[Dose-dependence of the analgesic action of metamizol]

Whereas dipyrone is used in many countries in clinical practice at doses up to 2.5 g, the dose-response relationship of the analgesic effect has not been investigated in humans. In the present study, doses of 0.5, 1.0, 1.5, 2.0, and 2.5 g dipyrone (Novalgin) were applied orally as film-coated tablets to 18 volunteers in a randomized, placebo-controlled, double-blind design. Pain attenuation was quantified following constant and painful electrical stimulation of tooth pulp at different time intervals up to 7 h after drug administration. Tooth pulp stimulation was performed by bipolar stimulation using individually formed impressions of the teeth with controlled current. Verbal pain ratings by the volunteers, measurement of the threshold of sensation on the tooth, and measurement of somatosensory evoked potential by an averaging technique were used as parameters for the quantification of the analgesic effect, intraindividually comparing the effects of the different doses. All doses of dipyrone had a significantly higher analgesic effect than placebo. Covering the dose range from 0.5-2.5 g dipyrone, the dose-response relationship was highly significant (Figs. 1-3). Maximal analgesia was observed 1 h after administration of the tablets, independent of the dose. An increase in analgesic effect related to dose was observed at this time, the increase being less pronounced with doses exceeding 1.5 g. Generally, analgesia persisted longer with increasing dose.(ABSTRACT TRUNCATED AT 250 WORDS)