Which CrCl equation should I use?

Most renal dosing references are validated against Cockcroft-Gault creatinine clearance rather than eGFR (CKD-EPI). For consistency, calculate CrCl using Cockcroft-Gault with actual or adjusted body weight where indicated.

Does this replace the official monograph?

No. These thresholds are simplified summaries for teaching and quick reference. Always confirm the exact dose against the current SmPC, BNF, or institutional renal dosing protocol before prescribing.

Why do some drugs reduce the dose and others extend the interval?

Time-dependent antibiotics often keep the dose but lengthen the interval to preserve peak efficacy, while concentration-independent drugs reduce the dose. The selector reflects the conventional approach for each listed drug.

What about dialysis patients?

This tool does not model haemodialysis or CRRT clearance. Dialysis dosing requires separate references and timing relative to the dialysis session, so always consult a renal pharmacist for those patients.

CrCl-Based Renal Drug Dosing Interval Selector

Renal drug dosing by creatinine clearance

Many medications are cleared by the kidneys, so reduced renal function raises the risk of accumulation and toxicity. Renal dose adjustment uses creatinine clearance (CrCl) bands to either lower the dose or extend the dosing interval. This selector maps a patient CrCl onto common published thresholds for a curated set of antibiotics, anticoagulants, and antivirals.

How it works

Each drug carries a small table of CrCl bands. The tool finds the band that contains the entered CrCl and returns the matching recommendation. For example, many drugs follow a pattern such as: CrCl above 50 mL/min = standard dose, 30 to 50 = reduced dose or extended interval, 10 to 30 = further reduction, and below 10 = avoid or specialist dosing only.

if CrCl >= threshold_high  -> standard dose
elif CrCl >= threshold_mid -> reduced dose / extended interval
elif CrCl >= threshold_low -> further reduction
else                       -> avoid / specialist only

Tips and cautions

These bands are deliberately simplified for fast bedside teaching and must be confirmed against the current SmPC, BNF, or local protocol before prescribing. Use Cockcroft-Gault CrCl rather than eGFR for consistency with the source references. The tool does not cover dialysis, CRRT, or paediatric dosing, all of which require dedicated references.