An eco-friendly and cost-effective HPTLC method for quantification of COVID-19 antiviral drug and co-administered medications in spiked human plasma.

The coronavirus-2 has led to a global pandemic of COVID-19 with an outbreak of severe acute respiratory syndrome leading to worldwide quarantine measures and a rise in death rates. The objective of this study is to propose a green, sensitive, and selective densitometric method to simultaneously quantify remdesivir (REM) in the presence of the co-administered drug linezolid (LNZ) and rivaroxaban (RIV) in spiked human plasma. TLC silica gel aluminum plates 60 F254 were used as the stationary phase, and the mobile phase was composed of dichloromethane (DCM): acetone (8.5:1.5, v/v) with densitometric detection at 254 nm. Well-resolved peaks have been observed with retardation factors (Rf) of 0.23, 0.53, and 0.72 for REM, LNZ, and RIV, respectively. A validation study was conducted according to ICH Q2 (R1) Guidelines. The method was rectilinear over the concentration ranges of 0.2-5.5 µg/band, 0.2-4.5 µg/band and 0.1-3.0 µg/band for REM, LNZ and RIV, respectively. The sensitivities of REM, LIN, and RIV were outstanding, with quantitation limits of 128.8, 50.5, and 55.8 ng/band, respectively. The approach has shown outstanding recoveries ranging from 98.3 to 101.2% when applied to pharmaceutical formulations and spiked human plasma. The method's greenness was assessed using Analytical Eco-scale, GAPI, and AGREE metrics.

Pharmacokinetics and pharmacodynamics of linezolid in plasma/cerebrospinal fluid in patients with cerebral hemorrhage after lateral ventricular drainage by Monte Carlo simulation.

OBJECTIVE: We investigated the pharmacokinetic (PK) and pharmacodynamic (PD) parameters of linezolid in patients who had suffered cerebral hemorrhage after lateral ventricular drainage. MATERIALS AND METHODS: Ten patients with cerebral hemorrhage after lateral ventricular drainage with stroke-associated pneumonia who were given linezolid were enrolled. Plasma and cerebrospinal fluid (CSF) samples were taken at appropriate intervals after the first administration of linezolid and assayed by high-performance liquid chromatography (HPLC). Then, PK parameters were estimated, and a Monte Carlo simulation was used to calculate the probability of target attainments (PTAs) for linezolid achieving the PK/PD index at different minimal inhibitory concentrations (MICs). RESULTS: The maximum concentration of linezolid in plasma and CSF was reached at 1.00 h and 3.10 h, respectively. The average penetration of linezolid in CSF was 56.81%. If the area under the plasma concentration vs time curve from zero to the final sampling time (AUC0-24 h)/MIC ≥ 59.1 was applied as a parameter, the PTA of linezolid in plasma could provide good coverage (PTA ≥ 90%) only for pathogens with a MIC of ≤2 µg/mL, whereas it could be achieved in CSF with a MIC of ≤1 µg/mL. If %T > MIC ≥ 40% was applied as a parameter, the PTA of linezolid in plasma/CSF could provide good coverage if the MIC was ≤4 µg/mL. CONCLUSIONS: For patients with infection of the central nervous system and who are sensitive to the drug, the usual dosing regimens of linezolid can achieve a good therapeutic effect. However, for critically ill or drug-resistant patients, an increase in dose, the frequency of administration, or longer infusion may be needed to improve the curative effect.

Population pharmacokinetics/pharmacodynamics of linezolid in sepsis patients with and without continuous renal replacement therapy.

PURPOSE: The purpose of this study was to identify the optimum dosing regimen of linezolid in sepsis patients with and without renal dysfunction and sepsis patients on low-dose continuous renal replacement therapy (CRRT) using a pharmacokinetics/pharmacokinetics (PK/PD) approach. METHODS: Sepsis patients with and without renal dysfunction (creatinine clearance < 50 mL/min), and sepsis patients on low-dose CRRT (dose: 800 mL/h) were studied. The PK data were modeled using a two-compartment model, and then used for simulation. The target PK/PD was the 24-h area under the concentration-time curve to minimum inhibitory concentration ratio of ≥ 80. Dosing regimens were evaluated using cumulative fraction of response (CFR) and safety probability (trough level < 7 µg/mL) by Monte Carlo simulation. RESULTS: Twenty-seven patients, including 8 patients with preserved renal function, 9 patients with renal dysfunction, and 10 patients on CRRT, were studied. The proposed regimen to attain CFR ≥ 90% was 800 mg every 12 h (safety probability 82.4%) for patients with preserved renal function. By contrast, the target CFR was attained with a decreased regimen in patients with renal dysfunction and those on CRRT [600 mg every 24h (safety probability 68.6%) and 800 mg every 24h (42.1%)]. CONCLUSIONS: We identified different dosage strategies to achieve target linezolid concentrations according to renal function and use of CRRT in sepsis patients. Because of unassured safety probability in patients without preserved renal function, dosing regimens should be adjusted based on the therapeutic drug monitoring.

Population Pharmacokinetics and Dosing Considerations for the Use of Linezolid in Overweight and Obese Adult Patients.

BACKGROUND: Linezolid is an anti-Gram-positive antimicrobial agent used at a fixed dose of 600 mg every 12 h. OBJECTIVES: The objective of this study was to assess the population pharmacokinetics and pharmacodynamics of linezolid in a retrospective cohort of overweight and obese hospitalized patients. PATIENTS AND METHODS: Population pharmacokinetic and Monte Carlo simulations were conducted to assess the probability of target attainment (PTA) of an area under the concentration-time curve from time zero to 24 h (AUC24)/minimum inhibitory concentration (MIC) ratio > 100, defined as the pharmacodynamic target of efficacy, with incremental candidate dosages. Maximum permissible doses were defined as those causing a ≤ 25% of probability of a linezolid trough of > 8.06 mg/L, associated with thrombocytopenia. The cumulative fraction of response was calculated for the permissible linezolid doses by testing the PTA against the MIC distributions of a large collection of Staphylococci and Enterococci. RESULTS: A total of 352 trough (minimum) and 293 peak (maximum) linezolid concentrations from 112 patients were included. The final mixed-saturative model accounted for 88% of drug concentrations variability over time, and estimated creatinine clearance [by means of the Chronic Kidney Diseases Epidemiology formula (CrCLCKD-EPI)] was the only covariate that improved the model fit. Dose reduction to 450 mg every 12 h may be optimal for patients with coagulase-negative staphylococcal infections and a CrCLCKD-EPI < 130 mL/min/1.73 m2. Dose escalation to 450 mg every 8 h may be optimal for patients with a CrCLCKD-EPI ≥ 60 mL/min/1.73 m2. Escalation to 600 mg every 8 h should not be recommended due to an unacceptable high risk of thrombocytopenia. Patients with CrCLCKD-EPI ≥ 130 mL/min/1.73 m2 and/or co-medication with P-glycoprotein modulators require therapeutic drug monitoring to optimize linezolid doses. CONCLUSIONS: Dosage adjustments of linezolid in this population should be based on CrCLCKD-EPI estimates, rather than on body size descriptors.

A 1 year retrospective audit of quality indicators of clinical pharmacological advice for personalized linezolid dosing: one stone for two birds?

AIM: This study explored the clinical and economic impact of clinical pharmacological advice (CPA) (based on therapeutic drug monitoring [TDM] results, and on patients' characteristics and co-medications) on personalized linezolid therapy in a tertiary care hospital. METHODS: A 1 year retrospective analysis of quality indicators of CPA (clinicians' adherence rate to CPA, pre-post rate of linezolid trough concentrations within the desired range and cost balance analysis) was conducted. RESULTS: Five hundred and forty-four CPAs were provided to clinicians during 2014 for personalizing linezolid therapy in 168 patients. Clinicians' adherence to CPAs was very high (94.7%). The pre-post rate of linezolid Cmin distribution showed a favourable impact of CPA on patient care (pre-post ratio of Cmin within the desired range + 23.4%, pre, 51.2% vs. post, 74.6%). Overall, linezolid dosage was mainly reduced (56.9% of cases), whereas dose augmentation was needed only in a minority of cases (7.7%). Cost balance analysis showed that overall 1258 standard doses of linezolid (unitary dose 600 mg) were spared for treating 168 patients with a personalized dosage for a median duration of 11 days (range 3-128 days) with a cost saving of 60038.05 €. CONCLUSION: Active computerized advice elaborated by the clinical pharmacologist on the basis of TDM results and of patient's pathophysiological data and co-medications may be cost-effective for personalizing linezolid treatment.