Compatibility and stability of linezolid injection admixed with three cephalosporin antibiotics.
OBJECTIVE
To evaluate the physical compatibility and chemical stability of linezolid (Zyvox-Pharmacia) 200 mg/100 mL admixed with cefazolin sodium 1 gram, ceftazidime 2 grams, and ceftriaxone sodium 1 gram for 7 days at 4 degrees C and 23 degrees C.


METHODS
Controlled experimental trial.


METHODS
Laboratory.


METHODS
The test samples were prepared by adding the required amount of the cephalosporin antibiotic to bags of linezolid injection 200 mg/100 mL.


METHODS
Physical stability and chemical stability based on drug concentrations initially and after 1, 3, 5, and 7 days of storage at 4 degrees C and 23 degrees C protected from light.


RESULTS
All of the linezolid admixtures with cephalosporins were clear when viewed in normal fluorescent room light and with a Tyndall beam. Measured turbidity and particulate content were low and exhibited little change. The cefazolin sodium-containing samples were colorless throughout the study. The admixtures with ceftazidime and ceftriaxone sodium had a slight yellow tinge initially, and the room temperature samples became a frank yellow color after 5 days. The refrigerated samples did not change color. High-performance liquid chromatography analysis found little or no loss of linezolid in any sample stored at either temperature throughout the study. Cefazolin sodium and ceftazidime in the linezolid admixtures at 4 degrees C remained stable for 7 days, but at 23 degrees C cefazolin sodium was stable for 3 days and ceftazidime for only 24 hours before cephalosporin decomposition exceeded 10%. Ceftriaxone sodium was less stable in the admixtures; 10% loss occurred in 3 days at 4 degrees C and more than 20% loss occurred in 24 hours at 23 degrees C.


CONCLUSIONS
Admixtures of linezolid 200 mg/100 mL with cefazolin sodium 1 gram and ceftazidime 2 grams were physically compatible and chemically stable for at least 7 days stored at 4 degrees C protected from light and for 3 days and 1 day, respectively, at 23 degrees C protected from light. Admixtures of linezolid with ceftriaxone sodium 1 gram exhibited a rapid rate of cephalosporin loss at 23 degrees C, which precludes admixture of the two drugs.
Division of Pharmacy, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA.
Q A
QA
Xu
L A
LA
Trissel
K Y
KY
Williams
D000081:Acetamides / Q000737:chemistry*; D000890:Anti-Infective Agents / Q000737:chemistry*; D002437:Cefazolin / Q000737:chemistry; D002442:Ceftazidime / Q000737:chemistry; D002443:Ceftriaxone / Q000737:chemistry; D002511:Cephalosporins / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D003116:Color; D004344:Drug Incompatibility; D004355:Drug Stability; D007275:Injections, Intravenous; D000069349:Linezolid; D009391:Nephelometry and Turbidimetry; D010080:Oxazoles / Q000737:chemistry*; D023303:Oxazolidinones; D013997:Time Factors
D000081:Acetamides; D000890:Anti-Infective Agents; D002511:Cephalosporins; D010080:Oxazoles; D023303:Oxazolidinones; D002443:Ceftriaxone; D002442:Ceftazidime; D002437:Cefazolin; D000069349:Linezolid