Questions on medicines, procedures and practice from hospice staff
1. Has there been a change to the dose of SC cyclizine?
At a recent conference, it was pointed out that the bioavailability of oral cyclizine is close to 50% so the practice of using the same maximum daily dose of 150mg by subcutaneous injection or infusion may need to be rethought. This is based on a PhD thesis and small number of healthy volunteers so data is limited. Some hospices are now being more cautious with SC cyclizine and using a maximum of 100mg. The SPC for cyclizine doesn’t suggest a lower dose when the drug is used parenterally so this is more of a theoretical change. Cyclizine is an antihistaminic and anticholinergic antiemetic and the listed side-effects are predictable: drowsiness, urinary retention and hypotension being among the most common. However, it has become a drug of interest recreationally as it can produce psychoactive effects, so using the minimum effective dose, as with all medicines, is wise.
2. Which oral opioids can be used via RIG?
Liquid formulations are always the best option for medicines given via any type of enteral tube so the oral liquid or the injection solutions may be used, but this clearly requires a four-hourly regime. If a modified-release product is preferable, two morphine products may be used. MST granule sachets are suitable provided they are diluted with at least 30ml of water and flushed with 3 to 50ml water. Zomorph capsules can be opened and the contents put down a tube, again, followed by 3 to 50ml water. The main reasons for a large flush is to ensure the whole dose is administered at the time intended, thus not leaving any part of the dose to be subsequently pushed in by the next administration of drug or feed. There is currently no formulation of modified-release oxycodone that can be given.
3. Can PPIs cause hyponatraemia?
There seems to be a connection with patients developing hyponatraemia who have recently started PPI therapy. A Swedish controlled study looked at patients admitted to hospital with hyponatraemia and found an association with those who had recently started taking PPIs. Lansoprazole was not associated with this in the population in the study (N=14,400) but other PPIs were. This has not been associated with ongoing PPI treatment but there seems to be a link on initiation. They recommend using lansoprazole where a PPI is indicated. The SPCs for omeprazole and esomeprazole both list hyponatraemia as a ‘rare’ adverse drug reaction (≥1/10,000 to <1/1000) but it is not listed in the SPC for lansoprazole.
Falhammar et al, European Journal of Internal Medicine, January 2019, Volume 59, Pages 65–69.
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