Figure 3
Isobolograms for the administration of the combination of methadone with morphine (3 A), methadone with fentanyl (3 B), fentanyl and morphine (3 C), tramadol and morphine (3 D),tramadol with methadone (3 E) and tramadol with fentanyl (3 F), in the hot plate test of mice. Theoretical ED50 value with 95% CL (●). Experimental ED50 value with 95% CL (○).