Physical Incompatibility between Parenteral Cloxacillin and Vancomycin

Abstract

Cloxacillin sodium is a s -lactam antibiotic commonly used to treat gram-positive infections, especially those caused by Staphylococcus aureus. Cloxacillin may be administered as an infusion prepared in 0.9% sodium chloride (normal saline [NS]), 5% dextrose in water, or lactated Ringer’s solution. Along with cloxacillin, patients may be receiving other drugs by simultaneous or sequential Y-site administration, including other glycopeptide antibiotics such as vancomycin hydrochlor ide. In clinical practice, cloxacillin and vancomycin have been initiated concurrently as empiric therapy while awaiting the results of organism identification and sensitivity testing. As well, in vitro synergy with the combination of glycopeptides and s -lactams has been described in clinical isolates of vancomycin-susceptible, methicillin-resistant S. aureus, hetero geneous glycopeptide intermediate resistant S. aureus, and glycopeptide-intermediate S. aureus. 1-3 No compatibility information for administering cloxacillin simultaneously or sequentially with vancomycin has been published. 4 This study was initiated after a nurse at the authors’ institution reported formation of a gel-like substance in the polyvinyl chloride (PVC) IV volume-control set and line. The observation was made during administration of cloxacillin and vancomycin sequentially through a Y-site connector (separated by NS flush). The drugs were being given for empiric treatment of infective endocarditis while awaiting results of sensitivity testing of S. aureus. The purpose of this study was to determine the physical compatibility of cloxacillin diluted for infusion with vancomycin during simulated Y-site administration, as assessed by visual observation.