How it's calculated
Meropenem is renally cleared, so reduced kidney function requires either a lower dose, a longer interval, or both, to avoid drug accumulation and toxicity while still maintaining adequate antibacterial exposure. This calculator estimates creatinine clearance (CrCl) directly from age, weight, sex, and serum creatinine using the Cockcroft-Gault equation — the same equation used by the site's Creatinine Clearance calculator — then applies the standard CrCl bands to the patient's normal (unadjusted) dose. Use actual body weight unless the patient is obese, in which case an adjusted body weight is generally used instead.
Clinical use
- This adjustment table applies to standard adult fixed dosing (500 mg-2 g by indication) — for the weight-based paediatric/neonatal starting dose, use the main Meropenem Dose Calculator; paediatric renal adjustment should be individualised with specialist/pharmacy input rather than scaled from this adult table.
- For patients on intermittent haemodialysis, give the adjusted dose after the dialysis session on dialysis days, since a substantial fraction of meropenem is removed by dialysis.
- Recalculate whenever renal function changes materially (e.g. evolving acute kidney injury) — a CrCl calculated on admission may no longer reflect current clearance days later.
- This is a starting-point reference adjustment — always cross-check against local antimicrobial stewardship/pharmacy renal dosing guidance and the product insert.
Frequently asked questions
Why does meropenem need renal dose adjustment?
Meropenem is predominantly cleared by the kidneys, so reduced renal function leads to drug accumulation, raising the risk of toxicity (including seizures at high concentrations) unless the dose and/or interval are adjusted downward.
How is meropenem dosed in haemodialysis?
Using the <10 mL/min CrCl band (half the normal dose, every 24 hours), given after the dialysis session on dialysis days — meropenem is significantly removed by haemodialysis, so dosing before a session risks giving a dose that's then partly cleared before it can act.
Does this apply to children?
No — this table reflects standard adult fixed dosing. Paediatric and neonatal renal dose adjustment is more individualised and should be guided by a specialist/clinical pharmacist rather than scaled directly from the adult CrCl bands shown here.
Do I need to calculate CrCl separately before using this calculator?
No — enter age, weight, sex, and serum creatinine directly here and the calculator computes CrCl (Cockcroft-Gault) and the adjusted meropenem dose in one step, showing the calculated CrCl value alongside the result. If you already have a known CrCl from elsewhere, you can back-calculate an equivalent creatinine value, but entering the actual lab values directly is simpler and more accurate.
References
- Meropenem (Merrem) Prescribing Information — Dosage and Administration, Use in Renal Impairment.
- British National Formulary (BNF) — Meropenem, renal impairment dosing.