(From BMJ learning module)
Palliative Care Adult Network Guidelines Plus are a useful resource.
Opiates in renal impairment
Some good ones:
- Oxycodone, which is 90% excreted by the liver and only needs dose reduction in CKD5
- Fentanyl – fine down to CKD3, adjustments needed in patients with more severe impairment.
- Immediate-release preparations rather than controlled-release
- Smaller doses
- Longer interval
(There’s also a bit on prescribing in liver disease, but it’s really not all that helpful and I haven’t made notes on it.)
Central causes: drugs, biochemistry, cranial radiotherapy
Peripheral causes: localised radiotherapy, bowel tumour/inflammation/bleed. Puzzlingly, the module also lists infection and RICP, which I would have thought were central causes, especially the latter (I suppose ‘infection’ may be meant to refer to gastrointestinal infection rather than general sepsis – it isn’t very clear).
Anyway, the point of all this is to help pick an effective antiemetic:
Cyclizine, haloperidol and dexamethasome are centrally-acting antiemetics
Metoclopramide and ondansetron are peripherally-acting antiemetics.
Levomepromazine has a combined effect.
So, in a recalcitrant case of N&V, it may be possible to reach the desired effect by combining antiemetics. However, do note that cyclizine is not a good one for combination in a syringe driver as it tends to precipitate.
Subacute malignant bowel obstruction
Options for management include:
- If death imminent and only small volumes of vomiting, manage with an antiemetic such as cyclizine in a syringe driver.
- If flatus being passed and no abdominal colic, try prokinetic plus lots of stool softener.
- If colic present, stop all prokinetics and use centrally-acting antiemetic (see above), Buscopan for the colic, and stool softener to keep the bowel contents as liquid as possible.
- If large volumes of vomiting, consider octreotide syringe driver or nasogastric tube.