Alfentanil is a selective mu-receptor opioid agonist, similar to fentanyl. It is mainly metabolised in the liver to inactive compounds. It has been given by CSCI in a syringe driver, and appears to mix with most other commonly used drugs in palliative care.[1] It should be diluted with water.

Compared to fentanyl, an equianalgesic dose can be used in a much smaller volume, making CSCI of large doses possible. It is thus a useful substitute for fentanyl if CSCI use is desired.

Alfentanil is rapidly eliminated (t½ 90mins)[2] and elimination appears unaffected by renal failure.[3-5] Its onset is more rapid than for fentanyl.[6]

Its short-lasting effect means it has been used for incident pain (dressing change)[7] and some have described intranasal use for breakthrough pain.[8,9]

Alfentanil is recommended by some as the opioid of choice for patients with end-stage renal failure,[10] as its elimination is largely independent of renal function. Fentanyl is probably a reasonable alternative, which some practitioners may be more familiar with.