title: Absence of long-term analgesic effect from a short-term S-ketamine infusion on fibromyalgia pain: a randomized, prospective, double blind, active placebo-controlled trial.
abstract: To assess the analgesic efficacy of the N-methyl-D-aspartate receptor antagonist S(+)-ketamine on fibromyalgia pain, the authors performed a randomized double blind, active placebo-controlled trial. Twenty-four fibromyalgia patients were randomized to receive a 30-min intravenous infusion with S(+)-ketamine (total dose 0.5mg/kg, n=12) or the active placebo, midazolam (5mg, n=12). Visual Analogue Pain Scores (VAS) and ketamine plasma samples were obtained for 2.5-h following termination of treatment; pain scores derived from the fibromyalgia impact questionnaire (FIQ) were collected weekly during an 8-week follow-up. Fifteen min after termination of infusion the number of patients showing a reduction in pain scores >50% was 8 vs. 3 (P<0.05), at t=180min 6 vs. 2 (ns), at the end of week-1 2 vs. 0 (ns) and at end of week-8 2 vs. 2 in the ketamine and midazolam groups, respectively. Ketamine effect on VAS closely followed ketamine plasma concentrations. For VAS and FIQ scores no significant differences in treatment effects were observed in the 2.5-h following infusion or during the 8-week follow-up. Side effects as measured by the Bowdle questionnaire (which scores for 13 separate psychedelic symptoms) were mild to moderate in both study groups and declined rapidly, indicating adequate blinding of treatments. Efficacy of ketamine was limited and restricted in duration to its pharmacokinetics. The authors argue that a short-term infusion of ketamine is insufficient to induce long-term analgesic effects in fibromyalgia patients.
authors.affiliation: Department of Anesthesiology, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Noppers
authors.forename: Marieke
authors.initials: M
authors.lastname: Niesters
authors.forename: Maarten
authors.initials: M
authors.lastname: Swartjes
authors.forename: Martin
authors.initials: M
authors.lastname: Bauer
authors.forename: Leon
authors.initials: L
authors.lastname: Aarts
authors.forename: Natasja
authors.initials: N
authors.lastname: Geleijnse
authors.forename: René
authors.initials: R
authors.lastname: Mooren
authors.forename: Albert
authors.initials: A
authors.lastname: Dahan
authors.forename: Elise
authors.initials: E
authors.lastname: Sarton
mesh_terms: D000698:Analgesia / Q000379:methods*; D000700:Analgesics / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D018691:Excitatory Amino Acid Antagonists / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D005356:Fibromyalgia / Q000188:drug therapy*; D006801:Humans; D007649:Ketamine / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000188:drug therapy*; D010147:Pain Measurement; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D000700:Analgesics; D018691:Excitatory Amino Acid Antagonists; D007649:Ketamine