This is the third of three articles by Lawrence F Muscarella, PhD, discusses the evolution of the labeling of a medical device – namely, of the “Instructions for Use” of the disinfectant “Cidex OPA” (which is used to high-level disinfection semi-critical devices, including gastrointestinal endoscopes).

Part 1 and Part 2 of this series were published in the article “Ortho-phthalaldehyde: A Tale of Three Labels,” which may be read by clicking here. Guidance for the save and proper use of this product is provided herein, in Part 3.

Although this article focuses on Cidex OPA, some of its content, including the provided recommendations, may also be applicable to other similar, products whose active ingredient is also “OPA,” known generically as ortho-phthalaldehyde.

Examples would include Metricide OPA Plus and Rapicide OPA 28.

A copy of Cidex OPA’s current labeling may be downloaded by clicking here; of Metricide OPA Plus’s labeling, by clicking here (oops! It’s not available on-line); and of Rapicide OPA 28’s labeling, by clicking here.PART 3 – RECOMMENDATIONS FOR THE SAFE AND PROPER USE OF CIDEX OPA

When used in accordance with its label, Cidex OPA (and comparable products whose active ingredient is ortho-phthalaldehyde), which is not to be confused with Cidex (2% glutaraldehyde), is reported to be safe, effective and a valued addition to an endoscopy department’s armamentarium of instrument reprocessing products.

For review, “OPA” (or Cidex OPA) has become a popular alternative to formulations of glutaraldehyde, hydrogen peroxide, and peracetic acid and may be favored by some endoscopy departments, because it is easy to use, does not require activation, and rapidly achieves high-level disinfection, both in 12 minutes at room temperature (20o C or 68o F) and in 5 minutes at 25o C (77o F).

Cidex OPA and other liquid chemical sterilants/disinfectants, or “LCSs,” that are rapidly tuberculocidal facilitate the quick decontamination of instruments, which are usually limited in number, for prompt reuse throughout the day, reducing strain on reprocessing staff.

Conversely, LCSs associated with a longer immersion time, such as 20 to 45 minutes, may require an endoscopy department to purchase additional instruments–some of which, like a colonoscope, may cost as much as $30,000 – to meet patient demand. GI endoscopy, bronchoscopy, anesthesiology, cardiology, gynecology, and the operating room are some of the departments and settings within a medical facility that may use Cidex OPA.


The following recommendations are provided for the safe and proper use of Cidex OPA.These recommendations are an adjunct to, not a replacement for, the current version of Cidex OPA’s label.

Many of these recommendations are not unique to Cidex OPA and are also provided for the safe and proper use of other LCSs. Adherence to these recommendations will minimize the risk of improper reprocessing.

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Click here to download recommendations for the safe and effective use of Cidex OPA and other high-level disinfectants that contain ortho-phthalaldehyde as their active ingredient (e.g., “Rapicide OPA-28” and “Metricide OPA Plus”). (The recommendations are not contained in this article.)

Click here to download recommendations for the safe and effective use of Cidex OPA and other high-level disinfectants that contain ortho-phthalaldehyde.


These comprehensive and detailed recommendations are provided for the safe and proper use of Cidex OPA, and many of them may also be applicable to 2% glutaraldehyde and other types of LCSs. Adherence to these recommendations will reduce the risk of both disease transmission to patients during flexible endoscopy and injury to healthcare staff members.

The use of an LCS to reprocess reusable (heat-sensitive, semi-critical) instruments manually or with an AER is ubiquitous in healthcare facilities and presents a challenging dynamic. In some instances, the labels of the LCS, the reusable instrument, and the AER may provide inconsistent reprocessing instructions, causing confusion and the potential for an increased risk of injury to both patients and healthcare staff members.

Healthcare facilities may resolve some potential reprocessing conflicts by a more thorough review of each label or by formal discussions with the manufacturers of the LCS, the instrument, and the AER, if one is used.

But, these efforts may not always yield a timely or suitable resolution, as a manufacturer may be unwilling to deviate, if only slightly, from the reprocessing instructions provided in its product’s label. In these instances, adherence to whichever label of the three that provides the widest margin of safety for the patient is recommended. Adoption of this paradigm may prove useful to the resolution of a reprocessing impasse or conflict.

Consider the following hypothetical example: The label of an LCS recommends rinsing an instrument three times with water following high-level disinfection, while the instrument’s label recommends two terminal water-rinses.

Further, an AER that may be used by the healthcare facility can be set to provide a single, double, or triple water-rinse after high-level disinfection. What are reprocessing staff members to do?  Would patient safety be compromised if staff were to manually rinse the instrument twice or to set the AER to rinse the instrument only once following high-level disinfection?

Adoption of the paradigm to err on the side of patient safety would suggest that healthcare staff members follow the label of the LCS during manual reprocessing, because its recommendation for three terminal water-rinses would presumably provide a wider margin of patient safety than two (assuming the volumes and durations of the two water-rinses are comparable).

Manually rinsing the instrument with water twice after chemical immersion as instructed by the instrument’s label would seem permissible and safe, however, provided the instrument’s manufacturer had demonstrated the safety and effectiveness of two water-rinses following high-level disinfection using this specific LCS, and that these data had been reviewed by the FDA. (In general, while it might not pose a risk, caution is advised whenever rinsing an instrument with water fewer times than indicated on the LCS’s label.)

If using an AER, however, that features a single water rinse setting to follow chemical immersion—a different and potentially less thorough and rigorous water-rinse than recommended by the labels of either the LCS (three water-rinses) or the instrument (two water-rinses)—adoption of the aforementioned paradigm would suggest that staff set the AER to rinse the instrument three times with water as instructed for manual reprocessing by the LCS’s label (e.g., the “3-2-1” recommendation).

In this example, however, setting the AER to rinse the instrument once with water after high-level disinfection would seem permissible and safe, provided the manufacturer of the AER had demonstrated the safety and effectiveness of rinsing this specific reusable instrument only once with water following high-level disinfection using this specific LCS in the AER, and that these data had been reviewed by the FDA.

If a manufacturer is unwilling to provide these data to a healthcare facility for its review, claiming, for instance, that these data are proprietary, then adoption of the paradigm to adhere to the label of the three that, again, provides the widest margin of patient safety would seem warranted.

Manufacturers of LCSs, reusable instruments, and AERs might want to consider more collaboration with one another to prevent the labels of their respective products from including potentially conflicting reprocessing instructions.

If a patient is injured by an instrument as a result of inadequate automated water rinsing, it is likely that the manufacturers of all three of these devices would be considered at fault.

By: Lawrence F Muscarella, PhD; posted: 5-6-2013; revised: 12-22-2014.

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2 thoughts on “Recommendations for the Safe and Effective Use of Ortho-phthalaldehyde”
  1. Larry, please correct your blog above, there is an error in the temperature above -it is NOT 200 ‘C it is 20 ‘C!!

    1. Monika, Thank you for your critical eye. The format intended to read 20 o Celsius; which causes the text to appear to say 200 C. I will edit the text using the tex “degrees” instead of “o” to avoid any confusion. Thank you again. Best regards, Larry

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