Antimicrobial dosing in continuous renal replacement is still guesswork

Design

Scoping review (executive summary) with a pharmacokinetic-factors checklist

Population

96 studies of antimicrobial pharmacokinetics in critically ill patients on CRRT

Primary outcome

Factors influencing antimicrobial pharmacokinetics during CRRT

Effect

Clearance altered by CRRT, patient and drug factors; evidence-based dosing guidance still lacking

A scoping review mapped 96 studies of antimicrobial pharmacokinetics in critically ill patients on continuous renal replacement therapy (CRRT), summarising why reliable dosing guidance is still missing and producing a checklist of the factors that matter.

CRRT substantially alters drug clearance, and on top of that the ICU population is highly variable; many pharmacokinetic studies exclude CRRT patients or are small and methodologically limited, leaving a genuine evidence gap. The review groups the determinants into CRRT-related (modality, flow rates, filter), patient-related and drug-related factors.

The usable message for prescribers is caution: do not assume a standard antibiotic, antifungal or antiviral dose is right for a patient on CRRT. Account for the CRRT prescription and the drug's properties, and use therapeutic drug monitoring where it is available, especially for agents with a narrow margin. This is a methods and gap-mapping review, not a new dosing guideline.

• CRRT markedly changes antimicrobial clearance, and dosing evidence remains thin.
• Many pharmacokinetic studies exclude CRRT patients or are small and limited.
• Dosing depends on CRRT settings, patient factors and the drug itself.
• Do not assume standard doses on CRRT; individualise and use monitoring.
• Prioritise therapeutic drug monitoring for narrow-margin agents.

Why it matters

Under- or over-dosing antimicrobials in CRRT risks treatment failure, resistance or toxicity, and standard doses are often wrong.

Don't overread it

This is a scoping and methods review that maps the gap; it does not itself provide validated dose recommendations.

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