Short duration (3-5 days) ketamine infusion for refractory cancer associated neuropahtic pain

Background information
Long term ketamine has been used sporadically for refractory cancer associated pain but the incidence of adverse psychomimetic effects is often quoted as a limiting factor to the wider use of this drug. This study differs in that ketamine was used in a 'burst' fashion ie three days of an effective, or the maximum tolerated, dose. The early results of the audit for all types of cancer pain have been reported(1). This report focuses on the neuropathic sub group from June 1998 to 2001.

Study design
An open label prospective audit to assess both efficacy and acceptability to patients of a short-term ketamine continuous subcutaneous infusion (CSO) for refractory cancer associated pain.

Methods
All patients in this report had refractory cancer associated neuropathic pain, ie

1. pain in which opioid dose escalation :t anti-inflamatories - NSAIDs and/or steroids
2. plus at least 2 adjuvant analgesics -anti-depressants and/or membrane stabilizers, had been ineffective or only partially effective.

Data was collected on dedicated charts and included 4 hourly patient assessed verbal reported (VRS) pain scores, regular and breakthrough opioid doses and a check list of potential adverse psychomimetic effects.

Ketamine was given as a continuous subcutaneous infusion (CSO) escalating daily if required from 100 -300 -500 mg/24hrs. the effective, or maximum tolerated dose, was continued for 3 days then ceased and patients were assessed as responders or non-responders at this time.

Associated Publication(s):
Jackson K, Ashby M, Martin P, Pisasale M, Brumley D, Hayes B. "Burst" ketamine for refractory cancer pain: an open-label audit of 39 patients. Journal of Pain and Symptom Management 2001 Oct; 22(4): 834-42