PERT Program

Tip of the Month: June 2004


METHADONE USE IN OPIOID-TOLERANT RESIDENTS

Recommendations for Prescribing Methadone for the Nursing Home Resident who has been on Continuous Opioid Therapy

Last month we described some of the pros and cons of using methadone as an analgesic for nursing home residents. This month we will focus on managing the resident who has been receiving routine dosing of other strong opioids and now needs to be switched to methadone.

As we described in the May 2004 Tip, An Overview of Methadone, there are advantages and disadvantages to choosing methadone over other long-acting opioids. In addition to being an effective analgesic, it has the added benefit of possibly being more successful than other opioids in treating neuropathic pain, due to its effect on the NMDA pain receptor. Once the decision to use methadone has been made, the research literature supports several ways to convert from previously prescribed strong opioids. In this tip we will focus on one such method. Before using methadone in a facility, we recommend that staff receive detailed education on the need for close nursing assessment and monitoring of the resident, particularly for the side effect of sedation.

What follows is the rapid conversion method for initiating methadone in the resident who has been maintained on another strong opioid. The term “rapid” refers to the process of discontinuing other long-acting opioids prior to initiating methadone; it does not refer to the speed of conversion. (The research literature describes another method of conversion that involves a taper of the previous long-acting opioid while simultaneously adding methadone.¹ Due to the complexity of that method, we will not review it in this tip.)

The table for Methadone Rapid Conversion is followed by a case example.

Methadone Rapid Conversion ² ³
(For residents who are already stable on continuous opioid therapy)
Current Morphine Equivalent Dose Ratio of MS:Methadone
< 500 mg/24h 5:1
501–1000 mg/24h 10:1
> 1000 mg/24h 20:1


Case example:
Mr. B. is on OxyContin 60 mg po BID. He is being converted to methadone due to reimbursement concerns. What is an appropriate conversion dosage?


The first step is to convert to morphine equivalents.
Set up your equation (for assistance with equianalgesic conversion, see the June 2003 Tip on Opioid Dosing):

oxycodone 20 mg
————————
morphine 30 mg 		= oxycodone 120 mg
————————
morphine X mg


Then, cross multiply:

30 × 120 = 20 × X

so...

3600 = 20 X

then reduce to get X alone, so that...

X = 180 mg morphine per 24 hrs



Now you can convert to methadone, using the 5:1 ratio, since the daily morphine equivalent is < 500 mg:

morphine 5 mg
————————
methadone 1 mg 		= morphine 180 mg
————————
methadone X mg


Cross multiply:

1 × 180 = 5 × X

so...

180 = 5X

and...

X = 36 mg methadone per 24 hrs


At this point, all other scheduled long-acting opioids should be discontinued. Methadone is ordered as 12 mg po every 8 hrs, using MSIR 10 mg po q 4 hr prn for breakthrough pain. An alternative for managing breakthrough pain is to use methadone at 10% of the 24-hour dose. In Mr. B’s case, this would be 4 mg every 8 hours.

On the 4th day of this regimen, Mr. B. reports good pain control with mild sedation. He is rouseable, alert, and his respiratory status is normal. He has not required any breakthrough medication. The staff will monitor him closely over the next week, paying particular attention to his level of consciousness.


This month's tip was provided by Anna Du Pen, ARNP and Beth Miller Kraybill, RN, CHPN with review and consultation by Polly Mazanec, MSN, APRN, BC, AOCN and Elizabeth Ford Pitorak, MSN, RN, CHPN.


You may ask questions about the use and management of methadone via the PERT Advisor. Or contact the PERT Program via the contact page, and we will forward your questions and comments to our experts.



References


  1. Bruera E, Sweeney C. Methadone use in cancer patients with pain: a review. Journal of Palliative Medicine. 2002;5(1):127-138.
  2. Mercadante S. Opioid rotation for cancer pain: rationale and clinical aspects. Cancer. 1999;86(9):1856-1866.
  3. Mercadante S, Casuccio A, Calderone L. Rapid switching from morphine to methadone in cancer patients with poor response to morphine. Journal of Clinical Oncology. 1999;17(10):3307-3312.