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Syringe driver drug combinations
It is possible to mix two, three or sometimes even more drugs in the same syringe driver providing they do not adversely react with each other. We will cover two common drug combinations that safely mix, one that does not and look at sources for checking compatibility of less common combinations.
Combinations that can be mixed
Diamorphine, Midazolam, Hyoscine butyl bromide
these might be given in combination to manage pain in a patient with terminal agitation and excess secretions.
Diamorphine, haloperidol, metoclopramide
These might be given in combination to manage pain in a patient with bowel obstruction and vomiting.
Other drugs that can be mixed with diamorphine include cyclizine and hyoscine hydrobromide. Care should be taken when using cyclizine with diamorphine - at higher concentrations of diamorphine, this can precipitate, and the site and driver should be checked regularly. The risk of this happening can be reduced by diluting the diamorphine as much as possible before adding the cyclizine.
Combination that cannot be mixed
Diamorphine, dexamethasone and levomepromazine
Dexamethasone and levomepromazine are not physically compatible and will precipitate. This combination might be used to manage pain in a patient with spinal cord compression and vomiting not treated by a first line antiemetic. In this case, the dexamethasone should be given separately either in a second syringe driver, or as a once daily dose subcutaneously via a butterfly cannula.
Drugs to avoid with syringe drivers
Chlorpromazine, prochlorperazine and diazepam are all contraindicated via syringe driver as they cause skin reactions at the injection site.
Checking compatibility
There are many source for checking drug compatibility in a syringe driver. Two popular sources are "The Syringe Driver"[1]and the "Palliative Care Formulary"[2]. A regularly updated online source is the SDrivers website. This can be accessed through our links page.
[1] Dickman A, Littlewood C, Varga J, (2002) The syringe driver: continuous subcutaneous infusions in palliative care, Oxford: Oxford University Press.
[2] Twycross R, Wilcock A, Charlesworth S, Dickman A (2002) Palliative Care Formulary (2nd edition), Oxford: Radcliffe Medical Press.