Initiating morphine: modified release method
It is possible to start an opioid naive patient directly on a modified release (MR) preparation. As with starting IR morphine, the dose must be gradually titrated to effect and the patient monitored closely.
For patients who require modified-release granules (for instance due to swallowing difficulties or feeding tubes), you must initiate morphine according to the immediate release method until the dose is high enough to convert to MR.
The following process is recommended.
1. First prescribe regular analgesia.
Prescribe 10mg of modified-release morphine to be taken twice daily (bd) 12 hours apart. . We recommend you consult your local formulary as tablets and capsules are available. Although MR morphine granules can be prescribed, the lowest available dose is 20mg (in the UK). This dose is too high to be safe for opioid-naive patients. Reduce dose if patient is at risk of opioid toxicity or side effects.
2. Next prescribe analgesia for breakthrough pain (BTP)
Rescue analgesia must be prescribed in case pain occurs between doses. Prescribe immediate release morphine (liquid or tablet formulation) 5mg every 1-2 hours as required. Reduce this dose if the background dose has also be reduced. Do not restrict to 4 hourly - if the patient needs pain relief they should be encouraged to take it. If you restrict the breakthrough morphine to 4 hourly you risk under-dosing.
3. Review after 24 hours
It is important to review the patient at this point in time to establish whether the benefits of treatment outweigh the risks. This can be delegated to another healthcare professional.
4. If pain is controlled, continue the regimen for a further 24 hours
MR preparations cannot be titrated until 48 - 72 hours after initiation or dose increase. This is to allow the drug to reach steady state. If pain is still controlled after 48 - 72 hours, go to step 7.
5. If pain is not controlled, take a full pain history
If the pain is responding to morphine (is it better/ worse/ same?). If it is not opioid-responsive pain, could it be neuropathic? In this case other medications may need to be considered and the opioid should be stopped. Take specialist advice if necessary. If pain is responding in part to morphine and they are not opioid toxic, go to step 7.
6. If the patient is sedated or shows signs of toxicity, reduce the dose
As this method uses MR morphine, the dose interval cannot be increased. You may therefore decide to convert the patient to the IR method. We will discuss how to manage opioid toxicity later in this course.
7. Calculate the total amount of morphine taken in the previous 24 hours (MR plus IR)
Divide this dose by 2 - this is the new 12 hourly dose. Do not exceed a 50% increase. If the total amount of morphine is more than 50% of the previous 24 hour total, consider whether the pain is opioid sensitive (step 5).
8. The breakthrough dose must increase when the background dose increases
Calculate the total amount of morphine (IR and MR) taken in the previous 24 hours. Divide the total 24 hour amount by 6 - this is the new breakthrough dose. Round up or down to nearest practical dose. Do not exceed a 50% increase.
9. Review after a further 24 hours and agree an ongoing review schedule
If pain is still not controlled, seek further advice.
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