Acute kidney injury, especially on top of CKD: stop nephrotoxic and renally cleared drugs, review doses, and hold the 'DAMN' drugs. Avoid metformin and NSAIDs.
Which measure to use
- Use eGFR for most drugs; use creatinine clearance (Cockcroft-Gault) for some narrow-therapeutic or renally cleared drugs (for example DOACs, some antimicrobials)
- Beware eGFR at extremes of body weight or muscle mass
- In AKI the eGFR lags: treat the clinical trajectory
Drugs needing care in renal impairment
- Hold in AKI (sick-day): ACE inhibitors or ARBs, diuretics, metformin, NSAIDs
- Also adjust or avoid: gabapentin or pregabalin, opioids (morphine), digoxin, LMWH, DOACs, lithium, many antimicrobials
- Avoid nitrofurantoin if eGFR under 45
- Account for contrast and other nephrotoxins
eGFR 60 or above
- Standard dosing (check the drug)
- Avoid nephrotoxins where possible
- Monitor U&E
eGFR 30 to 59
- Dose-reduce renally cleared drugs
- Caution: metformin, DOACs, opioids
- Hold nephrotoxins in acute illness
eGFR under 30 / AKI
- Avoid or markedly reduce (gabapentin, LMWH)
- Stop metformin, NSAIDs, SGLT2i
- Specialist and drug-level advice
Steps
1
1. Check function
Find the recent creatinine, eGFR and baseline; note the trend (is this AKI?).
Find the recent creatinine, eGFR and baseline; note the trend (is this AKI?).
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2
2. Consult the BNF
Check the renal impairment section for each drug and adjust dose or interval accordingly.
Check the renal impairment section for each drug and adjust dose or interval accordingly.
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3
3. Monitor
Therapeutic drug monitoring where relevant (digoxin, vancomycin, gentamicin, lithium) and repeat U&E.
Therapeutic drug monitoring where relevant (digoxin, vancomycin, gentamicin, lithium) and repeat U&E.
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4
4. AKI bundle
Treat the cause, optimise hydration and blood pressure, stop the nephrotoxins above, and review all drugs for accumulation.
Treat the cause, optimise hydration and blood pressure, stop the nephrotoxins above, and review all drugs for accumulation.
Think accumulation
- Opioids and gabapentinoids accumulate and cause toxicity
- LMWH accumulates (consider anti-Xa monitoring or UFH)
- Many antibiotics need renal dosing
Pitfalls
- Continuing metformin or NSAIDs in AKI
- Using eGFR for a drug that needs creatinine clearance
- Forgetting to re-dose as renal function changes
- Nitrofurantoin at low eGFR
MedPrep - www.medprep.uk - Educational revision aid only. Not clinical guidance. Doses are adult examples; check the BNF, current guidelines and local policy, and seek senior advice. Nov 2026