Opioid Conversions (Advanced) - Equivalent dosages
The opioid (equianalgesic) conversions calculator allows a clinician to generate an equivalent dose (equal amount of analgesia) when switching between different opioid analgesics. There may be several possible reasons to switch analgesics including: drug cost, availability, lack of effectiveness of the current drug, or to minimize adverse effects. This tool also provides precise control over methadone conversions as well as corrections for incomplete cross-tolerance.
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
* Ability to choose
up to 3 different opiates to convert to a final opiate.
* Ability to reduce
the final output based on incomplete cross-tolerance. Several choices are
available based on the clinical needs of the patient.
* Option for converting
final output into an equivalent fentanyl patch strength as long as published
guidelines exist for the current dose.
* Methadone conversion algorithm
including the ability to edit equianalgesic conversion factors if necessary in order
to reflect any changes in the literature.
(Total daily dose in mg)
Additional drugs to convert if present:
daily dose in mg)
dose in mg)
Reduction for incomplete cross tolerance:
Please review these important
- 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.
- Conversion ratios in many equianalgesic dosing tables do not apply to repeated doses of
- 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
- Review the concept of incomplete
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
- The use of high but ineffective doses of a previous opioid may result in overestimation of the converted opioid.
- 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.
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
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Advanced options (optional)
Review if converting 'FROM' or 'TO' I.V. or transdermal fentanyl
Converting FROM transdermal fentanyl:
Converting TO transdermal fentanyl:
Converting FROM IV fentanyl:
Converting TO IV fentanyl:
Derivation of default factors:
(note: default factors are set to maximize
safety - modify as needed):
Assumption one 11,15: morphine
(oral) 60 mg = Fentanyl transdermal 25
(600mcg/day). (x /30) * 60 = 0.6
or 60x = 18 --> x = 0.3
Assumption two 3,11: morphine
(oral) 2 mg = transdermal fentanyl 1 mcg/hour.
'Breitbart method' morphine (oral) 50mg =
transdermal fentanyl 25 mcg/hour.
(x /30) * 50 = 0.6 or 50x = 18 --> x
= 0.36 (conversion factor)
Fentanyl I.V. conversions:
1,11,15: morphine (oral) 30 mg =
morphine i.v. 10mg =fentanyl i.v. 0.1 mg
(100mcg) = ~4.1mcg/hr.
[e.g. morphine 4mg/hr =~ fentanyl I.V. 40
Assumption two 11:morphine
i.v. 4 mg/hr (96mg/day)=
fentanyl i.v. 100mcg/hour (2.4mg/day)
(x /10) * 96 = 2.4 or 96x = 24 -->
x = 0.25 (conversion factor)
conversions FROM or TO fentanyl i.v. and
transdermal fentanyl :
Conversion from these dosage forms are 1:1 but
require special handling. If you are converting a
patient TO or FROM fentanyl i.v. or
transdermal and these are the only drugs
present, the program can provide specialized
dosing information. Selecting 'yes' will
convert the first drug listed (fentanyl i.v.
or transdermal) to the opposite drug.
Select any drug in the final opiate section -
it will be ignored.
Enable specialized fentanyl conversion (TDF
<--> fentanyl i.v.) :
Review only if converting 'TO' chronic oral
Modify the factors below based on
your local protocols.
|Morphine equivalents | Methadone factor
|Default factors are based on the
Review only if converting FROM chronic oral
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
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
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
Additional conversion data
- American Pain Society (APS). Principles of Analgesic Use in the Treatment of Acute Pain and Cancer Pain, 6th edition. 2008. Glenview, IL 60025.
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
| <100 mg
- Breitbart W, Chandler S, Eagel B, et al. An alternative
algorithm for dosing transdermal fentanyl for
cancer-related pain. Oncology. 2000;14:695-705.
- Donner B, et al. Direct conversion from oral
morphine to transdermal fentanyl. Pain. 1996;
- Duragesic® Package Insert:
Accessed: October 2010.
- 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.
- Friedman LL, Rodgers PE. Pain management in
palliative care. Clin Fam Prac. 2004;6:371-393.
- 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:
Model For Methadone Conversion Examined:Link
- Fudin Factor graphically
compared to Ripamonte, Ayonrinde, and
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:
https://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
| <100 mg
Methadone PI (package insert). Dolophine hydrochloride, 5 mg, 10mg tablets.
|Oral Morphine to
Oral Methadone Conversion for Chronic Administration
(Package Insert versus GlobalRPh default factors)
|Total Daily Baseline Oral
||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%
|600 mg to 1000 mg
||5% to 10%
[Globalrph (500-999) 6.66%
|> 1000 mg
||< 5 %
[Globalrph (>1000) 5%
- McPherson ML. Demystifying opioid conversion
calculations. A guide for effective dosing. Bethesda:
American Society of Health System Pharmacists;2010.
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.
|> 300 mg
- Morley J, Makin M. The use of methadone in cancer
pain poorly responsive to other opiates. Pain Rev.1998;5:51-58.
- 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.
- Rosenquist EW. Overview of the treatment of
chronic pain. In: UpToDate, Aronson MD (Ed), UpToDate,
Waltham, MA. (Accessed on January 15, 2015.)