A nurse is reviewing the medication record for a client diagnosed with chronic kidney disease (CKD). Which of the following medications should the nurse identify as having the potential to cause nephrotoxicity?

A. Ondansetron: This antiemetic is used to prevent nausea and vomiting. It is generally well tolerated and not associated with nephrotoxicity, making it safe for use in clients with kidney disease. B. Diphenhydramine: This antihistamine may cause sedation and anticholinergic effects, but it is not known to be nephrotoxic. It does not pose a significant risk to renal function. C. Omeprazole: Long-term use of this proton pump inhibitor may be associated with electrolyte imbalances or interstitial nephritis, but the nephrotoxic risk is relatively low compared to other drugs. D. Vancomycin: This antibiotic is known for its potential to cause nephrotoxicity, especially in high doses or with prolonged use. It requires close monitoring of serum trough levels and renal function in clients with CKD.