How does the relationship between Vaporized Hydrogen Peroxide (VHP) concentration, exposure time, and environmental factors impact the decontamination

How does the relationship between Vaporized Hydrogen Peroxide (VHP) concentration, exposure time, and environmental factors impact the decontamination

The effectiveness of vaporized hydrogen peroxide (VHP) decontamination in pharmaceutical isolator systems is influenced by several key factors: the concentration of the sterilant, the duration of exposure, and the characteristics of the surface being decontaminated. These factors collectively determine the overall efficacy of the decontamination process.


VHP Cycle

A fundamental equation to represent the decontamination process is:

CT=C×t

Where:

  • CT = Decontamination efficacy (ppm-hours)
  • C = VHP concentration (ppm)
  • t = Exposure time (hours)

To enhance accuracy, an environmental impact factor (k) can be introduced:

CT_eff=k×(C×t)

Where k accounts for temperature, humidity, surface type, and microbial resistance.

Impact on VHP Effectiveness:

  1. Higher Concentration (C↑) → Faster Kill Rate: Increasing VHP concentration typically reduces required exposure time but may increase material degradation.
  2. Longer Exposure Time (t↑) → Greater Microbial Reduction: Extended exposure improves decontamination but may lead to excessive residue.
  3. Surface Material & Complexity: Porous or irregular surfaces may require longer exposure times or higher concentrations.
  4. Environmental Conditions (k factor): Higher Humidity (RH↑) → Enhances microbial kill by increasing VHP effectiveness. Lower Temperature (T↓) → Slows down microbial inactivation.Cause-and-Effect Diagram for VHP Decontamination Failure:

Here’s a Fishbone (Ishikawa) Diagram showing potential causes of VHP decontamination failure:

Main Causes of Failure:

?? Process Issues

  • Inadequate cycle time
  • Insufficient VHP concentration
  • Poor aeration phase

?? Equipment Failures

  • Leaks in the isolator
  • Inefficient vapor distribution
  • Sensor calibration errors

?? Environmental Factors

  • Incorrect humidity levels
  • Unfavorable temperature conditions
  • Poor airflow

?? Surface & Material Factors

  • Complex geometries/shadowed areas
  • Adsorption of VHP by certain materials
  • Presence of biofilms or organic residues

?? Microbial Resistance

  • High bioburden levels
  • Resistant spores
  • Incomplete kill due to suboptimal conditions

Pankaj Swain

Manager QC Microbiology (Injectable facility) Sterility Assurance, QMS, Media Fill participation, Successfully faced EU-GMP, UK-MHRA & USFDA.

18 小时前

Good insight

回复
Martin Kelly

Senior Quality Officer (Validation) at Phillips Medisize

3 天前

Many variables to consider dependent on if you're gassing a room or an enclosure. In an enclosure there's highly likely a load as it'll be used for an aseptic process so the porosity of the load for absorption needs to be considered, the total surface area of the load, surface temperatures, load placement to ensure minimal occluded surfaces as if the vapour cannot reach it, it will not be effective in decontamination. A robust gassing cycle development for each load pattern with a modest security margin applied (slightly extended conditioning phase or dwell) ensures effectiveness each time a cycle is run. All of course dependent on the customers process and the equipment they use for their VHP/HPV as some will have a full saturation with up to 100% humidity and others use a dry cycle. A really interesting topic though and the correct application is very efficient when correctly validated.

Bill Vasiliadis, MEng

Annex 1 Champion, Cross Functional Leader

3 天前

What residue do you expect from H2O2? It just dissociates to water

Much of this is based on the assumption that kill Is achieved best in the gas phase. If that is not the case a lot of this changes.

Palash Chandra Das , Thanks for sharing these insights on VHP decontamination! It’s so interesting to see how different factors play a role in effectiveness. I’ve faced challenges with humidity levels impacting results in the past. What strategies have you found most helpful for optimizing those conditions? ???? #Pharmaceuticals #Decontamination #Safety

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