Background and Objectives In recent years, research has provided experimental and subjective evidence that intravenous lipid emulsions (ILEs) reverse some hemodynamically considerable poisonings with various drugs. The aim of this study was to investigate the possible antidotal effect of ILE on acute tramadol poisoning.

Methods Thirty male New Zealand rabbits weighing 2.5 to 3 kg were divided into 6 groups, 5 in each. Two groups were considered controls, and the rest were treated intravenously with a dose of 50 mg/kg of tramadol. Thirty minutes later, infusions of either ILE 20% (3 doses of 6, 12, and 18 mL/kg) or normal saline (dose of 18 mL/kg) were administered. The survival of animals, total seizure time, and hemodynamic parameters were monitored immediately after infusions and subsequently for 3 observations during 24 hours.

Results Survival percentages at doses of 6 and 12 mL/kg of ILE were both 100% (P < 0.001), and 80% at a dose of 18 mL/kg (P < 0.01). Intravenous lipid emulsion reduced tramadol-induced tachycardia when administered within 30 minutes of poisoning (P < 0.01) and showed positive effects on normalizing mean arterial pressure and diastolic blood pressure (P < 0.05). However, ILE did not have major effect on systolic blood pressure. Intravenous lipid emulsion also prevented tramadol-related seizures in doses of 6 and 12 mL/kg (P < 0.001) and reduced elevated creatine phosphokinase levels with the 2 higher doses (P < 0.001).

Conclusions Intravenous lipid emulsion significantly reduced mortality due to acute toxicity with tramadol in rabbits, although increasing the ILE dose may cause reverse effects.