Ciprofloxacin and sodium phosphates not compatible during actual Y-site injection

Compatibility and stability of linezolid injection admixed with three quinolone antibiotics

OBJECTIVE

To evaluate the physical compatibility and chemical stability of linezolid 200 mg/100 mL admixed with ciprofloxacin 400 mg, ofloxacin 400 mg, and levofloxacin 500 mg for seven days at 4 and 23 degrees C.

METHODS

The test samples were prepared by adding the required amount of the quinolone antibiotic to bags of linezolid injection. Evaluations for physical and chemical stability were performed initially and after one, three, five, and seven days of storage at temperatures of 4 and 23 degrees C. Physical stability was assessed using visual observation in normal light and using a high-intensity monodirectional light beam. In addition, turbidity and particle content were measured electronically. Chemical stability of the drugs was evaluated by using stability-indicating HPLC analytical techniques.

RESULTS

The linezolid admixtures with levofloxacin and ofloxacin were clear and pale yellow when viewed in normal fluorescent room light, and slightly hazy with a green cast when viewed using a Tyndall beam. Measured turbidity and particulate content were low and exhibited little change. HPLC analysis found no loss of the drugs in any sample stored at either temperature throughout the study. The linezolid admixtures with ciprofloxacin stored at room temperature (23 degrees C) were clear and nearly colorless in normal room light and when viewed using a Tyndall beam. They exhibited little or no change in measured turbidity or particulate content during the study period. HPLC analysis found no loss of either drug in seven days. However, the refrigerated samples were only compatible for 24 hours and developed a gross white precipitate thereafter.

CONCLUSIONS

Admixtures of linezolid 200 mg/100 mL with levofloxacin 500 mg and with ofloxacin 400 mg were physically compatible and chemically stable for at least seven days stored at 4 and 23 degrees C. Admixtures of linezolid with ciprofloxacin 400 mg were compatible and stable for seven days at 23 degrees C, but ciprofloxacin precipitation occurred after 24 hours stored under refrigeration. Linezolid/ciprofloxacin admixtures should not be stored under refrigeration.

Compatibility Screening of Gatifloxacin during Simulated Y-Site Administration with other Drugs

The physical compatibility of gatifloxacin injection (Tequin, Bristol-Myers Squibb) with 110 other drugs during simulated Y-site injection was evaluated by visual observation and turbidity measurement, and by electronic particle content assessment if appropriate. Five-milli-liter samples of gatifloxacin injection 2 mg/mL in 5% dextrose injection were combined with 5 mL samples of 110 other drugs. The secondary test drugs included anti-infectives, analgesics, antihistamines, diuretics, steroids, and other supportive care drugs. Visual examinations were performed with the unaided eye in normal diffuse fluorescent light and using a Tyndall beam. The turbidity of each sample was measured as well. Most of the test drugs were compatible with the gatifloxacin admixture during the 4-hour observation period. However, 14 drugs resulted in physical incompatibilities when combined with the admixture. Gatifloxacin admixtures should not be administered simultaneously with these incompatible drugs.