Stability of sufentanil citrate in a portable pump reservoir, a glass container and a polyethylene container

The stability of sufentanil citrate (100 ml, 5 micrograms/ml) in an admixture with sodium chloride 0.9% injection was investigated when filled in a portable pump reservoir with PVC wall, a glass container and a polyethylene container, at 32 degrees C, 4 degrees C and -20 degrees C for up to 21 days. No change in colour was visually observed in any of the samples during the 21-day storage period. A slight precipitation was noticed in three out of nine portable pump reservoirs, one at each storage temperature. There was a slight rise in pH at each storage temperature in all samples. There was approximately 13% loss of sufentanil citrate in the portable pump reservoirs stored at 32 degrees C during 2 days and 60% loss after 21 days, due to absorption of sufentanil citrate in the reservoir wall. No loss of sufentanil citrate could be detected in the portable pump reservoirs when stored at -20 degrees C and 4 degrees C. However, a serious inhomogeneity of the sufentanil citrate solution occurred after thawing at room temperature in the portable pump reservoirs which had been kept at -20 degrees C. The homogeneity could be restored by shaking for approximately 10 min. There was no change in the sufentanil citrate concentrations in the glass containers and polyethylene containers stored at the three temperatures. The portable pump reservoirs stored at 32 degrees C also showed a significant loss of vehicle due to evaporation (1.0 +/- 0.1 ml a week). This could not be detected in any of the other samples.