Stability of fluorouracil administered through four portable infusion pumps

The stability of fluorouracil in four portable infusion pumps under simulated infusion conditions was studied. Three commercially available fluorouracil aqueous solutions (50 mg/mL) were used. Samples adjusted to six pH levels were examined for precipitate. Drug reservoirs of four different portable infusion pumps were filled with 70 mL of each fluorouracil injection. Under conditions simulating actual use, the reservoirs were attached to the pumps and the solutions were pumped at a rate of 10 mL/24 hours over a seven-day period at 25 degrees C and 37 degrees C. Samples at the distal end of the extension tubing were collected hourly for the first 10 hours and at 12-hour intervals thereafter. Visual observations and pH determinations were made immediately. Drug concentrations were determined by reverse-phase high-performance liquid chromatography. Diethylhexylphthalate (DEHP) concentrations (the result of leaching from the plastic tubing and container) were determined by gas chromatography. In the pH study, precipitate appeared immediately in all fluorouracil injections below pH 8.52; precipitate was observed after two to four hours at pH 8.60-8.68. Under simulated infusion conditions, no apparent changes in concentration or pH were detected with any of the brands of drugs or portable infusion devices. At 25 degrees C, a fine white precipitate was observed in the extension tubing of all devices with the Roche brand of fluorouracil 48 to 96 hours after the pumping cycle began. The amount of DEHP leached from the drug reservoirs over the seven-day period was less than 1 ppm at both temperatures. All tested brands of fluorouracil injection were found to be stable under simulated infusion conditions over a seven-day period at 37 degrees C.