Table 3

Concentration-response data for flunitrazepam and zopiclone on GABA-mediated current in recombinant α1β2γ2 or α1β2γ3 GABAA receptor expressed in Xenopus oocytes

Modulatorα1β2γ2α1β2γ3
EC50EmaxnHEC50EmaxnH
nM % control nM % control
Flunitrazepam5.9  ± 1.6 (3)215  ± 4.01.00  ± 0.0814.8  ± 2.9 (3)280  ± 6.20.91  ± 0.26
Zopiclone42.4  ± 2.5 (3)284  ± 3.10.99  ± 0.06135  ± 40 (4)419  ± 250.72  ± 0.09

Values (means ± S.E.) for the potency (EC50), maximum potentiation (E max), and Hill slope (n H) were determined for each experiment (n) using GraphPad Prism Software. E max,n H, and log (EC50) values were analyzed using a two-way ANOVA, followed by a post hoc Bonferroni test to determine the levels of significance. Flunitrazepam was more potent at α1β2γ2 and α1β2γ33-areceptors than zopiclone. Potency decreased at γ3-containing receptors for both flunitrazepam and zopiclone.3-b Zopiclone produced a greater maximal effect at γ2- and γ33-c-containing receptors. Both compounds were more efficacious at γ3-containing receptors than at γ2-containing receptors.3-d

    • 3-a  F = 58.68 (1,9);P < .0001.

    • 3-b  F = 15.04 (1,9);P < .005.

    • 3-c  F = 39.51 (1,9);P < .001.

    • 3-d  F = 36.53 (1,9);P < .001.