Dry-heat sterilization of parenteral oil vehicles.

The purpose of this study was to evalutate the effect of temperature and time on the dry-heat sterilization conditions of cottonseed, peanut and sesame-seed oils used as vehicles for parenteral drugs. The three oils were inidividually spiked wiht Bacillus subtilis spores and exposed to dry heat at four temperatures (150, 160, 170, and 180 deg C) for three different time intervals (one, 1.5 and two hours). Following inoculation and dry-heat sterilization, samples were placed in a laminar airflow hood and processed according to 71, "Sterility Tests" of the USP XXIV/NF 19 using thioglycolate broth and fluid D. The specimens were then placed into an incubator at 30 deg C and observed for three, five and seven days for bacterial growth. All tests were performed in triplicate. Positive and negative controls were conducted with each group. All three oils were found to be free of viable Bacillus subtilis following dry-heat sterilization at 150, 160, 170 and 180 deg C for one, 1.5 and two hours after incubation for seven days. The positive controls had no observed bacterial growth. Dry-heat sterilization of the three oils at 150 deg C for one hour appeared to be sufficient for time and temperature conditions. However, the authors recommend dry-heat sterilization procedures be validated for each product.