Simulated cycle profile generated from the selected preset. Switch to Manual or Paste mode for real thermocouple data.
| Time (min) | Temp (°C) | Lethality Rate | Cumulative F |
|---|
| Organism | Mode | D-value | Temp | ATCC |
|---|---|---|---|---|
| G. stearothermophilus | Moist heat | 1.5–2.0 min | 121°C | 7953 |
| B. atrophaeus | Dry heat | ≥ 2.5 min | 160°C | 9372 |
| C. sporogenes | Moist heat | 0.4–0.8 min | 121°C | 7955 |
| C. botulinum | Moist heat | 0.2–0.25 min | 121°C | — |
| Endotoxin (LPS) | Depyro | — | 250°C | — |
D-value = time at stated temperature to reduce population by 1 log (90%). Standard BI population: 10⁶ spores/unit.
F₀ (F-zero) is the equivalent time in minutes at 121.1°C that delivers the same sterilizing lethality as the actual time-temperature profile. It integrates lethality over the entire cycle including heat-up and cool-down phases using the formula: F₀ = Σ 10((T − 121.1) / 10) × Δt. A standard autoclave cycle of 121°C for 15 minutes delivers an F₀ of approximately 15 minutes, but the actual F₀ will be slightly higher due to lethality contributed during ramp-up and cool-down.
The European Pharmacopoeia specifies a minimum F₀ of 8 minutes. The FDA overkill approach requires F₀ ≥ 12 minutes (12-log reduction of a 10⁶ population with D121 = 1 min). The standard reference cycle is 121°C for 15 minutes (F₀ = 15 min). Many pharmaceutical SOPs use 121°C for 30 minutes (F₀ ≈ 30 min) for maximum safety margin.
The overkill approach assumes worst-case bioburden (10⁶ organisms with D121 = 1 min), requires F₀ ≥ 12 min, and is validated via the half-cycle method. It does not require routine bioburden monitoring. The bioburden-based approach uses actual bioburden data to calculate Fbio = D × (log N₀ + 6), allowing shorter cycles for heat-sensitive products. It requires ongoing bioburden testing and more complex validation.
Validation requires: (1) thermocouple mapping to identify cold spots in the chamber or vessel, (2) biological indicator (BI) challenges using G. stearothermophilus spores placed at cold spots, (3) F₀ calculation from thermocouple data demonstrating the target lethality is achieved at the coldest point, and (4) documented IQ/OQ/PQ protocols. For SIP, all drain points, valve seats, and filter housings must independently reach ≥121°C.
Depyrogenation is the destruction of bacterial endotoxins (pyrogens) using dry heat, typically 250°C for ≥30 minutes. It is validated using FD with Tref = 250°C and z = 46.4°C, targeting ≥3-log reduction of endotoxin. Validation uses spiked endotoxin indicators (≥1,000 EU) placed in the depyrogenation tunnel or oven. It applies to glassware, metal parts, and container components — not liquids or plastics.
For moist heat (steam): Geobacillus stearothermophilus (ATCC 7953), D121 = 1.5–2.0 min, population 10⁶ spores/unit. For dry heat: Bacillus atrophaeus (ATCC 9372), D160 ≥ 2.5 min. For depyrogenation: purified endotoxin indicators (≥1,000 EU) demonstrating ≥3-log reduction. BIs are placed at identified cold spots during validation runs.