Fig. 1.

Antifentanyl monoclonal antibody HY6-F9 reverses pharmacological effects of fentanyl. Sprague Dawley rats (n = 2–3 per group) were challenged with 0.1 mg/kg of fentanyl (s.c.) and monitored for fentanyl-induced antinociception, respiratory depression and bradycardia. (A) antinociception via latency to respond on the hot plate test; and (B) oxygen saturation, (C) bradycardia, and (D) breath rate measured by pulse oximetry. Immediately following the first measurement at 15 minutes, rats were passively immunized with 40 mg/kg of HY6-F9 (i.v.) or injected with saline (i.v.) or 0.1 mg/kg of naloxone (s.c.) as a positive control. Data are mean ± S.E.M. ****p<0.0001, **p<0.01, *p<0.05 relative to saline (control).