logo

Advanced Opioid Converter

Pain Management - Opioid Conversions  Neither GlobalRPh Inc. nor any other party involved in the preparation of this document shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user's use of or reliance upon this material.   DISCLAIMER
Recently updated:  [April 2013] - Improved handling of methadone with additional feedback and new  dosing schemes.

Converting From:

  (Total daily dose in mg)
Hint:    Popup calculator

Additional drugs to convert if present:

  (Total daily dose in mg)
  (Total daily dose in mg)

Converting To:

Reduction for incomplete cross tolerance:

Review only if converting 'TO' chronic oral methadone

Modify the factors below based on your local protocols.
Morphine equivalents Methadone factor
0-99 mg:  
100-299 mg:
300-499 mg:
500-999 mg:
1000-1999 mg:
geq2000 mg
Default factors are based on the following references:2,9,10,12

Review only if converting FROM chronic oral methadone

Converting FROM chronic Methadone to another opioid:  
Highly variable - extreme caution required.  Raising this value will lower the estimated dose of the new opioid.  Consider increasing this number for larger previous doses of methadone and monitor the patient closely.  The residual affects of methadone can last several days after discontinuation depending on the previous dose (long half-life).  New opioid:  Start LOW and go SLOW. 

When converting an opiate to methadone or switching a patient from methadone to another opiate, the conversion ratios are highly variable and precise conversions are almost impossible. To further complicate matters, the conversions between methadone and another opiate are not bi-directional. When converting a patient who was previously receiving chronic doses of methadone to another opiate, the conversion factor must be adjusted upward in order to reduce the calculated equianalgesic dosage of the new opioid. Currently, there is a lack of consensus regarding an accepted conversion ratio for substituting methadone with another opioid.

Please review these important points:

  1. Published equianalgesic ratios are considered crude estimates at best and therefore it is imperative that careful consideration is given to individualizing the dose of the selected opioid. Dosage titration of the new opioid should be completed slowly and with frequent monitoring. 
  2. Factors that must be addressed during the conversion process include: Age of the patient or presence of coexisting conditions. Use additional caution with elderly patients (65 years and older), and in patients with liver, renal, or pulmonary disease. 
  3. Conversion ratios in many equianalgesic dosing tables do not apply to repeated doses of opioids.
  4. The amount of residual drug in the patient's system must be accounted for. Example: fentanyl will continue to be released from the skin 12 to 36 hours after removal of the patch. Residual effects from discontinued long-acting formulations should also be assessed before converting a patient to a new opioid.
  5. Review the concept of incomplete cross-tolerance:
  6. D. McAuley:   "Incomplete cross-tolerance relates to tolerance to a currently administered opiate that does not extend completely to other opioids. This will tend to lower the required dose of the second opioid. This incomplete cross-tolerance exists between all of the opioids and the estimated difference between any two opiates could vary widely. This points out the inherent dangers of using an equianalgesic table and the importance of viewing the tabulated data as approximations. Many experts recommend - depending on age and prior side effects - reducing the dose of the new opiate by 33 to 50 percent to account for this incomplete cross-tolerance. (Example: a patient is receiving 200mg of oral morphine daily (chronic dosing), however, because of side effects a switch is made to oral hydromorphone 25 - 35mg daily - (this represents a 33 to 50 percent reduction in dose compared to the calculated 50mg conversion dose produced via the equianalgesic calculator). This new regimen can then be re-titrated to patient response. In all cases, repeated comprehensive assessments of pain are necessary in order to successfully control the pain while minimizing side-effects."
  7. The use of high but ineffective doses of a previous opioid may result in overestimation of the converted opioid. 
  8. Ideally, methadone conversions (especially patients who were previously receiving high doses of an opioid) should only be attempted in cooperation with a pain specialist or a specialist in palliative medicine. 


The authors make no claims of the accuracy of the information contained herein; and these suggested doses and/or guidelines are not a substitute for clinical judgment. Neither GlobalRPh Inc. nor any other party involved in the preparation of this document shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user's use of or reliance upon this material.    PLEASE READ THE
DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER.  
You must confirm that you have READ and AGREE with the terms and conditions listed above before continuing: led
  Disagree Agree

Background:

Equianalgesic dosage table
Buprenorphine (IM/IV): 0.4
Butorphanol (IM/IV): 2.0
Codeine (IM/IV): 120
Codeine (PO): 200
Fentanyl (IM/IV): 0.1
Fentanyl (Transdermal): 0.2
Hydrocodone (PO): 30
Hydromorphone (IV/IM/SC): 1.5
Hydromorphone (PO): 7.5
Levorphanol (acute PO): 4.0
Levorphanol (chronic PO): 1.0
Meperidine (IV/IM/SC): 75
Meperidine (PO): 300
Methadone (acute IV): 5.0
Methadone (acute PO): 10
Methadone (chronic PO): see table above
Morphine (IV/IM/SC): 10
Morphine (acute PO): 60
Morphine (chronic PO): 30
Nalbuphine (IV/IM/SC): 10
Oxycodone (PO): 20
Oxymorphone (IV/IM/SC): 1.0
Oxymorphone (PO): 10
Tapentadol (PO): 75-100
Fentanyl Patch Conversions - Package Insert Recommendations
RECOMMENDED INITIAL DURAGESIC® DOSE BASED UPON DAILY ORAL MORPHINE DOSE4
Oral 24-hour
Morphine
(mg/day)
DURAGESIC®
Dose
(mcg/h)
NOTE: In clinical trials, these ranges of daily oral morphine doses were used as a basis for conversion to DURAGESIC®.
This table should not be used to convert from DURAGESIC® to other therapies because this conversion to DURAGESIC® is conservative. Use of this table for conversion to other analgesic therapies can overestimate the dose of the new agent. 
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
Discontinuation of DURAGESIC®:
To convert patients to another opioid, remove DURAGESIC® and titrate the dose of the new analgesic based upon the patient's report of pain until adequate analgesia has been attained. Upon system removal, 17 hours or more are required for a 50% decrease in serum fentanyl concentrations. Opioid withdrawal symptoms (such as nausea, vomiting, diarrhea, anxiety, and shivering) are possible in some patients after conversion or dose adjustment. For patients requiring discontinuation of opioids, a gradual downward titration is recommended since it is not known at what dose level the opioid may be discontinued without producing the signs and symptoms of abrupt withdrawal.
References
  1. American Pain Society (APS). Principles of Analgesic Use in the Treatment of Acute Pain and Cancer Pain, 6th edition. 2008. Glenview, IL 60025. 
  2. Ayonrinde OT, Bridge DT. The rediscovery of methadone for cancer pain management. Med J Aust 2000; 173(10): 536-540.
    Daily oral morphine dose equivalents Conversion ratio of oral morphine to oral methadone
     <100 mg 3:1
    101-300 mg 5:1
    301-600 mg 10:1
    601-800 mg 12:1
    801-1000 mg 15:1
    >1000 mg 20:1
  3. Breitbart W, Chandler S, Eagel B, et al. An alternative algorithm for dosing transdermal fentanyl for cancer-related pain. Oncology. 2000;14:695-705.
  4. Donner B, et al. Direct conversion from oral morphine to transdermal fentanyl. Pain. 1996; 64:527-534.
  5. Duragesic® Package Insert: http://www.duragesic.com/prescribing-information.html     Accessed: October 2010.
  6. Fisch MJ, Cleeland CS: Managing cancer pain. In: Skeel RT, ed.: Handbook of Cancer Chemotherapy. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2003, pp 663. 
  7. Friedman LL, Rodgers PE. Pain management in palliative care. Clin Fam Prac. 2004;6:371-393.
  8. Fudin J, Marcoux MD, Fudin JA.  Mathematical Model For Methadone Conversion Examined. Practical Pain Management. 2012(Sep):46-51.
    • Jeffrey Fudin, B.S., Pharm.D., FCCP: http://paindr.com
    •  Mathematical Model For Methadone Conversion Examined:Link
    •  Fudin Factor graphically compared to Ripamonte, Ayonrinde, and Mercadante - jpeg
  9. Gazelle G, Fine PG. Fast Facts Documents #075 - Methadone for the Treatment of Pain, 2nd ed 2009. End of Life/ Palliative Education Resource Center. Link: http://www.eperc.mcw.edu/EPERC/FastFactsIndex/ff_075.htm(Revisited April 2013).
    "Due to incomplete cross-tolerance, it is recommended that the initial dose is 50-75% of the equianalgesic dose"  - Based on the Ayonrinde method above.
    Daily oral morphine dose equivalents Conversion ratio of oral morphine to oral methadone using 25% reduction (75% of equianalgesic dose)
     <100 mg 4:1
    101-300 mg 6.7:1
    301-600 mg 13.3:1
    601-800 mg 15.4:1
    801-1000 mg 20:1
    >1000 mg 26.7:1
  10. Methadone PI (package insert). Dolophine hydrochloride, 5 mg, 10mg tablets. July 2012.
    Oral Morphine to Oral Methadone Conversion for Chronic Administration (Package Insert versus GlobalRPh default factors)
    Total Daily Baseline Oral Morphine Dose Estimated Daily Oral Methadone Requirement as % of Total Daily Morphine Dose
    < 100 mg 20% to 30% 
    [Globalrph 25% (4:1)]
    100 to 300 mg 10% to 20% 
    [Globalrph 12.5% (8:1)]
    300 to 600 mg 8% to 12% 
    [Globalrph (300-499) 8.3% (12:1)]
    600 mg to 1000 mg 5% to 10% 
    [Globalrph (500-999) 6.66% (15:1)]
    > 1000 mg < 5 % 
    [Globalrph (>1000) 5% (20:1)  ]
  11. McPherson ML. Demystifying opioid conversion calculations. A guide for effective dosing. Bethesda: American Society of Health System Pharmacists;2010. [pp107-143]
  12. Mercadante S, Casuccio A, Fulfaro F, et al. Switching from morphine to methadone to improve analgesia and tolerability in cancer patients: A prospective study. J Clin Oncol. 2001;19:2898-2904.
    30-90 mg 4:1
    90-300 mg 8:1
    > 300 mg 12:1
  13. Morley J, Makin M. The use of methadone in cancer pain poorly responsive to other opiates. Pain Rev.1998;5:51-58.
  14. Ripamonti C, Groff L, Brunelli C, Polastri D, Stavrakis A, De Conno F. Switching from morphine to oral methadone in treating cancer pain: what is the equianalgesic dose ratio? J Clin Oncol. 1998;16(10):3216-3221.

Disclaimer

All calculations must be confirmed before use. The authors make no claims of the accuracy of the information contained herein; and these suggested doses are not a substitute for clinical judgement. Neither GlobalRPh Inc. nor any other party involved in the preparation of this program shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user's use of or reliance upon this material.PLEASE READ THE DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER.   Read the disclaimer
more Career Center image description
Medical Calculators - A thru Z
Lab Values - A thru Z