OBJECTIVE (1) to determine the stability of famotidine 200 micrograms/mL in admixtures with dextrose 5% injection (D5W) and NaCl 0.9% injection (NS) in polyvinyl chloride (PVC) minibags and polypropylene syringes, at room temperature (22 degrees C), protected and unprotected from light for 15 days; and (2) to evaluate the visual compatibility of famotidine with 34 selected drugs for four hours at room temperature. METHODS Concentration of famotidine samples was determined on day 0 and again on days 3, 6, 9, 12, and 15 by a stability-indicating HPLC. Inspection for visual and pH changes was also performed at these time intervals. RESULTS More than 95 percent of the day 0 famotidine concentration remained in all samples over the 15-day study period. During this period, all samples remained clear and colorless and no change in absorbance at 450 and 540 nm was observed. The pH of the samples also remained unchanged. Famotidine 2000 micrograms/mL was found to be compatible with 33 selected drugs; only furosemide was found to be incompatible. A white precipitate was observed when an equal volume of famotidine 2000 micrograms/mL in NS was mixed with furosemide 3000 micrograms/mL in D5W. The concentration of famotidine in the supernatant gradually decreased during the 4-hour study period. At 0.5, 1.0, 2.0, and 4.0 hours after mixture of famotidine with furosemide, famotidine concentrations were 97.5, 23.6, 21.7, and 17.2 percent of the initial famotidine concentration, respectively. CONCLUSIONS Our results show that famotidine 200 micrograms/mL was stable in admixture with D5W and NS in PVC minibags and polypropylene syringes when these solutions were stored at room temperature, protected and unprotected from light for 15 days. Famotidine 2000 micrograms/mL in NS was compatible with 33 of the drugs, and was incompatible with furosemide.