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. Author manuscript; available in PMC: 2009 Oct 1.
Published in final edited form as: Exp Clin Psychopharmacol. 2008 Oct;16(5):386–399. doi: 10.1037/a0013088

Figure 3. Dose ratios for fentanyl alone, U69,593 alone and U69.593/fentanyl mixtures.

Figure 3

Dose ratios were determined as ED50 or Zmix in the assay of thermal nociception ÷ ED50 or Zmix in the assay of schedule-controlled responding for food reinforcement. * Asterisks indicate the confidence limits for the ED50 or Zmix values in the two procedures did not overlap.