The results of a novel approach to the use of ketamine in refractory cancer
pain are reported. In this prospective, multicenter, unblinded, open-label
audit, 39 patients (with a total of 43 Pains) received a short duration (3
to 5 days) ketamine infusion. The initial (lose of 100 mg/24 hr was escala
ted if required to 300 mg/24 hr and then to a maximum dose of 500 mg/24hr T
he overall response rate was 29/43 (67%). Analysis of results according to
pain mechanisms showed that 15/17 somatic and 14/23 neuropathic pains respo
nded. In 5 patients who appeared to respond, it is possible that another co
ncurrent intervention may have contributed in whole or part for the pain re
lief observed. After cessation of ketamine, 24/29 maintained good pain cont
rol, with a maximum documented duration of eight weeks. However, 5 of the i
nitial 29 responders experienced a recurrence of pain within 24 hours, and
ketamine was recommenced. Of these, 2 underwent another intervention for Pa
in control while 3 continued on ketamine until their deaths between two and
four weeks late): Twelve patients reported adverse psychomimetic effects,
with the incidence rising with increasing dose. Four of these were non-resp
onders and the ketamine was stopped. Eight were responders, and in 3 the ad
verse effects were rendered acceptable with dose reduction; the other 5 rej
ected a dose reduction. The results reported suggest the need for further i
nvestigation of the place of ketamine in cancer pain management (C) US. Can
cer Pain Relief Committee, 2001.