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. Author manuscript; available in PMC: 2013 Jan 31.
Published in final edited form as: Anesthesiology. 2011 Jun;114(6):1435–1445. doi: 10.1097/ALN.0b013e318218a881

Figure 7.

Figure 7

Simulation study for a chronic pain paradigm. We performed simulations to estimate the effect of the large change in norketamine concentration and relatively modest change in ketamine concentration that we observed after rifampicin treatment on chronic pain relief. Induced by a 4-day intravenous ketamine infusion (grey bar: day 1 = 5 mg/h, day 2 = 10 mg/h, day 3 = 15 mg/h and day 4 = 20 mg/h). Simulations with 0, 10, and 25% norketamine contribution were made. The difference in effect observed in the simulated pain relief with and without rifampicin treatment will give an estimate of the norketamine contribution to effect. The top diagram shows the difference in VAS between placebo and rifampicin data for the three norketamine contribution to effect: 0, 10, and 25%. VAS is visual analogue score.