IC6 Supportive and Palliative Care (Opioids use) Flashcards
Do we have to follow the pain ladder strictly?
No, it is just a guide
Where do opioids come from?
Poppy plant
What are some examples of natural, semi-synthetic and synthetic opioids?
Natural (opiates) — heroin, morphine, codeine
Semi-synthetic — hydromorphone, oxycodone, oxymorohone, hydrocodone
Synthetic — tramadol, fentanyl
Which is a controlled drug — morphine syrup or oxycodone syrup?
Oxycodone syrup
What do you have to look out for when giving morphine?
What are the side effects of morphine?
- Active morphine-6-glucuronide is renally eliminated
- For dying patients, they don’t die of cancer but end organ damage becos the cancer would have infiltrated the organs brain, liver, kidneys, so kidney failure is common.
E.g. multiple myeloma → hallmark signs is renal impairment
Thus if give morphine to these patients, would cause respiratory depression, extreme somnolence since it is accumulated in the body - Came from the greek word morpheus (god of dreams/sleep)
Do we give short active or long acting opioids for chronic pain?
Scheduled dose or PRN?
- Short acting → Long Acting
- Chronic pain: scheduled doses (long term) superior to prn doses
- Add 50% to 100% of prn usage to around the clock scheduled doses, remember to institute plan to taper down when appropriate
Individualise the dosing - Rescue prn doses = 10% - 20% daily opioid requirements
Is the conversion from 1 opioids to another bidirectional?
No
If Mr TP is a 36 year old osteosarcoma patient with persistent bone pain. Patient says it is well controlled on current regimen. Taking:
- morphine controlled release 60mg PO TDS
- morphine syrup 10mg PO q4hrly PRN pain, avg 1-2 doses per day
Latest labs showed some new renal dysfunction. Need to recommend to switch to oxycodone. What is the dose and how to dosing instructions?
- Figure out the total baseline and total PRN in terms of morphine
- then convert it to oxycodone based on the ratio 3g.
- 30mg of morphine is = to 15-20mg of oxycodone
- There is 10mg oxycodone tablet in sg so we convert to 30-40mg tabs 3-4x a day, this is for baseline.
PO Oxycodone 30-40mg tablets TDS/QDS - PRN previously on syrup so gonna use the oxycodone syrup, so convert to 5-10mL q4hrs oxycodone syrup (the dosing for the PRN must follow the dosing instructions not what the patient is taking)
PO Oxycodone syrup 5-10mL q4hrly PRN
Oxycodone is similar to which other opioid?
Morphine
How many times is fentanyl stronger than heroin and morphine?
Is the half life short or long for IV fentanyl?
- 50x stronger than heroin
- 100x stronger than morphine
-
Very short half life
Use IV fentanyl a lot in ICU to sedate people, since it has fast onset and offset
What are the 2 common ratios we use when converting morphine to fentanyl?
- 2mg/day PO morphine = 1mcg/hr fentanyl patch OD
- 3.6mg PO morphine ≈ 1mcg/hr fentanyl patch (90/25)
Before starting patients on fentanyl patches, what should we ensure the patient has?
If patient does not have __, then what can we do if die die need to start fentanyl patch?
Opioid tolerance
- According to FDA, it means someone who can tolerate 60mg of oral morphine or equivalent per day
- Sometimes patient are not on that, prof dispense fentanyl patches in NUH where patient is only on morphine syrup, and they cant swallow, so want to start fentanyl patch, start with the smallest dose patch and use half a patch. Smallest dose patch is 12.5mcg/hr, so half is 6.25mcg/hr, so that’s about 15mg of oral morphine/day, and take 5mL of morphine per day so should be equivalent?
- But the problem is becos fentanyl is so potent, giving an equal analgesic dose, that’s not the full pic, equal analgesia does not mean equal side effects, they could stop breathing.
- So need to mention to the patient, becos can’t really change the minds of the dr. so want to see how to bring patient up to opioid tolerance first before changing to fentanyl patch but then they say no…
- So warn patient, say that when on this patch be around people that can monitor you, if you nodding off and breathing slowing, take that patch off since it might be overdosing.
- Is giving the smallest dose patch ok?
- They came up with the 60mg of morphine/day becos the smallest dose of fentanyl was 25mcg/hr
- But now with the smaller doses, is it safe? In practice it is done, but need to make sure that patient understand that it’s the same
How is the absorption like for fentanyl patches?
What to counsel the patient on when using the fentanyl patches?
What is the onset of effect for fentanyl patches?
- Absorption could be erratic, heat can increase absorption
- Don’t go out under the hot sun
- Fever?
- IV fentanyl has a very fast onset, but for fentanyl patch, it has to be absorbed into your skin first and then into your subcutaneous tissues, which acts like a depot before entering into your bloodstream. All these take time before getting to a steady state, so will need to wait to get the analgesic effect but also steady state of side effects, so need to monitor the patient.
- Onset slow → steady state slower
-
Q72hours for most patients
Some rx will say change every 48hrs, should be every 3 days, but some patients have a wearing off effect so must back it up with some PRN (short acting opioid for those breakthrough pain moments) - When patients are on fentanyl patches, must make sure that patients are educated
Don’t put on broken skin
If Mr TP is a 36 year old osteosarcoma patient with persistent bone pain. Patient says it is well controlled on current regimen. Taking:
- morphine controlled release 60mg PO TDS
- morphine syrup 10mg PO q4hrly PRN pain, avg 1-2 doses per day
Patient is having a hard time adhering to the TDS schedule and heard fentanyl patches might be more convenient.
Give a recommendation to switch to fentanyl patch. What is the dose and how to dosing instructions?
Student’s answer:
- 1 month’s supply, 10 patches
- Apply one 75mcg/hr fentanyl patch on unbroken skin every 72 hours
- They choose a dose in between of 50 and 90mcg
- Remember the duration of action for 1patch – 72hrs!!
How to decide between 2mg of morphine:1mcg or 3.6:1 ratio?
- Have 2 numbers so pick the middle (a valid way)
- This guy has been on morphine for a few months, so less scared of the side effects and more well controlled, ok so maybe want to be more aggressive. Or he never had fentanyl before so want to be more conservative
- Usually do 2mg:1mcg/hr since this is norm in the practice, the studies done for the table above is more conservative becos when it’s a drug company and want to sell drug, you cant have people dying on you:”)
- Need to consider patient factors e.g. how well can you trust the patient to take off the patch when the are in trouble, living alone? Blur? Brain cancer and cognitive impaired, so more conservative, i rather they be in pain than die of respiratory depression
- Some is based on experience, for the last 10 patients, you used 2:1 and they are ok:”)
For this case, he is taking the PRN 1-2 doses per day so it’s ok if we dont add it into the baseline. But if the patient is severely in pain 8-9 on the pain scale and is taking 7-8 doses per day then add some of that into fentanyl patch dose
Need to follow up and see how they do, be more aggressive up front, it is harder to scale back, so it’s sometimes better to be more conservative. Really depends on the situation:”)
What is patient controlled analgesia?
PCA (patient controlled analgesia)
- The patient-controlled analgesia (PCA) pump is a computerized machine that gives you medicine for pain when you press a button. In most cases, PCA pumps supply opioid pain-controlling medicines such as morphine, fentanyl and hydromorphone
- Self-limiting
If patient give themselves too much, they will fall asleep and so won’t continue pressing the button to give themselves more so hard to be overdosed
Usually what is the duration of opioid supply?
1 month
- For most opioids won’t give more than a month’s supply
Depending on laws/SOP, a month is a reasonable amount
