Compatibility screening of linezolid injection during simulated Y-site administration with other drugs and infusion solutions

OBJECTIVE: To evaluate the physical compatibility of linezolid injection (Zyvox-Pharmacia) during simulated Y-site administration with 8 infusion solutions and 110 selected other drugs. DESIGN: Controlled experimental trial. SETTING: Laboratory. INTERVENTIONS: Five-milliliter samples of linezolid injection 2 mg/mL were mixed with 5 mL samples of the selected infusion solutions and the selected other drugs diluted in 5% dextrose injection, or, if necessary to avoid incompatibility with the diluent, 0.9% sodium chloride injection. MAIN OUTCOME MEASURES: Visual examinations of the samples were performed in normal fluorescent light with the unaided eye and using a Tyndall beam (high-intensity monodirectional light source) to enhance visualization of small particles and low-level haze. The turbidity of each sample was measured, and for samples that did not exhibit visible precipitation, the particle content was measured, as well. All of the samples were assessed initially and at 1 and 4 hours. RESULTS: All of the infusion solutions and most of the test drugs were physically compatible with linezolid injection during the 4-hour observation period. Physical incompatibilities resulted when linezolid injection was combined with five of the drugs: amphotericin B, chlorpromazine hydrochloride, diazepam, pentamidine isethionate, and phenytoin sodium. Precipitation, turbidity formation, and/or unacceptable changes in measured haze levels were observed. CONCLUSION: Linezolid 2 mg/mL was physically compatible for 4 hours at room temperature with all 8 infusion solutions tested and 105 of the drugs tested. Simultaneous Y-site administration of linezolid injection with the five drugs resulting in physical incompatibilities should be avoided.