Stability of cimetidine hydrochloride in a total nutrient admixture

The stability of cimetidine hydrochloride in a total nutrient admixture was studied. A total nutrient admixture composed of 5% amino acid injection, 20% dextrose injection, and 3% intravenous fat emulsion was prepared aseptically in four 2-L ethylene-vinyl acetate bags. Cimetidine hydrochloride injection was added to three of the admixtures to yield final cimetidine concentrations of 600, 1200, and 1800 mg per 1500 mL of admixture; the fourth admixture served as a control. At 0, 24, and 48 hours, cimetidine content was measured by high-performance liquid chromatography, and the admixtures were tested for pH and visually inspected for signs of creaming, oiling out, or phase separation. Particle-size distribution in the admixtures was compared with that in 20% intravenous fat emulsion. No appreciable changes in cimetidine concentration or pH occurred over 48 hours, and no visual changes were observed. Particle sizes were comparable to those in the 20% intravenous fat emulsion control except in the admixture containing cimetidine hydrochloride 600 mg, which had significantly more particles larger than 9.9 microns at 48 hours. In the total nutrient admixture studied, cimetidine hydrochloride in concentrations up to 1800 mg per 1500 mL was stable for 24 hours at room temperature, and the lipid emulsion was apparently not altered during this period by cimetidine.