Opioid Risk and Dosing

When assessing Mr. Gateway's pain, you should also address any opioid risk factors he has. It's helpful to also distinguish between the following terms:

  • Tolerance - A state of adaptation in which exposure to a drug induces changes that result in a diminution of one or more opioid effects over time.

  • Physical dependence - A state of adaptation manifested by a drug class-specific withdrawal syndrome that can be produced by: abrupt cessation, rapid dose reduction, decreaing blood level of the drug, and/or administration of an antagonist.
  • Addiction - A primary, chronic, neurobiologic disease with genetic, psychosocial, and environmental factors. It's characterized by behaviors that include one or more of the following: impaired control over drug use, compulsive use, continued use despite harm, and/or craving.
  • Pseudoaddiciton - This is a "concept" and not a true diagnosis and is based off of case reports and small case studies. It can be understood as an iatrogenic syndrome resulting from misinterpretation of relief-seeking behaviors as though they are drug-seeking behaviors that are commonly seen with addiction. The relief-seeking behaviors resolve upon institution of effective analgesic therapy.
  • Aberrant behavior - Any medication behaviors departing from prescribed plan of care, ranging from mildly problematic, such as hoarding medications to use for times of severe pain, to selling medications.
  • Medication misuse - Use of a medication (with therapeutic intent) other than as directed or as indicated, whether willful or unintentional, and whether harm results or not.

Distinguishing between "addiction" and "pseudoaddiction" can be challenging and often cannot be reconciled.

Equianalgesic Example

From this table, you can compare potencies or "strengths" between the different opioids.

For instance, oral hydromorphone is more potent than oral oxycodone, which is more potent than oral morphine. Thus, lower doses of hydromorphone are needed for a similar effect of a higher dose of oxycodone.

Oral/Rectal Dose (mg) Opioid Analgesic Intravenous Dose (mg)
30 Morphine 10
0.4 Buprenorphine 0.3
200 Codeine 100
N/A Fentanyl 0.1
30 Hydrocodone N/A
7.5 Hydromorphone 1.5
20 Oxycodone N/A
100 Tramadol N/A

Equianalgesic Fentanyl

Calculations for transdermal fentanyl should be made based on the manufacturer's recommendations using the table below.

Oral 24-Hour Morphine Equivalent (mg/day) Transdermal Fentanyl Dose (mcg/hour)
60-134 25
135-224 50
225-314 75
315-404 100
405-494 125
495-584 150
585-674 175
675-764 200
765-854 225
855-944 250
945-1034 275
1035-1124 300

Equianalgesic Methadone

There are numerous calculation methods for conversion to methadone. One method commonly used in practice is listed below.

Oral 24-Hour Morphine Equivalent (mg/day) Oral Dose Ratio (Morphine:Methadone)
greater than 100 3:1
101-300 5:1
301-600 10:1
601-800 12:1
801-1000 15:1
greater than or equal to 1001 20:1
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