FIGURE 4.

Prevention of fentanyl/xylazine lethality by naloxone and/or yohimbine in male and female mice. Left: Lethality produced by 32 mg/kg fentanyl + 56 mg/kg xylazine in combination with vehicle, 3 mg/kg naloxone, 3 mg/kg yohimbine, and 3 mg/kg naloxone + 3 mg/kg yohimbine. Left axis depicts percentage (%) of mice dead after 24 h. Bottom axis depicts doses of fentanyl, xylazine, naloxone, and yohimbine. Numbers in circles indicate number of mice tested. Asterisks (*) indicate significant differences between groups (p < 0.05). Upper Right: Prevention of fentanyl/xylazine lethality by naloxone and/or yohimbine in male mice. Lower Right: Prevention of fentanyl/xylazine lethality by naloxone and/or yohimbine in female mice.