Stability of cefmetazole sodium in 5% dextrose injection and 0.9% sodium chloride injection.

The stability of cefmetazole sodium in 5% dextrose injection and 0.9% sodium choloride injection has been studied using a stability-indicating, high performance liquid chromatography (HPLC) assay method developed in our laboratory. This HPLC method is precise and accurate, with a percent relative standard deviation of 1.4 based on five readings. The admixtures were stable for two days at 25 deg C and for 28 days at 5 deg C, and they remained clear throughout the study period. The pH values decreased from 4.7 to 4.0 in 0.9% sodium chloride injection and from 4.8 to 4.2 in 5% dextrose injection. The expiry date of seven days at 5 deg C recommended by the manufacturer appears to be conservative from a chemical-stability standpoint.

Stability of ceftriaxone sodium when mixed with metronidazole injection.

The chemical stabilities of ceftriaxone sodium and metronidazole in a mixture have been studied using a stability-indicating, high-performance liquid chromatography (HPLC) assay method. The HPLC method is precise and accurate, with a percent relative standard deviation of 1.4 based on five readings. Metronidazole did not lose any potency for four days when stored at 25+/-1 deg C. Ceftriaxone sodium lost less than 6% ofpotency in three days at 25+/-1 deg C. The products of decomposition did not interfere with the assay procedure. They eluted before the ceftriaxone peak. The solution remained clear (light yellow) throughout the study period, and the pH value did not change. Ceftriaxone sodium and metronidazole, when mixed together, were stable for three days at 25+/-1 deg C.