1. Calculating and Using Morphine Equivalent Doses of Opioids
Wednesday, June 20, 2018
AR-IMPACT
TEXT:
Event ID:
Teresa Hudson, PharmD, PhD
Associate Professor of Psychiatry
UAMS COM, Department of Psychiatry

2. Today’s Objectives
Review strategy to calculate morphine equivalent doses for opioids
Discuss limitations of current opioid-conversion data
Explain how to modify opioid dosage regimens based on morphine equivalent dose
Identify 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.

3. 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

4. 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

5. 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

6. 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

7. Equianalgesic Chart* (example)
Drug
Parenteral (mg)
Oral (mg)
Duration (hours)
Morphine 10 30
24
Fentanyl
0.1 -
Hydrocodone
2-4
Hydromorphone
1.5
7.5
Methadone 5
68
Oxycodone 20
Oxymorphone 1
7-9
Meperidine
75100
300
Tramadol
4-6
Compiled from Johns Hopkins opioid program (hopontheweb.org) and CMS (

8. 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.

9. 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

11. 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)

12. 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.

13. Mr. R. Calculations – Current Regimen
OxyContin SR 30mg every 12 hours = 60mg daily
Oxycodone immediate release 5mg every 6 hours = 20mg/daily
= 80mg oxycodone daily
Conversion to MED
x/80*30/20 = 120mg MED daily

15. 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

16. Questions? Discussion?

17. 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

18. Which of the following would you select for Mr. R
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)