Cancer Care - Pain Prescribing

Question 1

Name 3 drugs which can be given for neuropathic pain + important SEs

Answer 1

• Amitriptyline: start at 10-25mg nocte- takes 4-5 days before starts working.
◦ SEs: confusion, hypotension, caution in CVS disease
• Gabapentin: 300mg TDS over 3/7
• Pregabalin: 75mg BD
◦ SEs: sedation, tremor, confusion, dizziness and caution in renal impairment.
*Full benefit often takes at least 5/7 and may need further titration

Question 2

What drugs are on the 1st and 2nd steps of the pain ladder?

Answer 2

Step 1:

• Paracetamol
• NSAIDs

Step 2: weak opioids

• Dihydrocodeine
• Codeine Phosphate
• Tramadol
• Co-codamol/Zapain

Question 3

What drugs are on the 3rd step of the pain ladder?

Answer 3

◦ Oxycodone (synthetic opioid)
◦ Morphine
◦ Fentanyl: not really excreted
◦ Diamorphine

Question 4

Name the most common SEs of opioids

Answer 4

• Constipation
• Dry mouth
• Nausea and vomiting
• Drowsiness and sedation

Question 5

How do opioids cause nausea?

Answer 5

• Delayed gastric emptying
• Opioids trigger the CTZ
• Direct stimulation of vestibular apparatus (mechanism unknown)

Question 6

Which pain medication drugs are safer in patients with renal impairment?

Answer 6

• Alfentanil
• Buprenorphine
• Fentanyl

Question 7

How do you convert codeine and tramadol to morphine PO?

Answer 7

• Codeine (PO)/10—> Morphine PO
• 240mg codeine = 24mg morphine
• Tramadol (PO)/10 —> Morphine PO

Question 8

How do you convert morphine PO to oxycodone (PO), Morphine SC, Diamorphine SC?

Answer 8

◦ Morphine (PO)/2 —> Oxycodone PO
◦ Morphine (PO)/2 —> Morphine SC
◦ Morphine (PO)/3 —> Diamorphine SC

Question 9

How do you convert oxycodone to Diamorphine?

Answer 9

• Oxycodone PO/1.5 —> Diamorphine SC

Question 11

What types of immediate release morphine are available?

Answer 11

◦ Oramorph: liquid comes in 10mg/5ml or 100mg/5ml concentrations
◦ Sevredol: tablets comes in 10, 20 and 50mg
*You must always prescribe IR alongside MR so that patients can have PRN rapid breakthrough pain relief

Question 12

What types of slow release morphine are available?

Answer 12

◦ Zomorph: capsules BD (10, 30, 60, 100 and 200mg)

◦ MST: tablets BD (5, 10, 15, 30, 60, 100 and 200 mg)

Question 13

How do fentanyl patches work? How often should they be changed?

Answer 13

• Concentrations available: 12 mcg/h, 25 mcg/h, 37.5 mcg/h, 50 mcg/h, 62.5 mcg/h, 87.5 mcg/h and 100 mcg/h
• 25mcg/h = 90mg morphine
• Applied for 3 days, changed every 72h at a regular time.

Question 14

How do you calculate a TDD?

Answer 14

• Add up 24 hours worth of morphine (don’t forget to account for the ‘BD’ of IR) + PRN doses
• TDD/2 = new morphine SR dose BD
• TDD/6 = new morphine IR PRN dose

Question 15

How do you calculate TDD for a syringe driver? What other additives would you consider for the driver?

Answer 15

• Calculate TDD and give whole dose of SC m over 24 hours
• Oral PRN is TDD/6
• Supply morphine for injection in 10mg/ml ampoules
• Other possible additives:
◦ Cyclizine: 150mg
◦ Dexamethasone
◦ Glycopyrronium

*remember SC morphine is 1/2 of PO morphine and Diamorphine is 1/3 of PO morphine