Synthesis of [(2)H6]ceftazidime as a stable isotopically labeled internal standard.

Ceftazidime is a third generation cephalosporin antibiotic that has activity against a wide range of Gram-negative and Gram-positive bacterial pathogens, including Escherichia coli and Pseudomonas aeruginosa. Stable isotope-labeled ceftazidime was required for use as an internal standard in LC-MS/MS assays, and a route was developed to make [(2)H6]ceftazidime in eight steps from the commercially available labeled starting material [(2)H7]isobutyric acid.