Can Imipenem Cause Acute Kidney Injury?
Yes, imipenem can cause acute kidney injury (AKI), though the formulation imipenem-cilastatin appears to have lower nephrotoxic potential than imipenem alone, and cilastatin itself provides some nephroprotective effects. 1
FDA-Documented Renal Toxicity
The FDA drug label explicitly lists renal adverse effects associated with imipenem-cilastatin:
- Acute renal failure is documented as a post-marketing adverse reaction 1
- Clinical trial data show oliguria/anuria occurred in 2.2% of neonates to 3-month-old infants 1
- Laboratory changes include increased BUN and creatinine 1
- Urinalysis abnormalities include proteinuria, hematuria, and presence of urinary casts 1
Mechanistic Understanding
The nephrotoxicity mechanism involves renal organic anion transporters (OATs). Imipenem exhibits OAT1/3-dependent cytotoxicity in renal proximal tubule cells 2. Importantly, cilastatin inhibits these transporters and reduces intracellular accumulation of imipenem in nephrocytes, which explains its nephroprotective role beyond simply inhibiting renal dehydropeptidase-I 2.
Clinical Evidence on Nephrotoxicity
Comparative Nephrotoxicity Studies
Imipenem-cilastatin demonstrates nephroprotective properties when combined with other nephrotoxic agents:
- In a translational rat model, vancomycin + imipenem-cilastatin was nephroprotective compared to vancomycin alone, with decreased urinary KIM-1 (kidney injury molecule-1) on Days 1 and 2 3
- However, in neonatal sepsis studies, imipenem-cilastatin worsened kidney function in newborns, increasing AKI marker levels 4
Dose-Dependent Toxicity
Animal studies reveal concerning dose-dependent effects:
- Subacute exposure in rats (7 days at 30-80 mg/kg/day) caused alkaline urine, polyuria, crystalluria, elevated urea/creatinine, oxidative stress, and crystal deposition in kidneys 5
- Urolithiasis developed even at therapeutic dose levels in a dose-dependent manner 5
- At concentrations >10-fold higher than peak human plasma levels, imipenem-cilastatin induced oxidative changes (GSH depletion, GSSG production), lipid peroxidation (MDA production), and nephrotoxic effects (reduced gluconeogenesis and PAH accumulation) 6
Clinical Context from Guidelines
While guidelines 7, 8 extensively discuss imipenem-relebactam for carbapenem-resistant infections, they emphasize that alternative agents like ceftolozane-tazobactam have lower nephrotoxicity risk compared to polymyxins or aminoglycosides 8. This indirectly positions imipenem-cilastatin as having intermediate nephrotoxic potential.
Key Clinical Caveats
Monitor renal function closely in these high-risk scenarios:
- Neonates and infants - particularly vulnerable population with documented oliguria/anuria rates of 2.2% 1, 4
- Elderly patients or those with baseline chronic kidney disease - at higher risk for developing kidney injury 8
- Combination with other nephrotoxic agents - effects vary depending on the co-administered drug (protective with vancomycin 3, but additive toxicity possible with others)
- Prolonged therapy (>7 days) - increased risk of crystal deposition and urolithiasis 5
Practical monitoring approach:
- Baseline and serial serum creatinine/BUN measurements
- Urinalysis for proteinuria, hematuria, and casts
- Urine output monitoring, especially in critically ill patients
- Consider dose adjustment in renal impairment per FDA recommendations 1
The cilastatin component provides meaningful nephroprotection through OAT inhibition 2, making the combination formulation safer than imipenem monotherapy would be, but AKI remains a documented and clinically relevant adverse effect requiring vigilant monitoring.