S8 opioids and ketamine
Part 2 of the Monitored Medicines Prescribing Code (the Code) outlines the prescribing conditions and requirements for S8 opioids and ketamine for all medical indications except pharmacotherapy for opioid dependence, including:
- when prescribers may prescribe them without authorisation of the CEO;
- when prescribers require written authorisation from the CEO before prescribing them.
Authorisation of the CEO
When is prior authorisation of the CEO required?
All prescribing must be in accordance with Part 1 and Part 2 of the Code.
Figure 2 from the Code summarises when authorisation from the CEO is and is not required for S8 opioids and ketamine.
Applying for authorisation
Where prescribing is not in accordance with Section 2.5 of the Code, written authorisation from the CEO is required prior to prescribing an S8 opioid or ketamine.
Applications for authorisation either need to be submitted by, or the proposed treatment regimen supported by, an Approved Specialist (Section 2.6.2 of the Code).
Applications must be on the application form, which must be completed in full and, where required, be accompanied by appropriate supporting documentation. Where Approved Specialist support is required for approval (see Section 2.6.2 of the Code), sufficient written evidence of this support must be included, at the time of application.
Application form
Calculating morphine dose equivalents
As part of determining if treatment meets the Product criteria (Section 2.5.3) outlined in the Code, practitioners must determine the total daily opioid dose as morphine equivalents (MEq). Written authorisation from the CEO is required before prescribing a total daily dose of opioids over 90mg morphine equivalents (in any formulation) or over 45mg morphine equivalents (immediate release opioids).
For the purposes of the Code, an approximate guide to the doses of opioids equivalent to an oral morphine dose of 90mg include:
Table 1: Calculating morphine dose
|
Opioid
|
Equivalent to 90mg morphine daily
|
Factor to convert doses to morphine milligram equivalents
|
|
Morphine
|
90mg
|
1
|
|
Hydromorphone
|
18mg
|
5
|
|
Oxycodone
|
60mg
|
1.5
|
|
Tapentadol
|
300mg
|
0.3
|
|
Buprenorphine patch
|
45mcg/hr weekly
|
2
|
|
Fentanyl patch
|
25mcg/hr every three days
|
3.6
|
For more information on dose equivalents prescribers can use the Dose Conversion Calculator (Excel 757KB).
This information is a guide to calculating morphine equivalents only. It is not intended to be used alone to switch patients from one opioid to another.
Prescribing methadone
All prescribing of methadone requires prior authorisation of the WA Department of Health.
Methadone is a high-risk, potent opioid, with complex pharmacokinetics. Deaths attributed to methadone are linked to prescribing by inexperienced practitioners, lack of consideration of the long and variable half-life, and use of inappropriately high doses. Dose conversion and titration between methadone and other opioids is complex and should be discussed with a pain specialist or pain management clinic.
In line with Royal Australian College of General Practitioners (RACGP)’s guidelines for opioids in acute and chronic pain (external site), treatment with methadone should only be commenced and titrated, with caution, by specialist practitioners with appropriate expertise and experience in its use. Patients should be monitored closely during dose titration.
More information
Medicines and Poisons Regulation Branch
Mailing address: PO Box 8172, Perth Business Centre, WA 6849
Phone: 9222 4424 (Monitored Medicines Prescriber Advisory Line)
Email: MPRB@health.wa.gov.au