Calculating and Using Morphine Equivalent Doses of Opioids Wednesday, June 20, 2018 AR-IMPACT   TEXT: 501-406-0076 Event ID: 25072-23985 Teresa Hudson, PharmD, PhD Associate Professor of Psychiatry UAMS COM, Department of Psychiatry

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.

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) 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 (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

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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

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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 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)