Dry Heat Sterilization
What a definition is not
A definition is SPEQ’s plain-language decode of how a term is used in practice, cited to the documents that define it. It is a practitioner reference, not legal or regulatory advice, it does not replace the definition in the source, and where a regulator’s wording differs the regulator’s wording governs.
A terminal sterilization and, at higher temperatures, depyrogenation method using hot air — typically 160–190°C for defined hold times — for heat-stable materials unsuited to moist heat, such as glass vials, metal components, powders, and non-aqueous liquids such as oils. Depyrogenation cycles (commonly ≥250°C) additionally destroy heat-stable bacterial endotoxin.
Dry heat transfers energy less efficiently than steam, so it requires substantially higher temperatures or longer exposure times than moist heat to achieve equivalent microbial lethality, and forced-air convection or tunnel systems are used to improve heat distribution.
A single dry-heat cycle can be validated to deliver both sterilization and depyrogenation when run at the higher temperature/time combination required to achieve a validated log reduction in endotoxin challenge, distinguishing it from a moist-heat cycle, which does not depyrogenate.
Continuous depyrogenation tunnels integrated into fill lines apply dry heat to washed glass containers immediately before filling, combining sterilization and endotoxin reduction in a single in-line step.
- —Used for heat-stable materials unsuitable for moist heat (glass, metal, powders, oils).
- —Runs at substantially higher temperatures than autoclaving for equivalent lethality.
- —A depyrogenation cycle is validated separately using an endotoxin challenge, not just a biological indicator.
- —Often delivered by tunnel or oven systems integrated into container-preparation lines.
EU GMP Annex 1 (2022); ISO 20857; USP <1211>
Frequently asked questions
What is Dry Heat Sterilization?
A terminal sterilization and, at higher temperatures, depyrogenation method using hot air — typically 160–190°C for defined hold times — for heat-stable materials unsuited to moist heat, such as glass vials, metal components, powders, and non-aqueous liquids such as oils. Depyrogenation cycles (commonly ≥250°C) additionally destroy heat-stable bacterial endotoxin.
Which regulations cover Dry Heat Sterilization?
EU GMP Annex 1 (2022); ISO 20857; USP <1211>