Transcript Opioid Dosing and Conversions

Opioid Dosing and Conversions
Key dosing points:
• Begin a bowel regimen when opioid therapy is initiated (senna + docusate).
• For CHRONIC pain, use a scheduled medication regimen. ( ex: Morphine ER
30 mg by mouth q8h around-the-clock)
• For ACUTE or BREAKTHROUGH pain, use immediate release
formulations on a prn basis. (ex: Morphine IR 15 mg by mouth q2h prn pain)
• For prn doses, use 10-20% of the total 24-hour scheduled dose.
• Prn doses can be safely redosed if pain persists and no sedation is observed
after peak opioid effects are reached. Oral = 1 hour, SC = 20-30 min, IV = 1020 min (fentanyl IV=6-10 min).
• Switching opioids:
• Use equianalgesic doses (See Table 1).
• Reduce the calculated dose 25-50% to account for lack of tolerance to the new
opioid and interpatient variability.
• Adjusting scheduled and/or prn opioids for inadequate pain relief:
• There are 3 options: 1) Add or increase a scheduled dose, 2) Increase the prn
dose, 3) Increase both the prn and scheduled dose.
• Dose increases less than 25% do not improve analgesia.
• For mild to moderate pain, increase the dose by 25-50%.
• For moderate to severe pain, increase the dose 50-100%.
Table 1: Equianalgesic Conversion of Opioids
Drug
SQ/IV Dose
Oral Dose
Morphine
10
30
Hydromorphone
1.5
6-7.5
Oxycodone
-----20-30
Oxymorphone
-----10
Hydrocodone^
-----30
120
Codeine
200
Fentanyl
0.1 mg (100 mcg)
Not established
^ Only available as a combination product.
Naloxone (Narcan®):
Reverses sedation, respiratory depression, and ANALGESIA. Careful titration
permits reversal of side effects without complete reversal of analgesia. Onset
of effect is ~1-2 minutes. Duration of effect is 20-60 min. Dilute one vial (0.4
mg) with 9 mL NS. Give IVP as 1-2 mL doses every 60 seconds, based on
patient response. Excess naloxone can cause seizures, tachycardia,
hypertension, and withdrawal.
For malignant pain or end-of-life
care, consider consulting
Pain/Palliative Medicine.
Phone: 293-2957, Fax: 688-3700
Please refer to the pharmacy intranet for references and further information.
Methadone:
Adverse events experienced with methadone use are generally related to:
• Inadvertent overdose due to a lack of knowledge with initiation/titration
• Due to methadone’s long half-life, accumulation occurs over 5-7 days.
• Monitor for sedation and/or respiratory depression, which may occur for up to 7
days after initiation or dose increases.
• Do not increase the methadone dose more often than every 72 hours.
• Drug interactions
• Methadone is metabolized primarily by CYP3A4 & CYP2D6.
• Cardiac arrhythmias (QT prolongation → Torsades de Pointes)
• Use caution in patients with baseline QT prolongation (QTc > 450 ms) or
concomitant QT prolonging medications.
• Monitoring should include an EKG at the start of therapy, within 30 days of
initiation or dose increases, and annually thereafter.
Table 2: Equianalgesic Conversion to Methadone*
Oral Morphine Equivalent
Morphine: Methadone Ratio
< 90 mg/day
4:1
90 - 300 mg/day
8:1
> 300 mg/day**
12:1
Oral methadone: IV methadone ratio= 2:1
* Ratios should only be used to convert TO methadone. Conversion ratios should NOT be used to
convert FROM methadone TO morphine or other opioids. Consult an experienced prescriber.
** Use caution when converting very high doses of opioids (> 800 oral morphine equivalents) to
methadone. Consult an experienced prescriber.
Fentanyl Transdermal System (Duragesic®):
Fentanyl patches should only be prescribed for CHRONIC PAIN in OPIOID
TOLERANT patients.1 Transdermal fentanyl can take 12-24 hours to begin
working and does not peak for up to 72 hours. Do not titrate patch doses
more frequently than every 72 hrs.
Table 3: Equianalgesic Conversion to Transdermal Fentanyl
Oral Morphine Equivalent
Transdermal Fentanyl Dose2
30 mg/day
60 mg/day
120 mg/day
180 mg/day
240 mg/day
12 mcg
25 mcg
50 mcg
75 mcg
100 mcg
1 Patients
with persistent, moderate to severe chronic pain who have been taking an
around-the-clock opioid for longer than a week and are considered opioid-tolerant.
2 Significant interpatient and intrapatient variability exists in absorption from transdermal
fentanyl. Example: patients with diffuse edema or cachexia have lower than anticipated
fentanyl absorption. External heat increases absorption from fentanyl patches.
Author(s): Hartman, Gustin; Department: Pharmacy; Date Originated: May 2009; Committee(s) Approved: P&T/MUE Executive Committee
This information has been developed by the authors and department listed above at The Ohio State University Medical Center and is
intended for use only within the institution. The information is not meant to be applied rigidly and followed in all cases. Professional
judgment must remain central to the application of this information. All rights reserved, including right of reproduction, in whole or in part, in
any form without permission from The Ohio State University Medical Center. Copyright: © 2009 The Ohio State University Medical Center.