FIGURE 2.

Lethal effects of fentanyl alone and in combination with 100 mg/kg xylazine in male and female mice. Left: Lethality produced by various doses of fentanyl alone (circles) and in combination with 100 mg/kg xylazine (triangles). All points represent data obtained from 6 to 16 mice. All other details are as described in Figure 1. Upper Right: Lethal effects of fentanyl alone and in combination with 100 mg/kg xylazine in male mice. All points represent data obtained from 3 to 8 mice. Lower Right: Lethal effects of fentanyl alone and in combination with 100 mg/kg xylazine in female mice. All points represent data obtained from 3 to 8 mice.