We have had some interesting queries over the past few months which have required some time to answer in full. We also had some feedback from previous queries which we respond to below. All our visiting pharmacists are there to respond to your queries and if they can’t answer the question on the spot, we will come back to you with a full response as soon as we can.
1. Erythromycin for constipation
We mentioned the use of erythromycin being used for constipation in the previous newsletter and a consultant queried whether we were seeing it used routinely as a laxative. To clarify, we are not aware of it being used more or in preference to conventional laxatives – we featured the query in case other healthcare professionals who may be new to palliative care had not come across this use before.
2. Anti-emetics least likely to cause hypotension
A variety of drugs are used as anti-emetics in palliative care and most are associated with hypotension. We were recently asked if we knew which would be least likely to cause this as a complication. There do not seem to be any consensus reports on this and there is some conflict between the sources but haloperidol and levomepromazine are most likely to cause a drop in blood pressure. There are also reports of cyclizine and metoclopramide doing the same but occurrences are listed in the SPC as ‘rare’. The least likely culprits are hyoscine butyl bromide, ondansetron, domperidone and olanzapine but there are other issues to consider – we know ondansetron is more constipating than the other, domperidone has QT interval prolongation as a known risk and is only available as an oral product. Olanzapine is a more recent addition to the list of antiemetics and is proving a useful third line choice but use by anything other than the oral route is uncommon in palliative care.
3. Suggestions for Ranitidine alternatives
Ranitidine products are not being manufactured at present due to the discovery of a toxic by-product being found in the high-temperature tests carried out in the process. It had been adopted as an effective drug for reducing secretions in intestinal obstruction and was starting to be used more widely in syringe pumps. Whilst it remains unobtainable, the PCF suggests the step-wise approach should be 1. metoclopramide (if no colic present) 2. If colic present, hyoscine butyl bromide with or without levomepromazine, then octreotide with dexamethasone as an adjunct in all three stages. Another suggestion from Andrew Dickman – Consultant Palliative Care pharmacist at the Palliative Care Institute in Liverpool – is to use glycopyrronium at antisecretory doses. It is familiar and less costly than octreotide.
4. Subcutaneous use of parecoxib
The use of NSAIDs has reduced considerably since their range of side effects was brought into sharper focus for older and frailer people. They can be very effective for pain which is less sensitive to opioids e.g. bone pain. Most clinicians seem to choose ibuprofen as a less potent agent and one of the selective COX2 inhibitors if that is not sufficient. When approaching the last days of life and the oral route is no longer available, parecoxib is available as an injectable option. It is unlikely to affect clotting and has a lower GI risk than standard NSAIDs. It can be given as a single 40mg in 2ml SC dose or as an infusion over 24 hours, diluted with sodium chloride 0.9% to the maximum volume in a 30ml syringe. Due to lack of data it must not be mixed with other drugs in a syringe. It has only been licensed for use for 3 days as it was developed as an adjunct to pain relief around surgery so if anyone does choose to use it for longer than this, it would be useful to report it as a case study so others can learn from experience.