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 ofthe patient or presence of coexisting conditions. Use additional caution withelderly patients (65 years and older), and in patients with liver, renal, orpulmonary disease.
Key Features:
* Ability to chooseup to 3 different opiates to convert to a final opiate.
* Ability to reducethe final output based on incomplete cross-tolerance. Several choices areavailable based on the clinical needs of the patient.
* Option for convertingfinal output into an equivalent fentanyl patch strength as long as publishedguidelines exist for the current dose.
* Methadone conversion algorithmincluding the ability to edit equianalgesic conversion factors if necessary in orderto reflect any changes in the literature.
Converting From:
Additional drugs to convert if present:
Converting To:
Reduction for incomplete cross tolerance:
- 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 ofopioids.
- 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 newopioid.
- Review the concept of incompletecross-tolerance:
- 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.
D. McAuley: "Incomplete cross-tolerance relates totolerance to a currently administered opiate that does notextend completely to other opioids. This will tend to lower therequired dose of the second opioid. This incompletecross-tolerance exists between all of the opioids and theestimated difference between any two opiates could vary widely.This points out the inherent dangers of using an equianalgesictable and the importance of viewing the tabulated data asapproximations. Many experts recommend - depending on age andprior side effects - reducing the dose of the new opiate by 33to 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 ismade to oral hydromorphone 25 - 35mg daily - (this represents a33 to 50 percent reduction in dose compared to the calculated50mg conversion dose produced via the equianalgesic calculator).This new regimen can then be re-titrated to patient response. Inall cases, repeated comprehensive assessments of pain arenecessary in order to successfully control the pain whileminimizing side-effects."
The authorsmake no claims of the accuracy of the information containedherein; and these suggested doses and/or guidelines are not asubstitute for clinical judgment. Neither GlobalRPh Inc. nor any other party involved in thepreparation of this document shall be liable for any special,consequential, or exemplary damages resulting in whole or part from anyuser's use of or reliance upon this material. PLEASEREAD THE DISCLAIMER CAREFULLY BEFOREACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREETO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER.You must confirm that you haveREAD andAGREE with the terms and conditions listed abovebefore continuing: 
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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:
TransdermalFentanyl conversions:
Assumption one 11,15: morphine(oral) 60 mg = Fentanyl transdermal 25mcg/hr
(600mcg/day). (x /30) * 60 = 0.6or 60x = 18 --> x = 0.3(conversion factor)
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:
Assumption one 1,11,15: morphine (oral) 30 mg =morphine i.v. 10mg =fentanyl i.v. 0.1 mg(100mcg) = ~4.1mcg/hr. Factor: 0.1[e.g. morphine 4mg/hr =~ fentanyl I.V. 40mcg/hr]
Assumption two 11:morphinei.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)
Singleconversions FROM or TO fentanyl i.v. andtransdermal fentanyl :
Conversion from these dosage forms are 1:1 butrequire special handling. If you are converting apatient TO or FROM fentanyl i.v. ortransdermal and these are the only drugspresent, the program can provide specializeddosing information. Selecting 'yes' willconvert 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 oralmethadone
| Modify the factors below based onyour local protocols. | |
| Morphine equivalents | Methadone factor | |
| 0-99mg: | 100-299 mg: |
| 300-499 mg: | 500-999 mg: |
| 1000-1999 mg: |  2000mg: |
| Default factors are based on thefollowing references:2,9,10,12 | |
Review only if converting FROM chronic oralmethadone
Highly variable - extreme cautionrequired. Raising this value will lower theestimated dose of the new opioid. Considerincreasing this number for larger previous doses ofmethadone and monitor the patient closely. Theresidual affects of methadone can last several days afterdiscontinuation depending on the previous dose (longhalf-life). New opioid: Start LOW and go SLOW.
When converting an opiate to methadone or switching apatient from methadone to another opiate, the conversionratios are highly variable and precise conversions arealmost impossible. To furthercomplicate matters, the conversions between methadone andanother opiate are not bi-directional.When converting a patient whowas previously receiving chronic doses of methadone toanother opiate, the conversion factor must be adjustedupward in order to reduce the calculated equianalgesicdosage of the new opioid. Currently, there is a lack ofconsensus regarding an accepted conversion ratio forsubstituting methadone withanother opioid.
Background:
| Equianalgesicdosage 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 tableabove 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 | |||||||||||||||||||||||||||||||||||||||||||||||||
| References | |||||||||||||||||||||||||||||||||||||||||||||||||
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