Palliative Care: Opioids Questions

Question 1

Patient with ongoing cancer pain in hospital has Oramorph 2 mg PO PRN prescribed. They have taken 5 doses of this in the past 24 hours, and a total of 11 doses in the past 48 hours with good effect and no side effects. How much MST would you start them on?

Answer 1

Patient is taking PO PRN Oramorph 2 mg.
They have taken 10 mg Oramorph in past 24 hours.
They have taken 22 mg in the past 48 hours (12 mg in previous 24 hours).
Oramorph is a short-acting preparation whilst MST is a long-acting one.

This is PO to PO and does not require a conversion.
She requires a 10 mg total dose.
5 mg B.D. MST is appropriate.

Question 2

What other medications would consider starting at this time?

Answer 2

• Laxative
• Anti-emetic
• Breakthrough opioid

Question 3

Patient on MST 45 mg B.D. - what is an appropriate oral breakthrough drug and dose? What about SC breakthrough dose?

Answer 3

What is an appropriate oral breakthrough drug and dose?

Patient on MST 45 mg B.D.
Total MST = 90 mg/day
In palliative care the standard dose of a strong opioid for breakthrough pain is 1/6th of regular 24 dose.
Therefore, 90/6 = 15 mg
Oramorph 15 mg PRN (repeated every 4-6 hours as required)

What about SC breakthrough dose?

To convert from oral oramorph to SC oramorph we must address our equivalence tables.
Oral morphine –> SC morphine - divide by 2.
Therefore, 15 mg / 2 = 7.5 mg
HOWEVER, prescribe this as 7 mg as this is safer (may be confused with 75 mg)

Question 4

Patient on oxycodone 60 mg via a continuous SC infusion using a syringe driver as they had been NBM. Can now start back on oral medication - how would you convert to oral oxycodone? What dose of Longtec would you start?

Answer 4

How would you convert to oral oxycodone?

SC morphine –> oral morphine (x2)

60 mg SC oxycodone x 2 = 120 mg oral oxycodone

What dose of Longtec would you start?

60 mg B.D. Longtec

Question 5

Specialist palliative care team have recommended an opioid switch from MST 30 mg B.D. to Longtec. What is the equivalent appropriate dose? If the patient was felt to have opioid toxicity on this dose of MST, and this was the reason for the switch, would this affect the dose you prescribe of Longtec?

Answer 5

What is the equivalent appropriate dose?

Conversion of oral morphine to oral oxycodone (divide by 2)
So, total oral MST is 30 mg x 2 = 60 mg PO MST
Therefore 60 mg / 2 = 30 mg Longtec
Requires B.D. so 30 / 2 = 15 mg PO Longtec B.D.

If the patient was felt to have opioid toxicity on this dose of MST, and this was the reason for the switch, would this affect the dose you prescribe of Longtec?

Yes, avoid toxicity where possible. Dose reduction appropriate. Reduce 1/3 if mild. 1/2 if moderate. Stop completely if severe.

Question 6

What are the most common symptoms and signs of opioid toxicity?

Answer 6

Think of it as a timeline (makes it easier), so first:

• Cognitive clouding
• Hallucination
• Micro-sleeping
• Myoclonic jerks
• Sedation (dropping GCS)
• Respiratory depression (only if SEVERE - shouldn’t get this far)