Intermittent subcutaneous doses in palliative care

Intermittent subcutaneous administration is useful for as-required dosing, or regular dosing of drugs with a long duration of effect (eg haloperidol) when oral administration is not possible. Intermittent subcutaneous doses can also be useful for patients who develop injection-site reactions with continuous subcutaneous infusions (CSCIs).

The generally accepted maximum volume for subcutaneous injection is 2 mL. If injected into the abdomen, 3 mL has been demonstrated as tolerable. It may be necessary to inject a large-volume dose divided across 2 separate sites.

Subcutaneous administration may cause stinging at the site of injection. This will be lessened if administered through a cannula. A small-volume flush (0.5 mL) of sodium chloride 0.9% is required after each dose of drug given through a cannula.

If a subcutaneous infusion is running concurrently, give the intermittent subcutaneous dose through a separate cannula to avoid interrupting the infusion. Injection through a side port would push through a dose of the infusion and leave a period of no drug administration while the flush volume of sodium chloride 0.9% is being infused.

Some services use programmable pumps with the capability to deliver patient-controlled administration (PCA) boluses to provide flexibility and control to the patient.