo simulations were performed using pre-filter and post-filter AUC0-24/MIC ratios on Days 1 and 2. The probability of target attainment (PTA) was calculated using AUC0-24/MIC cut-offs: 285 (C. parapsilosis), 3000 (all Candida spp.) and 5000 (non-parapsilosis Candida spp.). Cumulative fraction responses (CFRs) were calculated using EUCAST MIC distributions. RESULTS Mean post-filter AUC0-24 (mg·h/L) values were higher than pre-filter values on Day 1 (83.31 ± 15.87 versus 71.31 ± 14.24; P = 0.008) and Day 2 (119.01 ± 27.20 versus 104.54 ± 21.23; P = 0.005). PTAs were ≥90% for MICs of 0.125 mg/L (cut-off = 285), 0.016 mg/L (cut-off = 3000) and 0.008 mg/L (cut-off = 5000) on Day 1, and for MICs of 0.25 mg/L (cut-off = 285) and 0.016 mg/L (cut-off = 3000 and 5000) on Day 2, without differences between pre- and post-filter values. On Day 2, CFRs >90% were obtained for C. albicans (cut-off = 3000 and 5000) and C. glabrata (cut-off = 3000), but not for C. parapsilosis. CONCLUSIONS There was no removal of micafungin by CVVH or need for dose adjustment, and there was optimal PK/PD coverage for non-parapsilosis Candida and equivalence of pre- and post-filter PD.

Design of a score to identify hospitalized patients at risk of drug‐related problems

The potential impact of drug‐related problems (DRP) on morbidity and mortality is a serious concern in hospitalized patients. This study aimed to design a risk score to identify patients most at risk of a DRP.

Levofloxacin weight-adjusted dosing and pharmacokinetic disposition in a morbidly obese patient

Pharmacy Department, Hospital del Mar-IMIM, Parc de Salut Mar, Universitat Autónoma de Barcelona, Barcelona, Spain; PKPD Modelling and Simulation, CIM-ST Pau, Institut de Recerca HSCSP, Hospital de la Santa Creu i Sant Pau, Department of Pharmacology, Toxicology and Therapeutics, Universitat Autónoma de Barcelona, Barcelona, Spain; Pharmacy and Pharmaceutical Technology Department, Universidad de Salamanca, Salamanca, Spain; Pneumology Department, Hospital del Mar-IMIM, Parc de Salut Mar, Universitat Pompeu Fabra, CIBER, ISCIII, Barcelona, Spain

Differences in pharmacokinetics and pharmacodynamics of colistimethate sodium (CMS) and colistin between three different CMS dosage regimens in a critically ill patient infected by a multidrug-resistant Acinetobacter baumannii

Use of colistin has re-emerged for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria, but information on its pharmacokinetics and pharmacodynamics is limited, especially in critically ill patients. Recent data from pharmacokinetic/pharmacodynamic (PK/PD) population studies have suggested that this population could benefit from administration of higher than standard doses of colistimethate sodium (CMS), but the relationship between administration of incremental doses of CMS and corresponding PK/PD parameters as well as its efficacy and toxicity have not yet been investigated in a clinical setting. The objective was to study the PK/PD differences of CMS and colistin between three different CMS dosage regimens in the same critically ill patient. A critically ill patient with nosocomial pneumonia caused by a MDR Acinetobacter baumannii received incremental doses of CMS. During administration of the different CMS dosage regimens, CMS and colistin plasma concentrations were determined and PK/PD indexes were calculated. With administration of the highest CMS dose once daily (720 mg every 24h), the peak plasma concentration of CMS and colistin increased to 40.51 mg/L and 1.81 mg/L, respectively, and the AUC0-24/MIC of colistin was 184.41. This dosage regimen was efficacious, and no nephrotoxicity or neurotoxicity was observed. In conclusion, a higher and extended-interval CMS dosage made it possible to increase the exposure of CMS and colistin in a critically ill patient infected by a MDR A. baumannii and allowed a clinical and microbiological optimal response to be achieved without evidence of toxicity.

Plasma and cerebrospinal fluid concentrations of linezolid in neurosurgical critically ill patients with proven or suspected central nervous system infections.

Linezolid is a valuable treatment option for central nervous system (CNS) infections caused by multidrug-resistant Gram-positive micro-organisms. Data regarding its penetration into the CNS have shown wide variability. The aim of this study was to describe the population pharmacokinetics of linezolid in plasma and cerebrospinal fluid (CSF) in critically ill patients with external CSF drainage and proven or suspected CNS infections. This was an observational pharmacokinetic (PK) study in 11 critically ill patients with proven or suspected CNS infection receiving linezolid. Serial blood and CSF samples were taken and were subject to population PK analysis. The median (interquartile range) of AUC(0-12h) was 47.6 (17.9-58.6) mgh/L in plasma and 21.1 (18.8-30.4) mgh/L in CSF, with a median CSF/plasma ratio of 0.77. At pre-dose at steady state, a strong positive correlation was observed between linezolid concentrations in CSF and plasma (Spearmans rho=0.758; P=0.011). For a minimum inhibitory concentration (MIC) of 2 mg/L, the median AUC(0-24h)/MIC values in plasma and CSF were <80 in all patients. A three-compartment linear model was found to be most appropriate. The mean value for linezolid clearance was 16.6L/h and mean volume of distribution was 101.3 L. No covariate relationships could be supported on any of the parameters. Linezolid demonstrated good penetration into the CNS but high interindividual PK variability. Administration of higher than standard doses of linezolid and therapeutic drug monitoring should therefore be considered as options to optimise linezolid dosing in critically ill patients with CNS infections.

Validation of a colistin plasma concentration breakpoint as a predictor of nephrotoxicity in patients treated with colistin methanesulfonate

Nephrotoxicity limits the effective use of colistin for the treatment of multidrug-resistant Gram-negative bacteria (MDR-GNB) infections. We previously defined a steady-state colistin plasma concentration (Css) of 2.42 mg/L that predicted nephrotoxicity at end of treatment (EOT). The objective of this study was to validate this breakpoint in a prospective cohort. This was a multicentre, prospective, observational study conducted at three hospitals with a cohort of patients treated for MDR-GNB infection with colistin methanesulfonate from September 2011 until January 2015. Nephrotoxicity was evaluated at Day 7 and at EOT using the RIFLE criteria. Css values were measured and analysed using HPLC. Taking the previously defined breakpoint for colistin concentration as a criterion, patients were divided into two groups (Css, ≤2.42 mg/L vs. >2.42 mg/L). Sixty-four patients were included. Seven patients (10.9%) had a Css > 2.42 mg/L and were compared with the remaining patients. Bivariate analysis showed that patients with a Css > 2.42 mg/L were older and had a significantly higher incidence of nephrotoxicity at Day 7 and EOT. Although not statistically significant, nephrotoxicity occurred earlier in these patients (6.2 days vs. 9.2 days in patients with lower Css; P = 0.091). Multivariate analysis of nephrotoxicity showed that Css > 2.42 mg/L was the only predictive factor. Nephrotoxicity was more frequent and occurred earlier in patients with colistin plasma concentrations higher than the previously defined breakpoint (2.42 mg/L). Colistin therapeutic drug monitoring should be routinely considered to avoid reaching this toxicity threshold and potential clinical consequences.

Effective removal of colistin methanesulphonate and formed colistin during intermittent haemodialysis in a patient infected by polymyxin-only-susceptible Pseudomonas aeruginosa

Abstract Colistin use has reemerged for the treatment of infections caused by multidrug-resistant Gram-negative bacteria. However, the information on its pharmacokinetics is limited, especially in patients with end-stage renal disease, in which dosage adjustments are contradictory, and evidences the need to investigate the removal of colistin through renal replacement therapies like haemodialysis. This case study showed efficient removal of colistin methanesulphonate and formed colistin during intermittent haemodialysis in a patient infected by polymyxin-only-susceptible Pseudomonas aeruginosa. These results suggest the importance to monitor colistin plasma concentrations in these patients to minimize treatment failure due to suboptimal exposure to antibacterial colistin.