Steve Ariens

Many have pointed out the poor quality of studies/data that the CDC committee used to develop these guidelines and ignored other and often better studies/data that contradicted what was used.

Many healthcare entities are slicing and dicing the guidelines, implementing certain sections and ignoring/discarding other whole sections.

The one section of the guidelines that EVERYONE seems to include in their policies and procedures is the daily Morphine mgs Equivalent limits.

If one looks at these opiate conversion tables you will find warning like these:

http://clincalc.com/opioids/

Equianalgesic conversions used in this calculator are based on the American Pain Society guidelines and critical review papers regarding equianalgesic dosing.4,5,6,7 When possible, chronic-dosing studies have been used, including bidirectional and dose-dependent conversions.

There is an overall lack of data regarding most equianalgesic conversions, and there is a significant degree of interpatient variability. For this reason, reasonable clinical judgment, breakthrough (rescue) opioid regimens, and dose titration are of paramount importance.

reasonable clinical judgment, breakthrough (rescue) opioid regimens, and dose titration are of paramount importance

As a clinician, it is important to note that there are significant limitations to equianalgesic conversions and tables. While these equianalgesic tables are current the “best” solution, their limitations should be emphasized:

Single-dose studies: Early studies determining equianalgesia were based on single doses, not chronic administration. Due to drug accumulation, half-life, tolerance, and active metabolites, subsequent chronic administration studies often vary greatly from the original single-dose data.

Bidirectional conversions: When converting between certain opioids, the direction of conversion (eg, morphine to hydromorphone versus hydromorphone to morphine) will produce a different conversion ratio. These bidirectional differences are not captured in a traditional equianalgesic table.5,7

Dose-dependent conversions: The conversion ratio of certain opioids can be dependent on the dose of the original opioid. In the case of converting morphine to methadone, methadone has a relative potency of 4:1 at lower morphine doses, but becomes much more potent (12:1) in patients converting from very high morphine doses.5,7

Cross-tolerance: Many references recommend a cross-tolerance reduction between 25-50% when converting between unlike opioids.9 In patients with very high opioid requirements, the difference between 25% and 50% can be a very significant discrepancy.

Equianalgesic Discrepancies: There are significant discrepancies in equianalgesic dosing tables, with even FDA-approved drug labels not demonstrating agreement. These discrepancies are a factor of both references using old data (single-dose studies) and an overall paucity of data in chronic dosing studies.

Patient-specific factors: No equianalgesic table is able to take into account patient-specific factors — primarily hepatic function, renal function, and age. Opioid metabolism and excretion do differ among the opioids; therefore, alterations in drug disposition will alter the relative potencies of different opioids.

To put it in “layman’s terms”.. These opiate conversion tables are made up of “fuzzy math” with the exception of Methadone conversion, which is “FUZZIER MATH”.

The second variable that is ignored by the CDC guidelines is the variable of a pt’s Cytochrome P450 enzyme system. Which 20%-30% of the population has “defective” metabolism of opiates. Requiring higher and/or more frequent dosing to achieve adequate pain management.  http://www.medscape.com/viewarticle/771480

There are more than 57 genes in the CYP450 liver enzyme system that are used by the body to metabolize different medications but only three are primarily involved with opiate metabolism – except Methadone.

So we have two major variables that can dramatically affect the pt’s overall pain management and they are not on anyone’s “radar”.  So many healthcare professionals and healthcare entities just blindly following guidelines that were set up by a committee that intentionally or unintentionally set up guidelines that does not take a individual pt’s variable needs into consideration.