[Analgesic effect of ketamine in a patient with neuropathic pain].
We report the effect of a single daily dose of ketamine in a 54 year old woman with fibromyalgia and severe post-traumatic neuropathic pain. A number of different approaches for pain relief had been tried with little effect. An intramuscular test dose of 0.4 mg/kg ketamine combined with 0.05 mg/kg midazolam lead to analgesia which lasted for almost two days. Long-term analgesia was also obtained by 250 mg/kg ketamine hydrochloride taken orally in the form of capsules every night at bedtime. The patient has now used this dose for nine months. Ketamine is an NMDA receptor antagonist. A single sub-anaesthetic dose of ketamine causes a long-term depression of pain intensity in some, but not in all, patients suffering chronic pain. This effect is distinctly different from the short-lasting (10-30 min) analgesic effect in cases of acute nociceptive pain. The long-term depression of the intensity of chronic pain states may be due to a reversal of NMDA receptor-dependent long-term potentiation of synapses in central pain pathways. By giving ketamine as a single dose at night the mental side-effects are reduced or avoided.
Oye
I
I
Farmakologisk Institutt, Blindern, Oslo.
Rabben
T
T
Fagerlund
T H
TH
D000284:Administration, Oral; D000778:Anesthetics, Dissociative / Q000008:administration & dosage*; D005260:Female; D005356:Fibromyalgia / Q000188:drug therapy*; D006801:Humans; D007649:Ketamine / Q000008:administration & dosage*; D008875:Middle Aged; D009437:Neuralgia / Q000188:drug therapy; D009619:Nociceptors / Q000187:drug effects; D010146:Pain / Q000188:drug therapy*
D000778:Anesthetics, Dissociative; D007649:Ketamine