OPI vs. MOR: The Epic Showdown of Drug Test Lingo

OPI vs. MOR: The Epic Showdown of Drug Test Lingo

In the world of drug testing, and more specifically, rapid or Point-of-Care Testing (POCT), understanding the nuances and terminologies can be challenging, especially for those not directly involved in the industry. As the President of Labb, a leading specifications manufacturer, I’ve spent over 26 years developing rapid drug test kits, protocols, training, and certification programs. In all my years in drug testing, one of the greatest challenges has been effectively explaining questions regarding the terminology around Morphine/Codeine (MOR) assays versus Morphine/Codeine (OPI) assays. In my opinion, using the term Opiates or the abbreviation OPI contributes to this issue as the name Morphine is a far more accurate name for the assay.

A Brief History of Morphine/Codeine Assays

In the early days of rapid drug testing, the industry used a single standard cut-off level for Morphine/Codeine screens, set at 300 ng/mL. This cut-off level was universally accepted. This assay was variably labeled as either Opiates (OPI) or Morphine (MOR). As the field evolved, it became clear that a higher cut-off level for Morphine/Codeine was needed, and a 2,000 ng/mL level was introduced to minimize cross-reactions with poppy seed products. Tis was a result of the fact that it can be virtually impossible for a rapid or laboratory test to distinguish between an individual using Codeine and one consuming a product with poppy seeds. Consequently, the higher cut-off of 2,000 ng/mL was established to combat this cross reaction issue. Assays with the higher, 2,000 ng/mL level became known as OPI, while assays with the lower cut-off level of 300 ng/mL were termed MOR. Some manufacturers also introduced the designation MOP, further complicating the issue.

Understanding the Terminology: MOR, MOP, and OPI

It’s crucial to recognize that MOR, MOP, and OPI assays target the same compounds: Morphine and Codeine, with Morphine serving as the calibrator. There is no difference in the drugs that are detected regardless of the assays designation of OPI, MOR or MOP. The true fallacy in all of this is the term "Opiates," which actually refers to a class of drugs, not a specific drug, often leading to confusion.

Below is a breakdown of common opiate assays found in laboratory and rapid drug tests:

  • Morphine/Codeine
  • Oxycodone/Oxymorphone
  • 6AM / 6MAM (Heroin)
  • Hydrocodone/Hydromorphone
  • Fentanyl
  • Tramadol
  • Methadone
  • Buprenorphine

All of these are Opiate assays. The rapid tests labeled as OPI, MOR, or MOP detect only Morphine/Codeine, a small fraction of the Opiates available. The other opiates listed are not detected using the OPI, MOR, or MOP specific assay.

The Key Takeaway

There is no difference between a Morphine/Codeine assay labeled as OPI and one labeled MOR or MOP, apart from the name printed on the test kit. While there may be variations in cut-off levels across the market, it’s a misconception to assume that any particular abbreviation or designation corresponds to a specific cut-off level. There is a strong tendency for OPI to represent 2,000 ng/mL and for MOR or MOP to represent 300 ng/mL, but this is not a requirement. The terminology and abbreviations are established by the manufacturer or spec manufacturer.

Closing Thoughts

This topic is brought up by a Labb client on a monthly basis. There is often an auditor or self-proclaimed expert that refuses to acknowledge OPI and MOR as the same assay. Although I understand the topic may be confusing, if you are in a position of authority or overseeing a testing program, you owe it to your clients and donors to know what you are talking about. There is no excuse for anyone that is a professional in drug testing to proclaim that a MOR or MOP assay at 2,000 ng/mL is somehow different than a OPI assay at 2,000 ng/mL.  I hope this explanation helps demystify the terminology and usage of Morphine/Codeine assays in drug testing.

If you have any further questions or comments, we would love to hear what you have to say on this or any other topic. Send all comments and questions to James@Labb.com.

 

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