Estimate kidney function correctly in unstable AKI and adjust common ICU drugs, with loading doses unchanged.
At the bedside
- 1
Estimate clearance sensibly
Use Cockcroft-Gault for drug dosing (most labels); in unstable AKI assume GFR < 10-25 mL/min if creatinine rising rapidly or anuric. Measured 4-6 h urinary creatinine clearance is better in ICU.
- 2
Never reduce the loading dose
Antibiotics, antiepileptics, digoxin load: full dose. Underdosing antibiotics in early sepsis is a bigger risk than toxicity.
- 3
Adjust maintenance
Extend interval (aminoglycosides, vancomycin) or reduce dose (beta-lactams per CrCl). Reassess daily as AKI evolves; augment as kidneys recover.
- 4
Use TDM
Vancomycin trough or AUC (target AUC 400-600 mg.h/L), aminoglycoside levels, (beta-lactam TDM where available).
- 5
Avoid or replace nephrotoxins
NSAIDs, aminoglycosides (unless essential), IV contrast where possible, amphotericin deoxycholate (use liposomal), colistin with TDM/limit duration. Hold ACEi/ARB, metformin, SGLT2i during AKI.
- 6
Watch accumulating drugs
Morphine (active metabolites → use fentanyl), midazolam (active metabolite), pethidine (avoid), enoxaparin (CrCl < 30: 1 mg/kg once daily or UFH), gabapentin, pregabalin, digoxin, LMWH, meropenem/cefepime (neurotoxicity), sotalol.
Common ICU drugs: adjustment in AKI (CrCl < 30 mL/min, not on RRT)
| Drug | Usual adult dose | CrCl < 30 mL/min |
|---|---|---|
| Meropenem | 1 g q8h | CrCl 26-50: 1 g q12h; 10-25: 500 mg q12h; < 10: 500 mg q24h |
| Piperacillin-tazobactam | 4.5 g q6-8h | CrCl 20-40: 4.5 g q8h (or 3.375 g q6h); < 20: 4.5 g q12h (or 2.25 g q6h) |
| Cefepime | 2 g q8h | CrCl 30-60: 2 g q12h; 11-29: 2 g q24h; risk of neurotoxicity |
| Vancomycin | Load 25-30 mg/kg | Same load; maintenance by levels (often q24-48h) |
| Amikacin | 15-20 mg/kg q24h | Extend interval by levels (q36-48h) or avoid |
| Colistin (CBA) | Load 300 mg CBA (9 million units) | Same load; maintenance reduced per CrCl |
| Enoxaparin (treatment) | 1 mg/kg q12h | 1 mg/kg q24h; anti-Xa monitoring |
| Morphine | 2-5 mg IV | Avoid/caution; prefer fentanyl |
| Levetiracetam | 500-1,500 mg q12h | CrCl < 30: 250-500 mg q12h (load unchanged) |
| Fluconazole | Load 800 mg then 400 mg/day | Load unchanged; then 50% maintenance if CrCl < 50 |
Adapted from product labels and standard references; always cross-check with a current drug reference or ICU pharmacist.
Calculators for this topic
Pathophysiology
AKI reduces renal elimination but often coincides with increased volume of distribution (capillary leak, fluid resuscitation), hypoalbuminaemia (more free drug) and altered hepatic metabolism. Net effect: full loads, careful maintenance, frequent reassessment.
Evidence
- KDIGO 2012 recommends drug dose adjustment in AKI and TDM for aminoglycosides and vancomycin [KDIGO 2012].
- 2020 ASHP/IDSA vancomycin guideline recommends AUC-guided dosing (400-600 mg.h/L).
Controversies
- Optimal estimation of GFR in non-steady state (kinetic eGFR equations).
🇮🇳 India notes
- Colistin and aminoglycosides are frequently needed for CRE in Indian ICUs; nephrotoxicity is common: limit duration, ensure hydration and monitor creatinine daily.
- Vancomycin level testing is not available in all hospitals; use conservative dosing and creatinine monitoring.
References
Test yourself
Module quiz · score 70% to complete the module
Educational reference for trained clinicians. Check doses against your hospital protocol and the patient in front of you.