Pain Prescribing

Question 1

5 principles of effective analgesia?

Answer 1

By mouth - give orally when possible
By clock - give at fixed intervals for continuous relief
By ladder - following WHO analgesic ladder
For individual - no standard doses for opioids
Attention to detail - communicate, set times, side effects

Question 2

Describe the WHO analgesic ladder

Answer 2

1 Non-opioid (paracetamol, NSAIDs)
2 Opioid for mild/moderate pain e.g. codeine
3 opioid for moderate/severe pain e.g. morphine, diamorphine, oxycodone

Persisting increasing pain and side-effects inform the decision to step and and down the ladder

One step at a time to achieve pain relief without toxicity

Continue paracetamol at step 2 and 3 for opioid sparing effect
Stop step 2 opioids before step 3 opioids

Question 3

What should be used with strong opioids?

Answer 3

Anti-emetics

Laxatives

Question 4

What is starting dose of opioid? When should you consider a lower dose? What if pain is not controlled?

Answer 4

Oral morphine 5mg every 4h (20mg/day) plus 5mg PRN (maximum hourly) for breakthrough pain

Consider a lower starting dose if elderly, low BMI or renal impairment

If pain is not controlled increase dose by 30-50% every 24h

Question 5

What should you do when pain is controlled on starting opioid dose? Example?

Answer 5

Convert to modified release
Calculate total daily dose including PRN and divide into two 12h doses of a modified release preparation (e.g. MST Continus 12h)
MR preferred over transdermal patches

Question 6

How is PRN dose for breakthrough pain calculated?

Answer 6

1/6th of total daily dose as an immediate release preparation e.g. Oromorph

Question 7

What are side effects of opioids?

Answer 7

Drowsiness
Nausea/vomiting
– Usually transient, decreases after 5d

Constiaption
Dry mouth

consider oxycodone if not tolerating morphine and decrease dose by 25%

Question 8

What are signs of opioid toxicity?

Answer 8

Sedation
Respiratory depression
Visual hallucinations
Myoclonic jerks
Delirium

Question 9

Mx of opioid toxicity?

Answer 9

SaO2 - O2 if required
Consider hydration
Stop opioids and sedating drugs
Naloxone only for life-threatening respiratory depression - in patients on regular opiates it can precipitate pain crisis and fatal acute withdrawal

Question 10

What consideration of renal failure in opioid prescribing?

Answer 10

Renal impairment (GFR < 30) are at risk of toxicity due to accumulation of renal excreted opioids and metabolites

Fentanyl, buprenorphine have predominantly hepatic metabolism

Question 11

What concerns should you address about opioids?

Answer 11

Opioids are effective and safe when used properly

Question 12

What should you consider for morphine resistant pain?

Answer 12

Seek expert help

Methadone
Ketamine
NSAIDs
Steroids
Muscle relaxants
Anxiolytics
Nerve blocks

Amitriptyline
Pregabalin
Topical lidocaine

Psychological
Spiritual

Question 13

How do you convert oral codeine to oral morphine?

Answer 13

Divide by 10

Question 14

Oral tramadol to oral morphine

Answer 14

Divide by 10

Question 15

Oral morphine to oral oxycodone?

Answer 15

Divide by 1.5

Question 16

Oral morphine to SC morphine

Answer 16

Divide by 2

Question 17

Oral morphine to SC diamorphine

Answer 17

Divide by 3

Question 18

Oral oxycodone to SC diamorphine

Answer 18

Divide by 1.5

Question 19

Fentanyl patch to oral morphine

Who are patches good for?

Answer 19

12mcg patch = 30mg oral morphine

Patients who do not require regular titration of pain relief
Do not give to opioid naive patients

Question 20

Which opioids are preferred in CKD?

Answer 20

Buprenorphine
Alfentanil
Fentanyl

Question 21

What Mx for metastatic bone pain?

Answer 21

Strong opioids
Bisphosphonates
Radiotherapy