Cefuroxime-d3 is intended for use as an internal standard for the quantification of cefuroxime by GC- or LC-MS. Cefuroxime is a cephalosporin antibiotic with broad-spectrum activity against Gram-positive and Gram-negative bacteria including S. pyogenes, S. pneumoniae, S. viridans, E. coli, P. mirabilis, H. influenzae, and N. gonorrhoeae (mean MICs = 0.005-8.2 μg/ml). Like other cephalosporins, cefuroxime inhibits peptidoglycan crosslinking and bacterial cell wall synthesis. It is resistant to hydrolysis by bacterial β-lactamases, increasing its efficacy against β-lactamase-producing Gram-negative bacteria. Cefuroxime is protective against Gram-positive and Gram-negative infections in vivo with mean ED50 values ranging from 2 to 35 and 1 to 55 mg/kg, in mice and rats, respectively. Formulations containing cefuroxime have been used to treat urinary tract infections.