Compatibility of cefmetazole sodium with commonly used drugs during Y-site delivery

The compatibility of cefmetazole sodium and selected other drugs during Y-site delivery was evaluated. Cefmetazole 100 mg/mL (as the sodium salt) in sterile water for injection and each of 34 drugs or solutions commonly used with it were mixed together by Y-site injection. Secondary drugs were administered at selected concentrations and rates and delivered by the method (i.v. push, i.v. infusion, or syringe pump) commonly used for the drug at the institution where the study was done. Each injection set included a filter system with a 0.8-micron filter disk. Tests were done in triplicate. After each test, the Y injection site and the tubing after it were visually inspected for precipitate and color change. If no particles or color change was detected, the filter disk was observed under a microscope. Drugs were deemed compatible with cefmetazole if unaided observation detected no color change or particles and the number of particles detected by microscopic examination was below that specified in USP guidelines. A precipitate formed when cefmetazole sodium mixed with diphenhydramine hydrochloride, droperidol, erythromycin (50 mg/mL, as the lactobionate), haloperidol lactate, prochlorperazine edisylate, promethazine hydrochloride, or vancomycin (50 mg/mL, as the hydrochloride salt). No particles or color change was detected by unaided observation of mixtures containing dobutamine or erythromycin 10 mg/mL, but the number of particles detected by microscopic examination exceeded USP limits. All other drugs tested were compatible with cefmetazole. Cefmetazole 100 mg/mL (as the sodium salt) in sterile water for injection was shown to be compatible with 25 of 34 tested drug solutions during Y-site delivery.