The Overestimation of Vancomycin-Associated Nephrotoxicity: The Effect of Rhabdomyolysis and Nephrotoxicants at a Referral Poison Center, Tehran, Iran

Vancomycin is a first-line therapy for infections due to Methicillin-Resistant Staphylococcus aureus (MRSA). Nephrotoxicity subsequent to vancomycin administration has been discussed in many previous researches.
The present study aimed to determine the nephrotoxic potential of vancomycin among ventilator-associated pneumonia (VAP) poisoned patients after restricting the effect of risk factors such as rhabdomyolysis and other nephrotoxicants.
This two-year cross-sectional retrospective study was conducted among VAP patients, who received vancomycin at the toxicological intensive care unit of Loghman Hakim hospital of Iran from 2013 to 2015. Baseline and laboratory data of eligible patients were extracted from medical records. Nephrotoxicity was defined based on the risk, injury, failure, loss, and end state (RIFLE) criteria.
One hundred and fifty-four VAP patients’ profiles were reviewed, of whom 110 were eligible. The median age was 33.50 (12 to 94) years and 73.6% were male. The median time interval between poisoning and admission was four (0 to 48) hours. The most common cause of poisoning was opioids (33%). Ten patients developed new-onset nephrotoxic event, including four in risk, four in injury and two in failure class. Median vancomycin treatment time until a nephrotoxic event was three days. There was no significant difference between those who developed nephrotoxicity compared to those who did not except median vancomycin trough level (14.5 in nephrotoxic versus 13.7 in non-nephrotoxic, P = 0.007).
The result of this study indicated that nephrotoxicity rate among patients treated with vancomycin is under the influence of the poisoning by nephrotoxicants. Higher vancomycin trough level was associated with increasing nephrotoxicity rate..