Calculating and Using Morphine Equivalent Doses of Opioids - PowerPoint Presentation

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Calculating and Using Morphine Equivalent Doses of Opioids

Teresa Hudson, PharmD, PhDAssociate Professor of PsychiatryUAMS COM, Department of Psychiatry

Wednesday

, June 20, 2018

AR-IMPACT

TEXT:

501-406-0076

Event ID:

25072-23985

Today’s Objectives

Review strategy to calculate morphine equivalent doses for opioidsDiscuss limitations of current opioid-conversion dataExplain how to modify opioid dosage regimens based on morphine equivalent doseIdentify useful applications that can support conversion calculations

Caveat for today’s presentation:

Cases in this presentation have limited information due to time constraints. In addition, while we are concentrating on opioid dosing in today’s discussion, this does not imply that opioids should routinely be continued

in all patients

.

Equianalgesic Dosing of Opioids

Refers to doses of different opioid medications that provide similar pain relief

Morphine Equivalent Dose (MED) is most commonly used

When is

equianalgesic

dosing useful:

Understand patient’s total daily dose when using multiple opioids

Changing opioid regimens without losing pain control OR overdosing

Developing taper

Side effects with a particular opioid

General Approach

Determine patient’s total amount of opioid patient is currently taking every 24 hours

Use conversion chart/app to convert from opioid dose patient is currently taking to morphine equivalent

If converting from parenteral dosage form, convert to parenteral morphine first then from parenteral to oral morphine

Use conversion chart/app to convert from oral morphine equivalent to dose of desired opioid

Decrease

total daily dose

by up to 50

% - 75%

to account for incomplete cross tolerance between

opioids

Limitations of Current Equianalgesia Tables/Apps

Single dose studies

Broad guidelines

Calculated dose should be reduced due to incomplete cross tolerance but may risk exacerbation of pain

Clinical status of the patient not considered in table conversion

Age

Renal/hepatic function

Pain severity and recent opioid regimen

Many apps provide only MED but do not provide option to calculate equivalent dose of new opioid based on MED

Methadone – use caution when working with higher doses. Conversion factors varies at higher dose

Fentanyl – dose in mcg/

hr

instead of mg/day and absorption is affected by heat and other factors

A Couple Notes of Caution:

Methadone – use caution when working with higher doses. Conversion factors varies at higher

dose

Methadone 1-20mg = 7.5mg of morphine

Methadone 21-40mg = 3.75mg morphine

Methadone 41=60mg = 3mg morphine

Methadone >61mg = 2.5mg morphine

Fentanyl – dose in mcg/

hr

instead of mg/day

Transdermal absorption

is affected by heat and other factors

Equianalgesic Chart* (example)

DrugParenteral (mg)Oral (mg)Duration (hours)Morphine103024Fentanyl0.1-Hydrocodone-302-4Hydromorphone1.57.524Methadone51068Oxycodone2024Oxymorphone1107-9Meperidine7510030024Tramadol-3004-6

Compiled from Johns Hopkins opioid program (hopontheweb.org

) and CMS (https://

www.cms.gov/Medicare/Prescription-Drug-Coverage/PrescriptionDrugCovContra/Downloads/Opioid-Morphine-EQ-Conversion-Factors-March-2015.pdf)

Case of Miss B.

Miss B is a 35 y/o woman who comes

to

the clinic to follow-up on persistent back pain.

She has a current prescription for Percocet 7.5/325 (Oxycodone 7.5mg/acetaminophen 325mg). She takes 2 tablets every 3 hours.

She is not taking other medications for pain.

She has normal renal and hepatic function and does not have a history of substance abuse

You

decide to refer her to physical therapy and convert to an

equianalgesic

dose of another opioid to minimize her exposure to

acetaminophen. Ultimately the goal is to taper and discontinue opioid medications in Miss B.

Calculations for Miss B. Current MED

Current regimen:

oxycodone 7.5mg (2 tabs) q3h (8 doses/day) = 15x8=120mg/day of oxycodone

Calculate MED:

x/120*30/20 = 180mg Morphine Equivalent Dose (MED)

Decrease total daily dose to allow for cross tolerance :

180 x .75 = 135mg/day MED

180 x .50 = 90mg/day MED

Miss B. Options

Morphine

15mg

every

4 hours

15 x 6 = 90mg MED/day (50% of MED)

Easy to taper due to dosing flexibility of morphine

Vicodin 5/325 2 tablets every 3

hours

10mg x 8 = 80mg hydrocodone

x/80 * 1/1 = 80mg MED/day (45% MED)

Regimen contains over 5 gm acetaminophen daily

Tramadol 100mg every

6 hours

100x 4 = 400mg tramadol/day

x/400*30/300 = 40mg MED/day (22% MED)

Hydromorphone

15mg

every 6

hours

15 x 4 = 60mg hydromorphone/day

x/60*30/7.5 = 240mg MED/day (30% higher than MED)

Case of Mr. R.

Mr. R is a 60 year old male with chronic, severe pain in his right hip following a severe fracture and surgical repair after falling last winter on the ice. He is referred to you because he continues to have pain despite the following medication regimen:

OxyContin SR 30mg every 12 hours and

oxycontin

immediate release 5mg every 6 hours for breakthrough pain which he is taking regularly.

He has normal renal and hepatic function for his age, he is 5’10” and weighs 225 lbs.

You decide to convert him to immediate release opioid medications.

Mr. R. Calculations – Current Regimen

OxyContin

SR 30mg every 12 hours

= 60mg daily

Oxycodone

immediate release 5mg every 6 hours

= 20mg/daily

60 + 20 = 80mg oxycodone daily

Conversion to MED

x/80*30/20 = 120mg MED daily

Mr. R. Options

Morphine 25mg every 6 hours

100mg Morphine/day

80% of current MED

Methadone 10mg every 6 hours (Methadone 40mg/day)

x/40*30/10 = 120mg MED/day

100% of current MED

Tolerance to methadone likely to be low

Oxycontin

10mg every 4 hours (

Oxycontin

60mg/day)

x/60*30/20 = 90mg MED/day

75% of current total daily dose but larger doses every 4 hours

Hydrocodone 5/325 2 tablets every 6 hours (Hydrocodone 40mg/day)

x/40*30/30 = 40mg MED/day

33% of current MED

Questions? Discussion?

Which of the following regimens would you select for Miss B that would provide an equianalgesic dose but decrease the amount of acetaminophen she takes?

Morphine

15mg

every

4 hours

Vicodin

5/325 2 tablets every 3

hours

Tramadol

100mg every

6 hours

Hydromorphone 15mg

every 6

hours

Which of the following would you select for Mr. R. to continue pain relief without using a long-acting opioid medication?

Morphine 25mg every 6 hours

Methadone 10mg every 6 hours (Methadone 40mg/day)

Oxycontin

10mg every 4 hours (

Oxycontin

60mg/day)

Hydrocodone 5/325 2 tablets every 6 hours (Hydrocodone 40mg/day)