What is the most common steam sterilization cycle used for injectable products?

• A. 20 minutes at 15 psi and 121.5 C
• B. 30 minutes at 20 psi and 125 C
• C. 60 minutes at 15 psi and 134 C
• D. 10 minutes at 10 psi and 115 C

Answer: (A)

Moist heat sterilization relies on saturated steam to inactivate microorganisms by coagulating their proteins. For injectable products, the standard cycle uses saturated steam at 121.5°C with about 15 psi for roughly 20 minutes. This combination provides reliable microbial kill, including spores, while minimizing thermal stress on the drug product and its container. Higher temperatures or longer times can increase the risk of degrading sensitive drugs or damaging packaging, so they aren’t the go-to choice for routine sterilization of injectables. Shorter or lower-temperature settings (e.g., 115°C or 10 psi) would not achieve the same lethality, and longer or hotter cycles (e.g., 134°C) are used only in specific, non-standard scenarios. Therefore, the 20-minute cycle at 121.5°C and 15 psi is the most common for injectable products.