Elimination of three doses of gentamicin over three consecutive days using a polyacrylonitrile-derived filter: An in vitro assessment

Drug dosing optimization in critically ill children under continuous renal replacement therapy: from basic concepts to the bedside model informed precision dosing

INTRODUCTION

Optimizing drug dosage in critically ill children undergoing Continuous Renal Replacement Therapy (CRRT) is mandatory and challenging, given the many factors impacting pharmacokinetics and pharmacodynamics coupled with the vulnerability of this population.

AREAS COVERED

A good understanding of the mechanisms that determine drug elimination via the CRRT technique is useful to avoid prescription pitfalls, however limited by the high between and within subject variability. The developments of population pharmacokinetic and physiologically based pharmacokinetic models derived from in-vivo and in-vitro studies, are challenging, but remain the most appropriate tool to suggest adjusted dosage regimens for every patient, throughout treatment. We searched PubMed using the search string: 'pediatrics OR children' AN 'continuous renal replacement therapy' AND 'pharmacokinetics' AND 'model informed precision dosing' AND, 'physiologically based pharmacokinetics,' AND 'therapeutic drug monitoring' until January 2024, regardless of language or publication status.

EXPERT OPINION

Familiarizing the pediatric intensivists with the therapeutic drug monitoring and providing clinicians the individualized prescribing software such as Model Informed Precision Dosing would be a significant step forward. The clinical benefit for patients remains to be demonstrated.

Caspofungin sequestration in a polyacrylonitrile-derived filter: Increasing the dose does not mitigate sequestration

OBJECTIVES

Critically ill patients frequently require continuous renal replacement therapy. Echinocandins are recommended as first-line treatment of candidemia. Preliminary results suggested echinocandin sequestration in a polyacrylonitrile filter. The present study aimed to determine whether increasing the dose might balance sequestration.

METHODS

An STX filter (Baxter-Gambro) was used. A liquid chromatography-mass spectrometry method was used for dosage of caspofungin. In vitro drug disposition was evaluated by NeckEpur (Neckepur, Versailles, France) technology using a crystalloid medium instead of diluted/reconstituted blood, focusing on the disposition of the unbound fraction of drugs. Two concentrations were assessed.

RESULTS

At the low dose, the mean measured initial concentration in the central compartment (CC) was 5.1 ± 0.6 mg/L. One hundred percent of the initial amount was eliminated from the CC within the 6-h session. The mean total clearance from the CC was 9.6 ± 2.5 L/h. The mean percentages of elimination resulting from sequestration and diafiltration were 96.0 ± 5.0 and 4.0 ± 5.2%, respectively. At high dose, the mean measured initial concentration in the CC was 13.1 mg/L. One hundred percent of the initial amount was eliminated from the CC within the 6-h session. The mean total clearance from the CC was 9.5 L/h. The mean percentages of elimination resulting from sequestration and filtration were 88.5% and 11.5%, respectively.

CONCLUSION

Increasing the dose does not mitigate caspofungin sequestration in the STX filter. The results raise caution about the simultaneous use of caspofungin and polyacrylonitrile-derived filters. Intermittent modes of renal replacement therapy might be considered. For sensitive species, fluconazole might be an alternative.

Vancomycin Sequestration in ST Filters: An In Vitro Study

BACKGROUND

Sequestration of vancomycin in ST^® filters used in continuous renal therapy is a pending question. Direct vancomycin-ST^® interaction was assessed using the in vitro NeckEpur^® technology.

METHOD

ST150^® filter and Prismaflex dialyzer, Baxter-Gambro, were used. Two modes were assessed in duplicate: (i) continuous diafiltration (CDF): 4 L/h, (ii) continuous dialysis (CD): 2.5 L/h post-filtration.

RESULTS

The mean initial vancomycin concentration in the central compartment (CC) was 51.4 +/- 5.0 mg/L. The mean percentage eliminated from the CC over 6 h was 91 +/- 4%. The mean clearances from the CC by CDF and CD were 2.8 and 1.9 L/h, respectively. The mean clearances assessed using cumulative effluents were 4.4 and 2.2 L/h, respectively. The mean percentages of the initial dose eliminated in the effluents from the CC by CDF and CD were 114 and 108% with no detectable sequestration of vancomycin in both modes of elimination.

DISCUSSION

Significant sequestration adds a clearance to that provided by CDF and CD. The study provides multiple evidence from the CC, the filter, and the effluents of the lack of an increase in total clearance in comparison with the flow rates without significant sequestration in the ST^® filter comparing cumulative effluents to the initial dose in the CC.

CONCLUSIONS

There is no evidence ST^® filters directly sequestrate vancomycin.

Elimination of cefotaxime using polysulfone and polyacrylonitrile-derived filters: An in vitro assessment

Continuous renal replacement therapy (CCRT) efficiently eliminates cefotaxime. To our knowledge, there are no previous in vitro studies dealing with the disposition of cefotaxime. We studied the elimination of cefotaxime by two filters in a model mimicking a session of CRRT using the NeckEpur^® technology. The ST150^®-polyacrylonitrile filter with the Prismaflex, Baxter-Gambro, and the AV1000^®-polysulfone filter with the Multifiltrate Pro, Fresenius, were studied. Continuous filtration used a flowrate of 1 L/h in post-dilution only. Simulated blood flowrate was set at 200 mL/min. Routes of elimination were assessed using the NeckEpur^® technology. Cefotaxime concentrations were measured using ultra high-performance liquid chromatography, and tandem mass spectrometry. Two sessions were performed using the ST^® filter and three using the AV^® filter. Stability of cefotaxime during 6 h was assessed in triplicate with a mean variation of concentrations of 2.4 ± 1.5% at the end of the study. The mean measured initial concentration in the central compartment (CC) for the five sessions was 52.4 mg/L. The mean amount eliminated from the CC at the end of the sessions using the ST150^®-polyacrylonitrile and the AV1000^®-polysulfone filters were 72% and 73%, respectively. The clearances of cefotaxime from the central compartment (CC) were 1.1 and 1.2 L/h, respectively. The mean sieving coefficient were 0.99 and 0.99, respectively. The mean percentages of the amount eliminated from the CC by filtration/adsorption were 87/13% and 92/8%, respectively. Both adsorption percentages were below 15%. We conclude neither the ST150^®-polyacrylonitrile nor the AV1000^®-polysulfone filters result in clinically significant adsorption of cefotaxime.

Disposition of gentamicin and amikacin in extracorporeal membrane oxygenation using a heparin-coated filter: An in vitro assessment

Disposition of gentamicin and amikacin during extracorporeal membrane oxygenation has not been addressed in in vitro models. The HLS Advanced 7.0^® circuit with the Cardio Help^® monitor, Getinge, was used. The 5-L central compartment (CC) was loaded with gentamicin and amikacin at a targeted concentration of 40 and 80 mg/L in the same bag prior connection to the circuit. Samples were collected in the CC, the inlet and outlet ports from 15 min to 6 h post-connection. Pharmacokinetic analyses were performed using the NeckEpur^® method. Analysis of results of gentamicin and amikacin showed in the filter-pump block (i) the extremely low value of the extraction coefficients, (ii) similar values of the areas under the curve (AUCs) at the inlet and outlet ports, (iii) using the Wilcoxon matched pairs signed rank test no significant differences of the inlet-outlet concentrations in the filter-pump. In the whole system (i) the amounts recovered in the CC at the end of the 6-h session were not significantly different from the initial values, (ii) the extremely low values of the total clearance of gentamicin and amikacin from the CC in comparison with the measured simulated blood flowrate, (iii) the lack of significant time-concentration interactions in the CC and the inlet and outlet ports. These findings allow concluding no detectable adsorption of gentamicin and amikacin occurred in the HLS Advanced 7.0 circuit.