Miscellaneous

Question 1

In severe liver disease, which drugs can precipitate hepatic encephalopathy (when toxins are not cleared, therefore affect the brain)?

Answer 1

Sedative drugs, Opioid analgesics, diuretics producing hypokalaemia, constipation-inducing drugs (constipation = slow transit –> increases absorption of ammonia)

Question 2

What drugs can exacerbate fluid overload in chronic liver disease?

Answer 2

Drugs that give rise to fluid retention e.g. NSAIDs and corticosteroids

Question 3

Why does hypoalbuminemia in severe liver disease increase toxicity of drugs such as prendisolone and phenytoin?

Answer 3

Phenytoin and prednisolone are highly protein bound drugs so low albumin means high free drug concentration

Question 4

What period of pregnancy carries the highest risk in terms of teratogenicity?

Answer 4

First trimester - drugs can cause congenital malformations (teratogenesis) and period of greatest risk is 3rd to 11th week

Question 5

What can be given for pain in bone metastases? (unlikely to be tested)

Answer 5

Bisphosphonates + radioactive isotopes

Question 6

Can you give a brief overview of drug classes used to treat neuropathic pain?

Answer 6

Tricyclic antidepressant, Antiepileptic (gabapentin and pregabalin), Ketamine (if response to opioids is poor).
Pain due to nerve compression may be reduced by corticosteroid e.g. dexamethasone, which reduces oedema around tumour, thus reducing compression

Question 7

How do you calculate the rescue dose for breakthrough pain?

Answer 7

1/10 to 1/6 of regular 24-hour dose, repeated every 2 to 4 hours PRN (May need every hourly if severe pain or palliative)
Review pain management if 2+ daily rescue doses used
When adjusting morphine dose, do not include the rescue doses
Increments of morphine dose should not be >1/3 to 1/2 of total daily dose every 24 hours

Question 8

What is an adequate dose of morphine? How would you switch from I/R to M/R? How would you monitor?

Answer 8

Morphine I/R 30mg/ 4 hours or M/R 100mg/12 hourly.
The 4 hourly I/R can be given as same total daily dose but as M/R 12 hourly dose. The first dose of M/R is given with or within 4 hours of the last dose of I/R morphine.
Monitor constipation, nausea, vomiting - it is routine to Rx laxative