. Author manuscript; available in PMC: 2017 Mar 1.

Published in final edited form as: Psychopharmacology (Berl). 2015 Nov 28;233(5):873–882. doi: 10.1007/s00213-015-4166-9

Table 2.

Expected additive ED₅₀ values (Z_add), actual (experimentally determined) ED₅₀ values (Z_mix), and the ratio of expected/actual ED₅₀ values for drug mixtures for antinociception and response rate in rats.

Combination relative dose ratios	Z_add	Z_mix	Ratio Z_add/Z_mix
*von Frey*
2-BFI/acetaminophen
1:3	73.9 (72.8–75.0)	90.1 (60.1–135.0)	0.82
1:1	51.6 (49.5–53.8)	82.1 (61.7–109.1)^b	0.63
3:1	29.4 (29.2–30.6)	46.7 (31.1–70.2)^b	0.63
Phenyzoline/acetaminophen
1:3	82.5 (79.4–85.6)	58.6 (37.0–92.67)	1.41
1:1	68.9 (66.4–71.6)	69.0 (36.7–129.7)	1.00
3:1	55.5 (53.4–57.6)	32.9 (21.9–49.5)^a	1.68

*Hargreaves*
2-BFI/acetaminophen
1:3	121.1 (107.2–135.1)	170.6 (131.4–221.5)^b	0.71
1:1	84.3 (74.5–94.1)	97.1 (74.1–127.2)	0.87
3:1	46.8 (41.3–52.3)	57.6 (34.8–95.3)	0.81
Phenyzoline/acetaminophen
1:3	145.9 (120.6–171.3)	140.0 (79.1–247.9)	1.04
1:1	128.5 (106.5–150.4)	69.7 (22.1–219.5)	1.84
3:1	111.3 (92.5–130.0)	80.9 (64.2–102.0)	1.38

*Response Rate - Mixtures in von Frey*
2-BFI/acetaminophen
1:3	203.3 (191.5–215.0)	121.8 (98.8–150.3)^a	1.67
1:1	138.2 (130.1–146.2)	56.6 (42.2–75.8)^a	2.44
3:1	74.8 (70.4–79.1)	17.5 (13.9–22.0)^a	4.27
Phenyzoline/acetaminophen
1:3	216.8 (205.3–228.3)	63.8 (52.7–77.4)^a	3.40
1:1	165.8 (156.9–174.6)	33.1 (26.9–40.7)^a	5.01
3:1	114.5 (107.9–120.6)	20.1 (15.1–26.8)^a	5.70

*Response Rate – Mixtures in Hargreaves*
2-BFI/acetaminophen
1:3	203.3 (191.5–215.0)	78.8 (63.9–97.2)^a	2.58
1:1	138.2 (130.1–146.2)	37.9 (30.4–47.3)^a	3.64
3:1	74.8 (70.5–79.1)	9.2 (5.7–15.1)^a	8.10
Phenyzoline/acetaminophen
1:3	216.8 (205.3–228.3)	37.5 (29.2–48.1)^a	5.79
1:1	165.8 (156.9–174.6)	20.4 (12.2–34.3)^a	8.12
3:1	114.5 (107.9–120.6)	29.8 (21.8–40.7)^a	3.84

Note:

^ab

Indicates Z_mix confidence limits do not overlap with Z_add confidence limits. ^a Z_mix lower than Z_add (supra-additivity). ^b Z_mix higher than Z_add (infra-additivity).