title: Use of intravenous patient-controlled analgesia for the documentation of synergy between tramadol and metamizol.
abstract: The quantification of the synergistic interactions (beneficial and adverse) of analgesic drug combinations in humans has been elusive. We propose a new procedure based on analgesic requirements (i.v.-PCA) and pain intensity (VAS-PI). One hundred and one post-hysterectomy patients received at the time of analgesia request (TAR) tramadol (100 mg, group I) or metamizol (1.2 g, group II) alone, or combined in 1:1 (III), 1:0.3 (IV) or 1:3 ratio (V). After 15 min, they received the same treatment by PCA. VAS-PI, analgesic consumption and adverse effects were assessed at TAR, and periodically for 24 h. Data were analysed using interaction indexes and isobolograms. All treatments produced equivalent VAS-PI, per cent efficacy and adverse effects. When drugs were combined in a 1:1 ratio, synergy was present for the analgesic and adverse effects; all other treatments were additive.
authors.affiliation: Department of Anaesthesiology, Hospital Universitario del Mar, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Montes
authors.forename: W
authors.initials: W
authors.lastname: Warner
authors.forename: M M
authors.initials: MM
authors.lastname: Puig
mesh_terms: D000328:Adult; D000368:Aged; D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000627:therapeutic use*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D004177:Dipyrone / Q000627:therapeutic use*; D004357:Drug Synergism; D005260:Female; D006801:Humans; D008875:Middle Aged; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy*; D014147:Tramadol / Q000627:therapeutic use*
chemical_list: D000701:Analgesics, Opioid; D000894:Anti-Inflammatory Agents, Non-Steroidal; D014147:Tramadol; D004177:Dipyrone