What are morphine (opioid analgesic) equivalents?

From the Guidelines

Morphine equivalents can be calculated using the conversion factors provided in the 2022 CDC clinical practice guideline, where the dose of each opioid is multiplied by a specific conversion factor to determine the dose in morphine milligram equivalents (MME) 1. When determining morphine equivalents, it is essential to consider the specific conversion factors for each opioid, as outlined in the guideline.

• The conversion factors are as follows:
  • Codeine: 0.15
  • Fentanyl transdermal (in mcg/hr): 2.4
  • Hydrocodone: 1.0
  • Hydromorphone: 5.0
  • Methadone: 4.7
  • Morphine: 1.0
  • Oxycodone: 1.5
  • Oxymorphone: 3.0
  • Tapentadol: 0.4
  • Tramadol: 0.2 For example, to calculate the MME for a patient taking hydrocodone 5mg and acetaminophen 325mg four times a day, the total daily hydrocodone dose would be 20mg, which is equivalent to 20 MME daily 1. It is crucial to note that these conversion factors are estimates and may not account for individual variability in genetics and pharmacokinetics, and should not be used to determine doses when converting one opioid to another 1. Additionally, particular caution should be exercised when converting methadone doses due to its long and variable half-life, and when using transdermal fentanyl due to its unique dosing and absorption characteristics 1.
• Key considerations when using morphine equivalents include:
  • Higher MME values indicate stronger opioid doses and increased risk of adverse effects
  • Doses above 50 MME daily warrant extra precautions
  • Doses above 90 MME daily significantly increase overdose risk By using these conversion factors and considering the individual patient's needs and characteristics, clinicians can make more informed prescribing decisions and minimize the risks associated with opioid use 1.

From the FDA Drug Label

TABLE D*,† EQUIANALGESIC POTENCY CONVERSION Name Equianalgesic Dose (mg) IM‡,§ PO Morphine 10 60 (30)¶ Hydromorphone (Dilaudid®) 1.5 7.5 Methadone (Dolophine®) 10 20 Oxycodone 15 30 Levorphanol (Levo-Dromoran®) 2 4 Oxymorphone (Numorphan®) 1 10 (PR) Meperidine (Demerol®) 75 — Codeine 130 200

The morphine equivalents are as follows:

• Hydromorphone (Dilaudid): 1.5 mg IM or 7.5 mg PO is equivalent to 10 mg of morphine
• Methadone (Dolophine): 10 mg IM or 20 mg PO is equivalent to 10 mg of morphine
• Oxycodone: 15 mg IM or 30 mg PO is equivalent to 10 mg of morphine
• Levorphanol (Levo-Dromoran): 2 mg IM or 4 mg PO is equivalent to 10 mg of morphine
• Oxymorphone (Numorphan): 1 mg IM or 10 mg PO is equivalent to 10 mg of morphine
• Meperidine (Demerol): 75 mg IM is equivalent to 10 mg of morphine
• Codeine: 130 mg IM or 200 mg PO is equivalent to 10 mg of morphine 2

From the Research

Morphine Equivalents

Morphine equivalents are used to compare the potency of different opioid analgesics. The following are some key points to consider:

• Morphine milligram equivalent (MME) is a measure used to standardize the dosage of different opioids 3.
• Low dose is considered up to 40 MME, moderate dose is 41 to 90 MME, and high dose is greater than 91 MME 3.
• Most patients with chronic non-malignant pain can be managed with <300 mg/d of morphine (or equivalent) 4.
• The choice of opioid and dosage should be individualized based on the patient's needs and medical history 5.

Opioid Conversion

When converting between different opioids, the following should be considered:

• The potency of different opioids varies, and conversion ratios should be used to avoid overdose or underdose 3.
• Methadone, fentanyl, and buprenorphine are considered ideal analgesics in end-stage renal disease patients due to their pharmacokinetic properties 6.
• Tramadol, oxycodone, hydromorphone, and other opioids can also be used, but require careful dosing and monitoring 6.

Clinical Considerations

The following clinical considerations should be taken into account when using morphine equivalents:

• A thorough history, physical examination, and appropriate testing should be conducted before initiating opioid therapy 5.
• Patients should be monitored regularly for signs of addiction, abuse, or adverse effects 3, 5.
• Opioid therapy should be individualized and adjusted based on the patient's response to treatment 5.